[Analysis of the effect of morphine and promedol on uptake and release of noradrenaline by myocardial tissue].

A study was made of the effect of morphine and promedol on the content, uptake, and release of norepinephrine (NE) on rat myocardium. Promedol proved to decrease the NE level in the myocardium. Morphine failed to influence the release of the NE-14C from the isolated perfused heart, whereas promedol increased it significantly, altering both the "slow" and the "rapid" release of the mediator. Promedol failed to influence the uptake of NE-14C by the perfused heart, whereas morphine decreased it significantly. The competition between morphine and NE was characterized by the effect of incomplete inhibition: morphine and NE produced reciprocal effects on the affinity of one another to the receptor, and their interaction depended on the ratio of the concentrations of these drugs.