Rate of decay and distribution volume of MB isoenzyme of creatine kinase, intravenously injected into the baboon.

We determined the decay constant and distribution space of the MB isoenzyme of creatine kinase after intravenous injection of 440 to 720 U, in a group of seven adult baboons. The rate of decay of the isoenzyme was monoexponential, with a mean decay constant of 0.00175 min-1 (SD, 0.00019). The mean distribution volume obtained by extrapolation of the monoexponential curve to zero time was 5.22% (SD, 1.06) of body weight. We have determined these parameters with the purpose of using this isoenzyme in the baboon as an experimental model for measuring myocardial infarct size.