Characterization of Ryanodine-sensitive Ca 2+ Release from Microsomal Vesicles of Rat Parotid Acinar Cells: Regulation by Cyclic ADP-ribose

The ryanodine receptor mediates intracellular Ca2+ mobilization in muscle and nerve, but its physiological role in nonexcitable cells is less well defined. Like adenosine 3′,5′-cyclic monophosphate and inositol 1,4,5-trisphosphate, cyclic ADP-ribose (0.3–5 μM) and ADP (1–25 μM) produced a concentration-dependent rise in cytosolic Ca2+ in permeabilized rat parotid acinar cells. Adenosine and AMP were less effective. Ryanodine markedly depressed the Ca2+-mobilizing action of the adenine nucleotides and forskolin in permeabilized cells and was likewise effective in depressing the action of forskolin in intact cells. Cyclic ADP-ribose-evoked Ca2+ release was enhanced by calmodulin and depressed by W-7, a calmodulin inhibitor. A fluorescently labeled ligand, 4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3,4-diaza-s-indacene-3-propionic acid-glycyl ryanodine, was synthesized to detect the expression and distribution of ryanodine receptors. In addition, ryanodine receptor expression was detected in rat parotid cells with a sequence highly homologous to a rat skeletal muscle type 1 and a novel brain type 1 ryanodine receptor. These findings demonstrate the presence of a ryanodine-sensitive intracellular Ca2+ store in rat parotid cells that shares many of the characteristics of stores in muscle and nerve and may mediate Ca2+-induced Ca2+ release or a modified form of this process.

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Dispersed rat parotid acinar cells. III. Characterization of cholinergic receptors

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.3.566 ◽

1975 ◽

Vol 229 (3) ◽

pp. 566-569 ◽

Cited By ~ 31

Author(s):

JA Mangos ◽

NR McSherry ◽

T Barber

Keyword(s):

Cellular Response ◽

Acinar Cells ◽

Receptor Site ◽

Cholinergic Receptors ◽

Cholinergic Agonists ◽

Cholinergic Agonist ◽

Parotid Acinar Cells ◽

Rat Parotid

The in vitro characterization of cholinergic receptors in dispersed rat parotid acinar cells was accomplished through investigations of the net transmembrane fluxes of K in response to exposure of the cells to selected cholinergic agonists and antagonists. Interaction of acetylcholine bromide (ACh) and carbamylcholine (carbachol) with the cholinergic receptors resulted in rapid net efflux of K from the cells. This cellular response was demonstrable in concentrations of carbachol as low as 10(-8) M. With gradual increase in the concentrations of the agonist an increase in the K efflux was observed up to 10(-5) M. At higher concentrations of this cholinergic agonist no further increases in the net K efflux were observed. The response of the cells to cholinergic agonists was inhibited by atropine but not by the adrenergic antagonists phentolamine or propranolol, suggesting cholinergic agonist-antagonist interactions at the receptor site. The dispersed rat parotid acinar cells appear to have functionally intact cholinergic receptors and could be used as valuable experimental tools for the study of receptor physiology and pharmacology as well as of other aspects of secretory function at the cellular level.

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Characterization of a phosphorylation event resulting in upregulation of the salivary Na+-K+-2Cl−cotransporter

AJP Cell Physiology ◽

10.1152/ajpcell.1999.277.6.c1184 ◽

1999 ◽

Vol 277 (6) ◽

pp. C1184-C1193 ◽

Cited By ~ 44

Author(s):

Kinji Kurihara ◽

Marilyn L. Moore-Hoon ◽

Masato Saitoh ◽

R. James Turner

Keyword(s):

Binding Sites ◽

Acinar Cells ◽

Close Correlation ◽

Adrenergic Stimulation ◽

High Affinity ◽

Parotid Acinar Cells ◽

Phosphorylation Event ◽

Rat Parotid ◽

Stimulation Of

Previous studies from our laboratory have shown a close correlation between increased Na+-K+-2Cl−cotransporter activity and increased cotransporter phosphorylation after β-adrenergic stimulation of rat parotid acinar cells. We demonstrate here that these effects are paralleled by an increase in the number of high-affinity binding sites for the cotransporter inhibitor bumetanide in membranes prepared from stimulated acini. We also show that the sensitivity of cotransporter fluxes to inhibition by bumetanide is the same in both resting and isoproterenol-stimulated cells, consistent with the hypothesis that β-adrenergic stimulation and the accompanying phosphorylation result in the activation of previously quiescent transporters rather than in a change in the properties of already active proteins. In addition, we demonstrate that the increased phosphorylation on the cotransporter resulting from β-adrenergic stimulation is localized to a 30-kDa phosphopeptide obtained by cyanogen bromide digestion. Immunoprecipitation and Western blotting experiments demonstrate that this peptide is derived from the NH2-terminal cytosolic tail of the cotransporter, which surprisingly does not contain the sole protein kinase A consensus site on the molecule.

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Dispersed rat parotid acinar cells. II. Characterization of adrenergic receptors

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.3.560 ◽

1975 ◽

Vol 229 (3) ◽

pp. 560-565 ◽

Cited By ~ 42

Author(s):

JA Mangos ◽

NR McSherry ◽

T Barber ◽

SN Arvanitakis ◽

V Wagner

Keyword(s):

Adrenergic Receptors ◽

Acinar Cells ◽

Progressive Increase ◽

Cellular Level ◽

Alpha Adrenergic Receptors ◽

Parotid Acinar Cells ◽

In Vitro Characterization ◽

Rat Parotid

The in vitro characterization of adrenergic receptors in isolated rat parotid acinar cells was accomplished through investigations of the transmembrane influxes of K and of the secretion of amylase in response to interactions of the cells with selected agonists and antagonists. Interaction of epinephrine (EPI) at concentrations of 10(-3)-10(-9) M with the alpha-adrenergic receptors resulted in rapid efflux of K from the cells. This effect was inhibited by phentolamine but not by propranolol or atropine. The process of secretion of amylase by these cells involved the activation of the beta-adrenergic receptors by the adrenergic agonists DL-isoproterenol (IPR) and EPI at similar to above concentrations. The interaction of these agonists with the beta receptors was inhibited by propranolol but not by phentolamine or atropine. Dibutyryl clclic AMP stimulated secretion of amylase at concentrations of 10(-8) M. A progressive increase in the secretory response of the cells was observed with increases in the dibutyryl cyclic AMP concentrations up to 10(-5) M. This effect was not inhibited by propranolol. This study demonstrates that dispersed rat parotid acinar cells have functionally intact adrenergic receptors and could be used as experimental tools for the studies of receptor physiology and pharmacology as well as other aspects of secretion at the cellular level.

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