| |
Software Requirements
Microsoft Internet Explorer 5.01 or higher and Netscape Navigator 4.75 or higher are recommended. |
|
 |
J.Health Sci., 51(2), 138-146, 2005
Influence of Dietary Protein Levels on the Fate of
Methylmercury and on Amino Acid Transport at the Renal Brush Border Membrane in Rats
Tatsumi Adachi*, a and Kimiko
Hirayamab
aDepartment of Basic Medical Sciences, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto
867-0008, Japan and bKumamoto University College of Medical Science, 4-24-1 Kuhonji, Kumamoto 862-0976, Japan
We investigated the influence of dietary protein levels on the fate of methylmercury (MeHg) in rats, and the
difference in its urinary excretion was discussed from the viewpoint of the dietary protein level-dependent
alteration in activity of the neutral amino acid transport system, through which MeHg metabolites such as
MeHg-L-cysteine are reabsorbed, at the renal brush border membrane. When MeHg was administered to rats fed either a
24.8% protein diet (normal protein diet, NPD) or a 7.5% protein diet (low protein diet, LPD), urinary Hg
excretion was much lower in LPD-fed rats than in NPD-fed rats, whereas no difference was observed in fecal
excretion 1 day after MeHg administration. At that time, Hg concentrations in the brain and plasma were similar in the
two dietary groups, whereas the concentrations in liver and blood were higher, but the renal concentration was
lower in LPD-fed rats than in NPD-fed rats. Regardless of the presence of
Na+, uptake of 14C-L-phenylalanine
for the first 20 sec was higher in the renal brush border vehicles from LPD-fed rats than in those from NPD-fed
rats. These results suggest that dietary protein deficiency enhances the neutral amino acid transport at the renal
brush border membrane, which could lead efficient reabsorption of MeHg metabolites from the proximal
luminal space, and it might play a key role in the marked decrease in urinary excretion of MeHg.
|
|
