Heart Biochemical Responses 14 Days after +G sub Z Acceleration.

摘要

Myocardial biochemical responses were measured in miniature swine following +Gz stress. Unanesthetized animals were subjected to an acceleration profile encompassing 3, 5, 7, 9, and 11 +G(z). Acceleration exposure time at each G level varied from 60-120 s. At 14 d after +G(z) exposure, free lysosomal enzyme activity was reduced by 15-40% in both the epicardial and endocardial portions of the left ventricle while sequestered enzyme activity remained near control levels. Since free lysosomal enzyme activity was previously found to be elevated approximately two-fold in response to a single 9 + G(z) exposure, the responses observed 14 d after + G(z) acceleration would be consistent with a myocardial damage-repair phenomenon. The DNA levels in the left ventricle of + G(z) stressed animals were significantly lower than control values, while the RNA/DNA ratio was markedly elevated. The nucleic acid results imply a metabolic hyperfunction of the remaining nuclear material. (Author)