Glucocorticoids have an important role in renal acidification; however, a direct effect of glucocorticoids on proximal convoluted tubule (PCT) acidification has not been directly demonstrated. In the present in vitro microperfusion study PCT from animals receiving dexamethasone (600 micrograms/kg twice daily for 2 d and 2 h before killing) had a significantly higher rate of bicarbonate absorption than did controls (92.0 +/- 13.3 vs 59.9 +/- 3.2 pmol/mm.min, P < 0.01). To examine if glucocorticoids had a direct epithelial action, dexamethasone was added to the bath of PCT perfused in vitro. After 3 h of incubation in paired experiments 10(-6) M and 10(-5) M dexamethasone resulted in an approximately 30% stimulation in the rate of bicarbonate absorption. 10(-7) M dexamethasone and 10(-6) M aldosterone had no effect on bicarbonate absorption. The stimulation of acidification by 10(-5) M dexamethasone was blocked by actinomycin D and cycloheximide. These data are consistent with a direct effect of glucocorticoids on PCT acidification, and this effect is dependent upon protein synthesis.
M Baum, R Quigley
Title and authors | Publication | Year |
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Roles of cortisol and carbonic anhydrase in acid–base compensation in rainbow trout, Oncorhynchus mykiss
KM Gilmour, CL Collier, CJ Dey, SF Perry |
Journal of Comparative Physiology B | 2010 |