Effects of estradiol on carbonic anhydrase and Mg(2+)-HCO3(-)-ATPase activities in rat duodenal microvilli and kidney tubules

The cytosol carbonic anhydrase (CA) and microvillus membrane Mg(2+)-dependent, HCO3-(-)stimulated ATPase (Mg(2+)-HCO3-(-)ATPase) activities implicated in ion transport were determined in duodenal mucosa and renal tubule of ovariectomized and estradiol (E2)-treated ovariectomized rats. CA and Mg(2+)-HCO3-(-)ATPase activities in duodenum remained unchanged after ovariectomy, and sc E2 200 micrograms.d-1 x 7d decreased the activity of CA. Both the enzymes in kidney exhibited a similar sensitivity to ovariectomy, and the lowered activity of Mg(2+)-HCO3-(-)ATPase following ovariectomy was restored to near normal after administration of E2. These results suggest that E2 may be a factor in regulation of the above enzymes from the duodenum and kidney of rats, the regulation of E2 on these 2 enzymes in rat duodenum is greatly different from that in rat kidney.