The blood perfused isolated heart: characterization of the model

We have characterized the aerobic blood-perfused isolated heart model evalu ating the hemodynamics and metabolism of both the blood donor animal and th e isolated organ. Anaesthesia of the blood donor with sodium pentobarbital (30 mg/kg) increas es arterial concentration of non esterified fatty acids (NEFA) from 80 +/- 6 to 452 +/- 70 mu M; p < 0.01. Injection of 1.000 U/kg heparin causes a se cond significant increase from 452 +/- 70 to 1012 +/- 104 mu M; p < 0.01. I nsertion of the perfusion circuit, without the isolated heart, causes a red uction in blood pressure of the blood donor and a significant increase in n orepinephrine from 277 +/- 44 to 634 +/- 130 pg/ml; p < 0.05. Two hours of aerobic perfusion of the isolated heart inserted in the perfus ion circuit, decreases arterial pressure of the blood donor with a concomit ant 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 perfusio n, NEFA being the preferred substrate. Tissue content of high energy phosph ates at the end of the perfusion is high and similar to that observed "in v ivo". 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) th e perfusion procedure modifies the substrates concentration of the blood do nor animal which, in turn, results in the preferential NEFA utilization of the isolated heart. These changes do not affect the functional parameters o f the perfused heart.