Effects of amifostine on radiation-induced cardiac damage.

The purpose of this study was to investigate whether administration of amifostine prior to irradiation could reduce radiation damage of the rat heart. Female Spraque-Dawley rats were randomized to receive single-dose irradiation (0-22.5 Gy) locally to the heart. Fifteen to twenty minutes before radiation exposure, the animals received either intraperitoneally administered amifostine (160 mg/kg) or buffered saline solution. At 6 months post-irradiation, cardiac function was assessed by the in vitro working rat heart preparation. The severity of interstitial and/or perivascular fibrosis in different anatomical regions of the rat heart was assessed using a semi-quantitative scoring system. Radiation exposure to doses > or = 20 Gy markedly reduced coronary flow, aortic flow and cardiac output. Administration of amifostine prior to radiotherapy afforded protection against these effects and normal cardiac output was maintained, even after 22.5 Gy. A small, non-significant, reduction in histological damage (i.e. perivascular fibrosis and interstitial fibrosis) was also apparent in animals treated with amifostine. There was a clear protective effect of amifostine on the severity and extent of macroscopic damage in lung tissue included in the cardiac irradiation field. The findings of this study suggest that a single dose of amifostine administered prior to irradiation is effective in reducing cardiac damage.