The Dynamics of Testosterone and Dihydrotestosterone Metabolism in the Adult Male Rhesus Monkey*

MCRs of testosterone (T) and 5 alpha-dihydrotestosterone (DHT) were determined in the morning and evening in four chronically chaired adult rhesus monkeys (Macaca mulatta) by means of steady state infusion of [4-14C]testosterone and [1,2-3H]dihydrotestosterone. Morning and evening MCRs were comparable for both T and DHT, averaging 169 and 212 ml/min for T and 93 and 108 ml/min for DHT, respectively, indicating that temporal differences in blood steroid concentrations are the result of changes in glandular secretion and/or synthesis and not differences in MCRs. Blood transfer factors for the conversion of T to DHT were also similar at these two times (0.024 and 0.022). MCRs were determined in one monkey by the single injection of [14C]T and [3H]DHT. From the rates at which the hormones disappeared from the circulation, MCRT and MCRDHT were calculated to be 172 ml/min for T and 92.2 ml/min for DHT. The inner volumes of hormone distribution were 4.04 liters for T and 3.67 liters for DHT.