Rapid desensitization of substance P- but not carbachol-induced increases in inositol trisphosphate and intracellular Ca++ in rat parotid acinar cells

1987 ◽  
Vol 148 (3) ◽  
pp. 1017-1024 ◽  
Author(s):  
M.K. McMillian ◽  
S.P. Soltoff ◽  
B.R. Talamo
Keyword(s):  
Substance P ◽  
Inositol Trisphosphate ◽  
Acinar Cells ◽  
Parotid Acinar Cells ◽  
Intracellular Ca ◽  
Rat Parotid

scholarly journals Properties of receptor-controlled inositol trisphosphate formation in parotid acinar cells

1985 ◽  
Vol 225 (1) ◽  
pp. 263-266 ◽  
Author(s):  
D L Aub ◽  
J W Putney
Keyword(s):  
Inositol Phosphates ◽  
Inositol Trisphosphate ◽  
Calcium Ionophore ◽  
Acinar Cells ◽  
Receptor Occupancy ◽  
Parotid Acinar Cells ◽  
Parotid Cells ◽  
Rat Parotid ◽  
K Release ◽  
Substance P Receptors

Activation of muscarinic receptors in rat parotid cells results in breakdown of polyphosphoinositides liberating inositol phosphates, including inositol trisphosphate. Formation of inositol trisphosphate appears independent of agonist-induced Ca2+ mobilization, since neither formation nor degradation of inositol trisphosphate are appreciably altered in low-calcium media, and elevation of cytosolic Ca2+ with a calcium ionophore does not cause an increase in cellular inositol trisphosphate. Further, activation of substance P receptors and alpha 1-adrenoreceptors, but not beta-adrenoreceptors, increases inositol trisphosphate formation. The dose-response curve for methacholine activation of inositol trisphosphate formation more closely approximates the curve for receptor occupancy than for Ca2+-activated K+ release. These results are all consistent with the suggestion that inositol trisphosphate could function as a second messenger linking receptor occupation to cellular Ca2+ mobilization.

scholarly journals Regulation of phosphatidate synthesis by secretagogues in parotid acinar cells

1982 ◽  
Vol 204 (2) ◽  
pp. 587-592 ◽  
Author(s):  
S J Weiss ◽  
J S McKinney ◽  
J W Putney
Keyword(s):  
Steady State ◽  
Substance P ◽  
Specific Radioactivity ◽  
Acinar Cells ◽  
Half Time ◽  
Muscarinic Antagonist ◽  
Parotid Acinar Cells ◽  
Rat Parotid ◽  
In Cells

The metabolism of phosphatidate in rat parotid acinar cells was investigated, particularly with regard to the actions of agonists known to act by mobilizing Ca2+. When cells were incubated in medium containing 10 microM-[32P]Pi, phosphatidate was rapidly labelled, approaching an apparent steady-state with a half-time of approx. 20 min. Methacholine provoked a more than doubling of phosphatidate radioactivity, which was reversed by the muscarinic antagonist atropine. These results suggest that phosphatidate labels to near steady-state rapidly and that in cells prelabelled for 60 min the increase in radioactivity induced by agonists probably reflects net synthesis rather than an increase in specific radioactivity. Phosphatidate synthesis in response to methacholine was rapid and occurred, within the resolution of a few seconds, with no measurable latency. Adrenaline and substance P also stimulated phosphatidate synthesis but both agonists were less efficacious than methacholine. A Ca2+ ionophore, ionomycin, did not provoke phosphatidate synthesis. By using a protocol that eliminates the receptor-regulated Ca2+ pool, it was demonstrated that methacholine-induced phosphatidate formation does not come about as a consequence of Ca2+ influx nor of Ca2+ release. These results indicate that the phosphatidate synthesis response has characteristics compatible with its previously suggested role as a primary mediator of membrane Ca2+-gating.

Substance P-induced diacylglycerol formation in rat parotid acinar cells

1991 ◽  
Vol 207 (4) ◽  
pp. 329-335 ◽  
Author(s):  
Takao Komabayashi ◽  
Atsushi Yakata ◽  
Tetsuya Izawa ◽  
Kazuhiro Suda ◽  
Masamichi Noguchi ◽  
...  
Keyword(s):  
Substance P ◽  
Acinar Cells ◽  
Parotid Acinar Cells ◽  
Rat Parotid

scholarly journals Ryanodine receptor expression is associated with intracellular Ca2+ release in rat parotid acinar cells

1997 ◽  
Vol 273 (4) ◽  
pp. C1306-C1314 ◽  
Author(s):  
Xuejun Zhang ◽  
Jiayu Wen ◽  
Keshore R. Bidasee ◽  
Henry R. Besch ◽  
Ronald P. Rubin
Keyword(s):  
Ryanodine Receptor ◽  
Acinar Cells ◽  
Receptor Expression ◽  
Intact Cells ◽  
Parotid Acinar Cells ◽  
Cyclic Adp Ribose ◽  
Parotid Cells ◽  
Intracellular Ca ◽  
Rat Parotid

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.

scholarly journals Two modes of regulation of the phospholipase C-linked substance-P receptor in rat parotid acinar cells

1988 ◽  
Vol 253 (2) ◽  
pp. 459-466 ◽  
Author(s):  
H Sugiya ◽  
J F Obie ◽  
J W Putney
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Substance P ◽  
Acinar Cells ◽  
Control Mechanisms ◽  
Dependent Manner ◽  
Parotid Acinar Cells ◽  
Kinase C ◽  
Substance P Receptor ◽  
Rat Parotid

In rat parotid acinar cells prelabelled with [3H]inositol, substance P (100 nM) induced the formation of [3H]inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Ins(1,4,5)P3 reached a maximum 7 s after substance P stimulation, and thereafter decreased and reached a stable value at 60 s. When the cells were exposed to substance P for 10, 30, 60, or 300 s, washed, and re-exposed to this peptide, the formation of [3H]inositol trisphosphate (InsP3) was attenuated in a time-dependent manner. In the cells pretreated as described above, the number of [3H]substance-P-binding sites (Bmax) was also decreased. Possible role(s) of Ca2+ and protein kinase (protein kinase C) control mechanisms in regulating substance P responses were investigated. Desensitization of substance P-induced InsP3 was not affected by the Ca2+ ionophore ionomycin, nor was it dependent on Ca2+ mobilization. On the other hand, in the presence of 4 beta-phorbol 12,13-dibutyrate (PDBu) and 12-O-tetradecanoyl-4 beta-phorbol 13-acetate, known activators of protein kinase C, substance P-induced InsP3 formation was inhibited. However, PDBu had no effect on [3H]substance P binding, whether present during the assay or when cells were pretreated. The persistent desensitization of InsP3 formation induced by substance P was not affected by PDBu. These results suggest that the persistent desensitization of InsP3 formation induced by substance P is a homologous process involving down-regulation of the substance P receptor; the mechanism does not appear to involve, or to be affected by, the Ca2+ or protein kinase C signalling systems. Protein kinase C activation can, however, inhibit substance P-induced InsP3 formation, which may indicate the presence of a negative-feedback control on the substance P pathway.

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