Neurovascular control of oxygen tension in the testis and epididymis.

Abstract

Summary. Interstitial oxygen tension was recorded polarographically with gold-plated needle electrodes in the testis and cauda epididymidis of the rabbit, sheep and dog. The mean epididymal resting oxygen tension was about twice that of the testis in the rabbit and sheep, and nearly three times testis oxygen tension in the dog. A short period of oxygen breathing doubled testicular oxygen tension while nitrous oxide breathing more than halved it. The latency of the testis response was always much longer than that of the epididymal response in the rabbit and sheep, but only slightly longer in the dog. The discrepancy was accounted for by the arterial arrangement in the three species. Occlusion of the internal spermatic artery produced a drastic fall in testis oxygen tension in the rabbit, sheep and dog, and had little effect on epididymal oxygen tension. Vasal artery occlusion reduced oxygen tension in the cauda epididymidis but not the testis, and a large fall occurred only if collateral vessels from the internal spermatic or cremasteric arteries were also clamped. Circulatory hypotension produced by amyl nitrite inhalation reduced oxygen tension in the testis and epididymis of all three species. Local cooling of the scrotum depressed oxygen tension in the ipsilateral testis of the rabbit, sheep and dog. Conversely, local warming of the scrotum produced a rise of oxygen tension in the ipsilateral testis. Thoraco-lumbar spinal anaesthesia did not block these effects. Electrical stimulation of the sympathetic areas of the hypothalamus in the rabbit elicited a profound depression of testicular oxygen tension characterized by an initial rapid phase, which was abolished by posterior mesenteric ganglionectomy and hypogastric nerve section, and a secondary slower phase, which was abolished by adrenalectomy. The two phases could be mimicked by stimulation of the posterior mesenteric ganglion or hypogastric nerves, and by intravenous injection of adrenaline respectively.