GLOMERULAR HYPERTROPHY AFTER SUBTOTAL NEPHRECTOMY - RELATIONSHIP TO EARLY GLOMERULAR INJURY

Structural adaptations in response to approx. 70% nephrectomy were stu died in male Sprague-Dawley rats. Rats developed systemic hypertension as well as progressive albuminuria after nephrectomy. At 18-26 weeks after nephrectomy (n=6) or sham treatment (n=6) kidneys were perfusion -fixed and examined by light and electron microscopy. Glomerular tuft volume (+140%), capillary volume (+151%) and length (+77%), mesangial volume (+115%), podocyte volume (+96%), glomerular basement membrane s urface area (+107%) and filtration slit length (+85%) were all signifi cantly greater in nephrectomized rats. The incidence of segmental glom erular sclerosis was low and variable among these rats, but was signif icantly higher than in controls (P=0.037). Urinary albumin excretion w as elevated in the nephrectomized rats (89+/-72 SD mg/day vs 11+/-11 m g/day in control rats, P=0.01) and correlated significantly with the i ncidence of sclerosis (r=+0.8311, P<0.05). The relationships of the le vel of albuminuria and the sclerosis rate to various morphometric para meters were examined by regression analysis for the nephrectomy group. A significant negative correlation was found between albuminuria and average tuft volume (r=-0.8136) and glomerular basement membrane surfa ce area (r=-0.8168). Both sclerosis rate and albuminuria showed negati ve correlations with filtration slit length (r=-0.8180 and r=-0.8598). These findings suggest that under some circumstances, glomerular hype rtrophy may prevent or ameliorate the early stages of glomerular injur y after subtotal nephrectomy.