AN UNUSUAL VENOCONSTRICTION INDUCED BY ACETYLCHOLINE

¹ Department of Pharmacology, College of Medicine, University of Iowa, Iowa City, Iowa

The experiments were designed to study the effect of acetylcholine (ACh) on the accessory cephalic vein of the dog. Injections of high doses of ACh directly into the perfused accessory cephalic vein of the dog produce a marked rise in perfusion pressure. It was established that the response was not a compensatory reflex. The pressor response is blocked by atropine and phentolamine; it is antagonized by reserpine. Guanethidine, hexamethonium or chronic sympathectomy do not affect the response. Assay with chick cecum indicates the presence of catecholamines. The response may be mediated through a release of catecholamines from extraneural stores.