K. Uriu et al., Long-term oral intake of low-dose cadmium exacerbates age-related impairment of renal functional reserve in rats, TOX APPL PH, 169(2), 2000, pp. 151-158
Our study was designed to clarify whether renal functional reserve (RFR) wa
s impaired in rats chronically treated with oral low-dose cadmium (Cd). Rat
s (n = 15) were treated with 1 ppm of cadmium chloride added to drinking wa
ter. We measured RFR (representing the ability to increase glomerular filtr
ation rate [GFR] and renal plasma how [RPF] in response to infusion of glyc
ine) at 2 and 10 months after initiation of exposure to Cd. Urinary excreti
on of Cd was significantly higher in 10-month Cd-treated rats than in age-m
atched control rats (provided with distilled water only). Weight gain was n
oted in Cd-treated rats, which was identical to that in age-matched control
rats. Urinary volume and urinary excretions of sodium, protein, and glucos
e were similar in the two groups. There were no differences in the basal me
an arterial pressure (MAP) and renal hemodynamics between 2-month Cd-treate
d and age-matched control rats. Infusion of glycine resulted in significant
increases in GFR and RPF and a significant reduction in renal vascular res
istance (RVR) in both 2-month Cd-treated and age-matched control rats (cont
rol, GFR: 133 +/- 10%, RPF: 148 +/- 8%; 2-month Cd-treated rats, GFR: 152 /- 12% and RPF: 154 +/- 7%). The basal MAP and renal hemodynamics in 10-mon
th Cd-treated rats were also identical to those in age-matched control rats
. Infusion of glycine significantly increased GFR in 10-month control rats
(132 +/- 15%), but not in 10-month Cd-treated rats (98 +/- 11%), but did no
t change MAP, RPF, and RVR in both groups. In addition to age-related patho
logical changes, mild renal interstitial edema and degenerative mitochondri
a with diminished matrix density and loss of the cristae in the proximal tu
bular cells were more frequent in 10-month Cd-treated rats. Our results sug
gest that long-term oral intake of low-dose Cd in rats exacerbate age-relat
ed impairment of renal functional reserve and degeneration of the proximal
tubular epithelial cells. (C) 2000 Academic Press.