[Effect of aggregation inducers and inhibitors on the pentosephosphate pathway enzymes of glucose conversion in the thrombocytes].

Experiments with rabbit platelets in vitro revealed differences in the effect of the aggregation inducers (ADP and thrombin) and the aggregation inhibitor cyclic AMP on the activity of the enzymes of pentosephosphate pathway of glucose oxidation. ADP and thrombin decrease significantly the activity of glucoso-6-phosphate dehydrogenase (G-6-PDH) and riboso-5-phosphate-metabolizing enzymes (R-5-PME) in platelets during aggregation, whereas cyclic AMP produces no appreciable effect on the G-6-PDH activity, but increases significantly the R-5-PME activity. ADP decreases and cyclic AMP raises substantially the activity of R-5-PME. The differences were also revealed in the effects produced by cyclic AMP and cyclic GMP on the enzymes of pentosephosphate pathway of glucose oxidation. Unlike cyclic AMP, cyclic GMP decreased significantly the activity of G-6-PDH. The activity of R-5-PME and cyclic GMP transketolase was more pronounced than that of cyclic AMP. Like cyclic AMP, cyclic GMP differs from ADP and thrombin in the action produced on the enzymes of pentosephosphate pathway of glucose oxidation.