Arginine-vasopressin induced changes in testicular blood flow

As arginine-vasopressin (AVP) has been suggested as a possible paracrine regulator in the testis, the present study was designed to evaluate the effects of AVP on testicular blood flow and vascular permeability. Intratesticular injection of AVP caused a dose-dependent decrease in total testicular blood flow, with 1 ng AVP being the lowest dose that induced a decrease. The AVP-induced decrease in blood flow was blocked completely by treatment with an AVP antagonist, but the latter had no effect on its own. High doses of AVP (100 and 1000 ng) decreased testicular IF volume and slightly increased the IF testosterone concentration. At 10 min and 1 h after intratesticular injection of 100 ng AVP testicular blood flow was decreased, followed by an increase at 6 h; testosterone concentrations were increased at both 10 min and 6 h after this treatment. The microcirculatory blood flow pattern (vasomotion) was not influenced by AVP. The present study shows that AVP in low doses influences testicular blood flow rather selectively because AVP was without any major effect on vasomotion, interstitial fluid volume and testosterone production. AVP might therefore be of importance in the regulation of testicular blood flow.