PROTECTION OF MITOCHONDRIAL AND HEART FUNCTION BY AMINO-ACIDS AFTER ISCHEMIA AND CARDIOPLEGIA

The effects of amino acids in protecting against ischemic/reperfusion injury were tested in two experimental models: the isolated perfused r at heart subjected to 21 min of zero flow ischemia (37 degrees) follow ed by 40 min of reperfusion and the isolated perfused rabbit heart sub jected to 300 min of cardioplegic arrest (29 degrees) followed by 60 m in of reperfusion. In both cases, the addition of amino acids to the p erfusion medium significantly improved the recovery of cardiac contrac tile function. The protective effects of amino acids were associated w ith a preservation of mitochondrial respiratory activity. These findin gs suggest that amino acids by replenishing mitochondrial matrix level s of critical TCA cycle substrates, such as malate, stimulate mitochon drial respiration and thereby enhance the recovery of heart function.