[Apoptosis in the early stage of compensatory renal growth following uninephrectomy in the young and old rats]

Abstract

Objective: To investigate the role of apoptosis, one of the major factor to maintain homeostasis of cell number of organs, in the early process of compensatory renal growth, which have been considered to including cellular hyperplasia and hypertrophy, following uninephrectomy.

Method: DNA fragment gel electrophoresis, tissue sections photolebeling technique and in situ nick translation assay were used to analyze apoptotic cells in the compensatory and normal kidney in the young and old Wistar rats.

Results: Apoptosis affected normal kidney of the old group, but not the young. In the old rat's normal kidney, apoptosis index was higher in cortical tubules than that in the medullar tubules. In the compensatory remnant kidney, apoptosis was diminished in old rats, especially in the cortex, but increased in the young rats, especially in the medulla.

Conclusions: Compensatory renal growth includes cellular hypertrophy, hyperplasia and apoptosis. In the old, compensatory renal growth is mainly cellular hypertrophy, and reduction of cell death. In the young, compensatory renal growth is mainly cellular hyperplasia and hypertrophy, increased apoptosis may be responsible for the elimination of excess hyperplastic renal cell.