凝血酶对原代培养海马神经元游离钙浓度的影响

目的研究原代培养的海马神经元内游离Ca2 水平及凝血酶的影响.方法大鼠海马神经元进行体外原代培养,用钙离子指示剂Fura-2双波长法测定海马神经元内游离[Ca2 ]i及不同浓度的凝血酶作用后细胞内[Ca2 ]i.结果原代培养的海马神经元生长旺盛,密度高,符合实验要求.在胞外Ca2 浓度为0.0 mmol/L时,静息状态下海马神经元游离[Ca2 ]i为(79.83±18.78)nmol/L.当胞外Ca2 浓度为1.3 mmol/L时,海马神经元游离[Ca2 ]i为(106.41±22.53)nmo1/L.(1～40)U/ml凝血酶可使海马神经元内游离Ca2 水平显著升高,与对照组相比均有显著性差异(P＜0.01).随凝血酶浓度的增加,胞内游离[Ca2 ]i之呈剂量依赖性增加.结论凝血酶可使原代培养的海马神经元内游离Ca2 浓度明显升高.     

锂-毛果芸香碱致痫大鼠早期大脑NG2和O4表达及意义

目的探讨氯化锂-毛果芸香碱(匹罗卡品)致疒0 间大鼠早期大脑少突胶质前体细胞变化及意义.方法对雄性成年SD大鼠先后腹腔注射氯化锂、毛果芸香碱,制成癫癎持续状态动物模型;用免疫荧光组织化学法检测癎性发作后早期大鼠大脑皮质和海马CA1区NG2和O4阳性细胞数量.结果和对照组相比,除癫癎后1 d组外其余各组大鼠脑皮质内NG2和O4阳性细胞都有明显的增加;癫癎后1 d组海马CA1区的阳性细胞数明显减少;癫癎后7 d组皮质和海马CA1区NG2和O4阳性细胞数最多.结论氯化锂-毛果芸香碱致癎大鼠早期大脑NG2和O4表达增加,少突胶质前体细胞增多,并且和观测时间相关.     

喹啉对癫(癎)大鼠海马神经元连接蛋白36表达的影响

目的:探讨喹啉对癫癎大鼠海马神经元连接蛋白36(Cx36)表达的影响.方法:64只SD大鼠随机分为正常对照组、癫癎模型组、地西洋治疗组和喹治疗组,每组16只大鼠.采用氯化锂-匹罗卡品诱导制作癫癎大鼠模型,地西泮治疗组子以1mg/kg地西泮治疗,喹啉治疗组予以60mg/kg喹啉治疗.术后分别采用Racine评分和脑电图检查判断癫癎发作情况.分别用免疫荧光染色法、Western blot法检测各组大鼠术后2h、4h时海马神经元Cx36的表达.结果:与正常对照组比较,癫癎模型组和地西泮治疗组大鼠术后2h、4h时海马神经元Cx36表达水平显著升高(均P<0.01).癫癎模型组和地西泮治疗组大鼠术后2h、4h时海马神经元Cx36表达水平比较差异无统计学意义.与癫癎模型组及地西泮治疗组比较,喹啉治疗组大鼠术后2h、4h时海马神经元Cx36表达水平显著降低(均P<0.01).结论:癫癎大鼠海马神经元Cx36表达水平升高,喹啉能抑制这一变化.     

颞叶癫(癎)大鼠海马区NCX3 mRNA和蛋白的表达变化

目的:动态观察钠-钙交换体(NCX)mRNA和蛋白在氯化锂-匹罗卡品致(癎)模型大鼠海马CA1、CA3及齿状回区表达的变化,探讨其在癫(癎)发生发展中的作用.方法:用氯化锂-匹罗卡品制备癫(癎)动物模型;应用原位杂交和免疫组化技术检测各时间点NCX3 mRNA和蛋白的表达.结果:急性期(6～24 h)海马各区NCX3 mRNA表达均随时间的延长逐渐减少;进入静止期各区表达趋向回升,慢性反复自发发作期(30、60 d)各区表达又出现不同程度的两次下调.除致(癎)后6 h大鼠海马各区的NCX3蛋白表达无明显变化外,NCX3蛋白变化趋势与NCX3 mRNA基本一致.结论:NCX3表达下调可能通过增加神经元钙超载,改变海马神经元的兴奋性,促使癫(癎)发生.     

颞叶癫大鼠海马轴突导向分子Sema3F及其受体Np2表达的变化

目的 研究颞叶癫(癎)大鼠海马轴突导向分子Sema3F及其受体Np2表达的变化.方法 给SD大鼠腹腔注射匹罗卡品、氯化锂制作颞叶癫(癎)模型.用免疫组化法和原位杂交技术对致(癎)后不同时间点大鼠海马CA1区、CA3区、齿状回的Sema3F mRNA、Np2 mRNA和蛋白表达进行检测,并与正常对照组比较.结果 颞叶癫(癎)大鼠致(癎)后7 d、15 d,海马CA1区、CA3区Sema3F mRNA、Np2 mRNA和蛋白的表达明显低于正常对照组(P＜0.05～0.01), 致(癎)后30 d、60 d表达与正常对照组差异无统计学意义;而齿状回Sema3F mRNA、Np2 mRNA和蛋白的表达与正常对照组的差异无统计学意义.结论 颞叶癫(癎)大鼠海马CA1区、CA3区Sema3F、Np2表达在致(癎)后早期明显下调,而在慢性期恢复正常.     

普瑞巴林对慢性颞叶癫癎大鼠海马凋亡调控基因的影响

目的通过观察普瑞巴林对匹罗卡品慢性癫癎大鼠海马区Bcl-2和Bax表达的影响,探讨普瑞巴林治疗癫癎的药理学机制及对大鼠海马神经元的抗凋亡作用。方法采用氯化锂-匹罗卡品化学诱导方法建立慢性颞叶癫癎模型。经腹腔注射普瑞巴林40mg(/kg·d)连续治疗3周,免疫组织化学染色和Western blotting法检测不同处理组大鼠海马区Bcl-2和Bax表达变化。结果与生理盐水对照组比较,模型组大鼠海马区Bcl-2和Bax表达水平显著升高(均P=0.000);与模型组比较,普瑞巴林治疗组大鼠海马区Bcl-2表达水平升高、Bax表达水平降低,组间差异具有统计学意义(均P=0.000)。结论新型抗癫癎药物普瑞巴林可通过降低慢性颞叶癫癎大鼠海马区Bax表达、上调Bcl-2表达而抑制细胞凋亡,发挥神经元保护作用。     

Akt1在颞叶癫痫大鼠海马中的表达变化

目的研究颞叶癫癎模型海马区神经元Akt1表达变化,探讨其在癫癎发生发展中的作用。方法采用氯化锂-匹罗卡品方法制备颞叶癫癎大鼠模型,Western blotting检测海马区总蛋白、Quantity one软件行灰度值分析;免疫组织化学染色观察海马各区Akt1蛋白表达变化,计数不同处理组阳性神经元数目。结果 Western blotting检测结果显示,与正常对照组相比,癫癎模型组大鼠于癫癎持续状态发作即刻海马区Akt1蛋白表达升高(t=2.445,P=0.034),并于第30天时达峰值水平(t=1.214,P=0.002),发作后24 h表达水平迅速降低,并低于正常值范围(t=4.294,P=0.000),其余各测量时间点表达无明显改变;与氯化锂组相比,癫癎模型组大鼠于癫癎持续状态后1h海马区Akt1蛋白表达开始降低,24 h降至最低水平(t=4.134,P=0.000),至发作48 h后开始逐渐升高(t=2.481,P=0.002),并于发作第7天时升至氯化锂组水平。免疫组织化学染色显示,癫癎持续状态发作后海马CA3区Akt1蛋白表达阳性神经元数目立即增加,12h达高峰(t=16.586,P=0.000),48 h减少并降至正常值水平(t=0.357,P=0.089),发作后第10天再次增加(t=3.123,P=0.000),于第30天时阳性神经元数目再次达峰值水平(t=18.339,P=0.000),第50天开始恢复至正常值水平(t=3.219,P=0.000);氯化锂组仅海马CA3区Akt1蛋白表达于实验初始(0 h)升高并高于正常对照组(P<0.05),海马CA1和CA2区Akt1蛋白表达变化组间差异均无统计学意义(P>0.05)。结论海马及海马CA3区Akt1蛋白表达均呈现癫癎持续状态后升高、降低、再升高的动态过程,提示可能存在神经元保护作用,对抗细胞凋亡、促进细胞存活。     

高糖对缺氧神经元的影响及钙相关机制研究

研究高糖对神经元缺氧的影响,并探讨其钙相关机制.利用SD大鼠大脑皮质神经元体外缺氧模型,通过对细胞活力的检测,观察浓度分别为22.7(对照组),30,40,50,60(高糖组)mmol/L的葡萄糖对神经元缺氧的影响;以Fura-2/Am为荧光指示剂,测定细胞内游离钙离子浓度([Ca2+]i.结果发现当培养基中葡萄糖浓度达到60 mmol/L时,高糖可引起缺氧神经元损伤;与对照组相比,有钙介质与无钙介质中静息[Ca2+]i均升高,P＜0.01;但对照组与高糖组在有钙介质中对氯化钾(KCl)、谷氨酸(Glu)刺激引起的[Ca2+]i升高无明显差异,P＞0.05;在无钙介质中,对氯化钙(CaCl2)引起的[Ca2+]i增高率无明显差别,P＞0.05.本研究表明:高糖对神经元的损伤作用可能与其促进细胞内钙离子释放,诱发细胞内钙超载有关.     

匹罗卡品致(癎)大鼠海马γ-氨基丁酸能中间神经元生长抑素和微清蛋白mRNA表达研究

目的 观察匹罗卡品致(癎)大鼠海马γ-氨基丁酸能中间神经元生长抑素(SS)mRNA和微清蛋白(PV)mRNA表达水平变化,拟从基因水平探讨其表达阳性γ-氮基丁酸能中间神经元在颞叶癫(癎)发生发展中的作用.方法 建立匹罗卡品致(癎)大鼠模型,采用原位杂交法检测各观察时间点海马SSmRNA和PVmRNA表达阳性神经元数目.结果 模型组大鼠海马各区γ-氨基丁酸能中间神经元SSmRNA表达水平均于出现癫(癎)持续状态后3d降低最为显著(均P=0.000),随后逐渐升高;至发病后60d,海马CA3区SSmRNA表达水平高于对照组(t=1.021,P=0.005),海马门区(t=3.211,P=0.009)和CA1区(t=1.902,P=0.048)则仍低于对照组.模型组大鼠海马门区γ-氨基丁酸能中间神经元PVmRNA表达水平于出现癫(癎)持续状态后6h开始降低,至发病后60d降低最为显著(均P=0.000);海马CA1区PVmRNA表达水平于发病后3d降低最为显著(均P=0.000),随后逐渐升高但仍低于对照组(江2.216,P=0.048);癫(癎)持续状态早期,海马CA3区PVmRNA表达水平无明显变化,至发病后7d逐渐升高且高于对照组(t=1.021,P=0.005).结论 γ-氨基丁酸能中间神经元SSmRNA和PVmRNA表达水平的下调可能在颞叶癫(癎)的发生中起重要作用,至慢性期γ-氨基丁酸能中间神经元SSmRNA和PVmRNA表达水平的恢复或上调可能与颞叶癫(癎)的发展或修复有关.γ-氨基丁酸能中间神经元数目的 变化,部分是由于其标志物mRNA表达水平的调节所致,并非神经元数目变化的唯一因素.     

锂-匹罗卡品致癎幼鼠海马结构损伤的形态学及苔藓纤维发芽研究

目的 :观察幼鼠致后海马的组织病理学改变。方法 :采用氯化锂 匹罗卡品腹腔注射制成幼鼠癫持续状态模型 ,应用常规病理及电镜观察海马结构的形态学改变 ,同时应用Timm组织化学染色方法进行苔藓纤维发芽的研究。结果 :海马区神经元可见变性、坏死的改变 ,以CA1区、CA3区为重。Timm染色见齿状回内分子层和CA3区下锥体层苔藓纤维发芽增加。结论 :①氯化锂 匹罗卡品诱导的幼鼠癫持续状态可造成海马区神经元损伤 ;②幼鼠癫持续状态后海马CA1、CA3区神经元损伤较重 ;③幼鼠癫持续状态后可致苔藓纤维发芽增加。     

In vitro status epilepticus causes sustained elevation of intracellular calcium levels in hippocampal neurons

Calcium ions and calcium-dependent systems have been implicated in the pathophysiology of status epilepticus (SE). However, the dynamics of intracellular calcium ([Ca2+]i) levels during SE has not yet been studied. We have employed the hippocampal neuronal culture (HNC) model of in vitro SE that produces continuous epileptiform discharges to study spatial and dynamic changes in [Ca2+]i levels utilizing confocal laser scanning microscopy and the calcium binding dye, indo-1. During SE, the average [Ca2+]i levels increased from control levels of 150-200 nM to levels of 450-600 nM. This increased [Ca2+]i was maintained for the duration of SE. Following SE, [Ca2+]i levels gradually returned to basal values. The duration of SE was shown to affect the ability of the neuron to restore resting [Ca2+]i levels. Both N-methyl-D-aspartate (NMDA) receptor-gated and voltage-gated Ca2+ channels (VGCCs) contributed to the increased calcium entry during SE. Moreover, this elevation in [Ca2+]i occurred in both the nucleus and cytosol. These results provide the first dynamic measurement of [Ca2+]i during prolonged electrographic seizure discharges in an in vitro SE model and suggest that prolonged epileptiform discharges give rise to abnormal sustained increases in [Ca2+]i levels that may play a role in the neuronal cell damage and long-term plasticity changes associated with SE.     

Changes in intracellular calcium in brain cells of aged rats★

BACKGROUND: Studies have shown that voltage-dependent calcium influx, and enhancement of certain calcium-dependent processes in neurons, is related to aging. OBJECTIVE: To observe changes in intracellular calcium ([Ca2+]i) in neurons of aged rats, and to compare with young rats. DESIGN, TIME AND SETTING: A randomized control experiment of neurophysiology was performed at the Central Laboratory of School of Pharmaceutical Science, China Medical University from June to August 2004. MATERIALS: Ten male, healthy, Wistar rats, 19 months old, were selected for the aged group. Ten male, 3-month-old, Wistar rats were selected for the young control group. Fura-2/AM was provided by the Institute of Pharmaceutical Research of Chinese Academy of Medical Sciences, and the F-2000 fluorospectrophotometer was a product of Hitachi, Japan. METHODS: Fluorescence Fura-2 spectrophotometer was used to measure [Ca2+]i in acutely dissociated brain cells of aged and young rats. The concentration of extracellular potassium was controlled by adding different volumes of chloridated potassium solution of high concentration. MAIN OUTCOME MEASURES: [Ca2+]i in neurons of young and aged rats in the presence of 1 mmol/L extracellular calcium concentration and 0 mmol/L (resting state), 5, 10, 20, and 40 mmol/L extracellular potassium. Absolute increase of [Ca2+]i in neurons of young and aged rats when extracellular potassium was 5, 10, 20, 40 mmol/L. RESULTS: In the presence of 1 mmol/L extracellular Ca2+ and 0 mmol/L (resting state), 5, 10, 20, and 40 mmol/L extracellular potassium, [Ca2+]i in the neurons of aged rats was significantly less than that in young rats (P < 0.05). However, there was no significant difference in absolute [Ca2+]i increase induced by different concentrations of KCl between the aged and the young rats (P > 0.05). CONCLUSION: The overload of [Ca2+]i in neurons of aged rats is greater than that of young rats under the same circumstances. Key Words: aged rats; neuron; intracellular calcium     

Selective enhancement by basic fibroblast growth factor of NMDA receptor-mediated increase of intracellular Ca2+ concentration in hippocampal neurons.

The short-term effect of bFGF on intracellular Ca2+ concentration ([Ca2+]i) of hippocampal neurons was investigated using dissociated cell cultures. Changes in [Ca2+]i were measured by microfluorometrically monitoring the fluorescence intensities from individual neurons loaded with fura-2. Perfusion of bFGF (20 ng/ml) alone did not affect the basal level of [Ca2+]i in hippocampal neurons, but clearly enhanced the [Ca2+]i increase induced by NMDA. Quisqualate or KCl-induced [Ca2+]i increase was not influenced by bFGF. These results suggest that bFGF selectively enhances the NMDA receptor-mediated response in hippocampal neurons.     

丹参诱导大鼠骨髓间充质干细胞分化为神经元样细胞中的钙离子检测

目的 检测大鼠骨髓间充质干细胞经丹参注射液诱导分化的神经元样细胞内钙离子浓度,以期为骨髓间充质干细胞应用于神经系统疾病的治疗提供理论依据.方法 从成年大鼠骨髓中获取骨髓间充质干细胞,体外扩增培养,经碱性成纤维生长因子预诱导后施加10mL/L丹参注射液于骨髓间充质干细胞培养液中.运用免疫荧光检测神经元特异性核蛋白(NeuN)在诱导后细胞与经新生大鼠海马获取的体外培养海马神经元中的表达.激光共聚焦技术检测诱导后的细胞内钙离子浓度.并与原代培养海马神经元内的钙离子浓度进行比较.结果 大鼠骨髓间充质干细胞经碱性成纤维生长因子和丹参注射液处理后,可表达NeuN,并具有神经元样的表型.诱导分化的神经元样细胞内钙离子浓度为984.75±79.51,原代培养海马神经元内钙离子浓度为769.42±60.93,两者比较差异无统计学意义(P>0.05).结论 丹参注射液诱导骨髓间充质干细胞分化的神经元样细胞具有神经元的某些特征.     

Effects of dextroamphetamine,lithium chloride,sodium valproate and carbamazepine on intraplatelet Ca2+ levels

OBJECTIVE: To explore the possible involvement of second-messenger pathways in the pathophysiology of bipolar disorder and the mechanism of action of mood stabilizers, we investigated the effects of dextroamphetamine (a model for mania) and the most widely used mood stabilizers, lithium chloride, sodium valproate and carbamazepine, on intraplatelet levels of calcium ion ([Ca2+). DESIGN: In the first part of the study, dextroamphetamine was administered in vivo in a double-blind, placebo-controlled, crossover design. In the second part of the study, platelets from untreated subjects were incubated in vitro with dextroamphetamine, lithium chloride, sodium valproate or carbamazepine. PARTICIPANTS: Fifteen healthy men between 18 and 45 years of age. OUTCOME MEASURES: Basal, thrombin-induced and serotonin- (5-HT) induced intraplatelet [Ca2+] determined by means of fura-2 fluorescent intensity. RESULTS: In vivo administration of dextroamphetamine had no effect on basal or agonist-induced intraplatelet [Ca2+]. However, in vitro basal platelet [Ca2+] was significantly higher in samples incubated with dextroamphetamine (86.8 nmol/L [standard error of the mean, SEM, 3.9], p < 0.001), lithium chloride (76.4 nmol/L [SEM 3.1], p < 0.002), sodium valproate (82.7 nmol/L [SEM 3.7], p < 0.001) and carbamazepine (84.8 nmol/L [SEM 3.3], p < 0.001) than in the controls (58.2 nmol/L [SEM 2.3]). Thrombin-induced and 5-HT-induced peak cytosolic [Ca2+] were significantly greater than control levels in samples incubated with carbamazepine (277.1 nmol/L [SEM 19.9] v. 195.8 nmol/L [SEM 12.2], p < 0.002; and 153.0 nmol/L [SEM 8.2] v. 115.4 nmol/L [SEM 5.7], p < 0.003, respectively). CONCLUSIONS: This study does not support the involvement of intraplatelet [Ca2+] in the dextroamphetamine model of mania; however, the modulation of intraplatelet [Ca2+] by the mood stabilizers lithium chloride, sodium valproate and carbamazepine implicates intracellular [Ca2+] in the therapeutic mechanisms of these drugs and the pathophysiological basis of mania.     

Neuropeptide FF selectively attenuates the effects of nociceptin on acutely dissociated neurons of the rat dorsal raphe nucleus

Intracellular Ca2+ concentration ([Ca2+]i) was measured in neurons, acutely dissociated from the rat dorsal raphe nucleus (DRN), with the fluorescent calcium probe Fluo3. Nociceptin (300 nM) had no effect on resting [Ca2+]i but reduced the magnitude of the [Ca2+]i transient triggered by depolarization in 90% of neurons having polygonal or fusiform perikarya. In 94% of neurons with the same morphology 5-HT (30 microM) also reduced the magnitude of the [Ca2+]i transient. The selective 5-HT(1A) receptor antagonist 4-iodo-N-[2-[4-(methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-ben zamide hydrochloride (p-MPPI) (0.4 microM) strongly attenuated (by 72+/-7%, n=4) this effect. The responses to nociceptin and 5-HT were not affected by BaCl2 (100 microM). The neuropeptide FF analog [D-Tyr1, (N-Me)Phe3]NPFF (1DMe) altered neither the resting [Ca2+]i nor the [Ca2+]i transient triggered by depolarization but dose-dependently decreased the effect of nociceptin (EC50=1.8 nM, maximal reduction: 68+/-5%). 1DMe had no effect on the response to 5-HT. Another neuropeptide FF analog, exhibiting a different pharmacological activity in mice and rats, [D-Tyr1, D-Leu2, D-Phe3]NPFF (1 microM) also reduced the effect of nociceptin by 74+/-11% (n=4). Few neurons (5 out of 42), either with polygonal/fusiform or smaller ovoid cell bodies, responded to the mu-opioid receptor agonist [D-Ala2, (N-Me)Phe4, Gly-ol5]-enkephalin (DAGO) with a decrease in the depolarization-induced [Ca2+]i transient. 1DMe (100 nM) attenuated this response by 69+/-14%. These results suggest that, at the cellular level, neuropeptide FF selectively counteracts the effects of opioid receptor activation.     

Methamphetamine induces cytosolic Ca2+ oscillations in the VTA dopamine neurons

Methamphetamine (METH) induces a schizophrenia-like psychosis. The dopamine neurons in the ventral tegmental area (VTA) have been implicated in schizophrenia and drug abuse. The present study investigated direct effects of METH on VTA dopamine neurons. We treated adult SD rats with METH (5 mg/kg/day) or saline for 7 days, isolated single VTA neurons, and monitored neuronal activities by measuring cytosolic Ca2+ concentration ([Ca2+]i) in immunocytochemically identified dopamine neurons. Acutely administered METH increased [Ca2+]i in dopamine neurons from METH- and saline-treated rats and induced oscillations of [Ca2+]i in dopamine neurons only from METH-treated rats. The METH-induced [Ca2+]i oscillations were inhibited by Ca(2+)-free conditions and Ca2+ channel blockers. The results indicate that acute METH increases [Ca2+]i in VTA dopamine neurons and that subchronic METH treatment sensitizes them to this drug, resulting in induction of [Ca2+]i oscillations. The activation of VTA dopamine neurons may be related to psycho-stimulant effects of METH.     

大鼠小直径痛觉三叉神经节神经元同时存在三磷酸肌醇敏感性钙库和阿诺碱敏感性钙库？P2X和P2Y嘌呤受体介导细胞内钙信号转导通路的变化

背景： 面部创伤或面部手术等可能损伤三叉神经系统而导致三叉神经疼痛,由于其疼痛剧烈难忍、易复发,长期以来一直为口腔临床治疗的一大难题。现有大量研究发现嘌呤类受体与三叉神经痛相关,目前对其作用机制知之甚少。 目的：探讨在小直径三叉神经节神经元中嘌呤类受体介导钙信号途径。 方法：用Fura-2荧光染料通过显微镜荧光测定技术实时检测急性分离成年大鼠小直径三叉神经节神经元的细胞内钙离子浓度。 结果：用正常外液或去除细胞外Ca2+灌流细胞,分别给予thapsigargin（1 μmol/L）,内质网钙泵ATP酶抑制剂,和咖啡因（20 mmol/L）,ryanodine受体激动剂,均能够引起细胞内游离钙离子浓度（[Ca2+]i）不同程度地升高。ATP（100 μmol/L）也能够产生类似的效应。在去除细胞外Ca2+条件下,ATP引起的[Ca2+]i升高可被thapsigargin可逆性地抑制,而不能被咖啡因抑制;然而在正常外液环境中,ATP引起的细胞内[Ca2+]i 升高不能完全地被thapsigargin抑制。 结论：在痛觉三叉神经节神经元中,嘌呤类受体介导的[Ca2+]i升高有两条途径,一种途径是通过代谢型P2Y受体作用于三磷酸肌醇敏感性钙库;另一种途径是通过离子型受体P2X受体引起外钙内流。     

Calcium homeostasis and ultrastructural studies in a patient with limb girdle muscular dystrophy type 2C

There is increasing evidence that gamma-sarcoglycan is absent and other sarcoglycans are reduced in patients with the limb-girdle muscular dystrophy type 2C (LGMD2C) form of severe childhood autosomal recessive muscular dystrophy. In the present investigation, we combined microspectrofluorimetry and electron microscopy techniques to investigate the physiological function and the ultrastructure of control and LGMD2C myotubes. Results obtained from Ca2+ measurements showed that the resting level of the cytosolic free calcium ([Ca2+ ]i ) in control myotubes was 73+/-3.4 nmol/l (mean+/-se, n=35) and in LGMD2C myotubes was 69+/-4 nmol/l (n=44). Carbachol (CCh, 10 micromol/l ) induced a 335+/-10 nmol/l (n=8) rise in [Ca2+ ]i in control myotubes and 531.9+/-32 nmol/l (n=23) in LGMD2C myotubes. Similarly, elevations of [Ca2+ ]i by 35 mmol/l K+ were 324+/-32 nmol/l (n=8) in control myotubes and 442.8+/-24 nmol/l (n=22) in LGMD2C myotubes. Caffeine (10 mmol/l) activated similar [Ca2+]i peaks in control and LGMD2C myotubes but induced a biphasic response in LGMD2C in four out of 12 myotubes and only a monophasic response in control myotubes. The ultrastructural results showed that the plasma membrane was abnormally indented and convoluted in both the LGMD2C biopsy and the LGMD2C cultured myotubes. It is suggested that the reduction in components of the dystrophin-glycoprotein complex results in the instability and an increase in the surface area of the plasma membrane, which may result in a higher population of Ca2+ channels in the LGMD2C myotubes.