EFFECT OF METHOHEXITAL, FENTANYL, DROPERIDOL AND CHLORALOSE ON AORTIC BARORECEPTOR DISCHARGE OF DECEREBRATED CATS

Abstract

The effect of methohexitone, fentanyl, droperidol and chloralose on the response characteristics of aortic baroreceptors was studied in decerebrated cats. The drug effect on the stimulus-response curves of individual baroreceptor fibers of the aortic region relating the average discharge rate (spikes/s) to the average aortic arch pressure which was altered over wide ranges by a balloon catheter located in the thoracic aorta was analyzed. The stimulus response curves were shifted to higher activities by methohexitone and less obviously by droperidol. Chloralose and fentanyl shifted the curves to lower activities. The first 2 drugs increase the afferent receptor drive and favor the arterial hypotension development but the last 2 decrease the afferent receptor drive and act to stabilize arterial pressure. At comparable anesthesia depth arterial blood pressure levels tend to be lower with methohexitone and droperidol than chloralose and fentanyl.