Serum myocardial enzymes after +Gz acceleration.

Circulating levels of lactate dehydrogenase, glutamate-oxaloacetate, glutamate-pyruvate transaminase, and creatine phosphokinase, as well as its isoenzymes, were measured to investigate the possibility of myocardial damage during acceleration to high +Gz. Serum samples were analyzed in 12 human volunteers before, 6 h after, and 24 h after several bouts of accleration to 6, 8, 9, and 10 G. No substantial elevations of enzyme activities were observed. However, multivariate analysis of variance and multiple comparisons of the data indicated a small but statistically significant (p less than 0.01) increase in creatine phosphokinase. The results were consistent with enhanced skeletal muscle cell permeability consequent to muscular exercise.