Compared kinetics of plasma creatine kinase activity in rabbits after intravenous injection of different preparations of skeletal muscle.

The purpose of this study was to compare the disposition parameters of creatine kinase (CK) in rabbits after intravenous bolus administration of 3 CK preparations: 1) purified CK; 2) CK obtained from a muscular extract after a 3,000 g centrifugation (ie with cell remains) (3,000 g CK); or 3) a 105,000 g centrifugation (ie the cytosolic soluble phase) (105,000 g CK). The plasma half-lives were not significantly different (approximately 9 h). In contrast, the clearance of 3,000 g CK (3.25 +/- 0.33 ml.kg-1.h-1) was significantly lower than that of the 2 others (7.00 +/- 0.49 ml.kg-1.h-1 and 4.63 +/- 0.65 ml.kg-1.h-1 for 105,000 g and purified CK, respectively). These findings suggest that purified CK preparation is not the most appropriate form for determination of enzyme pharmacokinetic parameters following muscle damage.