AJP - GI AJP: Heart and Circulatory Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Gastrointest Liver Physiol 255: G253-G259, 1988;
0193-1857/88 $5.00
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Moseley, R. H.
Right arrow Articles by Murphy, S. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Moseley, R. H.
Right arrow Articles by Murphy, S. M.

AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 2 253-G259, Copyright © 1988 by American Physiological Society

ARTICLES

Na+-glycine cotransport in canalicular liver plasma membrane vesicles

R. H. Moseley, N. Ballatori and S. M. Murphy
Department of Internal Medicine, Veterans Administration Medical Center, Ann Arbor, Michigan.

By use of purified rat canalicular liver plasma membrane (cLPM) vesicles, the present study determined the driving forces for glycine transport across this membrane domain. Initial rates of [3H]glycine uptake (10 microM) in cLPM vesicles were stimulated by an inwardly directed Na+ gradient but not by a K+ gradient. Na+ gradient-dependent uptake of glycine demonstrated cation specificity for Na+, dependence on extravesicular Cl-, stimulation by an intravesicular-negative membrane potential, and inhibition by dissipation of the Na+ gradient with gramicidin D. Na+ gradient-dependent glycine cotransport also demonstrated greater sensitivity to inhibition by sarcosine than 2-(methylamino)-isobutyric acid. Accelerated exchange diffusion of [3H]glycine was demonstrated in the presence of Na+ when cLPM vesicles were preloaded with glycine but not with L-alanine or L-proline. Substrate velocity analysis of net Na+-dependent [3H]glycine uptake over the range of amino acid concentrations from 5 microM to 5 mM demonstrated two saturable transport systems, one of high capacity (2.2 +/- 0.2 nmol.mg protein-1.15 s-1) and low affinity (11.2 +/- 1.7 mM) and one of low capacity (51 +/- 14 pmol.mg protein.15 s-1) and comparatively high affinity (66 +/- 12 microM). These results indicate that, in addition to previously described neutral and anionic amino acid transport systems, Na+ gradient-dependent glycine transport mechanisms are present on the canalicular domain of the liver plasma membrane. These canalicular reabsorptive mechanisms may serve to reclaim some of the glycine generated within the canalicular lumen from the intrabiliary hydrolysis of glutathione.


This article has been cited by other articles:


Home page
 Am. J. Physiol. Renal Physiol.Home page
L. D. Parks and D. W. Barfuss
Transepithelial transport and metabolism of glycine in S1, S2, and S3 cell types of the rabbit proximal tubule
Am J Physiol Renal Physiol, December 1, 2002; 283(6): F1208 - F1215.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online