[Relationship between early peaking of serum myosin light chain 1 level and washout phenomenon of creatine kinase in acute myocardial infarction].

To investigate the serum levels of myosin light chain 1 (MLC1) during the acute phase of myocardial infarction, the MLC1 and creatine kinase (CK) levels were measured in samples from 59 consecutive patients with acute myocardial infarction. The serum concentration of MLC1 increased rapidly, reaching an early peak in 22 of the 59 patients (the MLP + group). Fifteen patients showed rapid increases in MLC1 levels without an early peak (the MLP - group). Serum MLC1 levels remained within normal limits (the MLN group) 10 hours after the onset of symptoms in the remaining 22 patients (but in eight of these serum MLC1 levels were abnormal 16-39 hours after the onset of symptoms). Serum level curves of CK showed a single episode of acute myocardial infarction in all patients. The patterns of MLC1 levels correlated with the washout phenomenon of CK (p < 0.001) and the maximum MLC1 level (p < 0.05). The ratio of serum MLC1 level during the early phase to the maximum level (EMR) decreased in the order of groups MLP+, MLP-, MLN (0.54 +/- 0.28, 0.31 +/- 0.22, 0.13 +/- 0.09, respectively). The EMR was correlated with the washout phenomenon of CK (p < 0.001), but not with the maximum MLC1 level which might reflect the size of the infarction. The patterns of neither MLC1 nor EMR were correlated with the administration of urokinase or the patency of the infarct-related artery at the early phase (within 10 hours of onset).(ABSTRACT TRUNCATED AT 250 WORDS)