We previously reported that in hyperuricemic rats, renal impairment occurred and organic ion transport activity decreased, accompanied with a specific decrease in the expression of rat
organic anion transporters, rOAT1 and rOAT3, and organic
cation transporter, rOCT2. In the present study, we investigated the reversibility of the organic ion transport activity and expression of organic ion transporters (slc22a) during recovery from
hyperuricemia.
Hyperuricemia was induced by the administration of a chow containing
uric acid and
oxonic acid, an inhibitor of
uric acid metabolism. Four days after discontinuance of the chow, the plasma
uric acid concentration returned to the normal level, and renal functions such as
creatinine clearance and BUN levels were restored, although the recovery of tubulointerstitial injury was varied in sites of the kidney. Basolateral uptake of
p-aminohippurate (PAH) and
tetraethylammonium (
TEA), and both
protein and
mRNA levels of rOAT1, rOAT3 and rOCT2 in the kidney gradually improved during 14 days of recovery from
hyperuricemia. Basolateral PAH transport showed a higher correlation with the
protein level of rOAT1 (r(2)=0.80) than rOAT3 (r(2)=0.34), whereas basolateral
TEA transport showed a strong correlation with rOCT2
protein (r(2)=0.91). The plasma
testosterone concentration, which is a dominant factor in the regulation of rOCT2, was gradually restored during the recovery from
hyperuricemia, but the correlation between the plasma
testosterone level and rOCT2
protein expression in the kidney was not significant. These results suggest that the regulation of organic ion transporters, rOAT1, rOAT3 and rOCT2, by
hyperuricemia is reversible, and the organic ion transport activity restores according to the expression levels of these transporters.