We investigated the effects of 2-methyl-5-HT and 1-phenylbiguanide on isolated and perfused rabbit common carotid arteries by a cannula insertion method. 1-Phenylbiguanide produced neither vasoconstriction nor dilation. On the other hand, 2-methyl-5-HT produced only a vasoconstriction, and the dose-response curve was shifted to the right in parallel by treatment with either ketanserin or bunazo...
