Ablation of the blood-testis barrier in rats and guinea pigs by 48/80, a histamine releaser, and cadmium chloride.

When adult male guinea pigs were injected unilaterally intratesticularly with compound 48/80 (1 mg in 0.05 ml saline), their testicular peritubular capillaries were engorged with blood, intratubular edema was present on the ipsilateral side, and the blood-testicular (BT) barrier (measured by the entrance of acriflavin into the seminiferous tubule) was ablated. The contralateral testis, when injected with saline, showed no pathological changes nor a breakdown of the BT barrier. Subcutaneous injection of guinea pigs with cadmium chloride resulted in a more intense intratubular fluorescence than was observed for 48/80-treated animals. The H1 and H2 receptor blockers (diphenhydramine and cimetidine, respectively) reduced the intensity of capillary engorgement and edema. Intraperitoneal injections of 48/80 (0.5 mg) was lethal to rats, and both diphenhydramine and cimetidine induced survival even with as much as 1 mg of 48/80. Intratubular fluorescence was less severe than that observed for similarly treated guinea pigs or from cadmium chloride-treated rat testes. Neither treatment (48/80 or cadmium chloride) altered the blood-epididymal barrier of either guinea pigs or rats. Species differences were observed in the lethal effects of exogenously administered histamine.