Potassium citrate administration ameliorates tubulointerstitial lesions in rats with uric acid nephropathy.

Although controversial, chronic uric acid nephropathy is a tubulointerstitial disease capable of developing renal function loss. On the other hand, potassium citrate (KCi) administration has demonstrated to be effective in calcium as well as uric acid nephrolithiasis therapy. Therefore, the aim of the present study was to evaluate the possible benefit of KCi treatment in the prevention or amelioration of renal interstitial damage in uric acid nephropathy. Two-month-old male Sprague-Dawley rats were divided into 3 groups: G1 hyperuricemic (HU), G2 hyperuricemic + KCi (HU+KCi), and G3 KCi. G1 and G2 were fed on oxonic acid (inhibitor of rat liver uricase), and a uric acid supplement, during 4 weeks. G2 and G3 were given 2% KCi in drinking water, and G1 regular tap water and standard rat chow. At the end of the study, renal tissue was processed for light and electron microscopy and immunostaining by alpha-smooth muscle actin (SMA). Tubulointerstitial lesions and the amount of alpha-SMA immunostaining in renal tissue were evaluated by histomorphometric quantitation. Rats belonging to the hyperuricemic groups treated with KCi (G2) showed fewer tubulointerstitial lesions as follows: % tubular atrophy: 1.7 +/- 0.3 versus 7.2 +/- 1.2, p < 0.05; inflammatory cells infiltrate (number of cells/area): 0.6 +/- 0.1 versus 2.4 +/- 0.2, p < 0.01; % interstitial fibrosis (cortex): 3.3 +/- 0.3 versus 9.3 +/- 0.5, p < 0.05; % interstitial fibrosis (medulla): 5.2 +/- 0.3 versus 21.9 +/- 1.2, p < 0.01, lower albuminuria (32.8 +/- 11.2 mg/day versus 128.5 +/- 10.4, p < 0.01), higher creatinine clearance ( 1.36 +/- 0.02 ml/min versus 0.74 +/- 0.01, p < 0.01 ) and less percentage of alpha-SMA in renal tissue (1.8 +/- 0.1 versus 10.5 +/- 1.4, p < 0.05), when compared with the hyperuricemic group not treated with KCi (G1). These data suggest that KCi administration could provide a substantial benefit in the regard to tubulointerstitial lesion and progressive renal damage.