Enhancement of vasoconstrictor responses to thiopental and barium chloride by intraluminal treatment with saponin in isolated canine mesenteric arteries.

Using a cannula-insertion method for isolated arteries, the effects of thiopental, barium chloride, and prostaglandin F2 alpha were investigated on isolated canine mesenteric arteries with and without saponin treatment. Thiopental caused a vasoconstriction in a dose-related manner. The observed vasoconstriction was not influenced by phentolamine in doses which inhibited norepinephrine-induced vasoconstriction. After intraluminal saponin treatment, thiopental- and barium chloride-induced constrictions were significantly enhanced, but prostaglandin F2 alpha-induced constriction was not potentiated. It is suggested that vasoconstrictor responses to thiopental and barium chloride may be enhanced by an increase in calcium influx after disrupting the endothelium of the artery.