AJP - Gastrointestinal and Liver Physiology, Vol 264, Issue 4 664-G670, Copyright © 1993 by American Physiological Society
Adenosine is a mediator of ethanol-induced gastric vasodilation in dogs
J. G. Wood, M. P. Darnell and L. Y. Cheung
Department of Surgery, University of Kansas Medical Center, Kansas City 66160.
The purpose of this study was to assess the role of histamine, adenosine,
and prostaglandins as mediators of ethanol-induced gastric vasodilation. In
an ex vivo segment of canine stomach, vasodilation occurred within the
first minute of replacing luminal saline with ethanol (40% vol/vol).
Ethanol caused vascular resistance to progressively decrease by
approximately 53% compared with control values. In other experiments,
intra-arterial infusion of histamine (300 ng/ml) or adenosine (30
micrograms/ml) to the gastric segment produced similar degrees of
vasodilation as observed with ethanol. The response to these vasodilators
could be markedly attenuated with specific antagonists of these substances
(histamine: pyrilamine plus cimetidine; adenosine: 8-phenyltheophylline).
In our final experiments, indomethacin or histamine- or adenosine-receptor
antagonists were given before application of topical ethanol. Indomethacin
or histamine antagonists had no significant effect on the time course or
magnitude of ethanol-induced vasodilation. In contrast, pretreatment with
8-phenyltheophylline significantly reduced changes in vascular resistance
during exposure to luminal ethanol. These results suggest that locally
released adenosine is an important mediator of ethanol-induced vasodilation
in the canine stomach under these conditions.
