AJP - Renal Physiology, Vol 248, Issue 2 233-F239, Copyright © 1985 by American Physiological Society

ARTICLES

Glucocorticoid activation of Na+/H+ exchange in renal brush border vesicles: kinetic effects

J. L. Kinsella, J. M. Freiberg and B. Sacktor

Administration of the synthetic glucocorticoid dexamethasone to adrenalectomized rats increased Na+/H+ exchange activity in isolated renal brush border membrane vesicles. Treatment altered the initial rate of Na+ uptake by increasing Vmax (19.90 +/- 2.17 vs. 27.32 +/- 1.50 nmol.mg protein-1.5 s-1) and not the apparent affinity KNa+ (8.33 +/- 1.11 vs. 7.94 +/- 1.60 mM). Dexamethasone treatment resulted in a proportional increase in 1 mM Na+ uptake at every intravesicular pH measured. When these data were analyzed by the Hill equation, it was found that dexamethasone treatment did not change the apparent number of H+ binding sites (1.24 vs. 1.26) or the [H+]0.5 (0.33 vs. 0.32 microM) but increased the apparent Vmax (0.98 vs. 0.55 nmol.mg protein-1.2 s-1). It was also found that dexamethasone injections of 60 micrograms/100 g body wt resulted in maximum stimulation of exchange activity and that a significant increase in amiloride-sensitive Na+ uptake was detected within 12 h after a single dose of dexamethasone.

This article has been cited by other articles:

				I. A. Bobulescu, V. Dwarakanath, L. Zou, J. Zhang, M. Baum, and O. W. Moe Glucocorticoids acutely increase cell surface Na+/H+ exchanger-3 (NHE3) by activation of NHE3 exocytosis Am J Physiol Renal Physiol, October 1, 2005; 289(4): F685 - F691. [Abstract] [Full Text] [PDF]

				N. Gupta, V. Dwarakanath, and M. Baum Maturation of the Na+/H+ antiporter (NHE3) in the proximal tubule of the hypothyroid adrenalectomized rat Am J Physiol Renal Physiol, September 1, 2004; 287(3): F521 - F527. [Abstract] [Full Text] [PDF]