FRACTIONATED-IRRADIATION AND LATE CHANGES IN RAT PAROTID-GLAND - EFFECTS ON THE NUMBER OF ACINAR-CELLS, POTASSIUM EFFLUX, AND AMYLASE SECRETION

Irradiation of head- and neck cancer commonly results in oral dryness and discomfort for the patients due to salivary gland damage. The exac t mechanisms behind the inherent radiosensitivity of salivary glands r emain to be elucidated. In the present study, we used different in vit ro secretory models and quantitative morphological characterization of rat parotid gland following fractionated unilateral irradiation to on e gland on a 5-day fraction schedule (Monday-Friday) with 6 MV photons (total dose 30, 35, 40 and 45 Gy) or a two-fractions regimen in 5 day s (Monday and Friday) with total dose of 24 and 32 Gy. The contralater al shielded gland served as control, and parallel analyses of irradiat ed and control glands were performed 180 days following the last irrad iation treatment. The relative noradrenaline stimulated electrolyte se cretion (rubidium-86 tracer for potassium) was decreased in the irradi ated compared with control glands. The noradrenaline-stimulated exocyt otic amylase release was not significantly affected by irradiation, bu t the gland content of amylase was decreased dose-dependently. The qua ntitative morphological analysis revealed a dose-dependent decline in the number of acinar cells, whereas the other parenchymal cells (inter calated, striated- and excretory duct cells) were un-, affected by the irradiation compared with control glands.