Adenosine is a mediator of ethanol-induced gastric vasodilation in dogs.
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.
Wood
J G
JG
Department of Surgery, University of Kansas Medical Center, Kansas City 66160.
Darnell
M P
MP
Cheung
L Y
LY
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D002927:Cimetidine / Q000494:pharmacology; D004285:Dogs; D000431:Ethanol / Q000494:pharmacology*; D006632:Histamine / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000098:blood supply; D058914:Purinergic Antagonists; D011738:Pyrilamine / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D013270:Stomach / Q000098:blood supply*; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
D058914:Purinergic Antagonists; D000431:Ethanol; D002927:Cimetidine; D006632:Histamine; D013806:Theophylline; C028322:8-phenyltheophylline; D011738:Pyrilamine; D000241:Adenosine; D007213:Indomethacin