Human kidney proximal tubules are the main source of plasma glutathione peroxidase

N. Avissar, D. B. Ornt, Y. Yagil, S. Horowitz, R. H. Watkins, E. A. Kerl, K. Takahashi, I. S. Palmer, H. J. Cohen

Research output: Contribution to journalArticlepeer-review

251 Scopus citations


The sites of synthesis of extracellular (E) glutathione peroxidase (GPX), a unique selenoglycoprotein present in plasma, are not known. To investigate the possibility that the kidney is the main source for the plasma GPX, we examined GPX activities and selenium concentrations in the plasma of patients with renal failure on dialysis and nephrectomized patients before and after kidney transplantation. Plasma GPX activities in these patients were 12, 22, and 180% of normal EGPX activity, respectively, whereas plasma Se levels were within the normal range. Twenty-four hours after nephrectomy of anesthetized rats, plasma GPX activity was 30.0 ± 6.4% of the activity at zero time. Northern hybridization analysis of eight human tissues probed with EGPX and cellular glutathione peroxidase (CGPX) cDNA revealed that the ratio of EGPX to CGPX was highest in the kidney, cRNA in situ hybridization studies on kidney slices showed that only proximal tubular epithelial cells and parietal epithelial cells of Bowman's capsule contained EGPX transcripts. Caki-2, a proximal tubular renal carcinoma cell line, makes and actively secretes EGPX. Taken together, these results strongly suggest that kidney proximal tubular cells are the main source for GPX activity in the plasma.

Original languageEnglish
Pages (from-to)C367-C375
JournalAmerican Journal of Physiology - Cell Physiology
Issue number2 35-2
StatePublished - 1 Jan 1994
Externally publishedYes


  • anephric patients and rats
  • brefeldin A
  • Caki- 2
  • extracellular enzyme
  • parietal epithelial cells
  • patients with renal failure on dialysis
  • selenium

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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