Blood Flow in the Testis of the Conscious Ram Measured with Krypton 85

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Abstract
Krypton85 in saline was injected through a catheter into the testicular artery or directly into the testis, and the radioactivity in the testis measured by external monitoring with a scintillation detector. The disappearance of Kr85 from the testis followed a single exponential curve during a fiftyfold decrease in radioactivity and showed no delay before beginning to fall. The partition coefficient for Kr85 between testis and blood was 0.85. The mean nutrient blood flow through the testes of 11 conscious rams was 8.4 ml/100 g/min (66 observations; standard deviation between rams 2.4; standard deviation of estimates on individual rams 2.1). Testicular blood flow was reduced by intraarterial infusions of epinephrine or norepinephrine, practically unaffected by acetylcholine, and increased by isoproterenol. Testicular blood flow was not changed by raising deep testicular temperature from the normal range (32 to 34°C) to body temperature (39 to 40°C). These results are discussed with a view to explaining, in vascular terms, the damage to spermatogenesis caused by elevation of environmental temperature.