Abstract
Summary
The circulatory effects of morphine sulfate were studied in anesthetized dogs in which myocardial infarction had been produced by serial ligation of coronary arteries. In control dogs, morphine sulfate (0.5 mg/kg) produced early and transient decreases in aortic mean pressure, the rate of rise of left ventricular pressure and systemic vascular resistance, without significant changes in left atrial pressure, heart rate, or aortic blood flow. Following myocardial infarction, morphine sulfate (0.5 mg/kg), produced a similar early and transient depression of aortic mean pressure. The rate of rise of left ventricular pressure was more greatly depressed and remained depressed for a longer period of time. Systemic vascular resistance fell initially but was elevated at 15 and 30 min. Left atrial pressure was markedly decreased while heart rate and aortic blood flow were moderately depressed. It is concluded that morphine sulfate has a mild transient depressant effect on the circulation in intact animals, while in animals with myocardial infarction, morphine sulfate has a more pronounced and more persistent depressant effect on the circulation.
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