Condensing enzyme levels in the serum after experimental myocardial infarction.

FOLLOWING tissue damage several tissue enzymes are released into the serum. On this basis, changes in serum glutamate-oxalacetate transaminase and lactate dehydrogenase have been used as indicators of the occurrence and severity of myocardial infarction. These tests lack specificity because damage to liver and other organs also causes an increase in the serum levels of these enzymes. Recently we observed that heart tissue contains singularly high levels of condensing enzyme (see reaction 2 below). We wondered whether a rise in serum condensing enzyme would prove to be an indicator of myocardial damage more specific than either glutamateoxalacetate transaminase or lactate dehydrogenase. The present study demonstrates the release of condensing enzyme into serum following experimental myocardial infarction in clogs. Methods One acute iind 5 chronic myocardial infarction preparations wore studied. Dogs were anesthetized by intravenous injection of sodium pentobarbital, 30 mg. per Kg. Myocardial infarots were then induced by tying the anterior descending coronary artery according to the procedure of Harris. The animals with chronic infarctions were studied for one week. Periodic venous blood samples were taken, allowed to clot, and centrifuged. The serum was analyzed for condensing enzyme, and glutamnte-oxalacetate transaminase. Both of these enzymes were stable in serum at -20 C. At the time blood samples were taken, standard lead II electrocardiograms were recorded on a direct-writing Cardiotron machine. Condensing enzyme was assayed by measuring the rate of increase of absorbency at 340 m/i duo