Vascular Responses of Isolated Canine Intermediate Auricular Artery to Vasoactive Substances

The stainless steel cannula inserting method was used to observe the effects of 7 vasoactive substances in the isolated intermediate auricular artery of the dog. The isolated artery was suspended in a bath at 37 degrees C and perfused with Ringer-Locke solution under a constant flow rate. Drugs were administered in the endothelial side of the artery through a cannulated tubing, and the response was obtained as changes in perfusion pressure. 5-Hydroxytryptamine (5-HT), norepinephrine (NE), tyramine, ATP and prostaglandin F2 alpha (PGF2 alpha) increased perfusion pressure in a dose-related manner. The order of potency for inducing vasoconstriction was 5-HT greater than NE = PGF2 alpha greater than tyramine greater than ATP greater than KCl. Histamine caused either slight biphasic responses or no change in perfusion pressure. The canine auricular artery would be a good in vitro model for studying pharmacological responses of cutaneous vessels.