Effects of CACNA1H gene knockout on autistic-like behaviors and the morphology of hippocampal neurons in mice / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effects of CACNA1H gene knockout (KO) on autistic-like behaviors and the morphology of hippocampal neurons in mice.@*METHODS@#In the study, 25 CACNA1H KO mice of 3-4 weeks old and C57BL/6 background were recruited as the experimental group, and 26 wild type (WT) mice of the same age and background were recruited as the control group. Three-chamber test and open field test were used to observe the social interaction, anxiety, and repetitive behaviors in mice. After that, their brain weight and size were measured, and the number of hippocampal neurons were observed by Nissl staining. Furthermore, the CACNA1H heterozygote mice were interbred with Thy1-GFP-O mice to generate CACNA1H-/--Thy1+(KO-GFP) and CACNA1H+/+-Thy1+ (WT-GFP) mice. The density and maturity of dendritic spines of hippocampal neurons were observed.@*RESULTS@#In the sociability test session of the three-chamber test, the KO mice spent more time in the chamber of the stranger mice than in the object one (F1, 14=95.086, P < 0.05; Post-Hoc: P < 0.05), without any significant difference for the explored preference index between the two groups (t=1.044, P>0.05). However, in the social novelty recognition test session, no difference was observed between the time of the KO mice spend in the chamber of new stranger mice and the stranger one (F1, 14=18.062, P < 0.05; Post-Hoc: P>0.05), and the explored preference index of the KO mice was less than that of the control group (t=2.390, P < 0.05). In the open field test, the KO mice spent less time in the center of the open field apparatus than the control group (t=2.503, P < 0.05), but the self-grooming time was significantly increased compared with the control group (t=-2.299, P < 0.05). Morphological results showed that the brain weight/body weight ratio (t=0.356, P>0.05) and brain size (t=-0.660, P>0.05) of the KO mice were not significantly different from those of the control group, but the number of neurons were significantly reduced in hippocampal dentate gyrus compared with the control group (t=2.323, P < 0.05). Moreover, the density of dendritic spine of dentate gyrus neurons in the KO-GFP mice was significantly increased compared with the control group (t=-2.374, P < 0.05), without any significant difference in spine maturity (t=-1.935, P>0.05).@*CONCLUSION@#CACNA1H KO mice represent autistic-like behavior, which may be related to the decrease in the number of neurons and the increase in the density of dendritic spine in the dentate gyrus.

A Computational Modeling Reveals That Strength of Inhibitory Input, E/I Balance, and Distance of Excitatory Input Modulate Thalamocortical Bursting Properties

The thalamus is a brain structure known to modulate sensory information before relaying to the cortex. The unique ability of a thalamocortical (TC) neuron to switch between the high frequency burst firing and single spike tonic firing has been implicated to have a key role in sensory modulation including pain. Of the two firing modes, burst firing, especially maintaining certain burst firing properties, was suggested to be critical in controlling nociceptive behaviors. Therefore, understanding the factors that influence burst firing properties would offer important insight into understanding sensory modulation. Using computational modeling, we investigated how the balance of excitatory and inhibitory inputs into a TC neuron influence TC bursting properties. We found that intensity of inhibitory inputs and the timing of excitatory input delivery control the dynamics of bursting properties. Then, to reflect a more realistic model, excitatory inputs delivered at different dendritic locations—proximal, intermediate, or distal—of a TC neuron were also investigated. Interestingly, excitatory input delivered into a distal dendrite, despite the furthest distance, had the strongest influence in shaping burst firing properties, suggesting that not all inputs equally contribute to modulating TC bursting properties. Overall, the results provide computational insights in understanding the detailed mechanism of the factors influencing temporal pattern of thalamic bursts.

T-Type Calcium Channels Are Required to Maintain Viability of Neural Progenitor Cells

T-type calcium channels are low voltage-activated calcium channels that evoke small and transient calcium currents. Recently, T-type calcium channels have been implicated in neurodevelopmental disorders such as autism spectrum disorder and neural tube defects. However, their function during embryonic development is largely unknown. Here, we investigated the function and expression of T-type calcium channels in embryonic neural progenitor cells (NPCs). First, we compared the expression of T-type calcium channel subtypes (CaV3.1, 3.2, and 3.3) in NPCs and differentiated neural cells (neurons and astrocytes). We detected all subtypes in neurons but not in astrocytes. In NPCs, CaV3.1 was the dominant subtype, whereas CaV3.2 was weakly expressed, and CaV3.3 was not detected. Next, we determined CaV3.1 expression levels in the cortex during early brain development. Expression levels of CaV3.1 in the embryonic period were transiently decreased during the perinatal period and increased at postnatal day 11. We then pharmacologically blocked T-type calcium channels to determine the effects in neuronal cells. The blockade of T-type calcium channels reduced cell viability, and induced apoptotic cell death in NPCs but not in differentiated astrocytes. Furthermore, blocking T-type calcium channels rapidly reduced AKT-phosphorylation (Ser473) and GSK3β-phosphorylation (Ser9). Our results suggest that T-type calcium channels play essential roles in maintaining NPC viability, and T-type calcium channel blockers are toxic to embryonic neural cells, and may potentially be responsible for neurodevelopmental disorders.

Rebound depolarization of substantia gelatinosa neurons and its modulatory mechanisms in rat spinal dorsal horn / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the rebound depolarization of substantia gelatinosa (SG) neurons in rat spinal dorsal horn and explore its modulatory mechanisms to provide better insights into rebound depolarization-related diseases.</p><p><b>METHODS</b>Parasagittal slices of the spinal cord were prepared from 3- to 5-week-old Sprague-Dawley rats. The electrophysiologic characteristics and responses to hyperpolarization stimulation were recorded using whole-cell patch-clamp technique. The effects of hyperpolarization-activated cyclic nucleotide gated cation (HCN) channel blockers and T-type calcium channel blockers on rebound depolarization of the neurons were studied.</p><p><b>RESULTS</b>A total of 63 SG neurons were recorded. Among them, 23 neurons showed no rebound depolarization, 19 neurons showed rebound depolarization without spikes, and 21 neurons showed rebound depolarization with spikes. The action potential thresholds of the neurons without rebound depolarization were significantly higher than those of the neurons with rebound depolarization and spikes (-28.7∓1.6 mV vs -36.0∓2.0 mV, P<0.05). The two HCN channel blockers CsCl and ZD7288 significantly delayed the latency of rebound depolarization with spike from 45.9∓11.6 ms to 121.6∓51.3 ms (P<0.05) and from 36.2∓10.3 ms to 73.6∓13.6 ms (P<0.05), respectively. ZD7288 also significantly prolonged the latency of rebound depolarization without spike from 71.9∓35.1 ms to 267.0∓68.8 ms (P<0.05). The T-type calcium channel blockers NiCl2 and mibefradil strongly decreased the amplitude of rebound depolarization with spike from 19.9∓6.3 mV to 9.5∓4.5 mV (P<0.05) and from 26.1∓9.4 mV to 15.5∓5.0 mV (P<0.05), respectively. Mibefradil also significantly decreased the amplitude of rebound depolarization without spike from 14.3∓3.0 mV to 7.9∓2.0 mV (P<0.05).</p><p><b>CONCLUSION</b>Nearly two-thirds of the SG neurons have rebound depolarizations modulated by HCN channel and T-type calcium channel.</p>

Role of calmodulin-dependent protein kinase II in bupivacaine hydrochloride-induced injury of SH-SY5Y cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of KN93, a calmodulin-dependent protein kinase II (CaMK II) inhibitor, on SH-SY5Y cell injury induced by bupivacaine hydrochloride.</p><p><b>METHODS</b>SH-SY5Y cells exposed for 24 h to 1 mmol/L KN93, 1 mmol/L bupivacaine hydrochloride, or both were examined for morphological changes and Cav3.1 protein expressions using Western blotting. The vitality and apoptosis rate of the cells at different time points during the exposures were assessed with MTT assay and flow cytometry, respectively.</p><p><b>RESULTS</b>Bupivacaine hydrochloride exposure caused obvious cell morphologial changes, reduced cell viability, increased cell apoptosis, and enhanced Cav3.1 protein expression. All these changes were partly reversed by treatment of the cells with 1 mmol/L KN93.</p><p><b>CONCLUSIONS</b>CaMKII may play a role in bupivacaine hydrochloride-induced SH-SY5Y cells injury, which is related with upregulated Cav3.1 protein expression.</p>

The expression levels of three T-type calcium channel receptors in inner ear of C57BL/6J mice with age / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To explore the expression levels of three T-type calcium channel receptors (α1G; α1H; α1I) in the cochlea and spiral ganglion neurons of C57BL/6J mice with different ages.@*METHOD@#Thirty cases of C57BL/6J mice were divided into three groups (6-8 W, 24-26 W, 42-44 W) according to the age. The expressions of three T-type calcium channel receptors were quantified by RT-PCR after hearing thresholds measured by ABR.@*RESULT@#Three receptors were detected in the cochlea and spiral ganglion neurons of 6-8 W C57BL/6J mice. The quantitative results showed that the expression levels of α1H and α1I were highest among three receptors in spiral ganglion neurons and in the cochlea respectively. The expression levels of three receptors significantly decreased with age,especially at the age of 4244 W.@*CONCLUSION@#The expression of T-type calcium channel receptors reduced with age in the inner ear of C57BL/6J mice.

Influence of acupuncture on expression of T-type calcium channel protein in airway smooth muscle cell in airway remodeling rats with asthma / 中国针灸

<p><b>OBJECTIVE</b>To observe the anti-remodeling effect of acupuncture on asthma and to explore the mechanism of T-type calcium channel protein in airway smooth muscle cell in airway remodeling effect in asthma.</p><p><b>METHODS</b>Thirty-two rats were randomly divided into a normal group, a model group, an acupuncture group and a sham acupuncture group, 8 rats in each group. The rats in the latter three groups were sensitized for consecutive 14 days by single peritoneal injection of aqueous suspension 1 mL of 10 mg ovalbumin (OVA), 200 mg aluminum hydroxide and saline together with 1 mL inactivated pertussis vaccine. From the 15th day, asthma was induced for 30 minutes by ultrasonic atomizing inhalation of 1% OVA for consecutive 14 days in the model group. The acupuncture group was treated with acupuncture at "Dazhui" (GV 14), "Fengmen" (BL 12) and "Feishu" (BL 13) for 30 minutes before the ultrasonic atomizing inhalation, once every two days for consecutive 14 days. The same acupoints selection and the course of treatment as the acupuncture group were produced in the sham acupuncture group and they were treated with acupuncture at 1 mm acupoint skin without retaining needles. The normal group remained unhandled. The respiratory function and the airway remodeling were evaluated by airway resistance and pulmonary histopathology, respectively, and the T-type calcium channel protein expression of Ca(v)3.1, Ca(v) 3.2, Ca, 3.3 in airway smooth muscle cell were detected by immunohistochemistry technique.</p><p><b>RESULTS</b>(1) The airway resistance in the model group was higher than that in the normal group and in the acupuncture group (both P < 0.05), and the airway resistance in the acupuncture group was lower than that in the sham acupuncture group (P < 0.05). (2) The ratios of the airway wall thickness to the basement membrane perimeter (Awt/Pbm) and the airway outer perimenter to the airway internal perimeter (Po/Pi) in the model group were higher than those in the normal group and in the acupuncture group (all P < 0.05), and the ratios of Awt/Pbm and Po/Pi in the acupuncture group were lower than those in the sham acupuncture group (both P < 0.05). (3) The average optical of Ca(v) 3.1 and Ca(v) 3.2 in airway smooth muscle cell in the model group were higher than that in the normal group and in the acupuncture group (both P < 0.05), and the average optical of Ca(v) 3.3 in airway smooth muscle cell in the model group was higher than that in the normal group (P < 0.05) and it was lower than that in the sham acupuncture group (P < 0.05).</p><p><b>CONCLUSION</b>Acupuncture can inhibit the airway remodeling and the accrementition of the airway smooth muscle and can reduce the airway resistance. The mechanism may be related to the inhibition of T-type calcium channel protein in airway smooth muscle cell, especially in relation to the protein expression of Ca(v) 3.1.</p>

Decreased mRNA expressions of T-type channel alpha1H and alpha1G in the sperm of varicocele patients and their implication / 中华男科学杂志

<p><b>OBJECTIVE</b>To study the relationship of varicocele (VC) with the expressions of T-type channel alpha1H and alpha1G in the sperm of VC patients.</p><p><b>METHODS</b>Based on the WHO criteria, we examined the semen samples by computer-aided sperm analysis (CASA), and divided the samples into groups A (normal semen from volunteers, n = 20), B (normal semen from VC patients, n = 16) and C (abnormal semen from VC patients, n = 44). We optimized the semen by discontinuous Percoll grade centrifugation, and determined the mRNA expressions of T-type channel alpha1H and alpha1G in the three groups using using reverse transcription polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Compared with group A, the mRNA expressions of alpha1H and alpha1G showed with no significant decrease in group B (P>0.05), but were remarkably reduced in group C (P<0.01).</p><p><b>CONCLUSION</b>The abnormal mRNA expressions of T-type channel alpha1H and alpha1G may be one of the causes of declined semen quality and consequently infertility in VC patients, which has pointed out a new direction for the studies of the causes and treatment of VC-related infertility.</p>

Effect of carvedilol on T-type calcium current in myocytes of non-infarcted area of the rabbit healed myocardial infarction / 药学学报

This article reports the investigation of the effect of carvedilol (Car) on T-type calcium current (I(Ca,T)) of noninfarcted ventricular myocytes in rabbit models of healed myocardial infarction (HMI). Rabbits with left anterior descending artery ligation were prepared and allowed to recover for 8 weeks, as HMI group. Animals undergoing an identical surgical procedure without coronary ligation were served as the sham-operated group (sham group). Whole cell voltage-clamp techniques were used to measure and compare currents in cells from the different groups. Noting that I(Ca,T) density in HMI cells increased markedly to -2.36 +/- 0.12 pA/pF (at -30 mV) compared with cells of sham, where little I(Ca,T) (-0.35 +/- 0.02 pA/pF) was observed. Meanwhile, further analysis revealed a significant hyperpolarizing shift of steady-state activation curve of I(Ca,T) in HMI cells, where the time constants of deactivation were prolonged and the time of recovery from inactivation was shortened. Finally, the amplitude of I(Ca,T) was increased. Carvedilol (1 micromol x L(-1)) was found to decrease the amplitude of I(Ca,T) to -1.38 +/- 0.07 pA/pF through inhibiting process of I(Ca,T) activation. Furthermore, carvedilol delayed recovery from inactivation of I(Ca,T) and shortened the time constants of deactivation in HMI cells. This study suggested that the application of carvedilol in HMI cells contributes to the dynamic changes in I(Ca,T) and may account for reduction of incidence of arrhythmia after myocardial infarction.

Effect of an L- and T-Type Calcium Channel Blocker on 24-Hour Systolic Blood Pressure and Heart Rate in Hypertensive Patients

BACKGROUND AND OBJECTIVES: The aim of this study was to evaluate the effects of an L- and T-type calcium channel blocker (CCB) on 24-hour systolic blood pressure (24-hour SBP) and heart rate (24-hour HR) profiles in essential hypertensive patients. SUBJECTS AND METHODS: Thirty-seven consecutive patients were enrolled in this study. The 24-hour SBP and HR were recorded before and after treatment with efonidipine (L- and T-type CCB, 40 mg), after waking. Changes in 24-hour SBP and HR and the diurnal to nocturnal SBP ratio were measured. The best-fit curves of changes in SBP and HR were depicted using a periodic function. RESULTS: The mean 24-hour SBP and HR decreased significantly after treatment. The diurnal to nocturnal SBP ratio in dipper-type hypertension cases decreased from 16.7+/-6.1% to 8.3+/-9.8% (p<0.05), whereas in non-dipper hypertension cases, it increased from 2.3+/-2.9% to 7.7+/-5.1% (p<0.01). The antihypertensive effect was minimal at 5.0 hours after drug administration and it slowly recovered at a constant rate (2.1 mm Hg/h) over 12 hours in dipper cases. The median 24-hour changes in HR in the dipper and non-dipper cases were -2.3/min and -5.4/min, respectively. A continuous reduction in the change in HR was seen from 3.5 to 23 hours after drug administration. CONCLUSION: The antihypertensive action of efonidipine was characterized by a slow recovery of the SBP decrease at a constant rate (2.1 mm Hg/h) and a non-administration time dependent reduction in 24-hour HR.

Intracisternal Administration of Voltage Dependent Calcium Channel Blockers Attenuates Orofacial Inflammatory Nociceptive Behavior in Rats

Voltage dependent calcium channel (VDCC), one of the most important regulator of Ca2+ concentration in neuron, play an essential role in the central processing of nociceptive information. The present study investigated the antinociceptive effects of L, T or N type VDCC blockers on the formalin-induced orofacial inflammatory pain. Experiments were carried out on adult male Sprague-Dawley rats weighing 220-280 g. Anesthetized rats were individually fixed on a stereotaxic frame and a polyethylene (PE) tube was implanted for intracisternal injection. After 72 hours, 5% formalin (50 microL) was applied subcutaneously to the vibrissa pad and nociceptive scratching behavior was recorded for nine successive 5 min intervals. VDCC blockers were administered intracisternally 20 minutes prior to subcutaneous injection of formalin into the orofacial area. The intracisternal administration of 350 or 700 microg of verapamil, a blocker of L type VDCC, significantly decreased the number of scratches and duration in the behavioral responses produced by formalin injection. Intracisternal administration of 75 or 150 microg of mibefradil, a T type VDCC blocker, or 11 or 22 microg of cilnidipine, a N type VDCC blocker, also produced significant suppression of the number of scratches and duration of scratching in the first and second phase. Neither intracisternal administration of all VDCC blockers nor vehicle did not affect in motor dysfunction. The present results suggest that central VDCCs play an important role in orofacial nociceptive transmission and a targeted inhibition of the VDCCs is a potentially important treatment approach for inflammatory pain originating in the orofacial area.

Quantitative expression of voltage-dependent calcium channels in prostate smooth muscle cells of rats with estradiol-induced chronic nonbacterial prostatitis / 中华男科学杂志

<p><b>OBJECTIVE</b>To construct a rat model of chronic nonbacterial prostatitis (CP) and investigate the difference in the quantitative expression of voltage-dependent calcium channels of prostate smooth muscle cells (PSMCs) between the models and controls.</p><p><b>METHODS</b>We established a CP rat model by estrogen induction, cultured and purified the PSMCs in vitro, and extracted total RNA by Trizol. Then we measured the mRNA expression of the cal subunit in the calcium channel subtypes by reverse transcription and SYBR Green I real time RT-PCR, and compared it with that of the controls.</p><p><b>RESULTS</b>The expressions of the L-, T- and P/Q-type calcium channels were found in both the CP and control groups, and that of the CaV1.2 L-type calcium channel was significantly increased in the former as compared with the latter (0.048 +/- 0.024 versus 0.031 +/- 0.015, t = 2.846, P = 0.007), but there were no statistically significant differences in the T- and P/Q-type calcium channels between the two groups.</p><p><b>CONCLUSION</b>The number of CaV1.2 L-type calcium channels of PSMCs and calcium influx were increased in CP patients, which may be involved in the mechanism of CP.</p>

The effects of simvastatin on cardiac hypertrophy and association on calcium channel modulation in rats with myocardial hypertrophy induced by abdominal aortic constriction / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effects of simvastatin (SIM)on cardiac hypertrophy and association with calcium channel modulation in rats with myocardial hypertrophy.</p><p><b>METHODS</b>Myocardial hypertrophy was induced by abdominal aortic constriction (AAC) in adult SD rats. Following groups were studied (n=8 each): sham group, AAC group, AAC+ verapamil group (10 mg x kg(-1) x d(-1) per gavage for 4 weeks), AAC +SIM group (10 mg x kg(-1) x d(-1) per gavage for 4 weeks) AAC + SIM + mevalonic acid (50 mg x kg(-1) x d(-1) per gavage for 4 weeks) group. Systolic blood pressure (SBP), echocardiography, heart weight/body weight (HW/BW) and left ventricle weight/body weight (LVW/BW) ratios were measured. The protein and mRNA expressions of L-type calcium channel subunit alpha1 C and T-type calcium channel subunit alpha1 G and alpha1 H were detected by Western blot and RT-PCR respectively.</p><p><b>RESULTS</b>SBP, HW/BW, LVW/BW, IVS and LVPW thickness, left ventricular weights were significantly increased in AAC rats and these effects could be significantly reduced by verapamil and SIM. The protein and mRNA expressions of alpha1 G and alpha1 H were significantly increased in AAC rats which could also be significantly inhibited by SIM or verapamil. The effects of SIM could be blocked by cotreatment with mevalonic acid. Protein and mRNA expressions of L-type calcium channel alpha1 C were similar among groups.</p><p><b>CONCLUSION</b>Similar as verapamil, SIM could prevent AAC induced cardiac hypertrophy, possibly via inhibiting T-type calcium channel subunit alpha1 G and alpha1 H re-expression.</p>

17 beta-estradiol inhibits T-type calcium channels in mouse spermatogenic cells / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effect of 17 beta-estradiol (E2) on T-type calcium currents (ICaT) in spermatogenic cells.</p><p><b>METHODS</b>Ca2+ currents were obtained in acutely dissociated mouse spermatogenic cells by the whole-cell patch clamp technique and the effects of E2 on ICaT were observed.</p><p><b>RESULTS</b>E2 at the concentrations of 1, 10 and 100 micromol/L significantly inhibited ICaT in the mouse spermatogenic cells, with the KC50 value of 8.89 micromol/L and the inhibition rates of (13.48 +/- 1.86) %, (28.98 +/- 2.70) and (52.93 +/- 3.42)%, respectively (n = 6, P < 0.05). E2 of 100 micromol/L significantly changed the activation and inactivation of ICaT: the half activation potential (Va 1/2) and the activation steepness factor (Ka) from ( -48.94 +/- 0.22) mV and (5.19 +/- 0.19) mV to (-54.34 +/- 1.02) mV and (6.02 +/- 0.84) mV ( n = 5, P < 0.05) , and the half inactivation potential (Vi 1/2) and the inactivation steepness factor (Ki) from (-56.51 +/- 0.13) mV and (3.36 +/- 0.11) mV to (-61.78 +/- 0.50) mV and (4.25 +/- 0.37) mV, respectively (n = 5, P < 0.05).</p><p><b>CONCLUSION</b>E2 has a significant inhibitory effect on ICaT in mouse spermatogenic cells in a con-centration-dependent manner.</p>

Calcium-transporters in myocardial cells.

This is a concise review of important calcium-transporters on the sarcolemma and organellar membranes of myocardial cells, and their functional roles in cell physiology. It briefly addresses L and T type calcium channels, store-operated calcium channel (SOC), sodium-calcium exchanger (NCX), and the plasma membrane calcium ATPase (PMCA) on the sarcolemma, ryanodine receptor (RyR), IP3 receptor (IP3R) and the sarcoplasmic reticulum (SR) calcium ATPase (SAERCA) on the SR membrane and their contributions to contraction and rhythm-generation. Several agonists and blockers for every transporter that are commonly used in research, and those with therapeutic applications have also been discussed.

Effects of flunarizine on T-type calcium channels in mouse spermatogenic cells / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effects of Flunarizine (Flu) on T-type calcium currents (ICaT) in spermatogenic cells.</p><p><b>METHODS</b>Ca2+ currents were obtained in acutely dissociated mouse spermatogenic cells using whole-cell patch clamp technique and the effects of Flu on ICaT were observed.</p><p><b>RESULTS</b>Flu of 0.1, 1, 10, 100 micromol/L inhibited ICaT in mouse spermatogenic cells significantly with the K50 value of 0.289 micromol/L (P < 0.05). With the holding potential at -90 mV and stimulating potential at -30 mV, the inhibition rates of Flu were (23.34 +/- 2.76)%, (46.04 +/- 3.52)%, (62.52 +/- 3.70)% and (73.52 +/- 3.12)%, respectively.</p><p><b>CONCLUSION</b>Flu has significant inhibitory effects on ICaT in mouse spermatogenic cells, with concentration dependence. Ca(v)3.2 is the main contributor to T-type Ca2+ currents in spermatogenic cells.</p>

The effect of CACNA1H gene G773D mutation on calcium channel function / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the effect of CACNA1H gene mutation G773D on calcium channel function.</p><p><b>METHODS</b>By the overlap extension PCR we introduced G773D mutation into a human Cav3.2acDNA for constructing the mutant. And then using whole cell clamp technique, we studied the alterations of channel behavior in transfected HEK-293 cells.</p><p><b>RESULTS</b>There were no difference in kinetics of activation and inactivation of calcium channel between wild type and mutant. However comparing with the wild-type Cav3.2 channel, G773D mutant could increase the calcium current density significantly.</p><p><b>CONCLUSION</b>CACNA1H gene G773D mutation is able to increase calcium current and neuronal excitability.</p>

T-type calcium channel gene-CACNA1H is a susceptibility gene to childhood absence epilepsy / 中华儿科杂志

<p><b>OBJECTIVE</b>Childhood absence epilepsy (CAE) is one of the most frequently recognized syndromes among the idiopathic generalized epilepsies (IGEs). It is considered to be a hereditary disease. The possible inheritance pattern of CAE is polygenic. The genes responsible for CAE, however, have not yet been identified. The aim of this study was to further investigate based on the authors' recent work whether or not T-type calcium channel gene-CACNA1H is a susceptibility gene to childhood absence epilepsy.</p><p><b>METHODS</b>The authors conducted the mutation screening of the exons 6-12 and the nearby partial introns of the CACNA1H gene using the method of direct sequencing of PCR products in 48 newly found CAE patients.</p><p><b>RESULTS</b>The authors found 13 single nucleotide polymorphisms (SNPs). They also found 4 mutations which only existed in CAE patients. Both G773D and H515Y mutations were heterozygous. The mutation of H515Y has never been reported previously. The patient inherited the mutation from his mother. The authors found two CAE patients with the mutation of G773D previously. This is the third time that the authors found one more CAE family with this G773D mutation, and the patient with the mutation G773D inherited the mutation from his father.</p><p><b>CONCLUSION</b>T-type calcium channel gene-CACNA1H might be a susceptibility gene to childhood absence epilepsy.</p>

CaV 3.1 and CaV 3.3 account for T-type Ca2+ current in GH3 cells

T-type Ca2+ channels are important for cell signaling by a variety of cells. We report here the electrophysiological and molecular characteristics of the whole-cell Ca2+ current in GH3 clonal pituitary cells. The current inactivation at 0 mV was described by a single exponential function with a time constant of 18.32 ñ 1.87 ms (N = 16). The I-V relationship measured with Ca2+ as a charge carrier was shifted to the left when we applied a conditioning pre-pulse of up to -120 mV, indicating that a low voltage-activated current may be present in GH3 cells. Transient currents were first activated at -50 mV and peaked around -20 mV. The half-maximal voltage activation and the slope factors for the two conditions are -35.02 ñ 2.4 and 6.7 ñ 0.3 mV (pre-pulse of -120 mV, N = 15), and -27.0 ñ 0.97 and 7.5 ñ 0.7 mV (pre-pulse of -40 mV, N = 9). The 8-mV shift in the activation mid-point was statistically significant (P < 0.05). The tail currents decayed bi-exponentially suggesting two different T-type Ca2+ channel populations. RT-PCR revealed the presence of a1G (CaV3.1) and a1I (CaV3.3) T-type Ca2+ channel mRNA transcripts.

Effects of amiloride on potassium and calcium currents in guinea pig ventricular myocytes / 药学学报

<p><b>AIM</b>To elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na+/H+ exchanger inhibitor--amiloride.</p><p><b>METHODS</b>Single ventricular cells were isolated using a double-enzyme method. Effects of amiloride on voltage-dependent potassium and calcium currents in isolated guinea pig ventricular myocyte were recorded by using whole-cell patch clamp techniques.</p><p><b>RESULTS</b>Exposure to amiloride (10 -100 micromol x L(-1)), the L-type and T-type calcium currents were depressed. Amiloride resulted in a concentration-dependent inhibition of peak (Ca,L), But amiloride did not change the shape of their I - V curves. It only decreased the amplitudes of the currents of the two types. When myocytes were incubated with 100 micromol x L(-1) amiloride, I(Kr) was slightly depressed and I(Ks) did not change. Amiloride (1 - 100 micromol x L(-10) depressed I(K1) in a concentration-dependent manner.</p><p><b>CONCLUSION</b>Amiloride depressed potassium and calcium currents, which may give support to its uses in some diseases of the cardiovascular system.</p>