L-cysteine influx and efflux in human erythrocytes: the role of red blood cells in redox and metabolite homeostasis in the plasma
Yükleniyor...
Tarih
2006
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Pharmaceutical Soc Japan
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
The objective of this study was to investigate L-cysteine influx and efflux in human erythrocytes. L-cysteine is an amino acid required for glutathione synthesis in erythrocytes. In addition to being incorporated into glutathione, the soluble antioxidant L-cysteine plays a role in the maintenance of a proper intracellular or extracellular redox status. Recent investigations have pointed out that L-cysteine may contribute to redox homeostasis in the plasma and in the periplasm of some bacteria. Thus L-cysteine availability in the plasma may influence the oxidized/reduced state of several other metabolites normally found in the plasma. Our L-cysteine uptake studies demonstrated that erythrocytes can respond to an increase in the L-cysteine concentration in the extracellular media and influx L-cysteine in a concentration dependent-manner. The L-cysteine efflux is also time and concentration dependent. Erythrocytes pretreated with higher concentration of L-cysteine displayed higher efflux rates. Erythrocytes pretreated with L-cysteine 1 mM displayed efflux and increased the free-SH concentrations up to 0.184 +/- 0.010 mM in the incubation media in 1 hr. While this concentration reached 0.843 +/- 0.012 mM in 10 mM-L-cysteine pretreated erythrocytes. Our results also showed that the L-cysteine efflux is partly mediated by the Alanine-Serine-Cysteine (ASC) system. The presence of alanine or serine in the incubation media decreased the rate of efflux by about 16%. Our results also showed that the L-cysteine efflux process is not a simple diffusion but a carrier-mediated process. When compared with N-acetyl-L-cysteine (NAC), which is known to diffuse through the membranes, L-cysteine displayed a higher efflux rate under the same conditions. Pretreatment of erythrocytes with L-cysteine 4 mM increased the free-SH concentration to 0.48 +/- 0.005 mM whereas the same concentration of NAC brought the free-SH concentration to 0.36 +/- 0.01 mM in the incubation media. Our results suggest that erythrocytes may contribute to redox and metabolite homeostasis of the plasma.
Açıklama
Anahtar Kelimeler
erythrocytes, cysteine efflux, redox homeostasis
Kaynak
Journal of Health Science
WoS Q Değeri
Q4
Scopus Q Değeri
N/A
Cilt
52
Sayı
2
