Experiments with isolated animal hearts showed that intracoronarily injected propranolol (beta-adrenoblocker) and nonachlasine (beta-adrenostimulator) lead to coronary dilatation changing into coronary constriction. Unlike propranolol, nonachlasine reduced the venous bed capacity. The use of nonachlasine resulted in primary reduction and consequent increase of myocardial contractility, propranolol leading to negative inotropic effect. The character and degree of the drug effect in hemodynamics depend on the initial activity of the sympathoadrenal system. The therapeutic effectiveness of the drugs also depends on the initial hemodynamic state and on the sympathoadrenal system activity. A comparative study of Ca2+ antagonists demonstrated corinfar to have positive ino- and chronotropic effect. Isoptine was shown to produce negative ino- and chronotropic action, with hemodynamics remaining indifferent to sensite. Ca2+ antagonists examined in the study are characterized by a diverse therapeutic effect and considerably differ in their influence on the circulatory system.
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