[The characteristics of the effect of catecholamines on the relaxation of ventricular myocardium in warm-blooded and cold-blooded animals].

The relaxation of the frog myocardium is decelerated by addition of adrenaline (10(-8)-10(-6) M) into the perfusion solution. The catecholamines in low concentrations up to 5.10(-8) M decelerate the relaxation, and in higher concentrations accelerate the drop of mechanical tension in capillary muscles of the cat ventricular myocardium. The catecholamines effects exerted upon the relaxation of myocardium seem to depend on a cooperative interaction among the calcium-troponine complexes at the actine filaments.