Tissue sites of aromatization in the female rhesus monkey

Nine female rhesus monkeys (four in the follicular and five in the luteal phases of their cycles) had catheters implanted and were infused iv with [7-3H]androstenedione (A) and [4-14C]estrone (E1) for 4 h. Blood samples were drawn at intervals from the hepatic, renal, jugular, uterine, and brachial veins and the femoral artery. The samples were analyzed for radioactivity as A and E1. The mean +/- SE MCRs for A and E1 were 280 +/- 40 and 270 +/- 30 liters/day, respectively. The mean extractions across the liver measured in six of the monkeys were 0.83 +/- 0.03 for A and 0.71 +/- 0.06 for E1. The percentage of A entering each tissue, which was measured as E1 leaving the tissue (pA,E1AV), was 0.20 +/- 0.10 for splanchnic, 0.21 +/- 0.11 for renal, 0.46 +/- 0.21 for jugular, 2.36 +/- 1.27 for arm, and 0.35 +/- 0.10 for uterine veins. Because of the sampling technique, the value for the uterus may be a reflection of ovarian blood admixture with uterine blood. There were no apparent differences in tissue aromatization between values in the follicular and luteal phases of the cycle. The overall mean value for the percentage of A infused and measured as E1 in arterial blood (pA,E1BB) was 1.01 +/- 0.38%. Using previously reported tissue blood flow, we calculate that the contributions to the overall aromatization rate of tissues drained by the brachial, renal, jugular, hepatic, and uterine veins are 23%, 5%, 5%, 4%, and 0.2%, respectively. Thus, the splanchnic tissue is a minor site for extraglandular aromatization of androgens in the rhesus monkey. An important site appears to be the arm, which reflects aromatization in adipose tissue, muscle, skin, and supporting structures.