Radioprotective effect of amifostine on parotid gland functioning is region dependent.

Abstract

To investigation the protective ability of amifostine during partial irradiation of the rat parotid gland. Single-dose X-ray irradiation was performed by use of collimators with conformal radiation portals for either the 100% volume (15 Gy) or the 50% cranial/caudal partial parotid gland volumes (30 Gy). Amifostine was administered intraperitoneally at a dose of 250 mg per kg body weight, 25 minutes before irradiation. Saliva flow rates, gland weights, and the tissues of the individual lobes were investigated up to 1 year after treatment. A clear protective effect of amifostine was found against loss of saliva flow, the altered appearance of gross morphology, loss of gland weight, and histopathologic changes for the 100% volume gland irradiations and for the 50% volume cranial irradiations but not for the 50% volume caudal irradiations. The protective ability of amifostine is strongly dependent on the irradiated glandular region and observed for later damage only. The major effect of the drug seems to be the prevention of volume effects caused by secondary damage that occurs in shielded parts of the gland. The results of the present study show that understanding of the anatomy and physiology of organs that are to be spared is necessary to ensure optimal preservation of function.