1. Sex and species differences during the metabolism of [4-(14)C]progesterone by liver homogenates from rat, rabbit, guinea pig and hamster have been investigated. 2. Liver homogenate from male rat formed ;water-soluble' metabolites faster and in significantly larger amounts than did liver homogenate from female rat. About 65-70% of the added progesterone was conjugated as glucuronide by liver ...

Figure Legend: Figure 1 Prostate Inflammation. Arrows indicate neutrophils passing through the acinar mucosa in a male F344/N rat from a chronic study. Figure 2 Prostate Inflammation. Suppurative inflammation of the prostate in a male F344/N rat from a chronic study. Figure 3 Prostate Inflammation. Inflammation of the prostate associated with epithelial degeneration in a male F344/N rat from a ...

Mendelson and Gorzalka recently described a bilevel chamber for the evaluation of rodent sexual behavior. In initial studies it was observed that during 5 min adaptation periods prior to the introduction of a sexually receptive female rat, male rats with prior sexual experience in these chambers would move from level to level in apparent search for the female rat. In Experiment 1, we examined t...

To assess the suitability of the male rat model for human studies on sildenafil metabolism, we examined the biotransformation of sildenafil in male rat liver microsomes and identified the role of specific cytochrome P450s (P450) using inhibitory antibodies and cDNA-expressed P450s. Rates of formation of the major circulating metabolite of sildenafil, UK-103,320, were 11-fold greater in the male...