Myocardial Oxygen Tension in Isolated Erythrocyte-perfused Rat Hearts and Comparison with Crystalloid Medi

The isolated heart, typically perfused with crystalloid media equilibrated with ≥95% O2to ensure adequate myocardial oxygen tension, is commonly used to study cardiac function. When hemoglobin is available for oxygen transport, equilibration with 21% O2is considered adequate to meet metabolic demands. This study presents the measurement of myocardial pO2in isolated hearts perfused with an erythrocyte suspension. Baseline myocardial pO2in erythrocyte-perfused hearts was 16.4±3.5 mmHg (mean± ). When compared to previous measurements of myocardial pO2in isolated hearts perfused with crystalloid media, the use of erythrocyte suspensions resulted in a 10-fold lower level of myocardial pO2, while avoiding very low and high values. The standard use of 95% oxygen with crystalloid results in myocardial levels of oxygen far above those usually found in the presence of hemoglobin and room air.