PATHOGENESIS OF GLOMERULAR INJURY IN THE FAWN-HOODED RAT - EFFECT OF UNILATERAL NEPHRECTOMY

Fawn-hooded (FH) rats with congenital proteinuria and systemic and glo merular hypertension are very susceptible to renal damage at a young a ge. In this study, the effects of unilateral nephrectomy (UNX) on the function and structure of the remaining kidney in the FHH substrain we re assessed. A long-term study was performed to determine the changes in systemic blood pressure, renal function, and proteinuria during the development of chronic renal failure in UNX-FHH and two-kidney (2K) F HH rats. Renal micropuncture and morphologic studies were performed at 4 wk after surgery. The long-term study showed that, after UNX, systo lic blood pressure did not differ significantly from that of 2K-FHH ra ts. After UNX, there was compensatory hyperfiltration, at about 70% of the 2K level, that could be maintained for 12 wk only. The subsequent fall in GFR was preceded by severe proteinuria. The mean survival tim e of UNX-FHH rats was only 35 wk. Micropuncture studies showed that th e high mean glomerular capillary pressure of 2K-FHH rats was further e levated after UNX. The glomerular capillary ultrafiltration coefficien t did not differ significantly between UNX-FHH and 2K-FHH rats. The we ight of the remaining kidney and the mean glomerular tuft volume in UN X-FHH were, on average, 36 and 31% greater than in 2K rats. The result s indicate that the FHH rat is extremely vulnerable to the adverse ren al effects of UNX. A comparison of the hemodynamic and structural data of this study with those reported for other rat strains indicated tha t the severe glomerular hypertension, but not the degree of glomerular hypertrophy, underlies the high susceptibility to renal damage in UNX -FHH rats.