THE ROLE OF SECRETORY GRANULES IN RADIATION-INDUCED DYSFUNCTION OF RAT SALIVARY-GLANDS

To investigate the possible role of secretory granules in radiation-in duced salivary gland dysfunction, rats were pretreated with isoprotere nol (5 mg/kg intraperitoneally) to degranulate salivary gland acini, A t maximal depletion, salivary glands were locally irradiated with a si ngle dose of 15 Gy of X rays. Parotid and submandibular/sublingual sal iva samples were collected before and 1-10 days after irradiation, The lag phase, flow rate, concentrations of potassium and sodium, and amy lase secretion were determined. Sham-treated, isoproterenol-treated an d irradiated animals provided reference data. In the parotid gland, bu t not in the submandibular gland, protection against radiation-induced changes in flow rate and composition of saliva occurred after pretrea tment with isoproterenol. Combining morphological data from a previous study with data from the current study, it is suggested that improvem ent of parotid gland function is attributed predominantly to a prolife rative stimulus on acinar cells by isoproterenol and not to its degran ulation effect, After pretreatment with isoproterenol, an earlier expr ession of radiation-induced acinar cell damage leading to death was ob served, followed by a faster tissue recovery, Thus the proliferative s timulus on acinar cells may accelerate the unmasking of latent lethal damage, resulting in the earlier replacement of dead cells by new, fun ctionally intact cells. (C) 1995 by Radiation Research Society