T-type calcium channel expression in cultured human neuroblastoma cells

Human neuroblastoma cells （SH-SY5Y） have similar structures and functions as neural cells and have been frequently used for cell culture studies of neural cell functions.Previous studies have revealed L-and N-type calcium channels in SH-SY5Y cells.However,the distribution of the low-voltage activated calcium channel （namely called T-type calcium channel,including Cav3.1,Cav3.2,and Cav3.3） in SH-SY5Y cells remains poorly understood.The present study detected mRNA and protein expres-sion of the T-type calcium channel （Cav3.1,Cav3.2,and Cav3.3） in cultured SH-SY5Y cells using real-time polymerase chain reaction （PCR） and western blot analysis.Results revealed mRNA and protein expression from all three T-type calcium channel subtypes in SH-SY5Y cells.Moreover,Cav3.1 was the predominant T-type calcium channel subtype in SH-SY5Y cells.

Calcium signaling and T-type calcium channels in cancer cell cycling

Regulation of intracellular calcium is an important signaling mechanism for cell proliferation in both normal and cancerous cells. In normal epithelial cells, free calcium concentration is essential for cells to enter and accomplish the S phase and the M phase of the cell cycle. In contrast, cancerous cells can pass these phases of the cell cycle with much lower cytoplasmic free calcium concentrations, indicating an alternative mechanism has developed for fulfilling the intracellular calcium requirement for an increased rate of DNA synthesis and mitosis of fast replicating cancerous cells. The detailed mechanism underlying the altered calcium loading pathway remains unclear; however, there is a growing body of evidence that suggests the T-type Ca2+ channel is abnormally expressed in cancerous cells and that blockade of these channels may reduce cell proliferation in addition to inducing apoptosis. Recent studies also show that the expression of T-type Ca2+ channels in breast cancer cells is proliferation state dependent, i.e. the channels are expressed at higher levels during the fast-replication period, and once the cells are in a non-proliferation state, expression of this channel isminimal. Therefore, selectively blocking calcium entry into cancerous cells may be a valuable approach for preventing tumor growth. Since T-type Ca2+ channels are not expressed in epithelial cells, selective T-type Ca2+ channel blockers may be useful in the treatment of certain types of cancers.

Formaldehyde increases intracellular calcium concentration in primary cultured hippocampal neurons partly through NMDA receptors and T-type calcium channels

Objective Formaldehyde at high concentrations is a contributor to air pollution. It is also an endogenous metabolic product in cells, and when beyond physiological concentrations, has pathological effects on neurons. Formaldehyde induces mis-folding and aggregation of neuronal tau protein, hippocampal neuronal apoptosis, cognitive impairment and loss of memory functions, as well as excitation of peripheral nociceptive neurons in cancer pain models. Intracellular calcium （[Ca2＋]i） is an important intracellular messenger, and plays a key role in many pathological processes. The present study aimed to investigate the effect of formaldehyde on [Ca2＋]i and the possible involvement of N-methyl-D-aspartate receptors （NMDARs） and T-type Ca2＋ channels on the cell membrane. Methods Using primary cultured hippocampal neurons as a model, changes of [Ca2＋]i in the presence of formaldehyde at a low concentration were detected by confocal laser scanning microscopy. Results Formaldehyde at 1 mmol/L approximately doubled [Ca2＋]i. （2R）-amino-5-phosphonopentanoate （AP5, 25 μmol/L, an NMDAR antagonist） and mibefradil （MIB, 1 μmol/L, a T-type Ca2＋ channel blocker）, given 5 min after formaldehyde perfusion, each partly inhibited the formaldehyde-induced increase of [Ca：＋]i, and this inhibitory effect was reinforced by combined application of AP5 and MIB. When applied 3 min before formaldehyde perfusion, AP5 （even at 50μmol/L） did not inhibit the formaldehyde-induced increase of [Ca2＋]i, but MIB （1 μmol/L） significantly inhibited this increase by 70%. Conclusion These results suggest that formaldehyde at a low concentration increases [Ca2＋]i in cultured hippocampal neurons; NMDARs and T-type Ca2＋ channels may be involved in this process.

Role of T-type Calcium Channels in Generating Hyperexcitatory Behaviors during Emergence from Sevoflurane Anesthesia in Neonatal Rats

In the current study,we sought to investigate whether T-type Ca^(2+)channels(TCCs)in the brain are involved in generating post-anesthetic hyperexcitatory behaviors(PAHBs).We found that younger rat pups(postnatal days 9-11)had a higher incidence of PAHBs and higher PAHB scores than older pups(postnatal days16-18)during emergence from sevoflurane anesthesia.The power spectrum of the theta oscillations(4 Hz-8 Hz)in the prefrontal cortex was significantly enhanced in younger pups when PAHBs occurred,while there were no significant changes in older pups.Both the power of theta oscillations and the level of PAHBs were significantly reduced by the administration of TCC inhibitors.Moreover,the sensitivity of TCCs in the medial dorsal thalamic nucleus to sevoflurane was found to increase with age by investigating the kinetic properties of TCCs in vitro.TCCs were activated by potentiated GABAergic depolarization with a sub-anesthetic dose of sevoflurane(1%).These data suggest that(1)TCCs in the brain contribute to the generation of PAHBs and the concomitant electroencephalographic changes;(2)the stronger inhibitory effect of sevoflurane contributes to the lack of PAHBs in older rats;and(3)the contribution of TCCs to PAHBs is not mediated by a direct effect of sevoflurane on TCCs.

Adjuvant role of a T-type calcium channel blocker, TTA-A2, in lung cancer treatment with paclitaxel

Aim:Chemoresistance is a prevalent issue in cancer treatment.Paclitaxel(PTX)is a microtubule-binding anticancer drug used in various cancer treatments.However,cancer cells often show chemoresistance against PTX with the help of P-glycoprotein(Pgp)-a drug efflux pump.It has also been observed that overexpressed T-type calcium channels(TTCCs)maintain calcium homeostasis in cancer cells,and calcium has a role in chemoresistance.Therefore,the aim of this study was to test the adjuvant role of TTA-A2,a TTCC blocker,in enhancing the anticancer effect of PTX on the A549 lung adenocarcinoma cell line.Methods:Morphology assay,calcium imaging assay,clonogenic assay,apoptosis assay,and real-time polymerase chain reaction(real-time PCR)were performed to find the adjuvant role of TTA-A2.Samples were treated with PTX at 10 nM concentration and TTA-A2 at 50 and 100 nM concentrations.PTX and TTA-A2 were used in the combination treatment at 10 and 100 nM concentrations,respectively.Results:Immunocytochemistry confirmed the expression of TTCC in A549 cells.Morphology assay showed altered morphology of A549 cells.The adjuvant role of TTA-A2 was observed in the calcium imaging assay in spheroids,in the clonogenic assay in monolayers,and in the apoptosis assay in both cultures.With real-time PCR,it was observed that,even though cells express the mRNA of Pgp,it is non-significant upon treatment with PTX and TTA-A2.Conclusion:TTA-A2 can be used as an adjuvant to reduce chemoresistance in cancer cells as well as to enhance the anticancer effect of the standard anticancer drug PTX.Being a potent TTCC inhibitor,TTA-A2 may also enhance the anticancer effects of other anticancer drugs.

Effects of Rhynchophyline on L-type Calcium Channels in Isolated Rat Cortical Neurons During Acute Hypoxia

目的：研究钩藤碱对急性分离的Ｗｉｓｔａｒ大鼠大脑皮层神经元低氧状态下Ｌ型钙通道的作用。方法：细胞贴附膜片钳技术，从－４０ｍＶ去极化至０ｍＶ激活Ｌ型钙通道。结果：低氧可激活皮层神经元Ｌ型钙通道开放，使平均开放时间延长，平均关闭时间缩短，开放概率增加。钩藤碱（１５和３０μｍｏｌ·Ｌ－１）可浓度依赖性抑制低氧状态下此钙通道的激活，缩短其平均开放时间（从８８７ｍｓ缩至３０３ｍｓ和２２３ｍｓ，Ｐ＜０００１），延长其平均关闭时间（从９２３ｍｓ延至３８８４和５４４３ｍｓ，Ｐ＜０００１）并降低其开放概率（从０１４２降至００３１和００２５，Ｐ＜０００１）此作用与维拉帕米（１５μｍｏｌ·Ｌ－１）相似，但稍弱。结论：钩藤碱对低氧大鼠大脑皮层神经元Ｌ型钙通道有阻滞作用，从而降低细胞内钙超载。

Antineoplastic Effect of Calcium Channel Blocker-Verapamil and 5-Fluorouracil Intraperitoneal Chemotherapy on Hepatocarcinoma-Bearing Rats

Objective To study the antineoplastic effect of the calcium channel blocker verapamil and 5-fluorouracil intraperitoneal chemotherapy on hepatocarcinoma-bearing rats,and examine the action between calcium channel blockers and cytotoxic drugs. Methods We adopted the method of subcapsular implantation of carcinoma tissues of walker-256 in the left liver lobe as a model of liver carcinoma-bearing rats.All experimental animals were divided into four groups.On the sixth day post implantation,in group A (control group) 6ml of saline was injected intraperitoneally once a day for 3 days.In group B(single chemotherapy group) 6ml of 5-Fu 75 mg/kg was injected intraperitoneally once a day for 3 days.In group C(combination of treatment group)both 5-Fu(75mg/kg) and verapamil (25mg/kg) were administered simultaneously as in A and B.In group D(simple verapamil group)only 6ml of verapamil(25mg/kg)was administered as above. Results Compared with groups A, B and D,The volume of cancer and the contents of liver cancer DNA and protein were significantly reduced.The rates of inhibiting cancer(89.9% in group C and 35.4% in group B)were significantly increased in groupC. Group C had significantly long survival time compared to groups A, B and D(P<0.05).By light microscopy, a number of focal necroses were found in cancer tissue in group C.Conclusion Calcium channel blockers can enhance the antineoplastic effect of 5-Fu intraperitonea chemotherapy to liver cancer;The use of verapamil can not increase the toxicity of 5-Fu.

Hydrogen sulfide-induced enhancement of gastric fundus smooth muscle tone is mediated by voltagedependent potassium and calcium channels in mice

AIM:To investigate the effect of hydrogen sulfide(H2S)on smooth muscle motility in the gastric fundus.METHODS:The expression of cystathionineβ-synthase(CBS)and cystathionineγ-lyase(CSE)in cultured smooth muscle cells from the gastric fundus was examined by the immunocytochemistry technique.The tension of the gastric fundus smooth muscle was recorded by an isometric force transducer under the condition of isometric contraction with each end of the smooth muscle strip tied with a silk thread.Intracellular recording was used to identify whether hydrogen sulfide affects the resting membrane potential of the gastric fundus in vitro.Cells were freshly separated from the gastric fundus of mice using a variety of enzyme digestion methods and whole-cell patch-clamp technique was used to find the effects of hydrogen sulfide on voltage-dependent potassium channel and calcium channel.Calcium imaging with fura-3AM loading was used to investigate the mechanism by which hydrogen sulfide regulates gastric fundus motility in cultured smooth muscle cells.RESULTS:We found that both CBS and CSE were expressed in the cul tured smooth muscle cel ls from the gastric fundus and that H2S increased the smooth muscle tension of the gastric fundus in mice at low concentrations.In addition,nicardipine and aminooxyacetic acid(AOAA),a CBS inhibitor,reduced the tension,whereas Nω-nitro-L-arginine methyl ester,a nonspecific nitric oxide synthase,increased the tension.The AOAA-induced relaxation was significantly recovered by H2S,and the Na HS-induced increase in tonic contraction was blocked by 5 mmol/L4-aminopyridine and 1μmol/L nicardipine.Na HS significantly depolarized the membrane potential and inhibited the voltage-dependent potassium currents.Moreover,Na HS increased L-type Ca2+currents and caused an elevation in intracellular calcium([Ca2+]i).CONCLUSION:These findings suggest that H2S may be an excitatory modulator in the gastric fundus in mice.The excitatory effect is mediated by voltagedependent potassium and L-type calcium channels.

Polydatin attenuated food allergy via store-operated calcium channels in mast cell

AIM: To investigate the effect of polydatin (PD), a resveratrol glucoside, on mast cell degranulation and antiallergic activity. METHODS: After the rats were orally sensitized with ovalbumin (OVA) for 48 d and underwent PD treatment for 4 d, all the rats were stimulated by 100 mg/mL OVA for24 h and then sacrificed for the following experiments. The small intestines from all the groups were prepared for morphology examination by hematoxylin and eosin staining. We also used a smooth muscle organ bath to evaluate the motility of the small intestines. The OVA-specific immunoglobulin E (IgE) production and interleu-kin-4 (IL-4) levels in serum or supernatant of intestinal mucosa homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA). Using toluidine blue stain, the activation and degranulation of isolated rat peritoneal mast cells (RPMCs) were analyzed. Release of histamine from RPMCs was measured by ELISA, and regulation of PD on intracellular Ca 2+ mobilization was investigated by probing intracellular Ca 2+ with fluo-4 fluo-rescent dye, with the signal recorded and analyzed. RESULTS: We found that intragastric treatment with PD significantly reduced loss of mucosal barrier integrity in the small intestine. However, OVA-sensitization caused significant hyperactivity in the small intestine of allergic rats, which was attenuated by PD administration by 42% (1.26 ± 0.13 g vs OVA 2.18 ± 0.21 g, P < 0.01). PD therapy also inhibited IgE production (3.95 ± 0.53 ng/mL vs OVA 4.53 ± 0.52 ng/mL, P < 0.05) by suppressing the secretion of Th2-type cytokine, IL-4, by 34% (38.58 ± 4.41 pg/mLvs OVA 58.15 ± 6.24 pg/mL, P < 0.01). The ratio of degranulated mast cells, as indicated by vehicles (at least five) around the cells, dramatically increased in the OVA group by 5.5 fold (63.50% ± 15.51% vs phosphate-buffered saline 11.15% ± 8.26%, P < 0.001) and fell by 65% after PD treatment (21.95% ± 4.37% vs OVA 63.50% ± 15.51%, P < 0.001). PD mediated attenuation of mast cell degranulation was further confirmed by decreased histamine levels in both serum (5.98 ± 0.17 vs OVA 6.67 ± 0.12, P < 0.05) and intestinal mucosa homogenates (5.83 ± 0.91 vs OVA 7.35 ± 0.97, P < 0.05). Furthermore, we demonstrated that administration with PD significantly decreased mast cell degranulation due to reduced Ca 2+ influx through store-operated calcium channels (SOCs) (2.35 ± 0.39vs OVA 3.51 ± 0.38,P < 0.01).CONCLUSION: Taken together, our data indicate that PD stabilizes mast cells by suppressing intracellular Ca 2+ mobilization, mainly through inhibiting Ca 2+ entry via SOCs, thus exerting a protective role against OVA-sensitized food allergy.

Calcium channel blocker monotherapy versus combination with reninangiotensin system inhibitors on the development of new-onset diabetes mellitus in hypertensive Korean patients

Background In real practice, two or more antihypertensive drugs are needed to achieve target blood pressure. We investigated the comparative beneficial actions of combination therapy of renin-angiotensin system inhibitors (RASI), with calcium channel blockers (CCB) over CCB monotherapy on the development of new-onset diabetes mellitus (NODM) in Korean patients during four-year follow-up periods. Methods A total of 3208 consecutive hypertensive patients without a history of diabetes mellitus who had been prescribed CCB were retrospectively enrolled from January 2004 to December 2012. These patients were divided into the two groups according to the additional use of RASI (the RASI group, n = 1221 and the no RASI group, n = 1987). Primary endpoint was NODM, defined as a fasting blood glucose ≥ 126 mg/dL or hemoglobin A1c ≥ 6.5%. Secondary endpoint was major adverse cardiac events (MACE) defined as total death, myocardial infarction (MI) and percutaneous coronary intervention (PCI). Results After propensity score-matched (PSM) analysis, two propensity- matched groups (939 pairs, n = 1878, C-statistic = 0.743) were generated. The incidences of NODM (HR = 1.009, 95% CI: 0.700–1.452, P = 0.962), MACE (HR = 0.877, 95% CI: 0.544–1.413, P = 0.589), total death, MI, PCI were similar between the two groups after PSM during four years. Conclusions The use of RASI in addition to CCB showed comparable incidences of NODM and MACE compared to CCB monotherapy in non-diabetic hypertensive Korean patients during four-year follow-up period. However, large-scaled randomized controlled clinical trials will be required for a more definitive conclusion.

Calcium channel blockers and Alzheimer's disease

Alzheimer＇s disease is characterized by two pathological hallmarks： amyloid plaques and neurofibrillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer＇s disease. Calcium channel blockers are effective therapeutics for treating Alzheimer＇s disease. This review provides an overview of the current research of calcium channel blockers involved in Alzheimer＇s disease theraov.

Effects of calcium channel on 3-morpholinosydnonimine-induced rat hippocampal neuronal apoptosis

Previous studies have demonstrated that increased chloride channel activity plays a role in nitric oxide-induced neuronal apoptosis in the rat hippocampus. The present study investigated the effects of the broad-spectrum calcium channel blocker CdCI2 on survival rate, percentage of apoptosis, and morphological changes in hippocampal neurons cultured in vitro, as well as the effects of calcium channels on neuronal apoptosis. The chloride channel blockers 4-acetamido-4＇-isothiocyanatostilbene-2, 2＇-disulfonic acid （SITS） or 4, 4＇-diisethiocyanostilbene-2, 2＇-disulfonic acid （DIDS） increased the survival rate of 3-morpholinosydnonimine （SIN-1）-treated neurons and suppressed SIN-l-induced neuronal apoptosis. The calcium channel blocker CdCI2 did not increase the survival rate of neurons and did not affect SIN-l-induced apoptosis or SITS- or DIDS-suppressed neuronal apoptosis. Results demonstrated that calcium channels did not significantly affect neuronal apoptosis.

Altered expression of stromal interaction molecule(STIM)-calcium release-activated calcium channel protein(ORAI) and inositol1,4,5-trisphosphate receptors(IP_3Rs)in cancer:will they become a new battlefield for oncotherapy?

The stromal interaction molecule(STIM)-calcium release-activated calcium channel protein(ORAI) and inositol1,4,5-trisphosphate receptors(IP_3Rs) play pivotal roles in the modulation of Ca^(2+)-regulated pathways from gene transcription to cell apoptosis by driving calcium-dependent signaling processes.Increasing evidence has implicated the dysregulation of STIM-ORAI and IP_3Rs in tumorigenesis and tumor progression.By controlling the activities,structure,and/or expression levels of these Ca^(2+)-transporting proteins,malignant cancer cells can hijack them to drive essential biological functions for tumor development.However,the molecular mechanisms underlying the participation of STIM-ORAI and IP_3Rs in the biological behavior of cancer remain elusive.In this review,we summarize recent advances regarding STIM-ORAI and IP_3Rs and discuss how they promote cell proliferation,apoptosis evasion,and cell migration through temporal and spatial rearrangements in certain types of malignant cells.An understanding of the essential roles of STIM-ORAI and IP_3Rs may provide new pharmacologic targets that achieve a better therapeutic effect by inhibiting their actions in key intracellular signaling pathways.

Voltage gated calcium channel antibody-related neurological diseases

Voltage gated calcium channel(VGCC) antibodies are generally associated with Lambert-Eaton myasthenic syndrome. However the presence of this antibody has been associated with paraneoplastic as well as nonparaneoplastic cerebellar degeneration. Most patients with VGCC-antibody-positivity have small cell lung cancer(SCLC). Lambert-Eaton myasthenic syndrome(LEMS)is an autoimmune disease of the presynaptic part of the neuromuscular junction. Its classical clinical triadis proximal muscle weakness, areflexia and autonomic dysfunction. Fifty to sixty percent of LEMS patients have a neoplasia, usually SCLC. The co-occurrence of SCLC and LEMS causes more severe and progressive disease and shorter survival than non-paraneoplastic LEMS. Treatment includes 3,4 diaminopyridine for symptomatic purposes and immunotherapy with prednisolone, azathioprine or intravenous immunoglobulin in patients unresponsive to 3,4 diaminopyridine. Paraneoplastic cerebellar degeneration(PCD) is a syndrome characterized with severe, subacute pancerebellar dysfunction. Serum is positive for VGCC antibody in 41%-44% of patients, usually with the co-occurrence of SCLC. Clinical and electrophysiological features of LEMS are also present in 20%-40% of these patients. Unfortunately, PCD symptoms do not improve with immunotherapy. The role of VGCC antibody in the immunopathogenesis of LEMS is well known whereas its role in PCD is still unclear. All patients presenting with LEMS or PCD must be investigated for SCLC.

Inhibitory actions of mibefradil on steroidogenesis in mouse Leydig cells： involvement of Ca^2＋ entry via the T-type Ca^2＋ channel

Intracellular cAMP and Ca^2＋ are involved in the regulation of steroidogenic activity in Leydig cells, which coordinate responses to luteinizing hormone （LH） and human ehorionic gonadotropin （hCG）. However, the identification of Ca^2＋ entry implicated in Leydig cell steroidogenesis is not well defined. The objective of this study was to identify the type of Ca^2＋ channel that affects Leydig cell steroidogenesis. In vitro steroidogenesis in the freshly dissociated Leydig cells of mice was induced by hCG incubation. The effects of mibefradil （a putative T-type Ca^2＋ channel blocker） on steroidogenesis were assessed using reverse transcription （RT）-polymerase chain reaction analysis for the steroidogenic acute regulatory protein （STAR） mRNA expression and testosterone production using radioimmunoassay. In the presence of 1.0 mmol L-1 extracellular Ca^2＋, hCG at 1 to 100 IU noticeably elevated both StAR mRNA level and testosterone secretion （P 〈 0.05）, and the stimulatory effects of hCG were markedly diminished by mibefradil in a dose-dependent manner （P 〈 0.05）. Moreover; the hCG-induced increase in testosterone production was completely removed when external Ca^2＋ was omitted, implying that Ca entry is needed for hCG-induced steroidogenesis. Furthermore, a patch-clamp study revealed the presence of mibefradil-sensitive Ca^24- currents seen at a concentration range that nearly paralleled those inhibiting steroidogenesis. Collectively, Our data provide evidence that hCG-stimulated steroidogenesis is mediated at least in part by Ca^2＋ entry carried out by the T-type Ca^2＋ channel in the Leydig cells of mice.

Antidiarrheal potential of Distemonanthus benthamianus Baillon. extracts via inhibiting voltage-dependent calcium channels and cholinergic receptors

Objective:To evaluate spasmolytic mechanisms of aqueous and methanolic extracts from Distemonanthus benthamianus trunk-bark.Methods:Spasmolytic activities of extracts were evaluated in vitro on spontaneous and potassium chloride-induced jejunum contractions,or against cholinergic[acetylcholine(0.3μmol/L)]stimulations.High performance liquid chromatography analysis of both extracts was performed in reference to standard compounds.Results:Extracts developed concentration-dependent inhibitory activities.The methanolic extract,which revealed better activity,produced spasmolytic and myorelaxant effects at concentrations of 0.01-0.30 mg/mL with EC(50)of 0.06 and 0.09 mg/mL(95%CI:0.03-0.3 mg/mL),respectively.Its anticholinergic effect was obtained at the same concentrations with EC(50)of 0.11 mg/mL(95%CI:0.03-0.3 mg/mL).Chromatograms showed the presence of gallic acid in both extracts,rutin being only detected in the aqueous extract.Conclusions:Distemonanthus benthamianus extracts exhibit verapamil and atropine-like activities,thus highlighting calcium channels and muscarinic receptors blocking potentials,which may be conveyed by some phenolic compounds.These results confirm the antidiarrheal activity of Distemonanthus benthamianus extracts.

Calcium channels and iron uptake into the heart

Iron overload can lead to iron deposits in many tissues,particularly in the heart.It has also been shown to be associated with elevated oxidative stress in tissues.Elevated cardiac iron deposits can lead to iron overload cardiomyopathy,a condition which provokes mortality due to heart failure in iron-overloaded patients.Currently,the mechanism of iron uptake into cardiomyocytes is still not clearly understood.Growing evidence suggests L-type Ca2+channels(LTCCs)as a possible pathway for ferrous iron(Fe2+)uptake into cardiomyocytes under iron overload conditions.Nevertheless,controversy still exists since some findings on pharmacological interventions and those using different cell types do not support LTCC’s role as a portal for iron uptake in cardiac cells.Recently,T-type Ca2+channels (TTCC)have been shown to play an important role in the diseased heart.Although TTCC and iron uptake in cardiomyocytes has not been investigated greatly,a recent finding indicated that TTCC could be an important portal in thalassemic hearts.In this review,comprehensive findings collected from previous studies as well as a discussion of the controversy regarding iron uptake mechanisms into cardiomyocytes via calcium channels are presented with the hope that understanding the cellular iron uptake mechanism in cardiomyocytes will lead to improved treatment and prevention strategies,particularly in iron-overloaded patients.

Effects and mechanisms of store-operated calcium channel blockade on hepatic ischemia-reperfusion injury in rats

AIM:To further investigate the important role of store-operated calcium channels (SOCs) in rat hepatocytes and to explore the effects of SOC blockers on hepatic ischemia-reperfusion injury (HIRI).METHODS:Using freshly isolated hepatocytes from a rat model of HIRI (and controls),we measured cyto-solic free Ca 2+ concentration (by calcium imaging),net Ca 2+ fluxes (by a non-invasive micro-test technique),the SOC current (I SOC ;by whole-cell patch-clamp record-ing),and taurocholate secretion [by high-performance liquid chromatography and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays].RESULTS:Ca 2+ oscillations and net Ca 2+ fluxes medi-ated by Ca 2+ entry via SOCs were observed in rat he-patocytes.I SOC was significantly higher in HIRI groups than in controls (57.0 ± 7.5 pA vs 31.6 ± 2.7 pA,P <0.05) and was inhibited by La 3+.Taurocholate secretion by hepatocytes into culture supernatant was distinctly lower in HIRI hepatocytes than in controls,an effect reversed by SOC blockers.CONCLUSION:SOCs are pivotal in HIRI.SOC blockers protected against HIRI and assisted the recovery of se-cretory function in hepatocytes.Thus,they are likely to become a novel class of effective drugs for prevention or therapy of HIRI patients in the future.

The opening of maitotoxin-sensitive calcium channels induces the acrosome reaction in human spermatozoa： differences from the zona pellucida

acrosome 反应(AR ) ，为精子的一个绝对要求和卵熔化，通过电压依赖者 Ca2+ 隧道和操作店的隧道要求 Ca2+ 的流入进精子。Maitotoxin (MTx ) ，一个动员 Ca2+ 代理人，被显示了是老鼠精子 AR 的有势力 inducer 与类似于带 pellucida (ZP ) 的药理学，可能为两 inducers 建议一条普通小径。使用的 recombinant 人 ZP3 (rhZP3 ) ，老鼠 ZP 和二 MTx 隧道 blockers (U73122 和 U73343 ) ，我们在人和老鼠精子调查了并且比较导致 MTx 、导致 ZP 的艺术。此处，我们报导 MTx 导致了 AR 并且提高了细胞内部的 Ca2+([Ca2+] 我) 在人的精子，哪个被 U73122 和 U73343 堵住。这二混合物也在老鼠精子禁止了导致 MTx 的 AR。在有我们的以前的建议的争论， AR 由 rhZP3 被触发或老鼠 ZP 没被 U73343 堵住，显示在人和老鼠精子，由生理的 ligands 或由 MTx 的 AR 正式就职通过不同小径发生了。U73122，然而并非 U73343 (不活跃的类似物) ，能堵住 phospholipase C (PLC ) 。另一个 PLC 禁止者， edelfosine，也堵住了导致 rhZP3 、导致 ZP 的艺术。这些调查结果在人和老鼠带证实了一条 PLC 依赖的发信号小径的参予导致蛋白质的 AR。尤其是， edelfosine 也禁止了导致 MTx 的老鼠精子 AR 然而并非人的，建议导致毒素的 AR 在老鼠是 PLC 依赖的并且在人 PLC 独立。

S6B-2 Matrine Inhibits Itching by Lowering the Activity of Calcium Channel

Sophorae Flavescentis Radix(SFR)is a medicinal herb with many functions that are involved in anti-inflammation,antinociception,and anticancer.SFR is also used to treat a variety of itching diseases.Matrine(MT)is one of the main constituents in SFR and also has the effect of relieving itching,but the antipruritic mechanism is still unclear.Here,we investigated the effect of MT on antipruritus.In acute and chronic itch models,MT significantly inhibited the scratching behavior not only in acute itching induced by histamine(His),chloroquine(CQ)and compound 48/80 with a dose-depended manner,but also in the chronic pruritus models of Atopic dermatitis(AD)and Acetone-ether-water(AEW)in mice.Furthermore,MT can be detected in the blood after intraperitoneal injection(i.p.)and subcutaneous injection(s.c.).Finally,electrophysiological and calcium image results show that MT inhibits the excitatory synaptic transmission from dorsal root ganglion(DRG)to the dorsal horn of the spinal cord by suppressing presynaptic N-type calcium channels.Taken together,we believe that MT is a novel drug candidate in treating pruritus diseases,especially for histamine-independent and chronic pruritus,which might be attributed to inhibition of presynaptic N-type calcium channels.