Abstract
Summary
The action of morphine upon isolated mammalian cardiac preparations was reevaluated in order to test the hypothesis that morphine has the ability to antagonize the action of catecholamines on the heart. Over a wide range of concentrations (0.3-100 μg/ml) morphine slightly depressed contractile force, heart rate and coronary flow. Following exposure of the whole isolated heart preparation to morphine (100 μg/ml) for one hour, ventricular catecholamine levels were similar to their untreated controls. Furthermore, no consistent alterations in physiological response to epinephrine, isoproterenol or tyramine could be correlated with the presence or absence of morphine regardless of its concentration in the perfusate. These data fail to confirm the suggestion that morphine acts as a sympatholytic on the heart.
Get full access to this article
View all access options for this article.