AJP - Renal Physiology, Vol 265, Issue 5 698-F704, Copyright © 1993 by American Physiological Society

ARTICLES

H(+)-K(+)-ATPase of rat inner medullary collecting duct in primary culture

J. G. Kleinman, P. Tipnis and R. Pscheidt
Nephrology Division, Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin.

pH recovery in response to addition of and removal from NH4Cl was examined using 2',7'-bis(2-carboxy-ethyl)-5(6)-carboxyfluorescein fluorescence in primary cultures of inner medullary collecting duct (IMCD) cells from rat kidneys. In 0 K+, pH recovery rate was 0.012 +/- 0.010 U/min; in 5 mM K+, the recovery rate was greater at 0.065 +/- 0.013 U/min (P = 0.026). The H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) inhibitors omeprazole and Sch-28080 and the P-type ATPase inhibitor vanadate significantly inhibited pH recovery at 100, 10, and 5 microM, respectively. The vacuolar H(+)-ATPase inhibitor bafilomycin failed to inhibit pH recovery, but N-ethylmaleimide (NEM) did. A range of Sch-28080 concentrations inhibited ouabain-resistant ATPase activity of microsomes from these cells in a reverse sigmoidal manner, with little inhibition < 1 microM, virtually 100% inhibition > 100 microM, and a 50% inhibitory concentration of approximately 20 microM. Bafilomycin only produced significant inhibition of activity at concentrations well in excess of those that are effective against the vacuolar H(+)-ATPase. The ouabain-resistant ATPase activity in cultured IMCD was also sensitive to vanadate (90% inhibition with 5 microM) but relatively resistant to N,N'-dicyclohexylcarbodiimide and NEM. These results indicate that pH regulation in primary cultures of IMCD cells, presumably reflecting H+ transport, is predominantly due to an H(+)-K(+)-ATPase.

This article has been cited by other articles:

				R. B. Silver and M. Soleimani H+-K+-ATPases: regulation and role in pathophysiological states Am J Physiol Renal Physiol, June 1, 1999; 276(6): F799 - F811. [Abstract] [Full Text] [PDF]

				T. Wang, N. Courtois-Coutry, G. Giebisch, and M. J. Caplan A tyrosine-based signal regulates H-K-ATPase-mediated potassium reabsorption in the kidney Am J Physiol Renal Physiol, November 1, 1998; 275(5): F818 - F826. [Abstract] [Full Text] [PDF]

				S. M. Wall, P. Mehta, and T. D. DuBose Jr. Dietary K+ restriction upregulates total and Sch-28080-sensitive bicarbonate absorption in rat tIMCD Am J Physiol Renal Physiol, October 1, 1998; 275(4): F543 - F549. [Abstract] [Full Text] [PDF]

				A. M. Weinstein A mathematical model of the inner medullary collecting duct of the rat: pathways for Na and K transport Am J Physiol Renal Physiol, May 1, 1998; 274(5): F841 - F855. [Abstract] [Full Text] [PDF]

				A. M. Weinstein A mathematical model of the inner medullary collecting duct of the rat: acid/base transport Am J Physiol Renal Physiol, May 1, 1998; 274(5): F856 - F867. [Abstract] [Full Text] [PDF]

				H. Amlal, Z. Wang, and M. Soleimani Functional upregulation of H+-ATPase by lethal acid stress in cultured inner medullary collecting duct cells Am J Physiol Cell Physiol, October 1, 1997; 273(4): C1194 - C1205. [Abstract] [Full Text] [PDF]