Heterogeneity of glutathione synthesis and secretion in the
proximal tubule of the rabbit.
Parks, Lisa D., Rudolfs K. Zalups, and Delon W. Barfuss.
Biology Department, Georgia State University, Atlanta, GA 30302
-4010. Division of Basic Medical Sciences, Mercer University School of
Medicine, Macon GA 31207
APStracts 5:0030F, 1998.
This study was designed to examine the synthesis and possible
secretion of glutathione (GSH) in the S1, S2, and S3 segments of the
rabbit proximal tubule. GSH synthesis and secretion rates were
measured in the three segments of the proximal tubule using the
isolated perfused renal tubule technique. Tritiated (3H)-glycine was
perfused into segments and synthesized 3H-GSH (3H on the glycine
residue) was measured in the bathing solution, collectate, and tubule
extract. In the S1 segments, GSH was synthesized at the rate of 8.65
+/- 0.88 fmol min-1mm-1 tubule length and preferentially secreted
into the lumen at the rate of 7.28 +/- 0.74. The difference between
synthesis and secretion appeared in the bathing solution. The S2
segment synthesized GSH at the rate of 3.88 +/- 0.82 and secreted GSH
at the rate of 2.78 +/- 0.57 fmol min-1mm-1. GSH synthesis and
secretion rates in the S3 segment were 5.45+/-1.19 and 4.22+/-1.16
fmol min-1mm-1, respectively. Cellular concentrations of 3H-GSH
increased along the length of the proximal tubule with the highest
concentrations in the S3 segment. The respective GSH cellular
concentration in the S1, S2, and S3 segments were 35.89 +/- 10.51,
49.65 +/- 9.32, and 116.90 +/- 15.76 [mu]M. These findings indicate
that there is heterogeneity of GSH synthesis along the proximal
tubule and synthesized GSH is secreted preferentially into the lumen.
Received 8 September 1997; accepted in final form 29 January
1998.
APS Manuscript Number F285-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 19 February 1998