BINDING OF THE SULPHATE ESTERS OF DEHYDROEPIANDROSTERONE, TESTOSTERONE, 17-ACETOXYPREGNENOLONE AND PREGNENOLONE IN THE PLASMA OF MAN, RABBIT AND RAT

Abstract

SUMMARY: The binding by plasma from man, rabbit and rat of the sulphate esters of dehydroepiandrosterone, testosterone, 17-acetoxypregnenolone and pregnenolone has been studied using equilibrium dialysis. The plasma of these species had a large capacity for binding dehydroepiandrosterone sulphate and testosterone sulphate. A large capacity for binding pregnenolone sulphate and 17-acetoxypregnenolone sulphate was observed with plasma from man and rabbit. The percentage binding of the steroid sulphates studied was higher for human plasma than for rabbit plasma and, in the case of the sulphates of dehydroepiandrosterone and testosterone, for rat plasma. The higher percentage binding by human plasma was confirmed using multiple equilibrium dialysis. Evidence is presented that suggests that the sulphate esters of dehydroepiandrosterone, testosterone and pregnenolone are bound to the same sites. Dehydroepiandrosterone sulphate was displaced by non-steroidal organic sulphates, suggesting that the binding sites involved are not specific for steroid sulphates.