Glucocorticoids stimulate rabbit proximal convoluted tubule acidification
1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas 75235-9063.
The Journal of Clinical Investigation
|January 1, 1993
Summary
Glucocorticoids directly enhance kidney proximal tubule acidification by increasing bicarbonate absorption. This effect requires protein synthesis, indicating a direct cellular mechanism for glucocorticoid action on renal function.
Area of Science:
- Nephrology
- Cellular Physiology
- Endocrinology
Background:
- Glucocorticoids are known to influence renal acidification.
- A direct impact of glucocorticoids on proximal convoluted tubule (PCT) acidification has not been previously established.
Purpose of the Study:
- To investigate the direct effect of glucocorticoids on proximal convoluted tubule (PCT) acidification.
- To determine if glucocorticoids exert a direct epithelial action on PCT bicarbonate absorption.
Main Methods:
- In vitro microperfusion of rat proximal convoluted tubules (PCT).
- Administration of dexamethasone to animals and direct addition to the perfusate bath.
- Measurement of bicarbonate absorption rates.
- Inhibition studies using actinomycin D and cycloheximide.
Main Results:
- PCT from animals treated with dexamethasone showed significantly higher bicarbonate absorption rates compared to controls.
- In vitro incubation of PCT with dexamethasone (10⁻⁶ M and 10⁻⁵ M) stimulated bicarbonate absorption by approximately 30%.
- Dexamethasone's stimulatory effect on acidification was blocked by actinomycin D and cycloheximide, indicating dependence on protein synthesis.
Conclusions:
- Glucocorticoids have a direct effect on proximal convoluted tubule (PCT) acidification.
- This direct effect is mediated by a mechanism dependent on protein synthesis.
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