Plasma and Urinary Heart-Type Cytoplasmic Fatty Acid-Binding Protein in Coronary Occlusion and Reperfusion Induced Myocardial Injury Model

Abstract

The leakage of heart-type cytoplasmic fatty acid-binding protein (H-FABP c ) from injured myocardial cells has been reported. We have previously proposed that its plasma and urinary levels could be used as an early indicator of myocardial injury and also reflect the severity of myocardial injury. To confirm this hypothesis, the time course of changes of the plasma and urinary H-FABP c was investigated during myocardial injury induced by coronary artery occlusion and reperfusion in dogs. The plasma elimination kinetics and urinary excretion kinetics of H-FABP c were also analysed in dogs which were given a bolus injection of exogenous H-FABP c . The distribution of circulating H-FABP c was determined in mice by whole-body autoradiography using 125I-labelled H-FABP c . In myocardial injury model, plasma and urinary H-FABP c level showed rapid increase after reperfusion. The elimination kinetic study revealed that H-FABP c was mono-exponentially cleared from the circulation. The elimination rate constant ( Ke) was 0.0275 ± 0.0094/min (mean ± S.D., n = 7) and the disappearance half-time ( t 1 2 ) was 27.5 ± 8.4 min (mean ± S.D., n = 7). Exogenous H-FABP c appeared in urine soon after administration, with the peak level being at 6.9 ± 2.0 min (mean ± S.D., n = 7). Whole-body autoradiography also demonstrated that 125I-H-FABP c accumulated rapidly in the kidneys. This study demonstrated that H-FABP c leaked rapidly from injured myocardium and rapidly appeared in plasma and urine. Infarct size was closely correlated with the calculated H-FABP c release ( r = 0.89, r 2 = 0.80, P < 0.01, n = 7) and with the amount of the urinary H-FABP c ( r = 0.94, r 2 = 0.88, P < 0.01, n = 7). These data suggest that measurement of the H-FABP c levels in plasma and urine might be useful for the early detection of myocardial injury and also for the assessment of infarct size.