Effect of testosterone on carbonic anhydrase and mg 2+-dependent HCO 3stagered−-stimulated ATPase activities in rat kidney: Comparison with estradiol effect

Abstract

Effects of testosterone administration (TP; 1–3 mg/kg body weight, SC, once daily for 7 days) on the cytosol carbonic anhydrase (CA) and tubular brush border mg 2+-dependent HCO 3 stagered−-stimulated ATPase mg 2+-HCO 3 stagered−-ATPase) activities of normal and castrated male and female rat kidney were compared with estradiol (E 2) effects, TP decreased kidney CA activity in a dose-dependent manner in all four animal conditions, and negative correlations were observed between cytosol CA activity and serum testosterone concentration. However, brush border mg 2+-HCO 3 stagered−-ATPase activity was not affected by testosterone. Orchiectomy increased only CA activity and its value recovered to normal levels by 3 mg/kg TP replacement, whereas mg 2+-HCO 3 stagered−-ATPase activity did not change. In the previous study, on the other hand, E 2 administration activated both kidney enzymes in normal male rats and only mg 2+-HCO 3 stagered−-ATPase in normal female rats. Testosterone and E 2 conversely affected kidney CA activity in male rats. These facts suggest that the cytosol CA may control kidney functions on H + and HCO 3 stagered− metabolism under the balance of both sex hormones in the living body.