Penetration of ethanol into the male reproductive tract.
We studied the pharmacokinetics of ethanol in the rat rete testis fluid, interstitial fluid, seminiferous tubules, epididymal fluid, and whole testis after 0.75 g/kg and 1.5 g/kg intraperitoneal injections. Ethanol concentration in these tissues was compared to that in capillary and arterial blood. The data was characterized by fitting to a mathematical model. The highest ethanol concentrations in orbital capillary blood were measured 10 min after the injections. Ethanol content in testis homogenate and interstitial fluid did not generally differ from that of orbital blood. However, in rete testis fluid the highest ethanol values were measured at 60 min by the 1.5 g/kg dose and at 30 min by 0.75 g/kg. Ethanol values before this differed from those of capillary blood and interstitial fluid (p less than 0.05-0.001). In seminiferous tubules, the highest ethanol concentration was reached at 20 min, and ethanol content was in general lower than in orbital blood (p less than 0.001-0.01). Ethanol levels in epididymal fluid were comparable to capillary blood. The transportability factor from the model for rete testis was low, which indicates a barrier of penetration of ethanol from blood. In addition, water contents of testicular compartments were calculated. The area under the curve values of rete testis and seminiferous tubules were approximately 10 and 30%, respectively, smaller than that of interstitial fluid, for example. Therefore, the germ cells are somewhat better protected from ethanol than the interstitial cells.