Creatine kinase B-subunit activity in human sera: temporal aspects of its sensitivity after myocardial infarction.

We assessed the changes in sensitivity and specificity of creatine kinase (CK) isoenzymes at various times after acute myocardial infarction. CK-B was measured by an immunoinhibition technique. CK-MB was measured both by column chromatography on Sephadex DEAE A-50 and by electrophoresis on agarose gel. For CK-B, the sensitivity in detecting infarct varied from 11% in the first 8 h after onset of symptoms to 80% at 32 h after the infarct. Sensitivities for CK-MB by column and by electrophoresis were 25 and 45% for the first 8-h period and 80 and 89% at the 32nd hour, respectively. Comparison of values for CK-B with values for CK-MB by column and by electrophoresis gave correlation coefficients of 0.935 and 0.896, respectively. Patients having macro CK-BB exhibit anomalously high values for CK-B with respect to total CK. Patients having a mild infarct may show no increase in CK-isoenzymes.