Uptake of Methylmercury Cysteine by Rat Erythrocytes at Lower Temperature

✍ Scribed by Guang Wu

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 734 KB
• Volume: 16
• Category: Article
• ISSN: 0260-437X
• DOI: 10.1002/(sici)1099-1263(199603)16:2<95::aid-jat332>3.0.co;2-s

✦ Synopsis

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+, Mgz+ and membrane potential on MeHg-cysteine uptake were examined. The results showed that MeHg-cysteine uptake was temperaturedependent, 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, p-alanine, cysteine sulphinic acid (CSA), y-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.

Erythrocyte samples

The rats were anaesthetized with diethyl ether and the blood was taken from hearts into heparinized syringes and then centrifuged at 1500 rpm for 15 min to CCC 0260437X/96/02009548