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This Article Full Text Full Text (PDF) All Versions of this Article: 578/2/413    most recent jphysiol.2006.118315v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cristià, E. Articles by Moretó, M. Search for Related Content PubMed PubMed Citation Articles by Cristià, E. Articles by Moretó, M. Related Collections Cellular

¹ Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
² Physiology Division, King's College London, Guys Campus, London, UK

The specific role of vasopressin in colonic crypt function and its possible synergistic action with aldosterone were studied. Sprague-Dawley rats fed a high-Na⁺ (HS; 150 mM NaCl) or a low-Na⁺ (LS; 150 µM NaCl) diet were deprived of water or infused with vasopressin, and some animals were treated with specific vasopressin receptor subtype V₁ and V₂ antagonists. The expression of the epithelial Na⁺ channel (ENaC), -smooth muscle actin (-SMA) and aquaporin-2 (AQP-2) were determined by immunolocalization in distal colonic mucosa. The pericryptal Na⁺ concentration was determined by confocal microscopy, using a low-affinity Na⁺-sensitive fluorescent dye (sodium red) and crypt permeability was measured by the rate of escape of fluorescein isothiocyanate-labelled dextran (10 kDa) from the crypt lumen into the pericryptal space in isolated rat distal colonic mucosa. A high plasma concentration of vasopressin raised -SMA expression in the pericryptal sheath (P < 0.05), increased the pericryptal Na⁺ accumulation in this space (P < 0.01) and caused a reduction of crypt wall permeability (P < 0.01). All these effects were reversed by selective blockade of V₁ and V₂ receptors. No synergistic effects with aldosterone were observed. Dehydration and vasopressin infusion increased AQP-2 expression in distal colonic mucosa (P < 0.05). This action of vasopressin was prevented by tolvaptan, a specific V₂ receptor antagonist (P < 0.05). It is concluded that vasopressin has trophic effects in the rat distal colon, increasing pericryptal myofibroblast growth which affects crypt absorption, and these effects are independent of the presence of aldosterone.

(Received 4 August 2006; accepted after revision 26 October 2006; first published online 2 November 2006)
Corresponding author M. Moretó: Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Av/Joan XXIII s/n, E-08028 Barcelona, Spain. Email: mmoreto{at}ub.edu