beta-Adrenergic mechanism of mammalian cells radioprotection by isoproterenol

In experiments on fibroblasts of Chinese hamster (B II d ii FAF-28, clone 431) it is shown that the specific beta-agonist isoproterenol causes an increase in the intracellular content of cAMP and a decrease in radiosensitivity of the cells. The beta-antagonist propranolol blocks the appearance of the above effects due to isoproterenol. Isoproterenol fails to affect either the intracellular cAMP level or radiosensitivity of mice fibroblasts L, clone B-82, endowed with a functioning adenylate cyclase system but deprived of beta-adrenergic receptors. It is presumed that an increase in radioresistance of mammalian cells due to the effect of isoproterenol is possible only in the presence of beta-receptors in the cells and that it is realized through the beta-adrenergic mechanism.