Dissociated effects of corticotropin-releasing factor on acid secretion and blood flow

Abstract

Peripherally administered corticotropin-releasing factor (CRF) inhibits gastric acid secretion in the rat via unknown mechanisms. Because intravenous CRF can produce marked systemic hypotension, the hypothesis that its antisecretory effect is due to a reduction in gastric mucosal blood flow (MBF) was tested. Corpus MBF was measured by hydrogen gas clearance in fasted, urethan-anesthetized rats. CRF (15 nmol.kg-1.h-1 iv) had no significant effect on MBF but significantly decreased systemic blood pressure (BP) by 21.8 +/- 3.4%. This dose of CRF significantly decreased acid secretion stimulated by 40 micrograms.kg-1.h-1 pentagastrin iv but did not decrease MBF despite a 30.3 +/- 2.3% decrease in BP. To avoid the confounding effect of systemic hypotension on MBF, close gastric intra-arterial infusions were performed. CRF (1.7 nmol/h ia) had no effect on BP and did not increase MBF. CRF (3.4 nmol/h ia) slightly decreased BP without modifying MBF. In contrast, histamine (200 micrograms/h ia) significantly increased MBF by 58 +/- 11%. We conclude that 1) the peripheral antisecretory effect of CRF is not related to a decrease in MBF, 2) the maintenance of MBF during CRF-induced hypotension is not due to a direct vasodilator effect of CRF on the gastric microvasculature.

Elevation of gastric blood flow as the mechanism of antiulcer effects of Pro-Gly-Pro

“…It is well known that changes in gastric blood flow do not necessarily correspond to systemic blood pressure fluctuations. Blood flow in GM remains unchanged during considerable fluctuations of systemic blood pressure, and vice versa [7,8].Here we evaluated the effects of PGP on IM-induced reduction of GM blood flow in narcotized rats. …”