Changes in elemental concentrations of rat parotid acinar cells following pilocarpine stimulation.

1. Quantitative electron microprobe analysis was used to measure elemental dry weight concentrations in cytoplasm, secretory granules and nuclei of resting and pilocarpine-stimulated rat parotid gland acinar cells. 2. Secretory granules in resting cells had lower concentrations of Na, Mg, P, Cl and K, and higher concentrations of S and Ca than cytoplasm or nuclei. Nuclei in resting cells had lower S and higher K concentrations than cytoplasm. 3. Three major pilocarpine-related changes were found: (i) cytoplasmic dry weight concentrations of Na and Ca increased and the concentration of K decreased, (ii) the nuclear concentration of Na increased while that of K decreased and (iii) the concentrations of Na and Cl increased in secretory granules. 4. These results indicate that the nuclear, and cytoplasmic compartments have different mechanisms for regulating their elemental concentrations relative to the secretory granules. 5. The present results are largely consistent with X-ray microanalysis results from the pilocarpine-stimulated dog submandibular gland.