The metabolism of estrone sulfate in the female rhesus monkey

In order to study the metabolism of estrone sulfate in the adult female rhesus monkey, we gave four monkeys a pulse injection of [3H]estrone sulfate and obtained blood samples at 15, 30, 60, 120, 300, and 1,440 minutes after the pulse. All blood samples were analyzed for [3H]estrone sulfate. The mean +/- SE for the initial volume of distribution was 4.6 +/- 0.9 L. The mean metabolic clearance rate (MCR) was 42.0 +/- 2.9 L/day. In addition, 2 monkeys were infused for 240 minutes with [3H]estrone sulfate and 5 monkeys were infused for 240 minutes with [3H]estrone sulfate/[14C]estrone. Three blood samples were obtained during the last hour of the infusions and analyzed for radioactivity as estrone sulfate, estrone, and estradiol, and MCRs, conversion ratios, and [rho]BB values were calculated. The mean +/- SE for the MCR was 67.5 +/- 8.3 L/day, and for the conversion ratio, estradiol to estrone sulfate was 0.054 +/- 0.016. The mean [rho]BB value for estrone sulfate conversion to estrone was 43.6 +/- 3.4% and for estrone conversion to estrone sulfate was 33.5 +/- 6.6%. Thus estrone sulfate is cleared slowly and is converted to both estrone and estradiol. The hydrolysis of estrone sulfate to estrone is not significantly different than the conversion of estrone to estrone sulfate.