Myocardial oxygen tension in isolated erythrocyte-perfused rat hearts and comparison with crystalloid media

The isolated heart, typically perfused with crystalloid media equilibrated with greater than or equal to 95% O-2 to ensure adequate myocardial oxygen tension, is commonly used to study cardiac function. When hemoglobin is available for oxygen transport, equilibration with 21% O-2 is considered adequate to meet metabolic demands. This study presents the measurement of myocardial pO(2) in isolated hearts perfused with an erythrocyte suspension. Baseline myocardial pO(2) in erythrocyte-perfused hearts was 16.4 +/- 3.5 mmHg (mean +/- S.E.). When compared to previous measurements of myocardial pO(2) in isolated hearts perfused with crystalloid media, the use of erythrocyte suspensions resulted in a 10-fold lower level of myocardial pO(2), 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. (C) 1997 Academic Press Limited.