title: L-cysteine influx in erythrocytes as a function of human age.
abstract: In erythrocytes, although three amino acids are required for the synthesis of reduced glutathione (GSH), the rate of GSH synthesis is determined only by the availability of L-cysteine. Cysteine supplementation has been shown to ameliorate several parameters that are known to degenerate during human aging; this has led to an interesting hypothesis that aging could be a cysteine deficiency syndrome. In the present study, we measured L-cysteine influx in human erythrocytes by suspending cells in solution containing 10 mM L-cysteine. We show a significant decline in the influx of L-cysteine in erythrocytes during aging in humans. The decrease in cysteine influx correlates with the decrease in antioxidant potential of plasma measured in terms of FRAP (ferric-reducing ability of plasma) during aging. We conclude that a decreased influx of L-cysteine may be an important factor contributing to the development of oxidative stress in human erythrocytes during aging.
authors.affiliation: Department of Biochemistry, University of Allahabad, Allahabad, India. rzv@rediffmail.com
authors.forename: Syed Ibrahim
authors.initials: SI
authors.lastname: Rizvi
authors.forename: Pawan Kumar
authors.initials: PK
authors.lastname: Maurya
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress
chemical_list: D003545:Cysteine