The significance of the serum glutamic oxalacetic transaminase activity following acute myocardial infarction.

The serum glutamic oxalacetic transamninase rose two to 20 times normal in 74 of 75 patients who had acute transmural myocardial infarction. The height of the enzymatic activity was roughly proportional to the size of the infarct. Serum glutamic oxalacetic transaminase is unaffecte:d by angina pectoris, coronary insufficiency, heart failure, or digitalis in the absence of active heart cell injury. Experimental myocardial infarction is followed consistently by a two to twenty-fold increase in serum glutamic oxalacetic transaminase activity. Increase in the serum activity of this enzyme appears to be a useful index of the presence of active heart muscle injury. S ERUM glutamic oxalacetic transaminase (SGO-T) is widely distributed in animal tissues but is most concentrated in heart muscle. This property led us to study its concentration in human serum following acute myocardial infarction. Serum glutamic oxal acetic transaminase permits the enzyme catalyzed reversible transfer of the alpha amino nitrogen of aspartic acid to alpha keto-glutaric acid with the synthesis of glutamic and oxalacetic acids as shown in figure 1. Table 1 indicates the relative rate of transamination by heart muscle, skeletal muscle, brain, liver, kidney, testis and lung.2 Earlier studies employing paper chromatography demonstrated that glutamic oxalacetic transaminase was present in normal human serum.5 The enzymatic activity was shown to be stable in serum stored at 0 to 5 C. for periods of up to two weeks and neither freezing nor lyophilization appreciably altered the tranis-aminase activity. The level of serum glutamic oxalacetic transaminase in normal individuals is essentially the same from day to day and remains unchanged in sera stored at 0 to 5 C. for at least two weeks. Heating of the sera to 109 C. will destroy the activity. Table 2 compares the activity of the serum glutamic oxalacetic Heart Association. 871 transaminase determined by paper chromatography with that obtained by the spectro-photometric method. The values are strikingly similar. A unit of activity is defined as a decrease in optical density of 0.001 mu per milliliter of serum per minute under the conditions described.5 Glutamic oxalacetic trans-aminase activity has been demonstrated in all suitably processed sera. The concentration is the same in serum and plasma but is 10 times greater in hemolyzed red blood cells. Normally the serum glutamic oxalacetic transaminase varies from 10 to 40 units per milliliter when tested at room temperature. Levels above this were not seen in patients with infectious, neoplastic, metabolic, …