IN-SITU DETECTION OF MYOCARDIAL-INFARCTION IN PIG BY MEASUREMENTS OF ASPARTATE-AMINOTRANSFERASE (ASAT) ACTIVITY IN THE INTERSTITIAL FLUID

Microdialysis probes permeable to large molecules (m.w. cut-off >200 k D) were introduced into the myocardium of anaesthetized pigs in order to, evaluate their potential for early detection of myocardial ischaem ia and enzyme markers for infarction. The left anterior descending cor onary artery was occluded for 30 min and the myocardium was reperfused for 3 h. The concentrations of aspartate aminotransferase (ASAT), lac tate, glucose and selected free amino acids were measured. The levels in the interstitium of ischaemic and non-ischaemic myocardium were com pared with those in plasma from the coronary sinus as well as from a p eripheral vein. Twelve probes were inserted in six pigs and withdrawn after 8-72 hours of sampling. No complications occurred. Simultaneous 100% increase of ASAT and lactate was found in myocardial dialysates a fter 30 min of ischaemia. ASAT activity remained at that level until t he end of reperfusion. The plasma peak ASAT level was not attained unt il after 3 h. Glutamate was the only amino acid which increased signif icantly in the myocardial interstitium during ischaemia, peaking after 30 min of reperfusion. Dialysates from the unaffected myocardium show ed no effects on lactate, ASAT or glutamate. The use of myocardial mic rodialysis for pre-and postoperative recordings in man is discussed.