Studies on the Mechanism of Cardiotonica with Reference to the Cardiac Glycoside, Calcium Ion and Myocardial Catecholamine in the Canine Heart

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With use of the myocardial tissue strip of the dog's left ventricle of the heart, the isometric contractility and poststimulation potentiation were measured. The studies were directed on the possible influence of calcium ion, potassium ion and the myocardial catecholamine on the positive inotropic action of the cardiac glycoside by employing the normal myocardial tissue piece. The studies were ex-tended to the use of various types of the autonomic nervous blocking agent on the myocardium in which the action of catecholamine was actively suppressed, and also tried on the hypertrophic heart muscle strip removed from the dog developed of the aortic insufficiency. It was concluded that the myocardial catecholamine exerts the regulatory function in the utilized process of the extracellular calcium ion relative to cardiac contraction in the normal and hypertrophic hearts.