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 testicular necrosis. However, the effects of low-dose oral Cd exposure, on a chronic basis, are not well documented. The present investigation was designed to examine the effects of such exposure on in situ pH, PCO2, and 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 administration of 50 or 100 ppm Cd was associated with significant alkalinization of luminal fluid in seminiferous tubules (ST) but did not alter 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 other 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 MCP 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. Furthermore, the traditional view of Cd-related testicular insult based on acute injection protocols needs to be reevaluated in terms of environmental relevance.