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Uptake of Methylmercury Cysteine by Rat Erythrocytes at Lower Temperature
Author(s) -
Wu Guang
Publication year - 1996
Publication title -
journal of applied toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.784
H-Index - 87
eISSN - 1099-1263
pISSN - 0260-437X
DOI - 10.1002/(sici)1099-1263(199603)16:2<95::aid-jat332>3.0.co;2-s
Subject(s) - cysteine , chemistry , taurine , phenylalanine , amino acid , methionine , cysteic acid , serine , glycine , biochemistry , alanine , cystine , tryptophan , enzyme
Methylmercury cysteine (MeHg–cysteine) uptake by rat erythrocytes (RBC) was undertaken at 5 and 20°C. The effects of several amino acids, their derivatives, ATP, Na+, Mg2+ and membrane potential on MeHg–cysteine uptake were examined. The results showed that MeHg–cysteine uptake was temperature‐dependent, Na+‐dependent at 20°C, partly Na+‐dependent at 5°C and Mg2+‐dependent at 5 and 20°C. The membrane potential had a very slight effect on MeHg–cysteine uptake. N‐Acetyl‐ l ‐cysteine (AC), alanine, β‐alanine, cysteine sulphinic acid (CSA), γ‐aminobutyric acid (GABA), d ‐phenylalanine, phenylalanine, serine and taurine inhibited MeHg–cysteine uptake at 5°C. Tryptophan both stimulated and inhibited at different sampling times at 5°C. Glycine and methionine had stimulation at 5°C. Aspartic acid, isoleucine, leucine and tyrosine had no effect on MeHg–cysteine uptake. GABA, d ‐phenylalanine and tryptophan lost their effects at 20°C. The effects of glycine and serine had reversed at 20°C. The half‐time of MeHg–cysteine uptake was ca. 0.57 h at 5°C and 0.23 h at 20°C. Several amino acids and their derivatives had an influence on the half‐times of MeHg–cysteine uptake. The present study suggested that MeHg–cysteine uptake by rat RBC at lower temperature involved several overlapping transport systems; the greatest contribution was likely to be due to system ASC. Direct evidence for system L in MeHg–cysteine uptake was not obtained in the present study.