OBJECTIVETo investigate the effect of L-arginine (L-arg) on early compensatory renal growth (CRG), tubulointerstitial accumulation of extracellular matrix (ECM), long term survival rate and renal scarring in rats with 5/6 nephrectomy (SNx).

METHODSThe experiment included four groups of rats (n = 5 each group): (1) Sham group, (2) SNx group, (3) SNx + L-arg group, and (4) Sham + L-arg group (L-arg 1% in drinking water). Parameters related with CRG and early tubulointerstitial expression of ECM and alpha smooth muscle actin (alphaSMA) were evaluated by immunohistochemistry at day 30. The survival rate and the extent of renal scarring in the rats were observed at day 120.

RESULTSL-arg significantly increased the early CRG of SNx rats as determined by the wet kidney weight (P < 0.05), total protein (P < 0.01), and DNA content (P < 0.001) of the remnant kidney. The cell proliferation in the tubulointerstitium as determined by immunostaining for proliferative cell nuclear antigen (PCNA) also markedly increased (P < 0.05). Furthermore, glomerular volume (Vg) in the SNx rats treated by L-arg increased 16% compared with that in the SNx group (P = 0.06). More specifically, L-arg significantly increased the interstitial immunostaining for collagen III, IV, and fibronectin (P < 0.05, 0.01, respectively), which were positively correlated with the increased expression of alpha-SMA (P < 0.001, respectively). In the long term experiment, L-arg significantly reduced the survival rate (P < 0.05) and increased the severity of renal scarring in the SNx rats (P < 0.05).

CONCLUSIONThis preliminary study suggested that early supplementation with L-arg might exacerbate the progression of renal scarring in rat remnant kidney.