<title>Hypokinesia of myocardium of perfused rat heart at different oxygenation of myoglobin and redox state of cytochrome</title>

Abstract

Questions about development of hypo-kinetic zones in myocardium of patients suffering from severe coronary heart disease are discussed controversially among heart surgeons. We established a model for isolated and hemoglobin free perfusion of rat heart in which sufficient flow was established within all capillaries and thus existence of ischemic capillaries could be excluded. A definite diagnosis of tissue anoxia is only possible by optical measurements of the oxidation and the reduction (redox state) of the cytochrome oxidase of intact myocytes. Therefore, we used an EMPHO for this kind of measurements. Intracellular oxygenation of myoglobin oxygenation (MbO<SUB>2</SUB>) and redox state of cytochrome aa<SUB>3</SUB>, b and c were recorded in the outer wall of working, hypo-kinetic and a-kinetic myocardium. As a result of our investigations we were able to prove that by lowering at the venous end of capillaries tissue pO<SUB>2</SUB> and myoglobin oxygenation stepwise below 5 mmHg and 50% of saturation respectively, a continuous decrease of myocardial contractility could be achieved.