Calcium ; metabolism ; Calcium Signaling ; Epinephrine ; pharmacology ; Hepatocytes ; drug effects ; metabolism ; Humans

The activation of Ca2+ entry through store-operated channels by agonists that deplete Ca2+ from the endoplasmic reticulum (ER) is a ubiquitous signaling mechanism, the molecular basis of which has remained elusive for the past two decades. Store-operated Ca2+-release-activated Ca2+ (CRAC) channels constitute the sole pathway for Ca2+ entry following antigen-receptor engagement. In a set of breakthrough studies over the past two years, stromal interaction molecule 1 (STIM1, the ER Ca2+ sensor) and Orai1 (a pore-forming subunit of the CRAC channel) have been identified. Here we review these recent studies and the insights they provide into the mechanism of store-operated Ca2+ channels (SOCCs).
Animals ; Calcium ; metabolism ; Calcium Channels ; metabolism ; Calcium Signaling ; drug effects ; Humans ; Membrane Proteins ; antagonists & inhibitors ; metabolism ; Protein Binding

OBJECTIVETo study the effect of human urotensin II (HU II) on secretion of adrenomedullin (ADM) from human vascular endothelial cells (HVEC) and its mechanism.

METHODSIn cultured HVEC, different concentrations of HUII were used to stimulate the ADM secretion from HVEC, and the inhibitors of different signal transduction pathway were used to investigate their effects on ADM secretion. The contents of ADM in medium were determined by radio immunoassay.

RESULTSHUII stimulated secretion of ADM from HVEC in a time-dependent and concentration-dependent manner. The contents of ADM in the experiment groups were changed compared with that in control group (P < 0.05). The increase of ADM could be inhibited by inhibitor of extracellular signal-regulated protein kinase (PD(98059)), inhibitor of P38 kinase (SB(202190)), inhibitor of calmodulin (W(7)) and inhibitor of Ca(2+) (nicardipine) (P < 0.05). The inhibition ratio in those groups was 68%, 78%, 24% and 25% respectively. But the inhibitor of Calcineurin (CaN) and inhibitor of protein kinase C (H(7)) had no influence on the secretion of ADM from HVEC (P > 0.05).

CONCLUSIONThe stimulated effect of HUII on the ADM secretion from HVEC may be mediated by Ca(2+), ERKs, CaM-PK and P38 signal transduction pathways.

Adrenomedullin ; metabolism ; Calcium ; metabolism ; Calcium Signaling ; Cells, Cultured ; Endothelial Cells ; secretion ; Humans ; Signal Transduction ; drug effects ; Urotensins ; pharmacology

Due to the complex circuitry and plethora of cell types involved in somatosensation, it is becoming increasingly important to be able to observe cellular activity at the population level. In addition, since cells rely on an intricate variety of extracellular factors, it is important to strive to maintain the physiological environment. Many electrophysiological techniques require the implementation of artificially-produced physiological environments and it can be difficult to assess the activity of many cells simultaneously. Moreover, imaging Ca transients using Ca-sensitive dyes often requires in vitro preparations or in vivo injections, which can lead to variable expression levels. With the development of more sensitive genetically-encoded Ca indicators (GECIs) it is now possible to observe changes in Ca transients in large populations of cells at the same time. Recently, groups have used a GECI called GCaMP to address fundamental questions in somatosensation. Researchers can now induce GCaMP expression in the mouse genome using viral or gene knock-in approaches and observe the activity of populations of cells in the pain pathway such as dorsal root ganglia (DRG), spinal neurons, or glia. This approach can be used in vivo and thus maintains the organism's biological integrity. The implementation of GCaMP imaging has led to many advances in our understanding of somatosensation. Here, we review the current findings in pain research using GCaMP imaging as well as discussing potential methodological considerations.
Afferent Pathways ; physiology ; Animals ; Calcium ; metabolism ; Calcium Signaling ; drug effects ; genetics ; Ganglia, Spinal ; metabolism ; Humans ; Pain ; metabolism ; pathology

AIMThe effects of angiotensin II on the changes of Ca2+ signal in cultured rat neonatal myocytes were investigated in order to reveal the localization and distribution of elementary Ca2+ signaling units.

METHODSThe cultured neonate rat myocytes were treated with angiotensin II, and calcium signal was detected using confocal laser scanning microscopy and fluo-4/AM calcium probe.

RESULTSThe propagation of Ca2+ waves was observed in rest and angiotensin II stimulated cardiac myocytes. Calcium fluorescent intensity oscillated slightly in myocytes and the average intensity was much higher in the nucleus than in the cytosol, all of which could be magnified significantly by AngII (10(-6) mol/L). Ca2+ oscillation induced by Ang II was completely blocked by NO donor sodium nitroprusside. AngII evoked Ca2+ sparks close to the cell surface membrane, and couldn't be abolished by sodium nitroprusside.

CONCLUSIONThere are spatiotemporal dynamics of Ca2+ signaling patterns such as Ca2+ wave, Ca2+ spikes, Ca2+ oscillation and the whole cell Ca2+ transients induced by angiotensin II, which might play very important roles in cellular cardiac function.

Angiotensin II ; pharmacology ; Animals ; Calcium ; metabolism ; Calcium Signaling ; Cells, Cultured ; Microscopy, Confocal ; Myocytes, Cardiac ; drug effects ; metabolism ; Rats

BACKGROUNDPreconditioning with remifentanil confers cardioprotection. Since Ca(2+) overload is a precipitating factor of injury, we determined the effects of remefentanil on intracellular Ca(2+) ([Ca(2+)](i)) and its transients induced by electrical stimulation and caffeine, which reflects Ca(2+) handling by Ca(2+) handling proteins, in rat ventricular myocytes.

METHODSFreshly isolated adult male Sprague-Dawley rat myocytes were loaded with Fura-2/AM and [Ca](i) was determined by spectrofluorometry. Remifentanil at 0.1 - 1000 microg/L was administered. Ten minutes after administration, either 0.2 Hz electrical stimulation was applied or 10 mmol/L caffeine was added. The [Ca(2+)](i), and the amplitude, time resting and 50% decay (t(50)) of both transients induced by electrical stimulation (E [Ca(2+)](i)) and caffeine (C [Ca(2+)](i)) were determined.

RESULTSRemifentanil (0.1 - 1000.0 microg/L) decreased the [Ca(2+)](i) in a dose-dependent manner. It also decreased the amplitude of both transients dose-dependently. Furthermore, it increased the time to peak and t(50) of both transients dose-dependently.

CONCLUSIONRemifentanil reduced the [Ca(2+)](i) and suppressed the transients induced by electrical stimulation and caffeine in rat ventricular myocytes.

Animals ; Caffeine ; pharmacology ; Calcium ; metabolism ; Calcium Signaling ; drug effects ; Cells, Cultured ; Electric Stimulation ; Male ; Myocytes, Cardiac ; drug effects ; metabolism ; Piperidines ; pharmacology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effect of emodin on the contraction of jejunum smooth muscle and its underlying mechanisms.

METHODSRats were randomly divided into 7 groups (n = 6): control group, emodin group (1, 5, 10, 20 micromol/L), propranolol (PRO) plus emodin group, glibenclamide (GLI) plus emodin group, NG-Nitro-L-arginine Methyl Ester (L-NAME) plus emodin group, calcium free control group and calcium free emodin group. The rats were sacrificed by cervical dislocation and the small intestine was isolated. The jejunum segment specimens were mounted on an Organ Bath System with a tension transducer. The effect of emodin on contraction of jejunum smooth muscle was measured by BL-420E+ biological signal processing system and the amplitude (AM), tension (TE) and frequency (FR) of contraction were determined.

RESULTS(1) Emodin inhibited the tension and amplitude of jejunum smooth muscle contraction in a dose-dependent manner (P < 0.05, P < 0.01) while the frequency was not obviously influenced. (2) PRO (P < 0.05) or GLI (P < 0.01) partly abolished the inhibitory effect of emodin on jejunum smooth muscle. (3) L-NAME had no obvious effect on the inhibitory effect of emodin. (4) Emodin attenuated the contraction of jejunum smooth muscle induced by calcium chloride application into calcium free K-H solution (P < 0.01).

CONCLUSIONEmodin obviously inhibits the amplitude and tension, while has no influence on the frequency of jejunum smooth muscle contraction in rats. Activation of beta adrenergic receptor, open of ATP sensitive potassium channels, and inhibition of the extracellular calcium influx through calcium channels of smooth muscle cell membrane might be involved in the process.

Animals ; Calcium Signaling ; Emodin ; pharmacology ; Glyburide ; pharmacology ; Jejunum ; drug effects ; Muscle Contraction ; drug effects ; Muscle, Smooth ; drug effects ; NG-Nitroarginine Methyl Ester ; pharmacology ; Propranolol ; pharmacology ; Rats

OBJECTIVES: To investigate the role of tetramethylpyrazine(TMP) nitrone in proliferation and differentiation of neural stem cells (NSCs). METHODS: We separated and cultivated the original generation of NSCs from cerebral cortex of 14 days rat embryo, and the phenotype characteristics of the third-generation NSCs was tested by immunofluorescence. The experiment was divided into control group, β-mercaptoethanol positive control group, tetramethylpyrazine nitrone group and tetramethylpyrazine nitrone + ethylene glycol tetraacetic acid(EGTA) group (=4). The third-generation cultivation of NSCs was used in the experiment. The effect of tetramethylpyrazine nitrone on the number of NSCs proliferation was determined by BrdU and MTT, and the differentiation of NSCs was determined by Western blot. RESULTS: The primary NSCs was isolated successfully, neurospheres with typical NSCs morphology and expressing nestin was formed at 3-5 days. As BrdU and MTT assay results shown, compared with the control group andβ-mercaptoethanol positive control group, the NSCs proliferation numbers of tetramethylpyrazine nitrone group increased significantly(<0.05). The results of Western blot showed that the neuronal differentiation rate of NSCs was increased significantly in both the tetramethylpyrazine nitrone group and tetramethylpyrazine nitrone + EGTA group, and the differentiation rate of NSCs in tetramethylpyrazine nitrone + EGTA group increased more significantly(<0.05). CONCLUSIONS Tetramethylpyrazine nitrone can significantly enhance the proliferation and neuronal differentiation rate of NSCs. Decrease in extracellular Ca can promote the differentiation of NSCs into neurons induced by tetramethylpyrazine nitrone. Ca signaling plays an important role in the differentiation of NSCs into neurons.
Animals ; Calcium Signaling ; Cell Differentiation ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Neural Stem Cells ; cytology ; drug effects ; Nitrogen Oxides ; pharmacology ; Pyrazines ; pharmacology ; Rats

The purpose of this study was to determine whether the Ca2+ signaling pathway is involved in the ability of osteoprotegerin (OPG) to inhibit osteoclast differentiation and maturation. RAW264.7 cells were incubated with macrophage colony-stimulating factor (M-CSF) + receptor activator of nuclear factor-kappaB ligand (RANKL) to stimulate osteoclastogenesis and then treated with different concentrations of OPG, an inhibitor of osteoclast differentiation. The intracellular Ca2+ concentration [Ca2+]i and phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) in the different treatment groups were measured by flow cytometry and Western blotting, respectively. The results confirmed that M-CSF + RANKL significantly increased [Ca2+]i and CaMKII phosphorylation in osteoclasts (p < 0.01), and that these effects were subsequently decreased by OPG treatment. Exposure to specific inhibitors of the Ca2+ signaling pathway revealed that these changes varied between the different OPG treatment groups. Findings from the present study indicated that the Ca2+ signaling pathway is involved in both the regulation of osteoclastogenesis as well as inhibition of osteoclast differentiation and activation by OPG.
Animals ; Calcium/*metabolism ; *Calcium Signaling ; *Cell Differentiation/drug effects ; Cell Line ; Cell Survival/drug effects ; Gene Expression Regulation/drug effects ; Macrophage Colony-Stimulating Factor/metabolism ; Mice ; Osteoclasts/*cytology/*drug effects/*metabolism ; Osteoprotegerin/*pharmacology ; RANK Ligand/metabolism

AIMTo investigate effects of hsBAFF synthesized in Escherichia coli on spleen B lymphocyte immune response and its intracellular free Ca2+ ([Ca2]i]) signaling in mice.

METHODSTwenty ICR mice, half males-half females, were chosen and randomly divided into a normal control group (n=10) and a hsBAFF treatment group (n-10). The mice in hsBAFF treatment group were given abdominal cavity injection of hsBAFF solution which was diluted with phosphate buffered saline (PBS) at dosage of 0.1 mg/kg body weight once each day for over eight days. The mice in control group were received abdominal injection of PBS at the same dose and frequency. Spleen B lymphocyte proliferation and its immune response to LPS stimulation in mice were evaluated using an MTT assay, and change of spleen B lymphocyte [Ca2+]i was assayed under a laser scanning confocal microscope.

RESULTSB lymphocyte proliferation and its immune response to LPS stimulation were significantly higher in hsBAFF-treated mice than in control mice (P < 0.05). The B lymphocyte [Ca2+]i fluorescence intensity in hsBAFF-treated mice maintained at a relatively high level fluctuation, and its average intensity was significantly higher to that of control mice (P < 0.01), but change rate of the intensity was lower compared to that of control group.

CONCLUSIONhsBAFF synthesized in Escherichia coli can enhance immune function in the body by increasing B lymphocyte proliferation and its immune response. hsBAFF-activated B lymphocyte function may be associated with increasing B lymphocytes [Ca2+]i.

Animals ; B-Cell Activating Factor ; immunology ; pharmacology ; B-Lymphocytes ; cytology ; drug effects ; immunology ; Calcium ; metabolism ; Calcium Signaling ; drug effects ; Cell Proliferation ; drug effects ; Female ; Male ; Mice ; Mice, Inbred ICR ; Spleen ; cytology ; drug effects ; immunology