Myoglobin kinetics in patients suffering from acute myocardial infarction in its early phase —as studied by the single injection method

Abstract

The turnover of myoglobin has been examined with the single injection technique in eight patients suffering from acute myocardial infarction during its early phase. All patients had elevated serum levels of myoglobin and creatine kinase-MB. The serum disappearance curve of [¹²⁵I]myoglobin could be fitted adequately by a two-compartment model. The kinetic parameters did not differ from those estimated for six healthy old volunteers, previously studied with the same technique. The average elimination rate constant was 0.80 ± 0.37 h⁻¹ and the average turnover time was 5.5 ± 3.2 h (SD). The values are in good agreement with corresponding estimates for the retinol-binding protein, with a molecular weight (21,000) close to that for myoglobin (mol. wt 17,800). In comparison with β₂-_-microglobulin, another low molecular weight protein (mol. wt 11,800), the elimination rate constant for myoglobin is significantly smaller and the turnover time is longer, as could be expected from the difference in molecular weight. Plasma protein binding of myoglobin could not be excluded, however.

Key Words:

• acute myocardial infarction
• Myoglobin
• single injection technique
• turnover
• two-compartment model