Production of microliths and sialadenitis in rats by a short combined course of isoprenaline and calcium gluconate.

The relationship between microliths and sialadenitis in man is unclear, so an attempt was made to investigate it experimentally in rats with the use of isoprenaline and calcium gluconate either alone or combined. The acini of the submandibular and parotid glands of rats that were given isoprenaline were enlarged, and degenerate acinar cells were seen, with extravasated secretions in the submandibular gland. Similar changes were seen in the submandibular and parotid glands of rats that were given isoprenaline combined with calcium gluconate; in addition, ductal microliths with regions of atrophic sialadenitis were observed. The results suggest that there is temporary obstruction to the salivary flow after isoprenaline is injected, and in the rats that were also given calcium gluconate some of the stagnant saliva calcified to form microliths, which produced a lasting obstruction and obstructive sialadenitis. This supports the possibility that microliths, which are present in normal salivary glands of man, are a primary etiologic factor in sialadenitis.