Abstract

A single dose of 2,5-dimethoxy-4-methylamphetamine (DOM) (246 µg/kg) produced a pressor response in vagotomized dogs. There was also an increase in pulse pressure. Tachyphylaxis developed rapidly after repeated doses of DOM. Responses to tyramine were not diminished after tachyphylaxis to DOM developed. DOM also enhanced pressor responses to norepinephrine, epinephrine and tyramine. In perfused dog fore limb DOM produced a vasodilation followed by a vasoconstriction. The vasoconstriction produced by DOM was not blocked by phentolamine but was antagonized by methysergide. In isolated superfused vascular strips of dog dorsal metatarsal vein, DOM elicited a muscle contraction which was not blocked by phentolamine or cocaine but was antagonized by cinanserin. It was concluded that DOM had a direct stimulatory effect on serotonin receptors. The vasodilation in the perfused fore limb of the dog induced by DOM was not antagonized by propranolol, atropine, pyrilamine or bulbocapnine. In isolated guinea-pig atria, DOM exhibited an antiicotine action and also blocked the inhibitory effect induced by vagus nerve stimulation.