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The Changes of potassium currents in Rabbit Ventricle with Healed Myocardial Infarction

Journal of Huazhong University of Science and Technology(Medical Sciences) 2004年第2期24卷 128-131页

作者：刘念牛惠燕李泱张存泰周强阮燕菲卜军陆再英 Department of Cardiology Tongji Hospital Tongji Medical College Huazhong University of Science and Technology

To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), the changes of action potential duration (APD), transient outward potassium current (I to), delayed rectifier potassium current (I K) and inward rectifier potassium current (I K1) of left ventricular myocytes in non-infarcted zone of HMI were investigated. Rabbits were randomly assigned into two groups: HMI group, in which animals were subjected to thoracotomy and ligation of the circumflex coronary and sham-operated group, in which rabbits underwent thoracotomy but no conorary ligation. 3 months after the operation, the whole myocyte patch clamp technique was used to record APD, I to, I K, and I K1 of ventricular myocytes in non-infarcted *** results showed that the membrane capacitance was larger in HMI group than in sham-operated group. Action potential duration was significantly lengthened in HMI group and early afterdepolarization (EAD) appeared in HMI group. The densities of I to, I K, tail, and I K1 were reduced significantly in HMI group, from 6.72±0.42 pA/pF, 1.54±0.13 pA/pF and 25.6±2.6 pA/pF in sham-operated group to 4.03±0.33 pA/pF, 1.14±0.11 pA/pF and 17.6 ±2.3 pA/pF, respectively. It is concluded that the reduced densities of I to , I K, tail and I K1 in ventricular myocytes of non-infarcted zone in HMI were responsible for the prolongation of APD and the presentation of EAD which played important roles in the development of malignant arrhythmia in HMI.

关键词： myocardial infarction potassium currents patch clamp

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Effect of etomidate on voltage-dependent potassium currents in rat isolated hippocampal pyramidal neurons

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Chinese Medical Journal 2010年第6期123卷 702-706页

作者： TAN Hong-yu SUN Li-na WANG Xiao-liang YE Tie-hu Key Laboratory of Carcinogenesis and Translational Research Ministry of Education Department of AnesthesiologyPeking University School of OncologyBeijing Cancer Hospital & InstituteBeijing 100142China Department of Anesthesiology Peking Union Medical College HospitalChinese Academy of Medical Sciences & Peking Union Medical CollegeBeijing 100730China Department of Pharmacology Capital Medical UniversityBeijing 100069China Department of Pharmacology Institute of Materia MedicaChinese Academy of Medical Sciences & Peking Union Medical CollegeBeijing 100730China

Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current （IK（DR）） and transient outward potassium current （I_K（A）） in acutely dissociated rat hippocampal pyramidal *** Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student＇s paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited IK（DR） by 49.2% at ＋40 mV when depolarized from -110 mV （P 〈0.01, n=8）, while did not affect IK（A）（/1=8, P 〉0.05）. The IC50value of etomidate for blocking IK（DR）was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V1/2 of activation curve was shifted from （17.3±1.5） mV to （10.7±9.9） mV （n=8, P 〈0.05）, the V1/2 of inactivation curve was shifted from （-18.3±2.2） mV to （-45.3±9.4） mV （n=8, P 〈0.05）. Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of IK（DR））to negative potential, but mainly affected the inactivation *** Etomidate potently inhibited IK（DR） but not IK（A） in rat hippocampal pyramidal neurons. IK（DR） was inhibited by etomidate in a concentration-dependent manner, while IK（A） remained unaffected.

关键词： etomidate hippocampus pyramidal neurons patch clamp potassium currents

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Rivastigmine inhibits voltage-activated potassium currents in rat hippocampal pyramidal neurons

Rivastigmine inhibits voltage-activated potassium currents i...

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2002全国青年药理学英文学术会议

作者： PAN Ya-Ping, XU Xiang-Hua, WANG Xiao-Liang(Department of Pharmacology, Institute of Materia Medica, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing 100050, China)

AIM: Rivastigmine is a new acetylcholinesterase (ACHE) inhibitor following tacrine and donepezil. It displays specificity for central ACHE. potassium channels in the brain has been found in close relationship with learning and memory. While no research about the action of rivastigmine on central potassium currents has been reported up to date. In the present study, we examined the effects of rivastigmine on two main voltage-activated outward potassium currents including transient outward potassium current (I) and delayed rectifier potassium current (I) in rat hippocampal neurons. METHODS: Hippocampal

关键词： rivastigmine hippocampus pyramidal neurons potassium currents patch clamp technique

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Postsynaptic Excitation of Prefrontal Cortical Pyramidal Neurons by Hypocretin-1/Orexin A Through the Inhibition of potassium currents

Postsynaptic Excitation of Prefrontal Cortical Pyramidal Neu...

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2006年中国睡眠研究会第四届学术年会

作者： Jianxia Xia, Xiaowei Chen, Chenghui Song, Jianning Ye, Zhengping Yu, and Zhian Hu Department of Neurobiology, Third Military Medical University, Chongqing, China Department of Neurology, Xinqiao Hospital. Third Military Medical University, Chongqing, China Department of Occupational Health, Third Military Medical University, Chongqing, China

＜正＞Hypocretins are crucial for the regulation of wakefulness by the excitatory actions on multiple subcortical arousal systems. To date, there is little information about the direct postsynaptic excitatory effects of hypocretins on the neurons in prefrontal cortex （PFC）, which is important for higher cognitive functions and is correlated with level of wakefulness. In this study, we tested the excitatory effects of hypocretin-1 on acutely isolated PFC pyramidal neurons of rats and studied the possible ionic mechanisms by using whole-cell patch-clamp techniques. Puff application of hypocretin-1 caused a dose-dependent excitation. Further observations that perfusion of Ca2+-free artificial cerebrospinal fluid did not influence the depolarizing effects of hypocretin-1, in conjunction with the findings that hypocretin-1 could decrease net whole-cell K+ currents, demonstrate that the excitatory effects of hypocretin-1 on PFC neurons are mediated by the inhibition of K+ currents but not Ca2+ influx. Finally, the decrease in K+ currents induced by hypocretin-1 was abolished by a protein kinase C （PKC） inhibitor （BIS Ⅱ） or a phospholipase C （PLC） inhibitor （D609）, suggesting that PKC and PLC appear to be involved in mediating the inhibitory effects of hypocretin-1 on K+ currents. These results indicate that hypocretin-1 exerts a postsynaptic excitatory action on PFC neurons through the inhibition of K+ currents, which probably results from activation of PKC and PLC signaling pathways, （?） 2005 wiley-Liss, Inc.

关键词： hypocretin potassium currents phospho-lipase C prefrontal cortex sleep

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Frequency Selectivity Behaviour in the Auditory Midbrain： Implications of Model Study

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Chinese Physics Letters 2006年第12期23卷 3380-3383页

作者：匡神兵王嘉赋曾婷 Department of Physical Science and Technology Wuhan University of Technology Wuhan 430070

By numerical simulations on frequency dependence of the spiking threshold, i.e. on the critical amplitude of periodic stimulus, for a neuron to fire, we find that bushy cells in the cochlear nuclear exhibit frequency selec- tivity behaviour. However, the selective frequency band of a bushy cell is far away from that of the preferred spectral range in human and mammal auditory perception. The mechanism underlying this neural activity is also discussed. Further studies show that the ion channel densities have little impact on the selective frequency band of bushy cells. These findings suggest that the neuronal behaviour of frequency selectivity in bushy cells at both the single cell and population levels may be not functionally relevant to frequency discrimination. Our results may reveal a neural hint to the reconsideration on the busily cell functional role in auditory information processing of sound frequency.

关键词： VENTRAL COCHLEAR NUCLEUS potassium currents NEURONS PREFERENCES VERTEBRATES MECHANISMS RESPONSES SYSTEMS PITCH

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CHARACTERISTICS　OF　ACTIONPOTENTIAL　AND　THEIR　UNDERLYING　OUTWARD　currents　IN　MAMMALIAN　TASTE　RECEPTOR　CELLS

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Journal of Pharmaceutical Analysis 1995年第2期9卷 189-189页

作者：陈玉社

Many rat taste receptor cells conduct action potentials(APs).APs had a mean threshold of -35 mV(n=95 cells)and a spike height of 52mV above threshold in current clamp(hold= -80mV).Aps could be classified into two significantly different (Pcurrents (mean1.3 ms and 2.7nA),and slow,with long duration and small outward currents(mean9.2ms and 0. 29nA).AP upstrokes were conducted by TTX-sensitive sodium currents whereas the downstroke by TEA-blockable outward currents. Voltage dependent analysis of outward current separated transient and sustained *** transient component was specifically blocked by 4-AP(1mmol/L).A calcium-dependent outward component was also revealed modulating voltage and external calcium *** fast recovery phase of the AP appears related the sustained outward current whereas the after hyperpolarization(AHP) was blocked by 4AP suggesting a significant contribution of the transient *** (FSK),which elevates cAMP,reversibly blocked the majority of the sustained current without influencing the transient. FSK greatly exaggerated the AHP without changing the spike height or duration. These data suggest that several components of the outward current contribute specifically to the gustatory AP and that the AP may be modulated by cyclic nucleotides.

关键词： taste patch-clamps action potential potassium currents forskolin

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