J. R. Campbell

INVESTIGATION OF RESPIRATORY AND CIRCULATORY EFFECTS OF ETHAMIVAN IN THE DOG AND CAT

SUMMARY Intravenous injections of ethamivan caused apnoea, bradycardia and hypotension in anaesthetized dogs whilst a similar circulatory response without apnoea was seen in anaesthetized cats. Apnoea and bradycardia were abolished and hypotension was reduced by bilateral vagotomy. Premedication with atropine abolished bradycardia but did not modify the other responses to ethamivan. The effect of intravenous injection of ethamivan was not altered by premedication with mepyramine or hexamethonium. Ethamivan did not cause apnoea when injected into the left auricle, the carotid artery or the posterior aorta. The effect on heart rate and blood pressure when injection was made at these sites was variable. It was concluded that ethamivan stimulated a chemo-reflex having receptors in the pulmonary circulation. The reflex was not, however, inhibited by intravenous infusions of procaine.