Effects of age and sex on microsomal heme oxygenase and cytochrome P-450 content in liver of rats.

Effects of age and sex on microsomal heme oxygenase activity and cytochrome P-450 content were investigated in Wister rats. Heme oxygenase activity declined with an increase in age, namely, its activity in 100 days old (young) rats was 58% in male and 72% in female rats as compared with respective 30 days old (immature) rats, and in 300 days old (old) rats it was 32% in male and 39% in female rats. In male rats, cytochrome P-450 content based on 100 g body weight decreased only in old rats as compared with immature rats, whereas a significant reduction was observed in female rats in the content based on mg microsomal protein as well as based on 100 g body weight in young and old animals. In littermate rats at the age of 56 days which obtained by in breeding in our laboratory, sex difference was apparent in heme oxygenase activity and cytochrome P-450 content, and further a good reciprocal correlation between that activity and content (r = 0.9730 in male, and r = -0.852 in female) was observed.