|
|
||||||||
AJP - Regulatory, Integrative and Comparative Physiology, Vol 266, Issue 3 979-R988, Copyright © 1994 by American Physiological Society
ARTICLES |
M. Ookhtens, A. V. Mittur and N. A. Erhart
Department of Medicine, University of Southern California School of Medicine, Los Angeles 90033.
We have previously shown that sinusoidal reduced glutathione (GSH) efflux declines during development because of a declining maximum transport rate [Am. J. Physiol. 261 (Gastrointest. Liver Physiol. 24): G648-G656, 1991]. Because rat liver serves as the principal source of plasma GSH, we studied the response of plasma GSH to this declining inflow from liver. In immature (28- to 42-day) and mature (90- to 151-day) rats we injected tracer boluses of [35S]GSH intravenously and collected arterial samples over a 0.75- to 8-min interval while plasma GSH pool remained at steady state. Concentrations and radioactivities of GSH, oxidized glutathione (GSSG), cysteine (CYSH), cystine (CYSS), and cysteine-glutathione disulfides (CYSSG) and the radio-activities of proteins were measured in plasma. Our results show the following changes in plasma concentrations (microM): decreases in unbound (free) GSH (26.0 +/- 2.1 to 12.4 +/- 0.98; P < 0.001), total unbound GSH equivalents GSH + 2GSSG (29.1 +/- 2.1 to 15.3 +/- 1.2; P < 0.001), total reducible (unbound + bound) GSH (39.3 +/- 2.2 to 28.9 +/- 2.6; P < 0.025), and free CYSH (57.6 +/- 8.5 to 29.9 +/- 4.0; P < 0.05); no changes in GSSG (1.57 +/- 0.27 vs. 1.47 +/- 0.41), CYSS (36.7 +/- 12 vs. 43.4 +/- 17), and total unbound CYSH equivalents CYSH + 2CYSS (131 +/- 15 vs. 117 +/- 18); increases in total reducible (unbound + bound) CYSH (158 +/- 8.1 to 203 +/- 24; P < 0.05) and CYSSG (1.80 +/- 0.42 to 4.94 +/- 1.4 in microM GSH equivalents; P < 0.05). A concurrent decline occurred in irreversible disposal rate (IDR) of plasma GSH from 38.5 +/- 4.9 to 16.4 +/- 1.4 nmol.min-1.ml-1 (P < 0.001) as determined by compartmental analysis of tracer data. This 57% decrease in IDR parallels a decrease of 53% in the inflow of GSH estimated by perfused livers (17.0 to 8.0 nmol.min-1.ml plasma-1). However, perfused liver estimates do not match > 44-49% of plasma IDR. Thus perfused liver appears to underestimate the true rate of sinusoidal GSH efflux taking place in vivo. Some earlier arteriovenous data and our present portal vein-to-hepatic vein difference measurements appear to corroborate this view.
This article has been cited by other articles:
![]() |
A. V. Mittur, N. Kaplowitz, E. S. Kempner, and M. Ookhtens Novel properties of hepatic canalicular reduced glutathione transport revealed by radiation inactivation Am J Physiol Gastrointest Liver Physiol, May 1, 1998; 274(5): G923 - G930. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |