Roles of reactive oxygen species and nitric oxide in compensatory renal and glomerular hypertrophy after uninephrectomy *
It is well known that compensatory renal hypertrophy is induced after a reduction in the number of nephrons. Both reactive oxygen species（ROS）and nitric oxide（NO）have been reported to be implicated in this process. However, the precise roles of ROS and NO in compensatory glomerular and renal hypertrophy remain to be elucidated. Therefore, to clarify the precise roles of ROS and NO in compensatory glomerular and renal hypertrophy after uninephrectomy, we examined the production of ROS and NO in the remaining kidney after uninephrectomy. Wistar rats were divided into three groups（a Sham-operation group（Sham），a Uninephrectomy group（1/2NX）and a group treated with tempol（3mol/l in drinking water）after uninephrectomy（1/2NX＋Tempol）．Rats were sacrificed at 12 hours, 48 hours, 1 week, and 4 weeks after uninephrectomy. At each time point we measured serum creatinine, urinary protein excretion and kidney weight. We also evaluated the production of ROS and NO by an in situ visualizing method using fluorescence that we developed recently. There were no significant changes in serum creatinine, urinary protein excretion and mean blood pressure. Glomerular volume significantly increased in the 1/2NX group from 12 hours and peaked at seven days after uninephrectomy compared to the Sham group（p＜0.05）．Renal ROS production in the 1/2NX group was greatest on day 7. These increases in glomerular volume and ROS were diminished by tempol. On the other hand, NO production in glomeruli peaked at 12 hours, and then gradually decreased to the base level by day 7. Furthermore, phosphorylation of Akt and ERK was observed at four weeks, but this was inhibited by tempol. Taken together, we can conclude that the transient increase in NO after uninephrectomy may be related to early phase glomerular hypertrophy due to vasodilation and that glomerular and renal hypertrophy in the kidney after the early phase may be related to the increase in ROS. (Accepted on 19 October，2006)
