Motility-induced but not vasoactive intestinal peptide-induced increase in luminal alkalinization in rat duodenum is dependent on luminal Cl-
2010 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 200, no 2, 181-191 p.Article in journal (Refereed) Published
Aim: To investigate whether the motility- and the vasoactive intestinal peptide (VIP)-induced increase in luminal alkalinization in the duodenum is dependent on luminal Cl-. Methods: Experiments were performed in anaesthetized rats in vivo. The proximal duodenum was perfused luminally with an isotonic solution, containing zero or low Cl- and the effects on luminal alkalinization, motility, fluid flux and epithelial permeability were determined. Parecoxib, a COX-2 inhibitor, was used to induce duodenal contractions. Results: Control rats lacked duodenal wall contractions while parecoxib-treated ones exhibited contractions throughout the experiment. Most animals had a net fluid absorption during the perfusion with isotonic NaCl. Luminal alkalinization was about 100% higher in parecoxib-treated rats than in controls. Cl--free solutions did not affect epithelial permeability or motility but decreased luminal alkalinization by >= 50% and decreased net fluid absorption in both control and parecoxib-treated animals. Reduction in luminal Cl- decreased alkalinization in a concentration-dependent manner. The parecoxib-induced increase in alkalinization was markedly reduced in the absence of luminal Cl-. VIP increased luminal alkalinization and induced fluid secretion. The lack of luminal Cl- did not affect the VIP-induced increase in alkalinization but reduced fluid secretion. Conclusions: The parecoxib-induced increase in luminal alkalinization is highly dependent on luminal Cl- and it is proposed that COX-2 inhibition, via induction of duodenal motility, enhances HCO3- efflux through stimulation of apical Cl-/HCO3- exchange in duodenal epithelial cells. Although the VIP-induced stimulation of fluid secretion is partly dependent on luminal Cl-, the VIP-induced increase in luminal alkalinization is not.
Place, publisher, year, edition, pages
2010. Vol. 200, no 2, 181-191 p.
bicarbonate transport, fluid secretion, jejunum, motility, mucosal permeability, parecoxib
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-134905DOI: 10.1111/j.1748-1716.2010.02112.xISI: 000281557700007OAI: oai:DiVA.org:uu-134905DiVA: diva2:374044