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Publication Type
Journal Article
Author, Analytic
Reid, M. ; Badaloo, A. ; Forrester, T. ; Jahoor, F.
Author Affiliation, Ana.
Tropical Medicine Research Institute
Article Title
In vivo rates of erythrocyte glutathione synthesis in adults with sickle cell disease
Medium Designator
n/a
Connective Phrase
n/a
Journal Title
Am J Physiol Endocrinol Metab
Translated Title
n/a
Reprint Status
n/a
Date of Publication
2006
Volume ID
291
Issue ID
1
Page(s)
E73-9
Language
eng
Connective Phrase
n/a
Location/URL
n/a
ISSN
0193-1849 (Print)
Notes
n/a
Abstract
Despite reports of lower GSH concentration in sickle cell disease (SCD), the in vivo kinetic mechanism(s) responsible for GSH deficiency is unknown. To determine whether suppressed synthesis was responsible for the lower erythrocyte GSH concentration, we used a primed intermittent infusion of [(2)H(2)]glycine to measure erythrocyte GSH synthesis in vivo in 23 individuals with homozygous beta(s) SCD and 8 healthy controls. Erythrocyte cysteine concentration, the rate-limiting precursor for GSH synthesis, plasma markers of oxidant damage, and dietary intakes of energy and protein were also measured. Compared with values of controls, SCD subjects had significantly lower erythrocyte GSH (P < 0.04) and cysteine concentrations (P < 0.004) but significantly faster fractional rates of GSH synthesis (P < 0.02). The absolute rates of GSH synthesis in SCD subjects compared with control subjects was greater by approximately 57% (P = 0.062). However, the concentrations of markers of oxidative damage, plasma derivatives of reactive oxygen metabolites, plasma nitrotyrosine, urinary isoprostane-to-creatinine ratio, and GSH-to-GSSG ratio, as well as dietary intakes of energy, protein, and GSH precursor amino acids, were not different between SCD subjects and controls. The findings of this study suggest that the lower erythrocyte GSH of SCD patients is not due to suppressed synthesis or impaired regeneration but rather to increased consumption. In addition, the lower erythrocyte cysteine concentration plus the faster rate of GSH synthesis strongly suggest that the endogenous cysteine supply is not sufficient to meet all anabolic demands; hence, cysteine may be a conditionally essential amino acid in individuals with SCD.....
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