[The effect of polyfunctional macroheterocycles on the rhythmic and contractile activity of the myocardium in animals].

The effect of the polyfunctional macroheterocycles on the rhythmic and contractile activity of the rat myocardium was found to depend on their concentration. A two-phasic effect upon contractility of the papillary muscles was revealed: a short-term (up to 20 sec) positive inotropic effect followed by a stable depression. The most active drug of this class, dicyclohexano-18-crown-6, prevented the positive inotropic action of classic stimulants (catecholamines and strophantin) upon the contractile function of the heart.