Inhibition of intracellular proton-sensitive Ca2+-permeable TRPV3 channels protects against ischemic brain injury

Ischemic brain stroke is pathologically characterized by tissue acidosis, sustained calcium entry and progressive cell death. Previous studies focusing on antagonizing N-methyl-d-aspartate (NMDA) receptors have failed to translate any clinical benefits, suggesting a non-NMDA mechanism involved in the sustained injury after stroke. Here, we report that inhibition of intracellular proton-sensitive Ca2+-permeable transient receptor potential vanilloid 3 (TRPV3) channel protects against cerebral ischemia/reperfusion (I/R) injury. TRPV3 expression is upregulated in mice subjected to cerebral I/R injury. Silencing of TRPV3 reduces intrinsic neuronal excitability, excitatory synaptic transmissions, and also attenuates cerebral I/R injury in mouse model of transient middle cerebral artery occlusion (tMCAO). Conversely, overexpressing or re-expressing TRPV3 increases neuronal excitability, excitatory synaptic transmissions and aggravates cerebral I/R injury. Furthermore, specific inhibition of TRPV3 by natural forsythoside B decreases neural excitability and attenuates cerebral I/R injury. Taken together, our findings for the first time reveal a causative role of neuronal TRPV3 channel in progressive cell death after stroke, and blocking overactive TRPV3 channel may provide therapeutic potential for ischemic brain injury.

Resveratrol inhibits Ca

BACKGROUND@#Resveratrol has been shown to inhibit platelet aggregation. However, the mechanism for this action of resveratrol remains to be clarified. The purpose of this study was to elucidate the Ca@*METHODS@#Ca@*RESULTS@#Thapsigargin-induced Ca@*CONCLUSIONS@#The results suggest that resveratrol inhibits thrombin-induced platelet aggregation through decreasing Ca

High salt inhibits nitric oxide production in thoracic aortic endothelial cells and its mechanism / 中国药理学通报

Aim To investigate the effect of high-salt model of mouse thoracic aortic endothelial cells on the production of nitric oxide (NO) . Methods After preincubation of thoracic aortic endothelial cells with transient receptor potential vanilloid 4 (TRPV4) inhibitor HC067047, the effects of TRPV4 on NO production were studied by Ca2+and NO staining with calcium ion fluorescent probe Fluo-4 and NO fluorescent probe DAF-FM DA. The thoracic aortic endothelial cells were stimulated with a high salt concentration of 60 mmo! L"1 to detect Ca2+influx and NO production Compared with control group, suppression of TRPV4 inhibited Ca2+influx and NO production in thoracic aortic endothelial cells, and high salt conditions inhibited TRPV4-medicated Ca2+influx and NO production compared with mannitol under the same osmotic pressure. Conclusion In high salt state, the inhibition of TRPV4 channel leads to the decrease of Ca2+influx and the down-regulation of NO synthesis.

Imidacloprid inhibits IgE-mediated RBL-2H3 cell degranulation and passive cutaneous anaphylaxis

BACKGROUND: Imidacloprid has been commonly used as a pesticide for crop protection and acts as nicotinic acetylcholine receptor agonists. Little information about the relationship between imidacloprid and allergy is available. OBJECTIVE: This study aims to examine the effects of imidacoprid on IgE-mediated mast cell activation. METHODS: The rat basophilic leukemia cell line RBL-2H3 (RBL-2H3 cells) were treated with 10⁻³ – 10⁻¹² mol/L imidacloprid, followed by measuring the mediator production, influx of Ca²⁺ in IgE-activated RBL-2H3 cells, and the possible effects of imidacoprid on anti-dinitrophenyl IgE-induced passive cutaneous anaphylaxis (PCA). RESULTS: It was shown that imidacoprid suppressed the production of histamine, β-hexosaminidase, leukotriene C4, interleukin-6, tumor necrosis factor-α, and Ca²⁺ mobilization in IgE-activated RBL-2H3 cells and decreased vascular extravasation in IgE-induced PCA. CONCLUSION: It is the first time to show that imidacloprid suppressed the activation of RBL-2H3 cells.

Hypericum caprifoliatum and Hypericum connatum affect human trophoblast-like cells differentiation and Ca(2+) influx

<p><b>OBJECTIVE</b>To study the effect of crude methanol and n-hexane extracts of Hypericum connatum (H. connatum) and Hypericum caprifoliatum on trophoblast-like cells.</p><p><b>METHODS</b>BeWo and JEG-3 trophoblast-like cells were submitted to different extract concentrations (1, 5, 10 and 15 µg/mL) and evaluated in relation to cell viability and in vitro trophoblast differentiation and function. Cell viability was evaluated using WST-1 reagent. Differentiation was measured by luciferase production, hCG production/release, and mitogen-activated protein kinase signaling pathway activation. The function of the trophoblast-like cells was measured by (45)Ca(2+) influx evaluation.</p><p><b>RESULTS</b>The results showed a decrease in cell viability/proliferation. Both plants and different extracts induced a significant decrease in hCG production/release and luciferase production. H. connatum did not cause mitogen-activated protein kinase signaling pathway disturbance; however, Hypericum caprifoliatum n-hexane extract at 15 µg/mL inhibited extracellular signal-regulated kinase 1/2 activation. The significant increase in Ca(2+) influx by JEG-3 cells was seen after short and long incubation times with H. connatum methanolic extract at 15 µg/mL.</p><p><b>CONCLUSIONS</b>The results indicated that these two Hypericum species extracts can interfere on trophoblast differentiation and Ca(2+) influx, according to their molecular diversity. Although in vivo experiments are necessary to establish their action on placental formation and function, this study suggests that attention must be paid to the potential toxic effect of these plants.</p>

Hypericum caprifoliatum and Hypericum connatum affect human trophoblast-like cells differentiation and Ca2+influx

Objective:To study the effect of crude methanol and n-hexane extracts of Hypericum connatum (H. connatum) and Hypericum caprifoliatum on trophoblast-like cells. Methods: BeWo and JEG-3 trophoblast-like cells were submitted to different extract concentrations (1, 5, 10 and 15 μg/mL) and evaluated in relation to cell viability and in vitro trophoblast differentiation and function. Cell viability was evaluated using WST-1 reagent. Differentiation was measured by luciferase production, hCG production/release, and mitogen-activated protein kinase signaling pathway activation. The function of the trophoblast-like cells was measured by 45Ca2+influx evaluation. Results:The results showed a decrease in cell viability/proliferation. Both plants and different extracts induced a significant decrease in hCG production/release and luciferase production. H. connatum did not cause mitogen-activated protein kinase signaling pathway disturbance;however, Hypericum caprifoliatum n-hexane extract at 15 μg/mL inhibited extracellular signal-regulated kinase 1/2 activation. The significant increase in Ca2+influx by JEG-3 cells was seen after short and long incubation times with H. connatum methanolic extract at 15 μg/mL. Conclusions: The results indicated that these two Hypericum species extracts can interfere on trophoblast differentiation and Ca2+influx, according to their molecular diversity. Although in vivo experiments are necessary to establish their action on placental formation and function, this study suggests that attention must be paid to the potential toxic effect of these plants.

Distinct Cellular Calcium Metabolism in Radiation-sensitive RKO Human Colorectal Cancer Cells

Radiation therapy for variety of human solid tumors utilizes mechanism of cell death after DNA damage caused by radiation. In response to DNA damage, cytochrome c was released from mitochondria by activation of pro-apoptotic Bcl-2 family proteins, and then elicits massive Ca2+ release from the ER that lead to cell death. It was also suggested that irradiation may cause the deregulation of Ca2+ homeostasis and trigger programmed cell death and regulate death specific enzymes. Thus, in this study, we investigated how cellular Ca2+ metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (gamma)-irradiation. In irradiated RKO cells, Ca2+ influx via activation of NCX reverse mode was enhanced and a decline of [Ca2+]i via forward mode was accelerated. The amount of Ca2+ released from the ER in RKO cells by the activation of IP3 receptor was also enhanced by irradiation. An increase in [Ca2+]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed. These results suggest that gamma-irradiation elicits enhancement of cellular Ca2+ metabolism in radiation-sensitive RKO cells yielding programmed cell death.

Effect of Elaeagnus pungens leaves on contraction of isolated guinea pig tracheal smooth muscle / 中草药

Objective: To investigate the effect of n-butanol fraction from Elaeagnus pungens leaves (BFEP) on the contraction of isolated guinea pig tracheal smooth muscle under the basal tonus or spasmogens. Methods: Guinea pig tracheal smooth muscle spiral strips were isolated. Under the normal state or the condition treated with acetylchohne (Ach), histamine (Hist), or KCl, Ca2+ release in cells without calcium, and extracellular Ca2+ influx at the high concentration of Ca2+, the effect of BFEP on the tension of isolated trachea was observed. Results: BFEP relaxed the tracheal strip significantly in the concentration-dependent manner under the basal tonus. The tested drug produced an unparallel rightward shift of the cumulative concentration-response curve of Hist or Ach. The contraction induced by high K+ and extracellular Ca2+ influx was inhibited. Conclusion: BFEP could inhibit the contraction of isolated guinea pig tracheal smooth muscle under the basal tonus or spasmogens.

Vasorelaxant mechanisms of ketamine in rabbit renal artery / 대한마취과학회지

BACKGROUND: Ketamine is a non-barbiturate anesthetic agent which has various effects on the cardiovascular system. Among them, ketamine is known for its hypotensive properties. The hypotension is thought to be mediated by a direct effect on vascular smooth muscles. This study is designed to examine the effects of ketamine on KCl- and histamine-induced contraction in isolated rabbit renal arteries. METHODS: Endothelium-intact or -denuded smooth muscle rings were prepared and mounted in myographs for isometric tension measurements. The inhibitory effect of ketamine were investigated in smooth muscle rings precontracted with either 50 mM KCl- or 10 microM histamine. RESULTS: Ketamine (0.1-100 microg/ml) produced similar concentration-dependent inhibition of contractile responses induced by either 50 mM KCl or 10 microM histamine. The respective IC50 values measured for ketamine following precontractions by 50 mM KCl and 10 microM histamine were 28.9 microg/ml (105.5 microM) and 26.7 microg/ml (97.5 microM). The inhibitory effect of 30 microg/ml ketamine were similarly observed after removal of endothelium or pretreatment with NG-Nitroarginine Methyl Ester (0.1 mM). The inhibitory effect of 30 microg/ml ketamine on histamine-evoked contraction was reduced by either tetraethylammonium (10 mM) or iberiotoxin, a large conductance Ca2+-activated K+ channel blocker. However, depletion of intracellular Ca2+ stores by ryanodine (10 microM) or thapsigargin (10 microM) showed no significant effect on 30 microg/ml ketamine-induced relaxation. Pre-incubation with 30 microg/ml ketamine significantly inhibited CaCl2-induced contraction at almost all ranges of concentration. CONCLUSIONS: Ketamine-induced relaxation of rabbit renal arteries is mediated by both the activation of large conductance Ca2+-activated K+ channel and the inhibition of Ca2+ influx.

STIM1/Orai1-mediated store-operated Ca2+ entry: the tip of the iceberg

Highly efficient mechanisms regulate intracellular calcium (Ca2+) levels. The recent discovery of new components linking intracellular Ca2+ stores to plasma membrane Ca2+ entry channels has brought new insight into the understanding of Ca2+ homeostasis. Stromal interaction molecule 1 (STIM1) was identified as a Ca2+ sensor essential for Ca2+ store depletion-triggered Ca2+ influx. Orai1 was recognized as being an essential component for the Ca2+ release-activated Ca2+ (CRAC) channel. Together, these proteins participate in store-operated Ca2+ channel function. Defective regulation of intracellular Ca2+ is a hallmark of several diseases. In this review, we focus on Ca2+ regulation by the STIM1/Orai1 pathway and review evidence that implicates STIM1/Orai1 in several pathological conditions including cardiovascular and pulmonary diseases, among others.

P2X7 Receptor-mediated Membrane Blebbing in Salivary Epithelial Cells

High concentrations of ATP induce membrane blebbing. However, the underlying mechanism involved in epithelial cells remains unclear. In this study, we investigated the role of the P2X7 receptor (P2X7R) in membrane blebbing using Par C5 cells. We stimulated the cells with 5 mM of ATP for 1~2 hrs and found the characteristics of membrane blebbing, a hallmark of apoptotic cell death. In addition, 500 micrometer Bz-ATP, a specific P2X7R agonist, induced membrane blebbing. However, 300 micrometer of Ox-ATP, a P2X7R antagonist, inhibited ATP-induced membrane blebbing, suggesting that ATP-induced membrane blebbing is mediated by P2X7R. We found that ATP-induced membrane blebbing was mediated by ROCK I activation and MLC phosphorylation, but not by caspase-3. Five mM of ATP evoked a biphasic [Ca2+]i response; a transient [Ca2+]i peak and sustained [Ca2+]i increase secondary to ATP-stimulated Ca2+ influx. These results suggest that P2X7R plays a role in membrane blebbing of the salivary gland epithelial cells.

Cardiovascular effects induced by the hydroalcoholic extract of the stem of Xylopia cayennensis in rats / Efeitos cardiovasculares induzidos pelo extrato hidroalcoólico das cascas de Xylopia cayennensis em ratos

The cardiovascular effects induced by the hydroalcoholic extract of the stem of Xylopia cayennensis (HEXC) were studied in rats using a combined in vivo and in vitro approach. In non-anesthetized rats, HEXC injections produced a significant and dose-dependent hypotension associated with an increase in heart rate. The hypotensive response was not attenuated after nitric oxide (NO) synthase blockade, L-NAME (20 mg/Kg, i.v.). In isolated rat superior aortic rings, HEXC was able to relax the tonus induced by phenylephrine (1 µM) and KCl (80 mM), (EC50 = 85±13 and 62±5 µg/mL, respectively). The smooth muscle-relaxant activity of HEXC was not inhibited by removal of vascular endothelium (EC50 = 58±6 µg/mL). HEXC antagonized CaCl2-induced contractions in depolarizing medium nominally without Ca2+. HEXC inhibited the intracellular calcium-dependent transient contractions induced by caffeine (20 mM) in Ca2+-free solution, but not those induced by norepinephrine (1 µM). In isolated rat atrial preparations, HEXC produced negative inotropic and chronotropic responses (IC50= 534±42 and 259±22 µg/mL, respectively). The results obtained suggest that the hypotensive effect of HEXC is probably due to a peripheral vasodilatation, at least, secondary to an interference with the Ca2+ mobilization as a consequence of voltage-dependent Ca2+ channel blockade and the inhibition of Ca2+ release from caffeine-sensitive intracellular stores. Finally, HEXC acts directly on the heart decreasing contractility and heart rate, these effects are of little importance to the expression of the hypotensive response induced by HEXC.

Os efeitos cardiovasculares induzidos pelo extrato hidroalcoólico do caule de Xylopia cayennensis (EHXC) foram estudados em ratos, utilizando uma abordagem combinada in vivo e in vitro. Em ratos não anestesiados, EHXC induziu uma hipotensão não dependente de dose associada com um aumento da freqüência cardíaca. Esta resposta hipontesora não foi atenuada depois do bloqueio com L-NAME (20 mg/Kg, i.v.). Em anéis de aorta isolados de rato, EHXC foi capaz de relaxar o tônus induzido por fenilefrina (1 µM) e KCl (80 mM), (CE50 = 85±13 e 62±5 µg/mL, respectivamente). A atividade vasorelaxante do HEXC não foi inibida pela remoção do endotélio vascular (CE50 = 58±6 µg/mL). HEXC antagonizou as contrações induzidas por CaCl2 em meio despolarizante nominalmente sem Ca+2. EHXC antagonizou de maneira dependente de concentração as contrações transientes induzidas por cafeína (20 mM), em meio livre de Ca2+, contudo não alterou aquelas induzidas por noradrenalina (1 µM). Em átrio isolado de rato, EHXC induziu um efeito inotrópico e cronotrópico negativo (CI50= 534±42 µg/mL e 259±22 µg/mL; respectivamente). Os resultados obtidos demonstram que EHXC apresenta um potente efeito hipotensor, provavelmente conseqüência da diminuição da resistência periférica total que parece ser, em parte, devido a uma ação inibitória sobre o influxo de Ca+2 através de canais de cálcio dependentes de voltagem e também através da inibição da liberação de Ca+2 dos estoques intracelulares sensíveis à cafeína. HEXC atua diretamente no coração diminuindo a contratilidade e a freqüência cardíaca, estes efeitos têm importância pequena na expressão da resposta hipotensiva induzida por HEXC.

Acetylcholine Induces Hyperpolarization Mediated by Activation of K (Ca) Channels in Cultured Chick Myoblasts

Our previous report demonstrated that chick myoblasts are equipped with Ca2+-permeable stretch- activated channels and Ca2+-activated potassium channels (KCa), and that hyperpolarization-induced by KCa channels provides driving force for Ca2+ influx through the stretch-activated channels into the cells. Here, we showed that acetylcholine (ACh) also hyperpolarized the membrane of cultured chick myoblasts, suggesting that nicotinic acetylcholine receptor (nAChR) may be another pathway for Ca2+ influx. Under cell-attatched patch configuration, ACh increased the open probability of KCa channels from 0.007 to 0.055 only when extracellular Ca2+ was present. Nicotine, a nAChR agonist, increased the open probability of KCa channels from 0.008 to 0.023, whereas muscarine failed to do so. Since the activity of KCa channel is sensitive to intracellular Ca2+ level, nAChR seems to be capable of inducing Ca2+ influx. Using the Ca2+ imaging analysis, we were able to provide direct evidence that ACh induced Ca2+ influx from extracellular solution, which was dramatically increased by valinomycin-mediated hyperpolarization. In addition, ACh hyperpolarized the membrane potential from -12.5+/-3 to -31.2+/-5 mV by generating the outward current through KCa channels. These results suggest that activation of nAChR increases Ca2+ influx, which activates KCa channels, thereby hyperpolarizing the membrane potential in chick myoblasts.

A Possible Role of Kainate Receptors in C2C12 Skeletal Myogenic Cells

Ca2+ influx appears to be important for triggering myoblast fusion. It remains, however, unclear how Ca2+ influx rises prior to myoblast fusion. Recently, several studies suggested that NMDA receptors may be involved in Ca2+ mobilization of muscle, and that Ca2+ influx is mediated by NMDA receptors in C2C12 myoblasts. Here, we report that other types of ionotropic glutamate receptors, non-NMDA receptors (AMPA and KA receptors), are also involved in Ca2+ influx in myoblasts. To explore which subtypes of non-NMDA receptors are expressed in C2C12 myogenic cells, RT-PCR was performed, and the results revealed that KA receptor subunits were expressed in both myoblasts and myotubes. However, AMPA receptor was not detected in myoblasts but expressed in myotubes. Using a Ca2+ imaging system, Ca2+ influx mediated by these receptors was directly measured in a single myoblast cell. Intracellular Ca2+ level was increased by KA, but not by AMPA. These results were consistent with RT-PCR data. In addition, KA-induced intracellular Ca2+ increase was completely suppressed by treatment of nifedifine, a L-type Ca2+ channel blocker. Furthermore, KA stimulated myoblast fusion in a dose-dependent manner. CNQX inhibited not only KA-induced myoblast fusion but also spontaneous myoblast fusion. Therefore, these results suggest that KA receptors are involved in intracellular Ca2+ increase in myoblasts and then may play an important role in myoblast fusion.

Neurotensin enhances gastric motility in antral circular muscle strip of guinea-pig

Many reports suggest that neurotensin (NT) in the gastrointestinal tract may play a possible role as a neurotransmitter, a circulating hormone, or a modulator of motor activity. NT exerts various actions in the intestine; it produces contractile and relaxant responses in intestinal smooth muscle. This study was designed to investigate the effect of NT on motility of antral circular muscle strips in guinea-pig stomach. To assess the role of Ca2+ influx in underlying mechanism, slow waves were simultaneously recorded with spontaneous contractions using conventional intracellular mircoelectrode technique. At the concentration of 10-7 M, where NT showed maximum response, NT enhanced the magnitude (863 +/- 198%, mean +/- SEM, n = 13) and the frequency (154 +/- 10.3%, n = 11) of spontaneous contractions. NT evoked a slight hyperpolarization of membrane potential, tall and steep slow waves with abortive spikes (278 +/- 50%, n = 4). These effects were not affected by atropine (2 micrometer), guanethidine (2 micrometer) and tetrodotoxin (0.2 micrometer). NT-induced contractile responses were abolished in Ca2+-free solution and reduced greatly to near abolition by 10 micrometer of verapamil or 0.2 mM of CdCl2. Verapamil attenuated the effects of NT on frequency and amplitude of the slow waves. Taken together, these results indicate that NT enhances contractility in guinea-pig gastric antral circular muscle and Ca2+ influx through the voltage-operated Ca2+ channel appears to play an important role in the NT-induced contractile mechanism.

notropic and Electrophysiologic Effect of Azumolene in Intact Myocardium In Vitro / 대한마취과학회지

BACKGROUND: The effects of various concentrations (10, 25 micrometer) of azumolene, an analogue of dantrolene, were studied in isolated guinea pig ventricular papillary muscles by measuring the effects on myocardial contractility and electrophysiologic parameters. METHODS: Isometric forces were studied in normal and 26 mM K Tyrode's solution. Rapid cooling contracture, an index of SR Ca2 content, was performed. Normal and slow action potentials (APs) were evaluated by using conventional microelectrode technique. RESULTS: Ten and 25 micrometer azumolene depressed peak force and maximum rate of force development ( 30 40%). Dose-dependent depression was shown at 2 and 3 Hz stimulation rate. Rapid cooling contractures following 10 and 25 micrometer azumolene was not altered compared to control while peak force at 2 Hz stimulation rate just prior to cooling was depressed similarly to normal Tyrode's solution. In 26 mM K Tyrode's solution, 10 and 25 micrometer azumolene caused depression of early (10 micrometer: 20%) and late (10 micrometer: 50%) force development. In slow APs, shortening of AP duration at 20, 50, and 90% of the repolarization phase, as well as a small but significant reduction of dV/dt-max ( 20%) were shown at 0.25 Hz stimulation rate. There was no alteration in AP parameters in normal APs. CONCLUSIONS: The direct myocardial depressant action of azumolene seems to be at least in part caused by inhibition of Ca2 influx via the Ca2 channel in sarcolemma. It seems likely that azumolene does not alter the sarcoplasmic reticulum function such as Ca2 uptake and release in cardiac muscle.

BDNF mRNA Expression and Calcium Influx Pathways in Kainate-induced Neurotoxicity

Kainate is known as a neurotoxin acting on the glutamate receptors in the central nervous system (CNS). Glutamate acts an excitatory neurotransmitter at physiological concentration but has a neurotoxic effect in excess amount. BDNF (brain-derived neurotrophic factor) has been reported to have a protective effect against the cellular toxicity and to plays an important role in neuronal survival and differentiation in peripheral nervous system. However, the functional mechanism of BDNF in CNS is unclear. This study was performed to examine the protective effect of BDNF in kainate-induced neurotoxicity and to observe the relation between BDNF mRNA expression and increasing pathways of intracellular Ca2+ concentration. Cultured hippocampal neurons were prepared from 17-18 day embryonic rats and used at the 7th day after neuronal culture. The amounts of BDNF mRNA were measured by reverse transcription polymerase chain reaction after the treatment of several glutamate receptor agonists: glutamate, kainate, -amino-3-hydroxyl-4-isoxazolepropionic acid, N-methyl-D-aspartate. Kainate showed the most prominent effect in an increase of BDNF mRNA expression among the glutamate receptor agonists. The maximal increase of BDNF mRNA expression was obtained in 50 M kainate at 3 hr after the treatment. Adding BDNF to kainate containing cultured hippocampal neurons diminished the increasing level of lactic dehydrogenase according to the single treatment of kainate. In the experiment to evaluate the Ca2+ influx pathways related in BDNF mRNA expression, nifedipine (10 M), a voltage-dependent Ca2+ channel blocker, decreased the both kainate (50 M) and KCl (50 mM) induced BDNF mRNA expressions by 18.4% and 35.0%, respectively. Ryanodine (10 M), a blocker of intracellular release from Ca2+ storage, however, did not show any effect in the both kainate- and KCl-treated neurons.These results suggest that BDNF has a protecting effect against the kainate-induced neurotoxicity in cultured rat hippocampal neurons, and its expression is more related with the Ca2+ influx through the voltage-dependent Ca2+ channels than the release from intracellular Ca2+ storage.

Effects of protein tyrosine kinase inhibitor on cerebrovascular smooth muscle cells Ca~(2+)store-operated Ca~(2+)influx / 中国药理学通报

AIM To study the effects of protein tyrosine kinase inhibitor and protein tyrosine phosphatase inhibitor on cultured bovine cerebrovascular smooth muscle cells (CSMC) Ca 2+ store operated Ca 2+ influx. METHODS Cell culture and single intracellular free Ca 2+ concentration was measured in fura 2/Am flueorescence probe by MetaFluor Fluorescence ratio imaging system. RESULTS (1) protein tyrosine kinase inhibitor (genistein,2.5,5,10 ?mol?L -1 )decreased Ca 2+ influx significantly induced by endothelin 1(ET 1),ATP,cyclopiazonic acid(CPA) in concentration dependent manner; (2) Protein tyrosine phosphatase inhibitor (vanadate,2,4,8 ?mol?L -1 ) increased Ca 2+ influx significantly induced by ET 1,ATP,CPA in concentration dependent manner. CONCLUSION Protein tyrosine kinase inhibitor and protein tyrosine phosphatase inhibitor have effects on Ca 2+ store operated Ca 2+ influx induced by ET 1, ATP, CPA. Protein tyrosine phosphorylation participats in the signal transduction of Ca 2+ store operat Ca 2+ influx in cerebrovascular smooth muscle cells.

Effects of S-nitrosocaptopril on cyclopiazonic acid-induced [Ca~(2+) ]_i change in rat aortic smooth muscle cells / 中国药理学通报

AIM To study the characteristics of Ca 2+ channel mediated store operated Ca 2+ influx on rat vascular smooth muscle. METHOD Fura 2 fluorescence technique was used to investigate the [Ca 2+ ] i change. RESULTS ① S nitrosocaptopril (CapNO,20～120 ?mol?L -1 ) produced a concentration dependent inhibitory effect on cyclopiazonic acid(CPA) induced [Ca 2+ ] i change. The maximal inhibitory effect(37%?17%) of CapNO was reached at a concentration of 80 ?mol?L -1 . The same concentration of Captopril had no effects. ② Inhibition rate of 80 ?mol?L -1 CapNO (The concentration of maximal effect, CME) on CPA induced [Ca 2+ ] i change was 30%?10%, subsequent addition of 1 ?mol?L -1 Nif (CME)did not further produced the decrease effect (54%?18%). subsequent addition of 20 ?mol?L -1 SK&F96365 (CME) further produced the decrease effect. The inhibitory effects of 20 ?mol?L -1 SK&F96365 were significantly different in the cases of CapNO and Nif pretreatment(24%?10%) and non treatment (54%?11%). ③ The inhibitory effects of 2 ?mol?L -1 tyrphostinAG490(AG490,CME) were significantly different in the cases of CapNO (CME) pretreatment (24%?9%)and non treatment (42%?10%). 80 ?mol?L -1 CapNO effect on CPA induced [Ca 2+ ] i changes in AG490 pretreatment condition(18%?7%) was different from that in non treatment case(37%?10%). CONCLUSION S nitrosocaptopril obviously inhibits the opening of SOCC and VDCC, which mediates store operated Ca 2+ influx. The inhibitory effects of CapNO is associated with both sensitive to and non sensitive to tyrosine kinase (Janus2).

The effect of glutamate on cytosolic Ca~(2+) concentration and Ca~(2+)influx induced by ATP in cultured calf middle cerebral artery smooth muscle cells / 中国药理学通报

AIM To investigate if glutamate has direct effects on both resting [Ca 2+ ] i and Ca 2+ influx induced by ATP in cultured calf middle artery cerebral smooth muscle cells. METHODS The effect of glutamate on [Ca 2+ ] i was determined with Fura2 fluorescence technique. RESULTS Glutamate(10～200 ?mol?L -1 )didnot elevate the resting [Ca 2+ ] i level and in the concentrations of 10～400 ?mol?L -1 failed to affect increase and decrese the Ca 2+ influx induced by ATP. CONCLUSION Glutamate hasn't directly effects on both resting [Ca 2+ ] i; and Ca 2+ influx in middle cerebral artery smooth muscle cells. Glutamate is unlikely to participate in regulation of cerebrovascular tention as a direct effector.