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  • 1.
    Edlund, Jenny
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Liss, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    The roles of NADPH-oxidase and nNOS for the increased oxidative stress and the oxygen consumption in the diabetic kidney2010In: Diabetes/Metabolism Research Reviews, ISSN 1520-7552, E-ISSN 1520-7560, Vol. 26, no 5, p. 349-356Article in journal (Refereed)
    Abstract [en]

    Background

    Sustained hyperglycaemia induces increased renal oxygen consumption resulting in reduced oxygen availability in the diabetic kidney. We investigated the roles of the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase and the neuronal nitric oxide synthase (nNOS) for the increased oxygen consumption in streptozotocin-diabetic rats.

    Methods

    Oxygen consumption was measured in isolated proximal tubular cells (PTC) from streptozotocin-induced diabetic rats (n = 7-9 per group) with and without chronic treatment with apocynin, a NADPH-oxidase inhibitor, or S-methyl-L-thiocitrulline (SMTC), a selective nNOS inhibitor, or a combination of the two and the results were compared to normoglycaemic controls (n = 10). Oxidative stress was estimated from thiobarbituric acid reactive substances and protein expression measured by Western blot.

    Results

    Proximal tubular cells from untreated diabetic rats had increased oxygen consumption compared to controls (40.6 +/- 7.9 versus 10.9 +/- 2.0 nmol/mg protein/min). All treatments reduced the diabetes-induced increase in oxygen consumption (apocynin 10.5 +/- 1.7, SMTC 19.7 +/- 3.0 and apocynin +/- SMTC 21.6 +/- 3.6 nmol/mg protein/min). Neither apocynin nor SMTC had any effect on the oxygen consumption in cells pre-incubated with ouabain, an inhibitor of active electrolyte transport. Oxidative stress was elevated in the diabetic kidney and inhibited by all treatments. The increased oxygen consumption by diabetic proximal tubular cells correlated with increased protein expressions of p47phox and nNOS and the treatments prevented these increases.

    Conclusions

    Diabetes induces oxidative stress, which increases oxygen consumption in proximal tubular cells. Inhibition of either NADPH-oxidase or nNOS prevented the increased oxygen consumption. The effect of blocking both these enzymes was less than additive suggesting overlapping pathways which warrant further studies.

  • 2. Franzen, Stephanie
    et al.
    Friederich-Persson, Malou
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Nangaku, Masaomi
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Differences in susceptibility to develop parameters of diabetic nephropathy in four mouse strains with type 1 diabetes2014In: American Journal of Physiology-Renal Physiology, ISSN 1931-857X, Vol. 306, no 10, p. F1171-F1178Article in journal (Refereed)
    Abstract [en]

    One-third of diabetes mellitus patients develop diabetic nephropathy, and with underlying mechanisms unknown it is imperative that diabetic animal models resemble human disease. The present study investigated the susceptibility to develop diabetic nephropathy in four commonly used and commercially available mouse strains with type 1 diabetes to determine the suitability of each strain. Type 1 diabetes was induced in C57Bl/6, NMRI, BALB/c, and 129Sv mice by alloxan, and conscious glomerular filtration rate, proteinuria, and oxidative stress levels were measured in control and diabetic animals at baseline and after 5 and 10 wk. Histological alterations were analyzed using periodic acid-Schiff staining. Diabetic C57Bl/6 displayed increased glomerular filtration rate, i.e., hyperfiltration, whereas all other parameters remained unchanged. Diabetic NMRI developed the most pronounced hyperfiltration as well as increased oxidative stress and proteinuria but without glomerular damage. Diabetic BALB/c did not develop hyperfiltration but presented with pronounced proteinuria, increased oxidative stress, and glomerular damage. Diabetic 129Sv displayed proteinuria and increased oxidative stress without glomerular hyperfiltration or damage. However, all strains displayed intras-train correlation between oxidative stress and proteinuria. In conclusion, diabetic C57Bl/6 and NMRI both developed glomerular hyperfiltration but neither presented with histological damage, although NMRI developed low-degree proteinuria. Thus these strains may be suitable when investigating the mechanism causing hyperfiltration. Neither BALB/c nor 129Sv developed hyperfiltration although both developed pronounced proteinuria. However, only BALB/c developed detectable histological damage. Thus BALB/c may be suitable when studying the roles of proteinuria and histological alterations for the progression of diabetic nephropathy.

  • 3.
    Franzén, Stephanie
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Pihl, Liselotte
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Intrarenal activation of endothelin type B receptors improves kidney oxygenation in type 1 diabetic rats2018In: American Journal of Physiology - Renal Physiology, ISSN 1931-857X, E-ISSN 1522-1466, Vol. 314, no 3, p. F439-F444Article in journal (Refereed)
    Abstract [en]

    About one-third of patients with type 1 diabetes develops kidney disease. The mechanism is largely unknown, but intrarenal hypoxia has been proposed as a unifying mechanism for chronic kidney disease, including diabetic nephropathy. The endothelin system has recently been demonstrated to regulate oxygen availability in the diabetic kidney via a pathway involving endothelin type A receptors (ETA-R). These receptors mainly mediate vasoconstriction and tubular sodium retention, and inhibition of ETA-R improves intrarenal oxygenation in the diabetic kidney. Endothelin type B receptors (ETB-R) can induce vasodilation of the renal vasculature and also regulate tubular sodium handling. However, the role of ETB-R in kidney oxygen homeostasis is unknown. The effects of acute intrarenal ETB-R activation (sarafotoxin 6c for 30-40 min; 0.78 pmol/h directly into the renal artery) on kidney function and oxygen metabolism were investigated in normoglycemic controls and insulinopenic male Sprague-Dawley rats administered streptozotocin (55 mg/kg) 2 wk before the acute experiments. Intrarenal activation of ETB-R improved oxygenation in the hypoxic diabetic kidney. However, the effects on diabetes-induced increased kidney oxygen consumption could not explain the improved oxygenation. Rather, the improved kidney oxygenation was due to hemodynamic effects increasing oxygen delivery without increasing glomerular filtration or tubular sodium load. In conclusion, increased ETB-R signaling in the diabetic kidney improves intrarenal tissue oxygenation due to increased oxygen delivery secondary to increased renal blood flow.

  • 4.
    Friederich, Malou
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Olerud, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Liss, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Radiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Uncoupling protein-2 in diabetic kidneys: increased protein expression correlates to increased non-transport related oxygen consumption2008In: Oxygen Transport to Tissue XXIX, Springer Berlin/Heidelberg, 2008, Vol. 614, p. 37-43Chapter in book (Refereed)
    Abstract [en]

    Diabetic patients have an elevated risk to develop renal dysfunction and it has been postulated that altered energy metabolism is involved. We have previously shown that diabetic rats have markedly decreased oxygen availability in the kidney, resulting from increased oxygen consumption. A substantial part of the increased oxygen consumption is unrelated to tubular transport, suggesting decreased mitochondrial efficiency. In this study, we investigated the protein expression of mitochondrial uncoupling protein (UCP)-2 in kidney tissue from control and streptozotocin (STZ)-induced diabetic rats. Protein levels of UCP-2 were measured in adult male control and STZ-diabetic Wistar Furth as well as Sprague Dawley rats in both the kidney cortex and medulla by Western blot technique. Two weeks of hyperglycemia resulted in increased protein levels of UCP-2 in kidneys from both Wistar Furth and Sprague Dawley rats. Both cortical and medullary UCP-2 levels were elevated 2-3 fold above control levels. We conclude that sustained STZ-induced hyperglycemia increases the kidney levels of mitochondrial UCP-2, which could explain the previously reported increase in non-transport related oxygen consumption in diabetic kidneys. The elevated UCP-2 levels may represent an effort to reduce the increased production of superoxide radicals which is evident during diabetes.

  • 5.
    Friederich-Persson, Malou
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Persson, Patrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Nangaku, Masaomi
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Renal hypoxia due to increased oxygen metabolism is an independent pathway to nephropathy2014In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 28, no 1, article id 890.6Article in journal (Other academic)
  • 6.
    Friederich-Persson, Malou
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Persson, Patrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Nordquist, Lina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Increased kidney metabolismas a pathway to kidney tissue hypoxia and damage: effects of triiodothyronine and dinitrophenol in normoglycemic rats2013In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 789, p. 9-14Article in journal (Refereed)
    Abstract [en]

    Intrarenal tissue hypoxia is an acknowledged common pathway to end-stage renal disease in clinically common conditions associated with development of chronic kidney disease, such as diabetes and hypertension. In diabetic kidneys, increased oxygen metabolism mediated by mitochondrial uncoupling results in decreased kidney oxygen tension (PO2) and contributes to the development of diabetic nephropathy. The present study investigated whether increased intrarenal oxygen metabolism per se can cause intrarenal tissue hypoxia and kidney damage, independently of confounding factors such as hyperglycemia and oxidative stress. Male Sprague-Dawley rats were untreated or treated with either triiodothyronine (T3, 10 g/kg bw/day, subcutaneously for 10 days) or the mitochondria uncoupler dinitrophenol (DNP, 30 mg/kg bw/day, oral gavage for 14 days), after which in vivo kidney function was evaluated in terms of glomerular filtration rate (GFR, inulin clearance), renal blood flow (RBF, Transonic, PAH clearance), cortical PO2 (Clark-type electrodes), kidney oxygen consumption (QO2), and proteinuria. Administration of both T3 and DNP increased kidney QO2 and decreased PO2 which resulted in proteinuria. However, GFR and RBF were unaltered by either treatment. The present study demonstrates that increased kidney metabolism per se can cause intrarenal tissue hypoxia which results in proteinuria. Increased kidney QO2 and concomitantly reduced PO2 may therefore be a mechanism for the development of chronic kidney disease and progression to end-stage renal disease.

  • 7.
    Liss, Per
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Radiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Carlsson, Per-Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Iodinated contrast media decrease renomedullary blood flow. A possible cause of contrast media-induced nephropathy2009In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 645, p. 213-218Article in journal (Refereed)
    Abstract [en]

    The renal medulla has been implicated as a key target for contrast media-induced nephropathy (CIN). Although the effects of contrast media (CM) on whole kidney blood flow are well characterized, the effect of CM on renal medullary blood flow has been controversial. It has been reported that an extremely high dose of a high osmolar CM (iothalamate; 2900 mg I/kg bw) injected rapidly increased the renal outer medullary blood flow (OMBF). However, more clinical relevant doses consistently result in a sustained decrease in medullary blood flow. Furthermore, simultaneous measurements using both laser-Doppler flowmetry and hydrogen washout yield similar results of a decrease in OMBF after CM administration. CM induced a transient 28% decrease in the laser-Doppler signal from the outer medulla, while the hydrogen washout rate in the same region was reduced by approximately 50%. Furthermore, CM administration consistently results in decreased medullary oxygen tension (PO2). The renal medulla works already during normal physiological conditions at the verge of hypoxia, and the majority of the studies published so far are in agreement with the hypothesis that CIN may have its origin in a further reduction in blood flow and/or oxygen availability of this region of the kidney.

  • 8.
    Liss, Per
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Iodinated contrast media inhibit oxygen consumption in freshly isolated proximal tubular cells from elderly humans and diabetic rats: Influence of nitric oxide.2016In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 121, no 1, p. 12-16Article in journal (Refereed)
    Abstract [en]

    Objectives Mechanisms underlying contrast medium (CM)-induced nephropathy remain elusive, but recent attention has been directed to oxygen availability. The purpose of this study was to evaluate the effect of the low-osmolar CM iopromide and the iso-osmolar CM iodixanol on oxygen consumption (QO2) in freshly isolated proximal tubular cells (PTC) from kidneys ablated from elderly humans undergoing nephrectomy for renal carcinomas and from normoglycemic or streptozotocin-diabetic rats. Materials PTC were isolated from human kidneys, or kidneys of normoglycemic or streptozotocin-diabetic rats. QO2 was measured with Clark-type microelectrodes in a gas-tight chamber with and without each CM (10 mg I/mL medium). L-NAME was used to inhibit nitric oxide (NO) production caused by nitric oxide synthase. Results Both CM reduced QO2 in human PTC (about -35%) which was prevented by L-NAME. PTC from normoglycemic rats were unaffected by iopromide, whereas iodixanol decreased QO2 (-34%). Both CM decreased QO2 in PTC from diabetic rats (-38% and -36%, respectively). L-NAME only prevented the effect of iopromide in the diabetic rat PTC. Conclusions These observations demonstrate that CM can induce NO release from isolated PTC in vitro, which affects QO2. Our results suggest that the induction of NO release and subsequent effect on the cellular oxygen metabolism are dependent on several factors, including CM type and pre-existing risk factors for the development of CM-induced nephropathy.

  • 9.
    Nordquist, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Brown, Russell
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Sjöquist, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Proinsulin C-peptide reduces diabetes-induced glomerular hyperfiltration via efferent arteriole dilation and inhibition of tubular sodium reabsorption2009In: American Journal of Physiology - Renal Physiology, ISSN 0363-6127, E-ISSN 1522-1466, Vol. 297, no 5, p. F1265-F1272Article in journal (Refereed)
    Abstract [en]

    C-peptide reduces diabetes-induced glomerular hyperfiltration in diabetic patients and experimental animal models. However, the mechanisms mediating the beneficial effect of C-peptide remain unclear. We investigated whether altered renal afferent-efferent arteriole tonus or alterations in tubular Na+ transport (T(Na)) in response to C-peptide administration mediate the reduction of diabetes-induced glomerular hyperfiltration. Glomerular filtration rate, filtration fraction, total and cortical renal blood flow, total kidney O2 consumption (QO2), T(Na), fractional Na+ and Li+ excretions, and tubular free-flow and stop-flow pressures were measured in anesthetized adult male normoglycemic and streptozotocin-diabetic Sprague-Dawley rats. The specific effect of C-peptide on transport-dependent QO2 was investigated in vitro in freshly isolated proximal tubular cells. C-peptide reduced glomerular filtration rate (-24%), stop-flow pressure (-8%), and filtration fraction (-17%) exclusively in diabetic rats without altering renal blood flow. Diabetic rats had higher baseline T(Na) (+40%), which was reduced by C-peptide. Similarly, C-peptide increased fractional Na+ (+80%) and Li+ (+47%) excretions only in the diabetic rats. None of these parameters was affected by vehicle treatments in either group. Baseline QO2 was 37% higher in proximal tubular cells from diabetic rats than controls and was normalized by C-peptide. C-peptide had no effect on ouabain-pretreated diabetic cells from diabetic rats. C-peptide reduced diabetes-induced hyperfiltration via a net dilation of the efferent arteriole and inhibition of tubular Na+ reabsorption, both potent regulators of the glomerular net filtration pressure. These findings provide new mechanistic insight into the beneficial effects of C-peptide on diabetic kidney function.

  • 10.
    Nordquist, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Friederich-Persson, Malou
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Liss, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology.
    Shoji, Kumi
    Nangaku, Masaomi
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Activation of Hypoxia-Inducible Factors Prevents Diabetic Nephropathy2015In: Journal of the American Society of Nephrology, ISSN 1046-6673, E-ISSN 1533-3450, Vol. 26, no 2, p. 328-338Article in journal (Refereed)
    Abstract [en]

    Hyperglycemia results in increased oxygen consumption and decreased oxygen tension in the kidney. We tested the hypothesis that activation of hypoxia-inducible factors (HIFs) protects against diabetes-induced alterations in oxygen metabolism and kidney function. Experimental groups consisted of control and streptozotocin-induced diabetic rats treated with or without chronic cobalt chloride to activate HIFs. We elucidated the involvement of oxidative stress by studying the effects of acute administration of the superoxide dismutase mimetic tempol. Compared with controls, diabetic rats displayed tissue hypoxia throughout the kidney, glomerular hyperfiltration, increased oxygen consumption, increased total mitochondrial leak respiration, and decreased tubular sodium transport efficiency. Diabetic kidneys showed proteinuria and tubulointerstitial damage. Cobalt chloride activated HIFs, prevented the diabetes-induced alterations in oxygen metabolism, mitochondrial leak respiration, and kidney function, and reduced proteinuria and tubulointerstitial damage. The beneficial effects of tempol were less pronounced after activation of HIFs, indicating improved oxidative stress status. In conclusion, activation of HIFs prevents diabetes-induced alteration in kidney oxygen metabolism by normalizing glomerular filtration, which reduces tubular electrolyte load, preventing mitochondrial leak respiration and improving tubular transport efficiency. These improvements could be related to reduced oxidative stress and account for the reduced proteinuria and tubulointerstitial damage. Thus, pharmacologic activation of the HIF system may prevent development of diabetic nephropathy.

  • 11.
    Nordquist, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Liss, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Hypoxia in the diabetic kidney is independent of advanced glycation end-products2013In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 765, p. 185-193Article in journal (Refereed)
    Abstract [en]

    Sustained hyperglycemia is closely associated with increased risk to develop nephropathy. We have previously reported alterations in the intrarenal oxygen metabolism already after the early onset of diabetes. Furthermore, formation of advanced glycation end-products (AGE) is postulated as a major contributor to diabetic nephropathy. We therefore investigated the possible relationship between altered oxygen metabolism and AGE in diabetic kidneys.Normoglycemic and streptozotocin-diabetic rats with and without chronic treatment with aminoguanidine (AGE inhibitor; 600 mg/kg bw/24 h in drinking water) or L-N6-(1-Iminoethyl)lysine (L-NIL, iNOS inhibitor, 1 mg/kg bw/24 h in drinking water) were studied 2 weeks after induction of diabetes. Glomerular filtration rate (GFR) was estimated by inulin clearance, oxygen tension (pO2) and interstitial pH by microelectrodes and regional renal blood flow (RBF) by laser-Doppler. Histological changes were evaluated on fixed tissue.Glomerular hyperfiltration was unaffected by aminoguanidine, whereas L-NIL normalized GFR in diabetic rats. pO2 and interstitial pH, but not RBF, were lower in both kidney cortex and medulla compared to control rats, but was unaffected by both chronic treatments. Urinary protein excretion was higher in diabetic rats and unaffected by L-NIL, whereas aminoguanidine paradoxically increased this parameter. Damage scores were similar in all groups.In conclusion, diabetes-induced alterations in intrarenal oxygen metabolism are independent of the AGE pathway, and precede any morphological changes. These findings highlight the early stage of diabetes as being a metabolic disorder also in the kidney.

  • 12.
    Odlind, Cecilia
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Department of Oncology, Radiology and Clinical Immunology.
    Liss, Per
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Cell Biology.
    Palm, Fredrik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Cell Biology.
    Hansell, Peter
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Cell Biology.
    Changing dopaminergic activity through different pathways: consequences for renal sodium excretion, regional blood flow and oxygen tension in the rat.2001In: Acta Physiol Scand, ISSN 0001-6772, Vol. 172, no 3, p. 219-26Article in journal (Other scientific)
  • 13. O'Neill, Julie
    et al.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Pihl, Liselotte
    Patinha, Daniela
    Franzen, Stephanie
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Acute SGLT inhibition normalizes O-2 tension in the renal cortex but causes hypoxia in the renal medulla in anaesthetized control and diabetic rats2015In: American Journal of Physiology - Renal Physiology, ISSN 0363-6127, E-ISSN 1522-1466, Vol. 309, no 3, p. F227-F234Article in journal (Refereed)
    Abstract [en]

    Early stage diabetic nephropathy is characterized by glomerular hyperfiltration and reduced renal tissue PO2. Recent observations have indicated that increased tubular Na+-glucose linked transport (SGLT) plays a role in the development of diabetes-induced hyperfiltration. The aim of the present study was to determine how inhibition of SLGT impacts upon PO2 in the diabetic rat kidney. Diabetes was induced by streptozotocin in Sprague-Dawley rats 2 wk before experimentation. Renal hemodynamics, excretory function, and renal O-2 homeostasis were measured in anesthetized control and diabetic rats during baseline and after acute SGLT inhibition using phlorizin (200 mg/kg ip). Baseline arterial pressure was similar in both groups and unaffected by SGLT inhibition. Diabetic animals displayed reduced baseline PO2 in both the cortex and medulla. SGLT inhibition improved cortical PO2 in the diabetic kidney, whereas it reduced medullary PO2 in both groups. SGLT inhibition reduced Na+ transport efficiency [tubular Na+ transport (TNa)/renal O-2 consumption (QO(2))] in the control kidney, whereas the already reduced TNa/QO(2) in the diabetic kidney was unaffected by SGLT inhibition. In conclusion, these data demonstrate that when SGLT is inhibited, renal cortex PO2 in the diabetic rat kidney is normalized, which implies that increased proximal tubule transport contributes to the development of hypoxia in the diabetic kidney. The reduction in medullary PO2 in both control and diabetic kidneys during the inhibition of proximal Na+ reabsorption suggests the redistribution of active Na+ transport to less efficient nephron segments, such as the medullary thick ascending limb, which results in medullary hypoxia.

  • 14.
    Palm, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Carlsson, Per-Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Liss, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Radiology.
    Diabetes-induced decrease in renal oxygen tension: effects of an altered metabolism2006In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 578, p. 161-166Article in journal (Refereed)
    Abstract [en]

    During conditions with experimental diabetes mellitus, it is evident that several alterations in renal oxygen metabolism occur, including increased mitochondrial respiration and increased lactate accumulation in the renal tissue. Consequently, these alterations will contribute to decrease the interstitial pO2, preferentially in the renal medulla of animals with sustained long-term hyperglycemia.

  • 15.
    Palm, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Carlsson, Per-Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Hellberg, Olof
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Nygren, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Liss, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Effects of the contrast medium iopromide on renal hemodynamics and oxygen tension in the diabetic rat kidney2003In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 530, p. 653-659Article in journal (Refereed)
    Abstract [en]

    We investigated the effects of the contrast medium (CM) iopromide on regional renal blood flow and oxygen tension (pO2) in the streptozotocin (STZ)-induced diabetic Wistar Furth rats. RESULTS: In normoglycemic rats, CM injection induced a transient decrease followed by an increase in renal cortical blood flow (CBF), whereas CBF increased directly in the diabetic animals. Renal outer medullary blood flow (OMBF) increased in controls, while it decreased in the diabetic animals following CM injection. In control rats a marked initial decrease in OM pO2 following injection of CM was observed. In animals diabetic for 4 weeks only a slight decrease was seen, whereas in 9-week diabetic animals a persistent increase was recorded. CONCLUSIONS: An altered oxygen tension and hemodynamic response to CM was found in diabetic rats. If these disturbances may contribute to the development of renal dysfunction by CM in the diabetic rat kidney remains to be elucidated.

  • 16.
    Patinha, Daniela
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Pinho, Dora
    Albino-Teixeira, Antonio
    Morato, Manuela
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Angiotensin II contributes to glomerular hyperfiltration in diabetic rats independently of adenosine type I receptors2013In: American Journal of Physiology - Renal Physiology, ISSN 0363-6127, E-ISSN 1522-1466, Vol. 304, no 5, p. F614-F622Article in journal (Refereed)
    Abstract [en]

    Increased angiotensin II (ANG II) or adenosine can potentiate each other in the regulation of renal hemodynamics and tubular function. Diabetes is characterized by hyperfiltration, yet the roles of ANG II and adenosine receptors for controlling baseline renal blood flow (RBF) or tubular Na+ handling in diabetes is presently unknown. Accordingly, the changes in their functions were investigated in control and 2-wk streptozotocin-diabetic rats after intrarenal infusion of the ANG II AT(1) receptor antagonist candesartan, the adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), or their combination. Compared with controls, the baseline blood pressure, RBF, and renal vascular resistance (RVR) were similar in diabetics, whereas the glomerular filtration rate (GFR) and filtration fraction (FF) were increased. Candesartan, DPCPX, or the combination increased RBF and decreased RVR similarly in all groups. In controls, the GFR was increased by DPCPX, but in diabetics, it was decreased by candesartan. The FF was decreased by candesartan and DPCPX, independently. DPCPX caused the most pronounced increase in fractional Na+ excretion in both controls and diabetics, whereas candesartan or the combination only affected fractional Li+ excretion in diabetics. These results suggest that RBF, via a unifying mechanism, and tubular function are under strict tonic control of both ANG II and adenosine in both control and diabetic kidneys. Furthermore, increased vascular AT(1) receptor activity is a contribution to diabetes-induced hyperfiltration independent of any effect of adenosine A(1) receptors.

  • 17.
    Persson, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Teerlink, Tom
    Vrije Univ Amsterdam, Med Ctr, Dept Clin Chem, Amsterdam, Netherlands.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Cellular transport of L-Arginine determines renal medullary blood flow in control rats, but not in diabetic rats despite enhanced cellular uptake capacity2017In: American Journal of Physiology - Renal Physiology, ISSN 0363-6127, E-ISSN 1522-1466, Vol. 312, no 2, p. F278-F283Article in journal (Refereed)
    Abstract [en]

    Diabetes mellitus is associated with decreased nitric oxide bioavailability thereby affecting renal blood flow regulation. Previous reports have demonstrated that cellular uptake of L-arginine is rate limiting for nitric oxide production, and that plasma L-arginine concentration is decreased in diabetes. We therefore investigated if regional renal blood flow regulation is affected by cellular L-arginine uptake in streptozotocin-induced diabetic rats. Rats were anesthetized with thiobutabarbital and left kidney was exposed. Total, cortical and medullary renal blood flow was investigated before and after renal artery infusion of increasing doses of either L-homoarginine to inhibit cellular uptake of L-arginine, or L-NAME to inhibit nitric oxide synthase. L-homoarginine infusion did not affect total or cortical blood flow in any of the groups, but caused a dose-dependent reduction in medullary blood flow. L-NAME decreased total, cortical and medullary blood flow in both groups. However, the reductions in medullary blood flow in response to both L-homoarginine and L-NAME were more pronounced in the control groups compared to the diabetic groups. Isolated cortical tubular cells displayed similar L-arginine uptake capacity whereas medullary tubular cells isolated from diabetic rats had increased L-arginine uptake capacity. Diabetics had reduced L-arginine concentrations in plasma and medullary tissue but increased L-arginine concentration in cortical tissue. In conclusion, the reduced L-arginine availability in plasma and medullary tissue in diabetes results in reduced nitric oxide-mediated regulation of renal medullary hemodynamics. Cortical blood flow regulation displays less dependency on extracellular L-arginine and the upregulated cortical tissue L-arginine may protect cortical hemodynamics in diabetes.

  • 18.
    Persson, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Teerlink, Tom
    Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    L-Citrulline, But Not L-Arginine, Prevents Diabetes Mellitus–Induced Glomerular Hyperfiltration and Proteinuria in Rat2014In: Hypertension, ISSN 0194-911X, E-ISSN 1524-4563, Vol. 64, no 2, p. 323-329Article in journal (Refereed)
    Abstract [en]

    Diabetes mellitus–induced oxidative stress causes increased renal oxygen consumption and intrarenal tissue hypoxia. Nitric oxide is an important determinant of renal oxygen consumption and electrolyte transport efficiency. The present study investigates whether l-arginine or l-citrulline to promote nitric oxide production prevents the diabetes mellitus–induced kidney dysfunction. Glomerular filtration rate, renal blood flow, in vivo oxygen consumption, tissue oxygen tension, and proteinuria were investigated in control and streptozotocin-diabetic rats with and without chronic l-arginine or l-citrulline treatment for 3 weeks. Untreated and l-arginine–treated diabetic rats displayed increased glomerular filtration rate (2600±162 versus 1599±127 and 2290±171 versus 1739±138 µL/min per kidney), whereas l-citrulline prevented the increase (1227±126 versus 1375±88 µL/min per kidney). Filtration fraction was increased in untreated diabetic rats because of the increase in glomerular filtration rate but not in l-arginine– or l-citrulline–treated diabetic rats. Urinary protein excretion was increased in untreated and l-arginine–treated diabetic rats (142±25 versus 75±7 and 128±7 versus 89±7 µg/min per kidney) but not in diabetic rats administered l-citrulline (67±7 versus 61±5 µg/min per kidney). The diabetes mellitus–induced tissue hypoxia, because of elevated oxygen consumption, was unaltered by any of the treatments. l-citrulline administered to diabetic rats increases plasma l-arginine concentration, which prevents the diabetes mellitus–induced glomerular hyperfiltration, filtration fraction, and proteinuria, possibly by a vascular effect.

  • 19.
    Persson, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Teerlink, Tom
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    L-citrulline, but not L-arginine, prevents diabetes-induced glomerular hyperfiltration and proteinuria2014In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 28, no 1, article id 689.12Article in journal (Other academic)
  • 20.
    Persson, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Friederich-Persson, Malou
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Inagi, Reiko
    University of Tokyo Graduate School of Medicine, Tokyo, Japan.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Adenosine A2 a receptor stimulation prevents proteinuria in diabetic rats by promoting an anti-inflammatory phenotype without affecting oxidative stress2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 214, no 3, p. 311-318Article in journal (Refereed)
    Abstract [en]

    AIM: Diabetic patients are at increased risk for kidney disease. There is presently no clinical treatment available that effectively protects kidney function in diabetics. The present study investigates if chronic stimulation of the adenosine A2a receptor (A2a AR) protects kidney function in insulinopenic diabetic rats.

    METHODS: Streptozotocin-induced diabetic rats and corresponding controls were chronically treated with the adenosine A2a AR agonist CGS21680 throughout the four-week diabetes duration. Kidney function was thereafter investigated and urine and plasma samples were collected for analysis of protein, oxidative stress and inflammatory markers.

    RESULTS: Glomerular filtration rate, renal blood flow, filtration fraction and diabetes-induced kidney hypoxia were all unaffected by chronic A2a AR stimulation. Furthermore, diabetic rats had increased oxidative stress, which was further increased by chronic A2a AR stimulation. However, the 10-fold increased urinary protein excretion observed in the diabetic rats was completely prevented by chronic A2a AR stimulation. These beneficial effects were accompanied by reduced levels of the pro-inflammatory TNF-α and increased levels of the anti-inflammatory IL-10 as well as decreased infiltration of macrophages, glomerular damage and basement membrane thickness.

    CONCLUSION: Chronic A2a AR stimulation prevents proteinuria and glomerular damage in experimental diabetes via an anti-inflammatory mechanism independent of oxidative stress and kidney hypoxia.

  • 21.
    Pihl, Liselotte
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Persson, Patrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    DiBona, Gerald F.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Insulin induces the correlation between renal blood flow and glomerular filtration rate in diabetes: implications for mechanisms causing hyperfiltration2012In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 303, no 1, p. R39-R47Article in journal (Refereed)
    Abstract [en]

    Glomerular filtration rate (GFR) and renal blood flow (RBF) are normally kept constant via renal autoregulation. However, early diabetes results in increased GFR and the potential mechanisms are debated. Tubuloglomerular feedback (TGF) inactivation, with concomitantly increased RBF, is proposed but challenged by the finding of glomerular hyperfiltration in diabetic adenosine A(1) receptor-deficient mice, which lack TGF. Furthermore, we consistently find elevated GFR in diabetes with only minor changes in RBF. This may relate to the use of a lower streptozotocin dose, which produces a degree of hyperglycemia, which is manageable without supplemental suboptimal insulin administration, as has been used by other investigators. Therefore, we examined the relationship between RBF and GFR in diabetic rats with (diabetes + insulin) and without suboptimal insulin administration (untreated diabetes). As insulin can affect nitric oxide (NO) release, the role of NO was also investigated. GFR, RBF, and glomerular filtration pressures were measured. Dynamic RBF autoregulation was examined by transfer function analysis between arterial pressure and RBF. Both diabetic groups had increased GFR (+60-67%) and RBF (+20-23%) compared with controls. However, only the diabetes + insulin group displayed a correlation between GFR and RBF (R-2 = 0.81, P < 0.0001). Net filtration pressure was increased in untreated diabetes compared with both other groups. The difference between untreated and insulin-treated diabetic rats disappeared after administering N-omega-nitro-L-arginine methyl ester to inhibit NO synthase and subsequent NO release. In conclusion, mechanisms causing diabetes-induced glomerular hyperfiltration are animal model-dependent. Supplemental insulin administration results in a RBF-dependent mechanism, whereas elevated GFR in untreated diabetes is mediated primarily by a tubular event. Insulin-induced NO release partially contributes to these differences.

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