HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 287/4/R878    most recent 00180.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Leong, P. K. K. Articles by McDonough, A. A. Search for Related Content PubMed PubMed Citation Articles by Leong, P. K. K. Articles by McDonough, A. A.

WATER AND ELECTROLYTE HOMEOSTASIS

Acute hypotension induced by aortic clamp vs. PTH provokes distinct proximal tubule Na⁺ transporter redistribution patterns

¹Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, California 90089-9142; and ²Department of Medical Physiology, Division of Renal and Cardiovascular Research, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark

Submitted 18 March 2004 ; accepted in final form 26 May 2004

Renal parathyroid hormone (PTH) action is often studied at high doses (100 µg PTH/kg) that lower mean arterial pressure significantly, albeit transiently, complicating interpretation of studies. Little is known about the effect of acute hypotension on proximal tubule Na⁺ transporters. This study aimed to determine the effects of acute hypotension, induced by aortic clamp or by high-dose PTH (100 µg PTH/kg), on renal hemodynamics and proximal tubule Na/H exchanger isoform 3 (NHE3) and type IIa Na-P_i cotransporter protein (NaPi2) distribution. Subcellular distribution was analyzed in renal cortical membranes fractionated on sorbitol density gradients. Aortic clamp-induced acute hypotension (from 100 ± 3 to 78 ± 2 mmHg) provoked a 62% decrease in urine output and a significant decrease in volume flow from the proximal tubule detected as a 66% decrease in endogenous lithium clearance. There was, however, no significant change in glomerular filtration rate (GFR) or subcellular distribution of NHE3 and NaPi2. In contrast, high-dose PTH rapidly (<2 min) decreased arterial blood pressure to 51 ± 3 mmHg, decreased urine output, and shifted NHE3 and NaPi2 out of the low-density membranes enriched in apical markers. PTH at much lower doses (<1.4 µg·kg^–1·h^–1) did not change blood pressure and was diuretic. In conclusion, acute hypotension per se increases proximal tubule Na⁺ reabsorption without changing NHE3 or NaPi2 subcellular distribution, indicating that trafficking of transporters to the surface is not the likely mechanism; in comparison, hypotension secondary to high-dose PTH blocks the primary diuretic effect of PTH but does not inhibit the PTH-stimulated redistribution of NHE3 and NaPi2 to the base of the microvilli.

kidney; lithium clearance; glomerular filtration rate; blood pressure; rats; parathyroid hormone

This article has been cited by other articles:

				A. D. M. Riquier, D. H. Lee, and A. A. McDonough Renal NHE3 and NaPi2 partition into distinct membrane domains Am J Physiol Cell Physiol, April 1, 2009; 296(4): C900 - C910. [Abstract] [Full Text] [PDF]

				C. N. A. Bezerra, A. C. C. Girardi, L. R. Carraro-Lacroix, and N. A. Reboucas Mechanisms underlying the long-term regulation of NHE3 by parathyroid hormone Am J Physiol Renal Physiol, May 1, 2008; 294(5): F1232 - F1237. [Abstract] [Full Text] [PDF]

				M. Donowitz and X. Li Regulatory Binding Partners and Complexes of NHE3 Physiol Rev, July 1, 2007; 87(3): 825 - 872. [Abstract] [Full Text] [PDF]

				P. K. K. Leong, A. Devillez, M. B. Sandberg, L. E. Yang, D. K. P. Yip, J. B. Klein, and A. A. McDonough Effects of ACE inhibition on proximal tubule sodium transport Am J Physiol Renal Physiol, April 1, 2006; 290(4): F854 - F863. [Abstract] [Full Text] [PDF]