LYSOSOMAL AND CYTOSOLIC ENZYME-RELEASE IN ACUTE MYOCARDIAL-INFARCTION - EFFECTS OF METHYLPREDNISOLONE

Serial venous blood samples were obtained from 45 patients suffering myocardial infarction. Ten of these patients received 25 mg/kg methylprednisolone sodium succinate intravenously within 4 hours of the onset of chest pain. The activities of creatine kinase (CK) and its MB-isoenzyme were assayed in the plasma. A lysosomal enzyme, N-acetyl-β-glucosaminidase (NAG) was also assayed. In the control group of patients the peak activity of CK occurred at a mean time of 21.3 ± 1.3 hours after the onset of chest pain, while the peak activities of CK-MB and NAG occurred at 18.1 ± 1.6 hours and 18.0 ± 1.0 hours, respectively. There was an exponential relationship between the peak values of CK and NAG activity and a linear relationship between peak CK-MB and NAG activity. In the patients who received methylprednisolone the peak enzyme activities were delayed until 27.1 hours for CK, 27.0 hours for CK-MB and 27.3 hours for NAG. The mean peak value for NAG activity was considerably lower in the treated patients and there was no relationship between the activities of the lysosomal enzyme and either CK or CK-MB. These findings are consistent with previous experimental results which suggest that methylprednisolone can delay tissue damage and stabilize lysosomal membranes during acute myocardial ischemia.