[A decrease in cardiac sensitivity after ischemia to a change in the extracellular concentration of calcium ions].

Reperfusion of the heart 30 min. after ischemia causes slight recovery of contractility and content of macroergic compounds in the myocardium tissue. Recovery of perfusion by the hypercalcium medium (0.05 mol/l) improves metabolism of the myocardium 30 min after ischemia. However, further perfusion by solution with physiological content of Ca2+ is followed by the development of the myocardium contracture, essential decrease in extracellular concentration of ATP and phosphocreatine. An increase in the extracellular sodium concentration and addition of macroergic compounds (ATR, phosphocreatine) adenosine, when reperfusing the heart by hypocalcium solution, improve the postischemic state of the myocardium and protect it from injuries during the following recovery of physiological Ca2+ content in the extracellular medium.