Effect of histamine and 1,4-methylhistamine on gastric vascular resistance in dogs.
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.
Wood
J G
JG
Department of Surgery, University of Kansas Medical Center, Kansas City 66103.
Wicina
G M
GM
Cheung
L Y
LY
D000818:Animals; D002927:Cimetidine / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000098:blood supply*; D010477:Perfusion; D011738:Pyrilamine / Q000494:pharmacology; D012039:Regional Blood Flow; D013270:Stomach / Q000098:blood supply*; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects*
D008761:Methylhistamines; D002927:Cimetidine; D006632:Histamine; D011738:Pyrilamine; C020404:tele-methylhistamine