Purpose: Despite an increasing usage of old or marginal donor kidneys in renal transplantation, little attention has been directed to the structural and functional changes occurring in the remnant kidney of old donor. In this study, the functional and structural changes were assessed in the remnant rat kidneys of early stages of aging after uninephrectomy (UNx) and compared with that of young rats.
Methods: Twelve month-old and 7～9 week-old Sprague- Dawley (SD) male rats underwent UNx and were sacrificed following 1, 3, and 5 weeks after UNx. Extract and Sham- operated kidneys were used as control. Serum creatinine, 24hr urinary protein excretion, and urinary nitric oxide (NO) were measured. The extract kidneys were examined for routine histology and also for immunohistochemical stains for ED-1, inducible NO synthase (iNOS), and PCNA and TUNEL assay.
Results: In control rats, there was no difference in 24hr urine protein excretion and urinary NO level between old and young rats. However, the mean serum creatinine level was higher in old rats than that of young rats. After UNx, urinary NO level was significantly increased in old but not in young rats, without accompanying a significant increase of proteinuria or serum creatinine level. Histological injuries of remnant kidneys were not significantly increased after 5 weeks in old rats. However, TUNEL indices were persistently increased at 5 weeks with a return of PCNA indices to a basal level, The number of ED-1 positive cells and interstitial iNOS expression were also increased in remnant kidney of old rats, however, they were not statistically significant.
Conclusion: UNx does not seem to affect the short-term renal function or histology in 12-month-old rats. However, persistent increase of TUNEL indices at 5 weeks may suggest parenchymal atrophy and a functional decrease in the long-run. A longer observation may be necessary to predict long-term sequelae of UNx in old rats. (J Korean Soc Transplant 2005;19:14-21)
|