Intracellular calcium store and transport of elements in acinar cells of the salivary gland determined by electron probe X-ray microanalysis.

Abstract

Electron probe X-ray microanalysis using freshly frozen hydrated and dried thin sections of dog submandibular gland was performed to determine the distribution of elements and water in the acinar cells of resting and stimulating states. The results obtained are as follows : (a) The secretory granules contained high concentrations of Ca and S while high concentrations of K and P were present in the cytoplasm and/or nucleus of acinar mucous cells of the gland in the resting state. (b) With pilocarpine stimulation, the concentration of Ca increased in the cytoplasm and decreased in the secretory granules, while there was an increase in the concentration of Na and Cl in both the cytoplasm and secretory granules of the cells. (c) The local dry-mass fractions of acinar cells, estimated by comparing the continuum radiation of X-ray spectrum from the frozen hydrated sections with that from the frozen dehydrated sections, were approximately 20 and 33 % in the cytoplasm and secretory granules of resting acinar cells, respectively, and each value was not significantly altered under conditions of stimulation having a tendency to decrease slightly. Therefore, the passive Na and Cl influx and the cytoplasmic Ca flowed in from extracellular spaces and released from secretory granules, an intracellular calcium store, by secretory stimulation probably triggers the passive or active Na and Cl extrusion and consequently the osmotic water flux from the basal part of acinar cells to the secretory granules and the lumen, as well as the serial exocytosis of the granules in the luminal side of the acinar cells.Key Words: electron probe X-ray microanalysis, dog salivary gland, pilocarpine stimulation, electrolyte transport, intracellular calcium store.Saliva is primarily secreted in the acini of the salivary glands and is followed by a secondary process of reabsorption in the duct system (YOUNG and MARTIN,

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

“…None the less, the submandibular gland acinar cytoplasmic results of Sasaki et al (1983) 300 mmol/kg dry mass and K to decrease to about 400 mmol/kg dry mass following pilocarpine stimulation (Table 2). Similar Na and K changes but of smaller magnitude were observed in dog pancreatic acini (Table 2).…”

“…Somlyo, Somlyo & Shuman (1979) confirmed the validity of Hall's method for ultra-thin cryosections in the freeze-dried state. Gupta & Hall (1983) used the technique to study cockroach salivary glands; Sasaki, Nakagaki, Mori & Imai (1983) K. T. IZUTSU AND D. E. JOHNSON and Roomans, Wei, Ceder & Kollberg (1982) to study mammalian submandibular salivary glands; and Muller & Roomans (1984) to study the resting rat parotid gland.…”

“…Pilocarpine was utilized as secretagogue in order to facilitate comparisons with previous microprobe secretion studies (Nakagaki, Sasaki, Shiguma & Imai, 1984;Sasaki et al 1983) and because the drug was previously found to be suitable for electrolyte and fluid secretion studies in salivary glands (Schneyer & Hall, 1965).…”

Intracellular Cl- activity of canine submandibular gland cells: An in vitro observation.

“…Our previous data obtained by X-Ray microanalysis in canine submandibular gland revealed that cellular organelles such as granules had a higher Cl-concentration than in cytoplasm (SASAKI et a!., 1983). When perfused with the low Na+ solution (41.15 mM concentration : n=10, 2 glands), the a,1, 4?Pm, and E01 were 62.5±1.2 mM (S.E.…”

A review of electron probe X‐ray microanalysis studies of salivary gland cells

“…Secretory granules. Thin section studies (Izutsu and Johnson, 1986;Izutsu et al, 1985;Sasaki et al, 1983) indicate that secretory granules typically have higher concentrations of Ca, and lower concentrations of K and P when compared with the cytoplasmic and nuclear concentrations of these elements (Table 3, Fig. 1).…”