GLYCINE PREVENTS TOXIC TUBULAR CELL INJURY

Glycine prevents tubular injury as suggested by in vitro cell culture studies, studies in the isolated perfused kidney, and in vivo studies. We have previously demonstrated that intratubular administration of u ranyl nitrate (UN) produces proximal tubular cell injury and decreases proximal tubular reabsorption (APR). The decrease in APR activates tu buloglomerular feedback and lowers nephron filtration rate (SNGFR). Th is study was designed to evaluate if glycine administration could prev ent the decrease in SNGFR after UN administration and if maintenance o f SNGFR was due to tubular cell cytoprotection or suppression of the t ubuloglomerular feedback. Administration of 0.65 ng of UN into the ear ly proximal tubule was associated with a decrease in distal SNGFR (SNG FR(D)) from 29 +/- 2 to 24 +/- 2 nL/min (p < .05) and late proximal SN GFR (SNGFR(LP)) from 37 +/- 2 to 26 +/- 2 nL/min, and APR from 14 +/- 1 to 10 +/- 1 nL/min. Systemic administration of glycine (20 g/dL, 1.4 mL/h) was associated with significant increases in SNGFR(D) and SNGFR (LP), and APR (38 +/- 3, 44 +/- 3, and 15 +/- 2 nL/min). UN administra tion did not affect APR or SNGFR in glycine-treated rats. These findin gs demonstrate that glycine prevents UN-induced decreases in SNGFR thr ough a cytoprotective effect on proximal tubular cells.