Vasoactive intestinal polypeptide reduces hydrochloric acid-induced duodenal mucosal permeability.
The duodenum in anesthetized rats was perfused with HCl, and mucosal integrity was assessed by measuring the clearance of 51Cr-labeled EDTA from blood to lumen and/or by morphological examination (lesion score). Duodenal blood flow was determined by laser Doppler flowmetry and luminal alkalinization as well as H+ disappearance by backtitration. Intravenous infusion of vasoactive intestinal polypeptide (VIP; 13.5 micrograms.kg-1.h-1) increased luminal alkalinization threefold and decreased clearance of 51Cr-EDTA by 50%. VIP also decreased arterial blood pressure and induced a small and irregular decrease in duodenal blood flow. Perfusion with 10 mM HCl increased clearance of 51Cr-EDTA 2.1-fold, but the lesion score was not different from that in saline-perfused animals. Perfusion with 20 mM HCl increased clearance of 51Cr-EDTA four-fold and induced a greater lesion score than did 10 mM. Perfusion with either 10 or 20 mM HCl did not affect the duodenal blood flow. VIP reduced the rise in clearance of 51Cr-EDTA in response to 10 mM but not that to 20 mM HCl. Intravenous injection of prazosin (50 micrograms/kg) decreased luminal alkalinization, clearance of 51Cr-EDTA, blood pressure, and duodenal blood flow. In prazosin-pretreated rats, perfusion with 10 mM HCl increased clearance of 51Cr-EDTA 2.6-fold, and the lesion score was greater in this group than in animals infused with VIP. A positive linear correlation was obtained between HCO3- secretion and the mean rate of H+ disappearance.(ABSTRACT TRUNCATED AT 250 WORDS)
Nylander
O
O
Department of Physiology and Medical Biophysics, Uppsala University, Sweden.
Wilander
E
E
Larson
G M
GM
Holm
L
L
D000818:Animals; D004386:Duodenum / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D006851:Hydrochloric Acid / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D008297:Male; D010539:Permeability / Q000187:drug effects; D011224:Prazosin / Q000494:pharmacology; D011522:Protons; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D011522:Protons; D014660:Vasoactive Intestinal Peptide; D006851:Hydrochloric Acid; D011224:Prazosin