The blood perfused isolated heart: characterization of the model

We have characterized the aerobic blood-perfused isolated heart model evaluating the hemodynamics and metabolism of both the blood donor animal and the isolated organ. Anaesthesia of the blood donor with sodium pentobarbital (30 mg/kg) increases arterial concentration of non esterified fatty acids (NEFA) from 80 +/- 6 to 452 +/- 70 microM; p < 0.01. Injection of 1,000 U/kg heparin causes a second significant increase from 452 +/- 70 to 1012 +/- 104 microM; p < 0.01. Insertion of the perfusion circuit, without the isolated heart, causes a reduction in blood pressure of the blood donor and a significant increase in norepinephrine from 277 +/- 44 to 634 +/- 130 pg/ml; p < 0.05. Two hours of aerobic perfusion of the isolated heart inserted in the perfusion circuit, decreases arterial pressure of the blood donor with a concomitant increase of plasma norepinephrine from 475 +/- 150 to 841 +/- 159 pg/ml; p < 0.05. Developed pressure, oxygen consumption, glucose and NEFA uptake of the isolated heart remain constant during two hours of aerobic perfusion, NEFA being the preferred substrate. Tissue content of high energy phosphates at the end of the perfusion is high and similar to that observed "in vivo". Despite this, there is a release of lactate and CPK from the isolated heart. We conclude that: 1) the model allows accurate measurement of hemodynamics and metabolism of both the isolated heart and the blood donor animal; 2) the perfusion procedure modifies the substrates concentration of the blood donor animal which, in turn, results in the preferential NEFA utilization of the isolated heart. These changes do not affect the functional parameters of the perfused heart.