Vocalization Response of Puppies to Intra-arterial Administration of Bradykinin and Other Algesic Agents, and Mode of Actions of Blocking Agents

Abstract

The mode of action of algesic agents administered into the mesenteric and femoral arteries through the chronically indwelling catheters was studied on 30 immature dogs, utilizing vocalization as an indicator of nociception. Since almost all puppies vocalized to nocive stimuli, the use of puppies was found to be advantageous for this sort of investigation. Bradykinin, eledoisin, histamine, acetylcholine and barium chloride administered into the mesenteric artery evoked vocalization without tachyphylaxis. Positive and negative dose-response relations were obtained for the duration and latency of vocalization respectively. Bradykinin and eledoisin were most potent and gave the dose-response relations with the least individual variations. 5-Hydroxytryptamine failed to cause vocalization. Atropine antagonized specifically the algesic action of acetylcholine, while tripelennamine and diphenhydramine antagonized that not only of histamine but also of acetylcholine and bradykinin. Papaverine blocked the effect of all of the algesic agents administered into the mesenteric artery but not that of bradykinin given into the femoral artery. Sodium salicylate and procaine blocked the effect of histamine and acetyylcholine given into the mesenteric artery and also abolished that of bradykinin injected into the femoral artery. However, sodium salicylate and procaine were ineffective against the action of bradykinin or eledoisin administered into the mesenteric artery.