Methylmercury–Cysteine Uptake by Rat Erythrocytes: Evidence for Several Transport Systems

✍ Scribed by Guang Wu

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 809 KB
• Volume: 16
• Category: Article
• ISSN: 0260-437X
• DOI: 10.1002/(sici)1099-1263(199601)16:1<77::aid-jat319>3.0.co;2-c

✦ Synopsis

The present study is a continuation of our experiments on methylmercury-cysteine (MeHg-cysteine) uptake by rat red blood cells (RBCs) at low temperature. Methylmercury-cysteine uptake by rat RBCs was conducted at 5°C and 2OOC. The effects of Ca2+, colchicine, cytochalasin B, 4,4'-diisothiocyano-2,2'-stilbenedisulphonic acid (DIDS), N-ethylmaleimide (NEM), D-glucose, hexanol, L-homocysteine, ouabain, probenecid, sodium fluoride (NaF), vinblastine, and anisotonic changes on MeHg-cysteine uptake were examined. The results showed that MeHg-cysteine uptake at 5°C could be described by Michaelis-Menten kinetics (v = V,,,S/(S + K,), where K , = 37.02 mM and V,,, = 320.84 mmol I-' RBCs h-I), but MeHg-cysteine uptake at 20°C could be described by Michaelis-Menten kinetics with a linear component ,,,J/(S + K,)] + KdS, where K , = 2.71 mM, V,,, = 250.72 mmol I-' RBCs h-', and Kd = 5.63 mM).

Methylmercury-cysteine uptake was inhibited by colchicine, cytochalasin B, D-glucose, hexanol, NaF, NEM, ouabain, probenecid, vinblastine and 230 mosM hypotonicity but stimulated by Ca2+, DIDS, L-homocysteine and 460 mosM hypertonicity. The results in the present study suggest that MeHg-cysteine uptake by rat RBCs might be involved in the following three transport systems: an energy transport system sensitive to Ca2+, ouabain and NaF and subjected to Michaelis-Menten kinetics; an organic anion transport system sensitive to probenecid; and a facilitated diffusive transport for D-glucose sensitive to cytochalasin B. It is likely that most of the transport systems work at temperatures higher than 5°C.