scholarly journals Intracellular calcium signalling in rat parotid acinar cells that lack secretory vesicles

1998 ◽  
Vol 330 (2) ◽  
pp. 847-852 ◽  
Author(s):  
Peixin LIU ◽  
John SCOTT ◽  
Peter Matthew SMITH
Keyword(s):  
Parotid Gland ◽  
Calcium Signalling ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Vesicles ◽  
Apical Pole ◽  
Parotid Acinar Cells ◽  
Parotid Duct ◽  
Rat Parotid ◽  
In Cells

Secretory vesicles from pancreatic acinar cells have recently been shown to release Ca2+ after stimulation with Ins(1,4,5)P3 [Gerasimenko, Gerasimenko, Belan and Petersen, (1996) Cell 84, 473-480]. These observations have been used in support of the hypothesis that Ca2+ release from secretory vesicles could be an important component of stimulus secretion coupling in exocrine acinar cells. In the rat, ligation of the parotid duct causes a reversible atrophy of the parotid gland. Most notably, after atrophy the acinar cells are reduced in size and no longer contain secretory vesicles [Liu, Smith, and Scott (1996) J. Dent. Res. 74, 900]. We have measured cytosolic free-Ca2+ concentration ([Ca2+]i) in single, acutely isolated, rat parotid acinar cells, and compared Ca2+ mobilization in response to acetylcholine (ACh) stimulation in cells obtained from control animals to that in cells lacking secretory vesicles obtained after atrophy of the parotid gland. Application of 50-5000 nM ACh to control cells gave rise to a typical, dose-dependent, biphasic increase in [Ca2+]i, of which the later, plateau, phase was acutely dependent on the extracellular Ca2+ concentration. An identical pattern of response was observed with cells obtained from atrophic glands. Low concentrations of ACh (10-100 nM) occasionally produced [Ca2+]i oscillations of a similar pattern in cells from both control and atrophic glands. We were able to show that Ca2+ rises first in the apical pole of the cell and the increase then spreads to the rest of the cell in cells from control glands but not in cells from atrophic glands. However, at present we are unable to determine whether this is due to the lack of secretory vesicles or whether the separation is too small to measure in the smaller acinar cells obtained from atrophic glands. We conclude therefore, that secretory vesicles make no significant contribution to overall Ca2+ mobilization in rat parotid acinar cells, nor are they required for oscillatory changes in [Ca2+]i to occur. However we are unable to eliminate completely any role for secretory vesicles in initiating Ca2+ mobilization at the apical pole of the cell.

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.

scholarly journals Identification and Localization of G Proteins in Exocrine Glands

1993 ◽  
Vol 4 (3) ◽  
pp. 407-414
Author(s):  
Eileen L. Watson ◽  
Dennis Di Julio ◽  
Dolphine Oda ◽  
Kenneth T. Izutsu ◽  
Constance Oliver
Keyword(s):  
Parotid Gland ◽  
Salivary Glands ◽  
G Proteins ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Cell Physiology ◽  
Exocrine Glands ◽  
Ductal Cells ◽  
Ductal Cell ◽  
Rat Parotid

GTP-binding proteins were identified in rat parotid acinar plasma-enriched membranes (PM) by immunoblot analysis and localized immunohistochemically in the parotid gland as well as in other exocrine glands by using affinity-purified antisera specific for alpha subunits of the G proteins. Isolated rat parotid acinar PM immunoreacted strongly to antisera directed against Gsa, Giα1/α2, Gia3, and Goa; the signal for Goa, however, was weak with crude Go antisera. Immunohistochemical studies to identify and localize Go in rat parotid tissue revealed that antisera to Goα immunoreacted with ductal cells. In addition, strong immunoreactivity to Goa antisera was noted in ductal cells of other salivary glands including rat submandibular, mouse parotid, and mouse submandibular glands. Light labeling of rat parotid and submandibular gland acinar cells was also noted. In contrast, in the rat and mouse pancreas, Go antisera immunoreacted primarily with islet cells. Ductal cells were negative, but there was light labeling of rat pancreatic acinar cells. The apparent ductal specificity of Goa staining was further verified by demonstrating that Goa antisera immunoreacted strongly with HSG-PA cells, a human transformed salivary ductal cell line. The results demonstrate that rat parotid acinar plasma membranes express a number of G proteins including Go and that Go appears to be selectively expressed in the ductal cells of rat parotid gland and other salivary glands. The selective enrichment of Go in ductal cells suggests that this G protein may play an important role in ductal cell physiology.

Transplantation of Immortalized, Nontumorigenic Parotid Acinar Cells into the Allogeneic Rat Parotid Gland and Oral Submucosa

1996 ◽  
Vol 212 (2) ◽  
pp. 160-164 ◽  
Author(s):  
G. E. Krause ◽  
F. G. L. Rosa ◽  
A. D. Meyers ◽  
R. Kumar ◽  
K. N. Prasad
Keyword(s):  
Parotid Gland ◽  
Acinar Cells ◽  
Parotid Acinar Cells ◽  
Rat Parotid Gland ◽  
Rat Parotid

Magnesium–calcium signalling in rat parotid acinar cells: effects of acetylcholine

2007 ◽  
Vol 307 (1-2) ◽  
pp. 193-207 ◽  
Author(s):  
Antonio Mata ◽  
Duarte Marques ◽  
María A. Martínez-Burgos ◽  
João Silveira ◽  
Joana Marques ◽  
...  
Keyword(s):  
Calcium Signalling ◽  
Acinar Cells ◽  
Parotid Acinar Cells ◽  
Rat Parotid

scholarly journals β-Adrenergic stimulation alters oligosaccharide pyrophosphoryl dolichol metabolism in rat parotid acinar cells

1985 ◽  
Vol 231 (2) ◽  
pp. 431-438 ◽  
Author(s):  
S R Grant ◽  
E E Kousvelari ◽  
D K Banerjee ◽  
B J Baum
Keyword(s):  
Half Life ◽  
Specific Radioactivity ◽  
Acinar Cells ◽  
Protein Glycosylation ◽  
Significant Enhancement ◽  
Adrenergic Stimulation ◽  
Parotid Acinar Cells ◽  
Secretory Glycoproteins ◽  
Rat Parotid ◽  
Stimulation Of

beta-Adrenergic stimulation of rat parotid acinar cells markedly increases [3H]mannose incorporation into N-linked glycoproteins [Kousvelari, Grant, Banerjee, Newby & Baum (1984) Biochem. J. 222, 17-24]. More than 90% of this protein-bound [3H]mannose was preferentially incorporated into four secretory glycoproteins. The ratio of [3H]mannose/[14C]leucine present in these individual proteins was 1.7-4-fold greater with isoproterenol-treated cells than with untreated controls. In isoproterenol-stimulated cells, [3H]mannose incorporation into mannosylphosphoryl dolichol and oligosaccharide-PP-dolichol was increased 2-3-fold over that observed in unstimulated cells. Similarly, formation of mannosylated oligosaccharide-PP-dolichol was increased approx. 4-fold in microsomes prepared from isoproterenol-treated cells. Also, turnover of oligosaccharide-PP-dolichol was significantly increased (5-fold) by β-adrenergic stimulation; the half-life for oligosaccharide-PP-dolichol decreased from 6 min in control cells to 1.2 min in isoproterenol-stimulated cells. By 15 min after isoproterenol addition to acinar cells, the specific radioactivity of parotid oligosaccharide moieties increased about 3-fold over the value observed in the absence of the agonist. Taken together, these results strongly suggest that elevation of N-linked protein glycosylation in rat parotid acinar cells after β-adrenoreceptor stimulation resulted from significant enhancement in the synthesis of mannosylphosphoryl dolichol and oligosaccharide-PP-dolichol and the turnover of oligosaccharide-PP-dolichol.

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