Browse
Submit Data
Databases
API
Help

Dataset Information

17 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Mucin release and calcium fluxes in isolated rat submandibular acini.

ABSTRACT: A method is described for preparing isolated rat submandibular acini by collagenase digestion followed by mechanical dispersion. As assessed by Trypan Blue exclusion, phase contrast microscopy, ATP content and release of mucins and lactate dehydrogenase, the acini are morphologically and functionally intact. Secretory function of isolated acini was similar to that of intact tissue in terms of time-course, dose dependence and degree of stimulation of mucin release by adrenergic secretagogues. Mucin release was increased to the same extent (approx. 3-4-fold) by either isoproterenol or noradrenaline at a maximally effective concentration (10 microM). Stimulation of mucin release by isoproterenol (10 microM), noradrenaline (10 microM) or adrenaline (10 microM) was inhibited by propranolol (30 microM) but not by phentolamine (30 microM). Isoproterenol (10 microM) increased both 45Ca2+ uptake and efflux from the acini, which was shown to represent a net release of calcium. However, there was a delay (approx. 10 min) in onset of stimulation of 45Ca2+ mobilization which was not apparent in isoproterenol stimulation of mucin release. Our results indicate that increases in intracellular calcium mobilization in response to a beta-adrenergic secretagogue do not trigger mucin secretion from rat submandibular acini.

SUBMITTER: McPherson MA

PROVIDER: S-EPMC1144455 | biostudies-other | 1984 Dec

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Homeostatic calcium fluxes, ER calcium release, SOCE, and calcium oscillations in cultured astrocytes are interlinked by a small calcium toolkit

Project description:We report the application of RNA-seq for molecular profiling of cultured, cortical astrocytes. Our data set is based on about 40 million unique reads per sample in four independent mRNA preparations. Cortical astrocytes are a prototypical cell model for investigating calcium signaling. For analysis of calcium fluxes, we performed direct calcium imaging in the endoplasmic reticulum and in the cytosol. We describe in our study the physiological profile of homeostatic and agonist-induced calcium fluxes. Furthermore, we show how ER calcium release shapes the cytosolic calcium signal. This transcriptome dataset was used to profile the calcium toolkit of astrocytes. The data suggest that a small number of calcium signaling-related proteins mediate calcium homeostasis in astrocytes.

2021-12-14 | GSE166464 | GEO

Purification and immunofluorescent localization of rat submandibular mucin.

Project description:Rat submandibular mucin (RSM) was purified by acid precipitation, then alcohol precipitation of the 30000g supernatant of gland homogenate, followed by column chromatography on Sephadex G-200. The mucin, which was eluted in the void volume, had an amino acid profile typical of a salivary mucus glycoprotein with high proportions of threonine, serine and proline (48.8% of total amino acids), and low proportions of aromatic and basic amino acids. It consisted of 63% (w/w) carbohydrate, which was shown by g.l.c. analysis to contain N-acetylglucosamine, N-acetylgalactosamine, galactose, sialic acid and fucose in the proportions 1.0:3.4:2.6:3.1:1.2. After staining of the mucin with periodic acid/Schiff reagent, analytical equilibrium ultracentrifugation in a CsCl density gradient produced a symmetrical peak of buoyant density 1.449g/ml, without evidence of protein contaminants. Sedimentation velocity centrifugation revealed a major periodate/Schiff-positive component (S(0) (20,w) 5.06) with an associated shoulder of slower sedimenting material, suggesting polydispersity in the size of the mucin. Our findings suggest that the RSM purified in these studies has a molecular weight between 200000 and 1x10(6). Antibody to RSM was prepared in a rabbit and produced a single precipitin line on immunoelectro-osmophoresis with the mucin. Immunofluorescence studies showed that the antibody localized only to submandibular acinar cells and confirmed that these cells were the source of RSM. The antibody was not directed towards the blood-group-A determinant (terminal N-acetylgalactosamine) present in the mucin.

| S-EPMC1158467 | biostudies-other

Adrenergic regulation of formation of inositol phosphates in rat submandibular acini.

Project description:Formation of inositol phosphates in response to adrenergic secretagogues was studied in rat submandibular acini labelled with myo-[2-3H]inositol. Noradrenaline rapidly (within 5 s) increased radioactivity incorporated into inositol 1,4,5-trisphosphate and inositol tetrakisphosphate, with less rapid (within 1 min) increases in inositol 1,3,4-trisphosphate being observed. Inositol polyphosphate formation was less sensitive to noradrenaline than was stimulation of mucin secretion and was mediated by stimulation of alpha- but not beta-adrenergic receptors. The beta-adrenergic agonist isoproterenol, which is a potent stimulator of mucin secretion [McPherson & Dormer (1984) Biochem. J. 224, 473-481] did not increase formation of inositol mono-, bis- or polyphosphates during a 15 min incubation. The results suggest that inositol phosphates do not mediate beta-adrenergic stimulation of mucin secretion in rat submandibular acini. In addition, rat submandibular acinar cells contain a Ca2+ pool which can be mobilized by isoproterenol [McPherson & Dormer (1984) Biochem. J. 224, 473-481], without involvement of inositol polyphosphates as second messengers.

| S-EPMC1147621 | biostudies-other

Calcium Fluxes in Work-Related Muscle Disorder: Implications from a Rat Model.

Project description:IntroductionCa2+ regulatory excitation-contraction coupling properties are key topics of interest in the development of work-related muscle myalgia and may constitute an underlying cause of muscle pain and loss of force generating capacity.MethodA well-established rat model of high repetition high force (HRHF) work was used to investigate if such exposure leads to an increase in cytosolic Ca2+ concentration ([Ca2+]i) and changes in sarcoplasmic reticulum (SR) vesicle Ca2+ uptake and release rates.ResultSix weeks exposure of rats to HRHF increased indicators of fatigue, pain behaviors, and [Ca2+]i, the latter implied by around 50-100% increases in pCam, as well as in the Ca2+ handling proteins RyR1 and Casq1 accompanied by an ∼10% increased SR Ca2+ uptake rate in extensor and flexor muscles compared to those of control rats. This demonstrated a work-related altered myocellular Ca2+ regulation, SR Ca2+ handling, and SR protein expression.DiscussionThese disturbances may mirror intracellular changes in early stages of human work-related myalgic muscle. Increased uptake of Ca2+ into the SR may reflect an early adaptation to avoid a sustained detrimental increase in [Ca2+]i similar to the previous findings of deteriorated Ca2+ regulation and impaired function in fatigued human muscle.

| S-EPMC6791278 | biostudies-literature

Bmi-1 regulates mucin levels and mucin O-glycosylation in the submandibular gland of mice.

Project description:Mucins, the major components of salivary mucus, are large glycoproteins abundantly modified with O-glycans. Mucins present on the surface of oral tissues contribute greatly to the maintenance of oral hygiene by selectively adhering to the surfaces of microbes via mucin O-glycans. However, due to the complex physicochemical properties of mucins, there have been relatively few detailed analyses of the mechanisms controlling the expression of mucin genes and the glycosyltransferase genes involved in glycosylation. Analysis performed using supported molecular matrix electrophoresis, a methodology developed for mucin analysis, and knockout mice without the polycomb group protein Bmi-1 revealed that Bmi-1 regulates mucin levels in the submandibular gland by suppressing the expression of the mucin Smgc gene, and that Bmi-1 also regulates mucin O-glycosylation via suppression of the glycosyltransferase Gcnt3 gene in the submandibular gland.

| S-EPMC7815129 | biostudies-literature

Elevated calcium and activation of trypsinogen in rat pancreatic acini.

Project description:BACKGROUND: Acute pancreatitis associated with hypercalcaemia has been described in humans and experimental animals. It has been demonstrated that calcium dose dependently accelerates trypsinogen activation, and it is generally believed that ectopic activation of digestive enzymes is an early event in the pathophysiology of acute pancreatitis. AIMS AND METHODS: Trypsinogen activation peptide (TAP) was measured in isolated rat pancreatic acini exposed to elevated extracellular calcium in order to investigate the association between calcium and trypsinogen activation in living cells. TAP was determined in the culture medium either before (extracellular compartment) or after (intracellular compartment) cell homogenisation. RESULTS: Neither secretory stimulation nor elevated calcium alone caused an increase in TAP levels. Maximal cerulein or carbachol stimulation superimposed on high medium calcium, however, significantly increased intracellular trypsinogen activation twofold. This increase was inhibited by either NG-monomethyl-L-arginine (L-NMMA) or verapamil. Acinar cell morphology and function remained intact as demonstrated by electron microscopy and secretagogue dose-response studies. CONCLUSIONS: These results support the hypothesis that increased intracellular trypsinogen activation is an early step in the pathogenesis of hypercalcaemia induced pancreatitis. The model may have a bearing on other types of pancreatitis as elevated cytosolic calcium is thought to be an early event in the pathogenesis of acute pancreatitis in general.

| S-EPMC1891503 | biostudies-other

Mitochondrial free calcium regulation during sarcoplasmic reticulum calcium release in rat cardiac myocytes.

Project description:Cardiac mitochondria can take up Ca(2+), competing with Ca(2+) transporters like the sarcoplasmic reticulum (SR) Ca(2+)-ATPase. Rapid mitochondrial [Ca(2+)] transients have been reported to be synchronized with normal cytosolic [Ca(2+)](i) transients. However, most intra-mitochondrial free [Ca(2+)] ([Ca(2+)](mito)) measurements have been uncalibrated, and potentially contaminated by non-mitochondrial signals. Here we measured calibrated [Ca(2+)](mito) in single rat myocytes using the ratiometric Ca(2+) indicator fura-2 AM and plasmalemmal permeabilization by saponin (to eliminate cytosolic fura-2). The steady-state [Ca(2+)](mito) dependence on [Ca(2+)](i) (with 5 mM EGTA) was sigmoid with [Ca(2+)](mito)<[Ca(2+)](i) for [Ca(2+)](i) below 475 nM. With low [EGTA] (50 microM) and 150 nM [Ca(2+)](i) (+/-15 mM Na(+)) cyclical spontaneous SR Ca(2+) release occurred (5-15/min). Changes in [Ca(2+)](mito) during individual [Ca(2+)](i) transients were small ( approximately 2-10 nM/beat), but integrated gradually to steady-state. Inhibition SR Ca(2+) handling by thapsigargin, 2 mM tetracaine or 10 mM caffeine all stopped the progressive rise in [Ca(2+)](mito) and spontaneous Ca(2+) transients (confirming that SR Ca(2+) releases caused the [Ca(2+)](mito) rise). Confocal imaging of local [Ca(2+)](mito) (using rhod-2) showed that [Ca(2+)](mito) rose rapidly with a delay after SR Ca(2+) release (with amplitude up to 10 nM), but declined much more slowly than [Ca(2+)](i) (time constant 2.8+/-0.7 s vs. 0.19+/-0.06 s). Total Ca(2+) uptake for larger [Ca(2+)](mito) transients was approximately 0.5 micromol/L cytosol (assuming 100:1 mitochondrial Ca(2+) buffering), consistent with prior indirect estimates from [Ca(2+)](i) measurements, and corresponds to approximately 1% of the SR Ca(2+) uptake during a normal Ca(2+) transient. Thus small phasic [Ca(2+)](mito) transients and gradually integrating [Ca(2+)](mito) signals occur during repeating [Ca(2+)](i) transients.

| S-EPMC2683203 | biostudies-literature

Biosynthesis of a low-molecular-mass rat submandibular gland mucin glycoprotein in COS7 cells.

Project description:We have examined the biosynthesis of a low-molecular-mass mucin from rat submandibular gland (RSMG) expressed recombinantly in COS7 tissue culture cells, focusing primarily on the addition of carbohydrate to the protein core of the mucin. We find evidence for N-linked glycosylation, but this modification is not required for secretion of the mucin. Similarly, although the recombinant RSMG mucin, like its native counterpart, contains large amounts of O-linked carbohydrate, chain extension beyond the initial O-linked GalNAc moiety is not required for secretion. We have identified partially glycosylated mucin by a combination of metabolic pulse-chase and lectin precipitations of the biosynthetic intermediates. Our results suggest that the addition of GalNAc to threonine and serine in the RSMG mucin does not occur simultaneously, as has been described for other O-glycosylated proteins.

| S-EPMC1218347 | biostudies-other

Homeostatic calcium fluxes, ER calcium release, SOCE, and calcium oscillations in cultured astrocytes are interlinked by a small calcium toolkit

Project description:Homeostatic calcium fluxes, ER calcium release, SOCE, and calcium oscillations in cultured astrocytes are interlinked by a small calcium toolkit

| PRJNA701007 | ENA

Stable changes to calcium fluxes in mitochondria isolated from rat livers perfused with alpha-adrenergic agonists and with glucagon.

Project description:Mitochondria isolated from rat liver after a short-term perfusion with the alpha-adrenergic agonist phenylephrine or with glucagon exhibited enhanced rates of uptake of Ca2+ and prolonged retention of Ca2+ in the presence of 4mm-P(i). The effect of Ca2+ retention was apparent after perfusion with phenylephrine for only 1min and was maximal after 7min of treatment. The changes induced by glucagon, although similar, were less rapid. Adrenaline caused similar changes to phenylephrine and its effects were blocked by the alpha-adrenergic antagonist phenoxybenzamine, but not by the beta-antagonist propranolol. The Ca2+ content of the isolated mitochondria decreased by 30% 1min after the onset of perfusion with phenylephrine; by 6min it had begun to return to the original value which was reached at 10min. A similar loss in calcium content was induced by glucagon but the changes were not as great and occurred more slowly. Mitochondria from phenylephrine-treated livers exhibited decreased rates of Ca2+ efflux induced by addition of 2mm-EGTA, a 50% increase in the contents of ADP and total adenine nucleotides, a small increase in the transmembrane pH gradient, and a reduced rate of oxaloacetate-induced NADPH oxidation. This study thus shows that stimulation of liver by alpha-adrenergic agonists, like that by glucagon, induces within minutes a stable modification of mitochondria leading to alterations in the Ca2+-translocation cycle (increased Ca2+ uptake and retention) and alterations in mitochondrial energy-linked reactions.

| S-EPMC1161887 | biostudies-other

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data