X-irradiation induced degranulation of cells of convoluted granular tubules of murine submandibular salivary glands.

A single dose of 800 rad x-irradiation was shown to cause degranulation of the cells of the convoluted granular tubules of adult male Swiss white mice. By direct immunofluorescence, the degranulation was found to be associated with loss of immunoreactive epidermal growth factor (EGF) from the convoluted granular tubules. Immunoreactive EGF was found in some cells of tubules that were severely degranulated, and this was interpreted to be related to the greater sensitivity of the immunofluorescence method. The degranulation progressed from 2 h post-irradiation to be complete by 2 days, from which time a slow return to normal granular appearance and EGF-positive immunofluorescence occurred by 76 days. It was found that the degranulation process could be inhibited by the alpha-adrenergic blocking drug phentolamine (1 mg/ml in drinking water) suggesting that the effect of the x-irradiation was at least partly mediated by way of an alpha-adrenergic mechanism. It was speculated that this mechanism could have derived from an effect of the x-irradiation on neural elements, or by way of increased circulating catecholamines caused by the stress of the x-irradiation, in addition to direct effects of irradiation on the cells of the convoluted granular tubules.