Radiation nephropathy in rats and its modification by the angiotensin converting enzyme inhibitor enalapril

The ability of prophylactic enalapril treatment to prevent or retard the development of radiation-induced nephropathy was studied in male Wistar rats.

Prior to irradiation, the rats were randomized to groups receiving enalapril or no treatment, and both kidneys of rats were irradiated with either a 10 Gy single dose or 26 Gy at a rate of 2 Gy per fraction per day. Renal function was assessed prior to radiotherapy and at intervals of 8 weeks thereafter. A subgroup of animals was sacrificed for histopathology at 4, 8, 16, and 24 weeks after irradiation.

At 16 weeks after irradiation, renal function showed deterioration without any significant differences between groups. At 24 weeks after irradiation, all irradiation dose groups with or without enalapril treatment showed some improvement in functional terms. Morphological evaluation revealed that enalapril had a marked beneficial effect on renal radiation injury in the 10 Gy single-dose group and at 8 weeks after irradiation. At 16 weeks after irradiation the histological appearance of the dose groups with or without enalapril treatment was similar.

We conclude that enalapril, when used preventively from the time of irradiation, has a beneficial effect only after high doses per fraction and at the early phases of renal radiation injury.