Intracellular calcium localization in stimulated and non-stimulated extraorbital lacrimal glands of rats.

Acinar cells of extraorbital lacrimal glands from control, pilocarpine-treated, atropine-treated and atropine + pilocarpine-treated rats were studied using a potassium pyroantimonate technique and X-ray microanalysis for calcium localization at the ultrastructural level. This was done in order to identify intracellular compartmentalization of calcium and to elucidate any calcium translocation that might occur during the secretory process. Calcium-pyroantimonate complexes were identified in the mitochondria, plasma membrane and cytoplasmic vesicles of the untreated specimens and in the plasma membrane of atropine-treated specimens, these complexes decreased drastically in the actively-secreting cells. The function of calcium in lacrimal gland secretion and the action of pilocarpine and atropine on membrane calcium are discussed.