EFFECT OF ORALLY-ADMINISTERED CADMIUM ON IN-SITU PH, PCO2, AND BICARBONATE CONCENTRATION IN RAT TESTIS AND EPIDIDYMIS

Acute injections of high doses of cadmium (Cd) induce marked testicula r necrosis. However, the effects of low-dose oral Cd exposure, on a ch ronic basis, are not well documented. The present investigation was de signed to examine the effects of such exposure on in situ pH, PCO2, an d bicarbonate concentration ([HCO3-]) in the rat testis and epididymis , plasma testosterone levels, and testis and epididymis weights. Male Sprague-Dawley rats were exposed to 50 or 100 ppm Cd for 40 d. Oral ad ministration of 50 or 100 ppm Cd was associated with significant alkal inization of luminal fluid in seminiferous tubules (ST) but did not al ter in situ pH values in proximal caput (PCP), middle caput (MCP), or proximal cauda epididymidis (PCD). The in situ PCO2 values in ST, PCP, MCP, and PCD of control animals were indistinguishable from each othe r and from values after Cd exposure, and all values were significantly higher than system arterial blood (SAB) PCO2. Oral Cd exposure at 50 or 100 ppm did not change the values for bicarbonate in SAB, PCP, or M CP but increased markedly the value in ST. Plasma testosterone levels and testis and epididymis weights were not altered after oral cadmium administration. These findings suggest that, at the doses employed in this study, Cd exposure may result in subtle alterations in the blood- testis barrier and subsequent impairment of acid-base pathways. Furthe rmore, the traditional view of Cd-related testicular insult based on a cute injection protocols needs to be reevaluated in terms of environme ntal relevance.