ANTAGONISM OF MORPHINE WITH NALOXONE IN DOGS: CARDIOVASCULAR EFFECTS WITH SPECIAL REFERENCE TO THE CORONARY CIRCULATION

Publisher Website
Google Scholar
Abstract
Cardiovascular effects of naloxone 15 .mu.g/kg following morphine 2.0 mg/kg were studied in closed-chest dogs during light NO2-halothane anesthesia. The bolus injection of naloxone caused an increase in heart rate (73%), cardiac output (20%) and mean arterial pressure (20%). Total peripheral resistance was unaffected. LV dP/dt max [left ventricular maximum change in pressure with time] and LV dP/dt max/IP [preload independent index of myocardial contractility] increased by 25% and 14%, respectively, but positive inotropic effects could not be shown when load data, heart rate and decrease in left ventricular ejection fraction (22%) were taken into consideration. Cardiovascular stimulation resulted in an increase in myocardial O2 demand (66%) which was met by an increase in coronary blood flow (59%). Narcotic antagonism with high naloxone doses may impair myocardial O2 supply in patients suffering from coronary insufficiency. Naloxone apparently should be titrated for each patient to ensure adequate reversal of respiratory depression and to avoid circulatory stress.

This publication has 2 references indexed in Scilit: