Pharmacological analysis of vasoconstrictor responses to ATP of isolated, perfused dog mesenteric arteries.

The stainless steel cannula inserting method was used to analyze the characteristics of the vasoconstriction induced by ATP in isolated, perfused dog mesenteric arteries. A dose of 100-1000 micrograms of ATP induced vasoconstriction. It was produced repetitively at 20-min intervals. The vasoconstriction was not modified by phentolamine in doses which completely inhibited norepinephrine-induced vasoconstriction. Aminophylline significantly suppressed ATP-induced vasoconstrictions. KCl-induced vasoconstriction was significantly depressed by a potent Ca antagonist, diltiazem. ATP-induced vasoconstriction was also significantly suppressed by diltiazem but to a lesser degree. ATP-induced vasoconstriction was not significantly suppressed by 30 and 100 micrograms of dipyridamole. After treatment with intraluminal saponin (0.3-3 mg) which caused a disappearance of the vascular endothelium, the ATP-induced vasoconstrictor response was significantly enhanced. From these results it is concluded that ATP-induced vasoconstriction may be mediated via P1-purinoceptors and be partially due to increases in activation of Ca inward current.