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sodium current kinetics of transitional myocytes in Koch triangle of rabbit hearts

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Chinese Medical Journal 2008年第21期121卷 2185-2191页

作者： REN Fu-xian NIU Xiao-lin OU Yan XIE Song-mei LING Feng-dong ZHOU Shi-sheng LI Ya-jie Department of Cardiology Second Hospital Xi'an Jiaotong University Xi'an Shaanxi 710004 China Key Laboratory of Environment and Genes Related to Diseases Ministry of Education Xi'an Shaanxi 710061 China Department of Anatomy Xi'an Jiaotong University School of Medicine Xi'an Shaanxi 710061 China Institute of Basic Medical Science Dalian University School of Medicine Dalian Liaoning 116622 China

Background Few studies have explored the inward sodium current （INa） kinetics of transitional cardiomyocytes. This study aimed to explore the kinetics of transitional cardiomyocytes types α and β. Methods The whole-cell patch clamp technique was used to study the rapid INa of isolated transitional cardiomyocytes in the Koch triangle of rabbit hearts. Results Maximal amplitude and density of INa in type a and type β was （-1627±288） pA （α）, （-35.17±6.56） pA/pF （β） and （-3845±467） pA （α）, （-65.64±10.23） pA/pF （β）（P 〈0.05）. Steady state activation curves of INa, fitted to a Boltzmann distribution for both types, were sigmoid in shape. Half activation voltage and slope factors did not significantly differ between types at （-43.46±0.85） mV （α）, （-41.39±0.47） mV （β） or （9.04±0.66） mV （α）, （11.08±0.89） mV （β）. Steady state inactivation curves of INa, fitted to a Boltzmann distribution in both types were inverse ＂S＂ shape. Half inactivation voltage and slope factors were （-109.9±0.62） mV （α）, （-107.5±0.49） mV （β） and （11.78±0.36） mV （α）, （11.57±0.27） mV （β）, （P〉0.05）, but time constants of inactivation were significantly different at （1.10±0.19） mV （α） and （2.37±0.33） ms （β）, （P 〈0.05）. Time constants of recovery from inactivation of INa for both types were （122.16±27.43） mV （α） and （103.84±2.8.97） ms （β）（P 〈0.05）. Conclusions Transitional cardiomyocytes in rabbit hearts show a heterogeneous, voltage gated and time dependent fast inward sodium current. Types α and β show the features of INa similar to those in slow- and fast-response myocytes, with probably better automaticity and conductivity, respectively.

关键词： sodium current transitional myocyte Koch triangle tachycardia

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Biphasic effects of haloperidol on sodium currents in guinea pig ventricular myocytes

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Acta Pharmacologica Sinica 2007年第6期28卷 783-788页

作者： Subat TURDI Parhat KERRAM Department of Pharmacology School of PharmacyXinjiang Medical UniversityUrumqi 830054China

Aim:To study the effects of haloperidol on sodium currents (INa) in guinea pigventricular ***:Whole-cell patch clamp technique was employedto evaluate the effects of haloperidol on INain individual ventricular ***:Haloperidol （0.1-3 μmol/L） inhibited INain a concentration-dependentmanner with an IC50of 0.253±0.015 μmol/*** inhibition rate of haloperidol （0.3μmol/L） on INawas 22.14%±0.02%,and the maximum conductance was *** significantly reduced the midpoints for the activation and inactiva-tion of INaby 2.09 and 4.09 mV,*** time constant of recovery *** increase in time intervals could only recover by 90.14%±1.4%（n=6）;however,haloperidol at 0.03 μmol/L enhanced *** mid-points for the activation and inactivation of INawere shifted by 1.38 and 5.69 mV,respectively,at this concentration of ***:Haloperidol dis-played a biphasic effect on INain guinea pig cardiac *** concentra-tions of haloperidol inhibited INa,while lower concentrations of haloperidol shiftedthe activation and inactivation curve to the *** recovery of recovery curvewas not achieved after 0.3 μmol/L haloperidol administration,indicating that thedrug affects the inactivated state of sodium channels.

关键词： haloperidol sodium current ventricular myocytes

Effect of New O-Superfamily Conotoxin on Voltage-Activated currents of Hippocampal Neurons

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Tsinghua Science and Technology 2004年第1期9卷 64-68页

作者：李湛何湘平戴秋云黄培堂谢佐平 Department of Biological Sciences and Technology Tsinghua University Beijing 100084 China Institute of Biotechnology Beijing 100071 China

The effects of a new O-superfamily conotoxin, SO3, on sodium current (INa), transient A-type potassium currents (IA),and delayed rectified potassium currents (IK), were examined in cultured rat hippocampal neurons using the whole-cell patch clamp technique. Addition of SO3 caused a concentration-dependent, rapidly developing, and reversible inhibition of voltage-activated currents. The IC50 values for the blockage of INa , IA, and IK were calculated as 0.49, 33.9, and 7.6 mmol/L, respectively. The determined Hill coefficients were 1.7, 0.6, and 1.2, respectively. These results indicate that SO3 can selectively inhibit neuronal sodium and potassium currents.

关键词： hippocampal neuron patch-clamp SO3 sodium current potassium current

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Morphological and electrophysiological properties of single myocardial cells from Koch triangle of rabbit heart

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Chinese Medical Journal 2006年第24期119卷 2075-2084页

作者： REN Fu-xian NIU Xiao-lin OU Yan HAN Zhen-hua LING Feng-dong ZHOU Shi-sheng LI Ya-jie Department of Cardiology Second Hospital Xi＇an Jiaotong University Xi＇an 710004 China Key Laboratory of Environment and Genes Related to Diseases Ministry of Education Xi＇an 710061 China Department of Anatomy Xi＇an Jiaotong University School of Medicine Xi＇an 710061 China Institute of Basic Medical Science Dalian University School of Medicine Dalian 116622 China （Zhou SS and Li YJ）

Background The morphological and electrophysiological characteristics of cardiac cells in Koch triangle are still disputed. We studied the appearance and electrical properties of these diverse myocytes to elucidate their complex electrophysiological phenomena. Methods Experiments were conducted using cooled charge coupling device （CCD） system and whole cell, patch clamp technique to determine the morphology, action potential and sodium current density of single viable myocytes enzymatically isolated from the Koch triangle of rabbit hearts. Results Morphologically, cardiac cells in shape of spider, tiny spindle, slender spindle, rod and strip were observed in percentage of 3.0±0.3, 35.0±5.0, 15.0±2.0, 40.0±5.0 and 6.0±0.7 respectively. The cellular dimensions and capacitance gradually increased in the above order （all P〈0.05）. Electrophysiologically, action potential configurations recorded from them were similar respectively to nodal （N）, atrial nodal （AN）, nodal Hisian （NH）, atrial （A） and Hisian like potentials obtained from the intact atrioventricular nodal preparations. Diastolic depolarization appeared in all myocytes except for rod cells. sodium current density increased in the order of tiny spindle, strip, rod, slender spindle cell （all P〈0.05）, but could not be detected in spider-shaped cells. Linear regression analysis revealed that membrane capacitance was correlated negatively to the rate of diastolic depolarization r=-0.70, P〈0.001, but positively to maximum depolarization potential, amplitude of action potential, upstroke velocity and maximum peak value of sodium current density r=0.84, 0.80, 0.87 and 0.75, respectively; all P〈0.001. Conclusions The results demonstrated that spider-shaped, spindle, rod and strip cells in Koch triangle might correspond to pacemaking, transitional, atrial and Purkinje like cells, respectively. Furthermore, tiny spindle and slender spindle cells were referred to transitional cell α （TCα） and β （TCβ） accordingly considering

关键词： triangle of Koch transitional cell action potential sodium current patch clamp

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