EFFECTS OF DROPERIDOL ON ACTIVITY OF CAROTID BODY CHEMORECEPTORS IN CAT

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Abstract
The effect of droperidol on the spontaneous activity of carotid body chemoreceptors and on their response to various stimuli was studied in 21 anaesthetized, paralyzed and artificially ventilated cats. Carotid body blood flow was controlled with a perfusion pump, and drugs were injected into the perfusion circuit. In low doses, droperidol transiently increased the rate of spontaneous chemoreceptor activity, but in higher doses it depressed chemoreceptor activity after an initial stimulation. Droperidol reduced or abolished the normal increase in chemoreceptor activity produced by stagnant asphyxia. This effect did not depend solely on the ability of droperidol to suppress spontaneously occurring impulses. Chemoreceptor responses to sodium cyanide, and to dopamine were also inhibited. Dopamine antagonists other than droperidol were also studied for their effect on chemoreceptor activity. Chlorpromazine depressed spontaneous chemoreceptor activity and also reduced the chemoreceptor responses to sodium cyanide and dopamine, as did pimozide. The effects of these dopamine antagonists were much briefer and less marked than those of droperidol. Although the influence that we have shown droperidol to have on peripheral chemoreceptor activity has an uncertain basis, it may have important implications in human and veterinary medicine.