|
|
||||||||
AJP - Renal Physiology, Vol 258, Issue 2 266-F272, Copyright © 1990 by American Physiological Society
ARTICLES |
S. P. Nadler
Department of Medicine, University of Ottawa, Ontario, Canada.
To assess the effects of increased tonicity on water reabsorption (Jv) in inner medullary collecting ducts (IMCD), antidiuretic hormone (ADH)-stimulated Jv and water permeability (PF) were determined in microperfused IMCD dissected from the inner medulla of rat kidney. In IMCD exposed to a 150-mosmol/kgH2O gradient in isotonic bath, ADH-stimulated PF averaged 719 +/- 93 microns/s. Symmetric addition of 75 mM NaCl to perfusate and bath resulted in a significant augmentation of ADH-stimulated PF (56%) that was reversible when initial solutions were restored. Despite the increase in PF, JV did not change but would have decreased by 16% (P less than 0.01) had PF not increased, because of the greater absolute axial increase in luminal tonicity that occurs with more hypertonic luminal solutions. When 150 mM mannitol was used to increase tonicity, similar effects were observed. However, 150 mM urea had no effect on ADH-stimulated PF. In IMCD exposed to 8-para-(chlorophenylthio)-adenosine 3',5'-cyclic monophosphate, addition of 75 mM NaCl to both and perfusate also resulted in a 76% increase in PF. These results are the first to demonstrate directly that increased effective tonicity augments ADH-stimulated PF in rat IMCD at a site distal to adenosine 3',5'-cyclic monophosphate generation. This effect may contribute to maintenance of medullary interstitial tonicity during antidiuresis by ensuring that most water reabsorption occurs more proximally within the IMCD.
This article has been cited by other articles:
![]() |
J. Zimpelmann, N. Li, and K. D. Burns Nitric oxide inhibits superoxide-stimulated urea permeability in the rat inner medullary collecting duct Am J Physiol Renal Physiol, December 1, 2003; 285(6): F1160 - F1167. [Abstract] [Full Text] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |