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Transepidermal water loss in developing rats: Role of aquaporins in the immature skin
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
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2003 (English)In: Pediatric Research, ISSN 0031-3998, E-ISSN 1530-0447, Vol. 53, no 4, 558-565 p.Article in journal (Refereed) Published
Abstract [en]

In the extremely preterm infant, high transepidermal water loss (TEWL) can result in severe dehydration. TEWL has been attributed to the structural properties of the epidermis but might also be influenced by mechanisms that facilitate water transport. To investigate whether aquaporins (AQP) may be involved in the extreme losses of water through immature skin, we examined the presence and cellular distributions of AQP-1 and AQP-3 in embryonic and adult rat skin by immunohistochemistry. The expression of AQP mRNA in skin was analyzed with the use of semiquantitative reverse transcription-PCR. In rat pups of different embryonic (E) and postnatal (P) ages (days), TEWL and skin hydration were measured. AQP-1 was detected in dermal capillaries, and AQP-3 was abundant in basal epidermal layers. Both AQP displayed several times higher expression in embryonic than in adult skin. TEWL was highest at embryonic day 18 (E18) (133 +/- 18 g/m2h) and lower at E20 (25 +/- 1 g/m2h) and P4 (9 +/- 2 g/m2h). Skin hydration measured as skin electrical capacitance paralleled TEWL, being highest in fetal skin (794 +/- 15 pF at E18) and decreasing to 109 +/- 11 pF at E20 and to 0 +/- 0 pF at P4. We conclude that, as in infants, water loss through the skin of rats decreases markedly with maturation during the perinatal period. The expression and cellular localization of the AQP are such that they might influence skin hydration and water transport and contribute to the high losses of water through the immature skin.

Place, publisher, year, edition, pages
2003. Vol. 53, no 4, 558-565 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-90230DOI: 10.1203/01.PDR.0000055777.25933.98PubMedID: 12612219OAI: oai:DiVA.org:uu-90230DiVA: diva2:162517
Available from: 2003-04-16 Created: 2003-04-16 Last updated: 2010-09-03Bibliographically approved
In thesis
1. Water transport through perinatal skin: Barrier function and aquaporin water channels
Open this publication in new window or tab >>Water transport through perinatal skin: Barrier function and aquaporin water channels
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

While constituting a well functioning interface with the aqueous environment in utero, the skin offers a poor barrier after very preterm birth. As a result, transepidermal water loss (TEWL) is high, a fact which has important clinical consequences in these infants. To investigate the transport of water through perinatal skin and the potential role of aquaporin (AQP), a water channel protein, in this process, we determined TEWL in a group of extremely preterm infants, and in an experimental rat model we analyzed the expression and distribution of AQP in perinatal skin in relation to TEWL, skin surface hydration and water content. The effects of antenatal corticosteroids (ANS) and of restricted intake of fluids and nutrients on barrier characteristics of the perinatal skin and its AQP expression were also studied.

In infants born at 24 and 25 weeks of gestation TEWL was very high in the first days after birth and decreased with increasing postnatal age. At a postnatal age of 4 weeks, TEWL was still twice as high as previously reported in infants born at a gestational age of 25-27 weeks and four times higher than in infants born at term. In the rat model, immunohistochemical analysis revealed that AQP1 and AQP3 are abundantly expressed in the skin. AQP1 was expressed exclusively in dermal capillaries and AQP3 in basal layers of the epidermis. AQP1 and AQP3 mRNA as assessed by semiquantitative RT-PCR was higher in fetal than in adult skin. As in infants, TEWL and skin surface hydration were inversely related to gestational age in the rat. In preterm rat pups exposed to ANS, TEWL and skin surface hydration were lower than in unexposed controls, and AQP3 expression was selectively induced by ANS. In term newborn rat pups, restriction of fluid and nutrient intake resulted in a higher skin water content and higher TEWL early after birth, while at an age of 7 days TEWL was lower in fasting rat pups than in controls, although skin water content was still higher.

To conclude, TEWL is very high in extremely preterm infants early after birth and then decreases at a slower rate than previously reported for a group of slightly more mature infants.

This is the first time that the distribution and gene expression of AQP1 and AQP3 have been demonstrated in perinatal skin. The localization and expression of AQP in the skin might indicate that these water channels are involved in the regulation of skin hydration and transepidermal water transport in the fetus and newborn infant.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 48 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 0282-7476 ; 1249
Pediatrics, Preterm infant, Transepidermal water loss, Aquaporin, Skin biology, Hyperosmolarity, Pediatrik
National Category
Research subject
urn:nbn:se:uu:diva-3369 (URN)91-554-5597-2 (ISBN)
Public defence
2003-06-02, Auditorium Minus, Gustavianum, Uppsala, 09:15
Available from: 2003-04-16 Created: 2003-04-16Bibliographically approved

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