AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 3 440-G446, Copyright © 1990 by American Physiological Society
Effect of histamine and 1,4-methylhistamine on gastric vascular resistance in dogs
J. G. Wood, G. M. Wicina and L. Y. Cheung
Department of Surgery, University of Kansas Medical Center, Kansas City 66103.
The goal of this study was to compare the relative potency of histamine and
its metabolite, 1,4-methylhistamine, as vasodilators of the gastric
circulation. Changes in vascular resistance were measured during local
intra-arterial infusion of graded doses of histamine and
1,4-methylhistamine to an ex vivo segment of dog stomach. Infusate
concentrations were adjusted to deliver calculated arterial blood
concentrations of 0, 3.7, 11, 33, 100, 300, and 900 ng/ml of each substance
to the stomach segment. We found that histamine caused rapid dose-related
decreases in gastric vascular resistance of up to -47.6 +/- 1.3% compared
with control values. The effects of histamine were reversible when
infusions ended. In contrast, there were no statistically significant
changes in vascular resistance at any dose of 1,4-methylhistamine. In
addition, modifications to previous methods using histamine antagonists
resulted in greater attenuation of histamine-induced gastric vasodilation.
Our results support a role for locally released histamine, but not for
1,4-methylhistamine, as a mediator of gastric vasodilation.
