High incidence of glomerular sclerosis in rats subjected to uninephrectomy at young age.

To examine the effect of age on a compensatory renal growth, adaptive renal hemodynamics and renal histology in solitary kidney, unilateral nephrectomy was performed in young rats at 4 weeks of age (group 4-UN) or in adult rats at 10 weeks of age (group 10-UN). Urinary protein was measured every 4 weeks until the 48th week. Serial changes in kidney weight, glomerular filtration rate (GFR), renal plasma flow (RPF) and renal histology were investigated at weeks 4, 8, 24 and 48 after the uninephrectomy. Increase in proteinuria was significantly greater in group 4-Un than in group 10-UN from weeks 32-48 after uninephrectomy. The remnant kidney showed a compensatory enlargement which was more marked in group 4-UN than in group 10-UN at weeks 24 and 48. GFR or RPF in group 4-UN was significantly greater than that in group 10-UN at weeks 4, 8, and 24. Focal and segmental glomerular sclerosis was evident at week 24 or later in the uninephrectomized rats, being more severe in group 4-UN than in group 10-UN at week 48. We conclude that uninephrectomy in young rats leads to augmented compensatory renal growth and glomerular hyperperfusion, resulting in extensive glomerular sclerosis compared to that in adult rats.