Alterations in neuronal calcium levels are associated with cognitive deficits after traumatic brain injury

Traumatic brain injury (TBI) survivors often suffer from a post-traumatic syndrome with deficits in learning and memory. Calcium (Ca(2+)) has been implicated in the pathophysiology of TBI-induced neuronal death. However, the role of long-term changes in neuronal Ca(2+) function in surviving neurons and the potential impact on TBI-induced cognitive impairments are less understood. Here we evaluated neuronal death and basal free intracellular Ca(2+) ([Ca(2+)](i)) in acutely isolated rat CA3 hippocampal neurons using the Ca(2+) indicator, Fura-2, at seven and thirty days after moderate central fluid percussion injury. In moderate TBI, cognitive deficits as evaluated by the Morris Water Maze (MWM), occur after injury but resolve after several weeks. Using MWM paradigm we compared alterations in [Ca(2+)](i) and cognitive deficits. Moderate TBI did not cause significant hippocampal neuronal death. However, basal [Ca(2+)](i) was significantly elevated when measured seven days post-TBI. At the same time, these animals exhibited significant cognitive impairment (F(2,25)=3.43, p<0.05). When measured 30 days post-TBI, both basal [Ca(2+)](i) and cognitive functions had returned to normal. Pretreatment with MK-801 blocked this elevation in [Ca(2+)](i) and also prevented MWM deficits. These studies provide evidence for a link between elevated [Ca(2+)](i) and altered cognition. Since no significant neuronal death was observed, the alterations in Ca(2+) homeostasis in the traumatized, but surviving neurons may play a role in the pathophysiology of cognitive deficits that manifest in the acute setting after TBI and represent a novel target for therapeutic intervention following TBI.     

Aging does not alter cytosolic calcium levels of cortical synaptosomes in Fischer 344 rats

Several lines of experimental evidence support an association between altered Ca²⁺ regulation and aging. It has been supposed that free cytosolic Ca²⁺ concentrations ([Ca²⁺]_i) may decrease or increase in aged animals. In this study, both resting and KCl-stimulated [Ca²⁺]_i were measured in purified cortical synaptosomes from young (3 mo.), middle-aged (12 mo.), and old (24 mo.) Fischer 344 rats. Two additional groups of rats were included, one middle-aged and one old which were trained on a treadmill for 6 months prior to experimentation. The [Ca²⁺]_i was determined using the fluorescent Ca²⁺ chelator fura-2. Net KCl-dependent changes (ΔK) in [Ca²⁺]_i were determined by the difference between stimulatory (100 μM Ca²⁺/60 mM KCl) and resting (100 μM Ca²⁺/5 mM KCl buffer) conditions among the 3 age groups. Significant increases in [Ca²⁺]_i were observed in each age group upon depolarization with 60 mM KCl. However, there were no significant age-dependent differences in either resting [Ca²⁺]_i or KCl-stimulated [Ca²⁺]_i.     

Impaired calcium homeostasis in aged hippocampal neurons

Development of neurodegenerative diseases such as Alzheimer's and Parkinson's disease is strongly age-associated. The impairment of calcium homeostasis is considered to be a key pathological event leading to neuronal dysfunction and cell death. However, the exact impact of aging on calcium homeostasis in neurons remains largely unknown. In the present work we have investigated intracellular calcium levels in cultured primary hippocampal neurons from young (2 months) and aged (24 months) rat brains. Upon stimulation with glutamate or hydrogen peroxide aged neurons in comparison to young neurons demonstrated an increased vulnerability to these disease-related toxins. Measurement of calpain activity using Western blot analysis showed a significant increase in basal activity of calpains in aged neurons. The observed increase of calpain activity was correlated with elevated protein levels of μ-calpain. Ca²⁺-imaging experiments performed on living individual neurons using the dye calcium green demonstrated a twofold increase in intracellular calcium concentration in aged neurons as compared to young neurons. The observed changes of intracellular calcium in aged neurons might play a role in their increased vulnerability to neurodegeneration.     

Effects of calcium chelators on intracellular calcium and excitotoxicity

In an attempt to probe the relationship between excitotoxicity and increases in intracellular calcium ([Ca²⁺]_i), BAPTA-AM and its analogs were applied to cultured hippocampal neurons. Chelation of [Ca²⁺]_i depressed and prolonged transient responses to glutamate and did not effect elevation of [Ca²⁺]_i by prolonged exposure. This explains the inability of the chelators to prevent glutamate-induced toxicity.     

PKD1 haploinsufficiency is associated with altered vascular reactivity and abnormal calcium signaling in the mouse aorta

Mutations in PKD1 are associated with autosomal dominant polycystic kidney disease (ADPKD), which leads to major cardiovascular complications. We used mice with a heterozygous deletion of Pkd1 (Pkd1 ^+/− ) and wild-type (Pkd1 ^+/+ ) littermates to test whether Pkd1 haploinsufficiency is associated with a vascular phenotype in different age groups. Systolic blood pressure measured by the tail-cuff method was similar up to 20 weeks of age, but significantly higher in 30-week-old Pkd1 ^+/− compared to Pkd1 ^+/+. By contrast, similar telemetric recordings were obtained in unrestrained Pkd1 ^+/− and Pkd1 ^+/+ mice. The contractile responses evoked by KCl or phenylephrine were similar in young animals but increased in abdominal aortas of 30-week-old Pkd1 ^+/− mice, and acetylcholine-evoked relaxation was depressed. Basal cytosolic calcium, KCl, and phenylephrine-evoked calcium signals were significantly lower in the Pkd1 ^+/− aortas, whereas calcium release evoked by caffeine or thapsigargin was significantly larger. These changes were paralleled with a significant change in the mRNA expression of Pkd2, Trpc1, Orai1, and Serca2a in the aortas from Pkd1 ^+/− vs. Pkd1 ^+/+. These results are the first to indicate that haploinsufficiency in Pkd1 is associated with altered intracellular calcium homeostasis and increased vascular reactivity in the aorta with compensatory changes in transport proteins involved in the calcium signaling network.     

Role of intracellular calcium in fatigue in single skeletal muscle fibers isolated from the rat

The aim of the present study was to demonstrate the role of intracellular calcium ([Ca²⁺]_i) in the performance of fatigued muscle fibers isolated from the skeletal muscle of the rat. We measured developed tension of a single myocyte during short tetanic electrical stimulation of various intensities along with [Ca²⁺]_i dynamics by fura-2. The performance of individual muscle fiber was assessed by developed tension during 100 Hz tetanic stimulation (‘100 Hz force’). We regarded the muscle fiber fatigued when, after repeated tetanic stimulations, the developed tension declined to 50% of the initial level. When fatigue was induced by maximal stimulation (100 Hz tetani), the 100 Hz force measured immediately following completion of fatigue was considerably decreased (48% of control). This change in the muscle performance was associated with significant increase in the resting [Ca²⁺]_i (280% of control) and decrease in Ca²⁺ transient (54% of control). The 50% relaxation time after cessation of tetanic stimulation (RT₅₀) was also prolonged. In contrast, when fatigue was induced by low frequency electrical stimulation (30 Hz tetani), neither the 100 Hz force, RT₅₀, nor Ca²⁺ transient in fatigue were significantly different from the controls, while the resting [Ca²⁺]_i increased only slightly. These findings suggest a tight relationship between [Ca²⁺]_i and the performance of fatigued single isolated skeletal muscles. Also, the results show that performance of the fatigued muscle fiber may in part depend on the protocol used to produce muscle fatigue.     

GABA-induced calcium signaling in cultured enteric neurons is reinforced by activation of cholinergic pathways

GABA is an important inhibitory transmitter in the CNS. In the enteric nervous system, however, both excitatory and inhibitory actions have been reported. Here, we investigated the effects of GABA on the intracellular Ca2+ concentration of guinea-pig myenteric neurons (at 35 degrees C) using Fura-2-AM. Neurons were identified by 75 mM K+ depolarization (5 s), which evoked a transient intracellular Ca2+ concentration increase. GABA (10 s) induced a dose dependent (5 nM-1 microM) transient intracellular Ca2+ concentration rise in the majority of neurons (500 nM GABA: 251+/-17 nM, n=232/289). Interestingly, the response to 5 microM GABA (n=18) lasted several minutes and did not fully recover. GABA response amplitudes were significantly (P<0.001) reduced by GABAA and GABAB receptor antagonists (10 microM) bicuculline and phaclofen. The GABAA agonist isoguvacine (10 microM) and GABAB agonist baclofen (10 microM) induced similar responses as 50 nM GABA, while the GABAC agonist cis-4-aminocrotonic acid (CACA) (10 microM) only elicited small responses in a minority of neurons. Removal of extracellular Ca2+ abolished all responses while depletion of intracellular Ca2+ stores by thapsigargin (5 microM) did not alter the responses to 500 nM GABA (n=13), but reduction of Ca2+ influx through voltage-dependent Ca2+ channels did. The nicotinic antagonist hexamethonium (100 microM) also reduced GABA responses by almost 70% suggesting that GABA stimulates cholinergic pathways, while the purinergic receptor blocker pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) and the 5-HT3 receptor blocker ondansetron only had minor effects. Conclusion: GABA elicits transient intracellular Ca2+ concentration responses in the majority of myenteric neurons through activation of GABAA and GABAB receptors and much of the response can be attributed to facilitation of ACh release. Thus GABA may act mainly as a modulator that sets the state of excitability of the enteric nerve network. A concentration of 5 microM GABA, although frequently used in pharmacological experiments, seems to cause a detrimental response reminiscent of the neurotoxic effects glutamate has in the CNS.     

Acute effects of taurine on intracellular calcium in normal and diabetic cardiac myocytes

The present study investigated the acute effects of taurine on intracellular Ca²⁺ ([Ca²⁺]_i) in normal and diabetic cardiac myocytes. [Ca²⁺]_i was monitored using fura-2 in single myocytes isolated from control or streptozotocin-treated rats and paced at frequencies between 0.33 Hz and 2.0 Hz in the absence or presence of 20 mM taurine. Increasing stimulus frequency resulted in significant increases in resting and peak [Ca²⁺]_i, and amplitude of the Ca²⁺ transient in both control and diabetic myocytes. The amplitude of the Ca²⁺ transient and the extent of its increase with increasing frequency was, however, significantly lower in the diabetic myocytes. Taurine significantly increased resting [Ca²⁺]_i, peak [Ca²⁺]_i, and the amplitude of the Ca²⁺ transient in both control and diabetic myocytes at all stimulus frequencies examined. The degree of potentiation of the Ca²⁺ transient decreased with increasing stimulus frequency in control cells but not in diabetic cells. In the absence of taurine the decay of the Ca²⁺ transient was significantly slower in diabetic than control myocytes. Taurine was without significant effect on the time course of the Ca²⁺ transient decay in control cells, however, in diabetic cells it significantly accelerated the rate of decay. The data demonstrate directly that taurine is able to increase [Ca²⁺]_i and the amplitude of the Ca²⁺ transient in both normal and diabetic cardiac myocytes. In addition several of the effects of taurine appeared to be more pronounced in diabetic than control cells. Received: 13 January 1999 / Received after revision: 12 March 1999 / Accepted: 14 April 1999     

NMDAR1单克隆抗体抑制谷氨酸诱导的大鼠海马神经元Ca2+内流

目的观察人N-甲基-D-门冬氨酸受体(NMDAR,NR)主亚基(NR1)单克隆抗体mAbN1对谷氨酸诱导的大鼠海马神经元Ca2 内流的影响。方法建立谷氨酸介导的大鼠海马神经元兴奋毒性损伤模型,以mAbN1及MK-801分别预处理海马神经元,用Fluo-3/AM法,在激光扫描共聚焦显微镜下观察对细胞内游离Ca2 浓度([Ca2 ]i)的影响。结果mAbN1能显著抑制谷氨酸所致海马神经元[Ca2 ]i升高,此作用强于MK-801,且其本身对生理状态下神经元[Ca2 ]i无影响。结论mAbN1的抗兴奋毒性作用可能是通过改变NR的蛋白质二级结构从而影响兴奋毒性作用中的Ca2 内流实现的。     

Amitriptyline modulates calcium currents and intracellular calcium concentration in mouse trigeminal ganglion neurons

Migraine is increasingly recognized as a channelopathy, and abnormalities of voltage-activated ionic channels could represent the molecular basis for the altered neuronal functioning. The high-voltage-activated (HVA) Ca²⁺ channels in the trigeminovascular system play a role in the pathophysiology of migraine. In the present study, effects of amitriptyline (AMT), a commonly used migraine prophylactic drug, on the HVA calcium currents (I_Ca) were examined in mouse trigeminal ganglion neurons using whole-cell patch clamp technique. AMT produced concentration- and use-dependent inhibition of HVA I_Ca. Bath application of GÖ-6983 (a selective protein kinase C inhibitor) or H89 (a protein kinase A inhibitor) did not reduce the AMT-induced inhibition of HVA I_Ca. A similar inhibition was observed when calcium imaging was used to directly monitor the effects of AMT on KCl-induced increments of intracellular Ca²⁺ concentration ([Ca²⁺]_i). By blocking HVA Ca²⁺ channels and Ca²⁺ entry into cells, AMT could prevent the release of neurotransmitters and help restore the neuronal threshold for excitation. Our findings suggest interesting therapeutic mechanisms for AMT in migraine prevention.     

白果内酯对糖氧剥夺小鼠原代海马神经元内钙离子浓度的影响

目的:观察白果内酯对糖氧剥夺(OGD)后小鼠原代海马神经元内游离钙离子浓度的影响及机制探究。方法:分离和培养小鼠原代海马神经元,实验分为对照组(control)、糖氧剥夺组(OGD)和白果内酯组(OGD+bilobalide),对照组予以常规培养小鼠原代海马神经元,糖氧剥夺组利用氧葡萄糖剥夺/再恢复模型模拟小鼠原代海马神经元的缺血再灌注损伤,白果内酯组在氧葡萄糖剥夺后再恢复前应用20μmol/L的白果内酯。利用流式细胞仪检测各组小鼠原代海马神经元内游离的钙离子浓度,利用Western Blot技术检测各组小鼠原代海马神经元Cav1. 2蛋白的表达,最后利用膜片钳技术检测各组小鼠原代海马神经元L型电压依赖型钙离子通道的功能。结果:与糖氧剥夺组相比,白果内酯组小鼠原代海马神经元游离钙离子浓度降低(P <0. 05)、Cav1. 2蛋白表达量减少(P <0. 05)、L型电压依赖性钙离子通道功能减弱(P <0. 05),但仍未恢复到对照组水平(P <0. 05)。结论:白果内酯可能通过减少小鼠原代海马神经元Cav1. 2表达和L型电压依赖性钙离子通道的功能降低细胞内游...     

Two mechanisms that raise free intracellular calcium in rat hippocampal neurons during hypoosmotic and low NaCl treatment

Previous studies have shown that exposing hippocampal slices to low osmolarity (pi(o)) or to low extracellular NaCl concentration ([NaCl](o)) enhances synaptic transmission and also causes interstitial calcium ([Ca(2+)](o)) to decrease. Reduction of [Ca(2+)](o) suggests cellular uptake and could explain the potentiation of synaptic transmission. We measured intracellular calcium activity ([Ca(2+)](i)) using fluorescent indicator dyes. In CA1 hippocampal pyramidal neurons in tissue slices, lowering pi(o) by approximately 70 mOsm caused "resting" [Ca(2+)](i) as well as synaptically or directly stimulated transient increases of calcium activity (Delta[Ca(2+)](i)) to transiently decrease and then to increase. In dissociated cells, lowering pi(o) by approximately 70 mOsm caused [Ca(2+)](i) to almost double on average from 83 to 155 nM. The increase of [Ca(2+)](i) was not significantly correlated with hypotonic cell swelling. Isoosmotic (mannitol- or sucrose-substituted) lowering of [NaCl](o), which did not cause cell swelling, also raised [Ca(2+)](i). Substituting NaCl with choline-Cl or Na-methyl-sulfate did not affect [Ca(2+)](i). In neurons bathed in calcium-free medium, lowering pi(o) caused a milder increase of [Ca(2+)](i), which was correlated with cell swelling, but in the absence of external Ca(2+), isotonic lowering of [NaCl](o) triggered only a brief, transient response. We conclude that decrease of extracellular ionic strength (i.e., in both low pi(o) and low [NaCl](o)) causes a net influx of Ca(2+) from the extracellular medium whereas cell swelling, or the increase in membrane tension, is a signal for the release of Ca(2+) from intracellular stores.     

Aging does not affect calcium response to CCL2 and LPS in human monocytes

Monocytes play important roles in anti-microbial and anti-viral responses and chronic inflammatory diseases. Monocytes' functions are altered by aging. We investigated age-changes in calcium (Ca²⁺) response to CCL2 and LPS in human monocytes. CCL2 and LPS induced a slow increase of the cytosolic Ca²⁺ level, with a maximum response at ～360 s and ～300 s, respectively, in monocytes of young and older adults. No difference was observed in the magnitude and in the Ca²⁺ kinetic with both stimuli. Furthermore, store-operated Ca²⁺ entry and plasma membrane expression of ORAI1 showed no difference between both groups. In summary, monocytes from older adults maintained the capacity to mobilize calcium as their counterparts in young adults suggesting that the mechanisms underlying the dysfunctions in monocytes in aging might not involve alterations in Ca²⁺ flow through the plasma membrane.     

白细胞介素-2对缺氧/复氧心肌细胞[Ca2+]i的作用

目的:观察白细胞介素-2(IL-2)对心肌细胞在缺氧/复氧过程中电刺激诱导的[Ca²⁺]i的作用。方法:采用酶解分离成年大鼠心室肌细胞化学缺氧模型, 以Fura-2/AM为钙探针, 用细胞内双波长钙荧光系统检测心肌[Ca²⁺]i的变化。结果:①缺氧/复氧过程中, 缺氧5min时, 心肌[Ca²⁺]i幅度降低、舒张末期[Ca²⁺]i升高, [Ca²⁺]i达峰时间(TTP)延长, 恢复时间(RT)延长。复氧10min后, 心肌[Ca²⁺]i幅度、舒张末期[Ca²⁺]i、TTP及RT逐渐回复, 但不能完全恢复到对照水平;②在缺氧期间加入IL-2(2×10⁵U/L), 复氧期间[Ca²⁺]i各参数回复减慢;③用κ-阿片受体拮抗剂nor-BNI(10^-8mol/L)预处理后, 缺氧+IL-2对复氧时[Ca²⁺]i作用的影响被减弱, 而δ-阿片受体拮抗剂纳曲吲哚(10^-6mol/L)预处理则无此作用。结论:缺氧时同时存在IL-2, 可加剧复氧时心肌[Ca²⁺]i的变化, 其机制可能是IL-2通过心肌κ-阿片受体而发挥作用。     

IL—2对神经元NMDAR1m RNA表达和细胞内钙浓度的影响

Ｎ－甲基－Ｄ－天门冬氨酸（ＮＭＤＡ）受体和细胞内游离钙浓度（［Ｃａ２＋］ｉ）的变化与神经元的兴奋性关系密切。本文报道以大鼠大脑皮层神经元为研究对象，通过Ｎｏｒｔｈｅｒｎ印迹杂交并以Ｆｕｒａ－２作为Ｃａ２＋荧光指示剂，观察了外源性白细胞介素－２（ＩＬ－２）对ＮＭＤＡ受体１型亚单位（ＮＭＤＡＲ１）ｍＲＮＡ表达量及［Ｃａ２＋］ｉ的影响。结果显示：不同浓度的ＩＬ－２（１～２００Ｕ／ｍｌ）作用于原代培养的胚胎大鼠大脑皮层神经元６小时后其ＮＭＤＡＲ１ｍＲＮＡ表达量明显增加，并与ＩＬ－２浓度呈正相关关系。当其浓度为２５～２００Ｕ／ｍｌ时，ＮＭＤＡＲ１ｍＲＮＡ表达量增加４４．３％～２１９．７％（Ｐ＜０．０５）。ＩＬ－２（１～２００Ｕ／ｍｌ）与新生大鼠大脑皮层神经元共同孵育５～１０分钟后，［Ｃａ２＋］ｉ增加２７．１％～９４．２％（Ｐ＜０．０５）。钙通道阻断剂ｎｉｆｅｄｉｐｉｎｅ可完全阻断ＩＬ－２引起的［Ｃａ２＋］ｉ升高，而ＮＭＤＡ受体拮抗剂ＭＫ－８０１无此作用。本文结果提示：外源性ＩＬ－２具有兴奋性神经调质样作用，可能参与或介导了神经兴奋毒性作用和惊厥性疾病的发生与发展过程。     

Extracellular Ca2+-dependent and independent calcium transient in fetal myotubes

Spatio-temporal changes in the intracellular calcium concentration [Ca²⁺]_i of dissociated mice myotubes from 14-day and 18-day-old fetuses were studied using digital imaging analysis of the Ca²⁺ indicator fura-2. Myotubes from 18-day-old fetuses displayed a transient [Ca²⁺]_i increase upon electrical stimulation either in nominally calcium-free external solution or in Krebs solution containing 100 M lanthanum. Thus, at this developmental stage, membrane depolarization appears to increase [Ca²⁺]_i by stimulating Ca²⁺ release from the sarcoplasmic reticulum independently of extracellular Ca²⁺ influx. Similarly, myotubes from 14-day-old fetuses also showed a calcium transient upon electrical stimulation in Krebs solution. However, in 46% of these myotubes the calcium transient was abolished when Ca²⁺ entry through calcium channels was suppressed.     

Subjective memory complaints in aging are associated with elevated cortisol levels

The origin and clinical significance of subjective memory complaints among middle aged and older individuals is not well understood. Associations with objective memory impairments, personality traits or mood disturbances have been reported. Elevated cortisol levels occur in aging and depression and causal links to cognitive or emotional problems have been suggested. The goal of this study was to investigate the associations between basal and feedback indices of cortisol regulation and subjective memory impairment in a sample of healthy middle aged and older subjects (mean age 61.8 years) with (n = 27) and without (n = 19) subjective memory complaints. Participants with memory complaints had both higher basal cortisol levels and higher cortisol levels after dexamethasone. There was a significant group by gender interaction for basal cortisol levels, where women without memory complaints showed significantly lower cortisol levels, whereas no such difference was found for the men. All effects were not due to slight differences in depression scores. Differences in personality traits or in stress susceptibility might underlie the present findings. Future studies of memory complaints should take a comprehensive approach including relevant endocrine parameters.     

Serum calcium level is associated with metabolic syndrome in elderly women

Objective

To investigate the association between serum calcium level and metabolic syndrome, defined using the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) definition, in Korean elderly women.

Study design

We conducted a cross-sectional study of 1941 elderly women (mean age: 65.16 ± 4.58 years) who participated in annual health examinations at Korea university Medical Center between January 1, 2006 and December 31, 2009 and had normal serum calcium levels.

Results

Women with metabolic syndrome had higher serum calcium levels than those without metabolic syndrome (9.26 ± 0.35 vs. 9.20 ± 0.33, P < 0.001). In multiple logistic regression analysis, serum calcium level within normal range was positively associated with the risk of having metabolic syndrome (odds ratio 2.12, 95% confidence interval 1.50–2.98). With regard to components of metabolic syndrome, serum calcium level was also positively associated with the risk of having high triglyceride, and high glucose, whereas it was inversely associated with the risk of having low high density lipoprotein. However, there was no association of serum calcium level with abdominal obesity or high blood pressure.

Conclusions

The higher was the level of calcium within normal range, the greater were the odds of metabolic syndrome in healthy and elderly women. Prospective studies are needed to investigate the role of calcium in the development of metabolic syndrome in the future.     

Diabetes-induced abnormalities in ER calcium mobilization in primary and secondary nociceptive neurons

Development of diabetic sensory polyneuropathy is associated with alterations in intracellular calcium homeostasis in primary and secondary nociceptive neurons. We have shown previously that in a model of streptozotocin (STZ)-induced diabetes, the calcium signal is prolonged and calcium release from ryanodine-sensitive calcium stores down-regulated in neurons of the nociceptive system. The aim of the present study was a more detailed characterization of calcium homeostasis in primary (dorsal root ganglia, DRG) and secondary (dorsal horn, DH) nociceptive neurons in STZ-induced diabetes. Fluorescence video-imaging was used to measure free cytosolic [Ca²⁺] ([Ca²⁺]_i) in lumbar nociceptive neurons of control and streptozotocin-diabetic rats. Resting [Ca²⁺]_i rose progressively in these neurons with the duration of diabetes and calcium mobilization from the endoplasmic reticulum (ER) decreased during diabetes. The amplitude of calcium release from both ryanodine- and IP₃-sensitive calcium stores induced by caffeine, ionomycin, ATP or glutamate was significantly (P<0.01) lower in DRG and DH neurons from 6-week STZ-diabetic rats. Diabetes-induced changes in the calcium homeostasis were similar in DRG and DH neurons indicating that they might be general for many types of neurons from the central and peripheral nervous systems.     

红藻氨酸对大鼠海马锥体细胞钙电流的影响

目的：应用膜片钳技术,观察红藻氨酸（KA）对大鼠海马锥体细胞ca2＋电流的影响,以研究癫痫的发病机制。方法：采用酶加机械分离法制备出生10～12d的大鼠海马锥体神经元标本,用全细胞膜片钳技术测定其生理学特性及观察KA对ca2＋电流的影响。结果：分离出的海马锥体细胞形态正常,有较长突起;用膜片钳技术证实,其保存了主要的离子通道活性。KA20μmol／L和100μmol／L的浓度均可使海马锥体细胞ca2＋电流峰值增大（n=8,P〈0．01）。结论：①大鼠海马锥体神经细胞具有明显的突起,细胞膜表面光洁、晕光好,适用于膜片钳实验研究;②KA使ca2＋内流增加,引起“Ca”超载”导致细胞毒性等一系列反应;③KA通过激活α-氨基羟甲基恶唑丙酸（AMPA）受体,诱发快速的兴奋性突触后电位（EPSP）,参与兴奋性突触传递。AMPA受体的激活可能是癫痫的发病机制之一。