Testicular blood flow and a study of the testicular venous to arterial transfer of radioactive krypton and testosterone in the rhesus monkey.

1. Testicular blood flow (ml. 100 g(-1).min(-1); mean +/- S.E. of the mean) measured in monkeys by (133)Xe clearance was 15.9 +/- 1.2 (twenty-six estimations on three monkeys; six testes) within 15 min of anaesthesia and 7.5 +/- 0.8 (twelve estimates; four monkeys, eight testes), after 1-2 hr of anaesthesia; and, when measured by (85)Kr clearance in the second hour of anaesthesia was 9.1 +/- 3.7 (seven estimates; four monkeys, four testes). Testicular temperature was 32.9 +/- 0.2 degrees C (mean +/- S.E. of mean) when deep body temperature was 37.2 +/- 0.2 degrees C.2. Blood flow in the caput epididymidis was 27.4 +/- 2.1 ml. 100 g(-1).min(-1) (mean +/- S.E. of mean; four estimates).3. Radioactivity accumulated in the ipsilateral testis and epididymis but not in the contralateral tissues, during the infusion of (85)Kr saline into the testicular veins.4. During [(3)H]testosterone infusions into the testicular veins, radioactivity was consistently higher in ipsilateral testicular arterial plasma than in plasma withdrawn simultaneously from the aorta in four of five experiments with no difference in one. After two such infusions, the radioactivity was up to 5 times greater in the ipsilateral testis and epididymis than in the contralateral tissues.5. During one infusion of [(125)I]bovine serum albumin into the testicular veins, there was no accumulation of radioactivity in the ipsilateral tissues.6. Testosterone concentrations (ng.ml(-1); mean +/- S.E. of mean) in plasma from seven anaesthetized monkeys which were sexually experienced were: testicular vein 53.22 +/- 8.03 (eight estimates); testicular artery, 4.58 +/- 0.94 (14); saphenous vein, 3.81 +/- 0.68 (14). The corresponding values from four sexually inexperienced monkeys were 25.27 +/- 2.11 (12); 2.89 +/- 1.99 (12); aorta 2.76 +/- 0.57 (12).7. The results are discussed as evidence for vascular exchange of molecules between the testicular veins and artery in the spermatic cord.