[INFLUENCE OF Р-ENDORPHIN ON FUNCTIONAL ACTIVITY OF ISOLATED RAT HEART].

We have studied the effect of Р-endorphin (an endogenous opioid peptide) on the functional characteristics of isolated rat heart. In physiological concentrations (6.3 X 10-10 M) Р-endorphin induces a negative inotropic effect, accompanied by a slight decrease in the heart rate, and has no effect on the perfusion pressure of the coronary vessels.