Effects of palmatine on potassium and calcium currents in isolated rat hepatocytes  

作　　者：FangWang Hong-YiZhou LanCheng GangZhao JiZhou Li-YingFu Wei-XingYao 

机构地区：[1]DepartmentofPharmacology,TongjiMedicalCollegeofHuazhongUniversityofScienceandTechnology,Wuhan430030,HubeiProvinceChina [2]DepartmentofPancreaticSurgeryCenter,UnionHospital,TongjiMedicalCollegeofHuazhongUniversityofScienceandTechnology,Wuhan430022,HubeiProvinceChina

出　　处：《World Journal of Gastroenterology》2003年第2期329-333,共5页世界胃肠病学杂志（英文版）

摘　　要：AIM: To study the effects of palmatine, a known inhibitoron delayed rectifier potassium current and L-type calciumcurrent (ICa,L) in guinea pig ventricular myocytes, on thepotassium and calcium currents in isolated rat hepatocytes.METHODS: Tight-seal wh ole-cell patch-clamp techniqueswere performed to investigate the effects of palmatine onthe delayed outward potassium currents (IK), inward rectifierpotassium current (IK1) and Ca2+ release-activated Ca2+current (ICRAC) in enzymatically isolated rat hepatocytes.RESULTS: Palmatine 0.3-100 μM reduced IK in a concentationdependent manner with EC50of 41.62±10.11 μM and nH,0.48±0.07 (n=8). The effect of the drug was poorly reversibleafter washout. When the bath solution was changed totetraethylammonium (TEA) 8 mM, IK was inhibited.Palmatine 10 μM and 100 μM shifted the I-V curves of IKdownward, and the block of IK was voltage-independent.Palmatine 0.3-100 μM also inhibited ICRAC in a concentration-dependent manner. The fitting parameters were as follows:ECs0=51.19±15.18 μM, and nH=0.46+0.07 (n=8). The peakvalue of ICRAC in the I-V relationship was decreased bypalmatine 10 μM and 100 μM. But the reverse potential ofIcRAcoCcurred at Voltage=0 mV in all cells. Palmatine 0.3-100 μM failed to have any significant effect on either inwardor outward components of IK1 at any membrane potentialexamined.CONCLUSION: The inhibitory effects on IK and ICRAC couldbe one of the mechanisms that palmatine exerts protectiveeffect on hepatocytes.AIM:To study the effects of palmatine,a known inhibitor on delayed rectifier potassium current and L-type calcium current(I_(Ca,L))in guinea pig ventricular myocytes,on the potassium and calcium currents in isolated rat hepatocytes. METHODS:Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of palmatine on the delayed outward potassium currents(I_K),inward rectifier potassium current(I_(K1))and Ca^(2+)release-activated Ca^(2+) current(I_(CRAC))in enzymatically isolated rat hepatocytes. RESULTS:Palmatine 0.3-100 μM reduced I_K in a concentration- dependent manner with EC_(50)of 41.62±10.11 μM and n_H, 0.48±0.07(n=8).The effect of the drug was poorly reversible after washout.When the bath solution was changed to tetraethylammonium(TEA)8 raM,I_K was inhibited. Palmatine 10 μM and 100 μM shifted the Ⅰ-Ⅴ curves of I_K downward,and the block of I_K was voltage-independent. Palmatine 0.3-100 μM also inhibited I_(CRAC)in a concentration- dependent manner.The fitting parameters were as follows: EC_(50)=51.19±15.18 μM,and nH=0.46±0.07(n=8).The peak value of I_(CRAC)in the Ⅰ-Ⅴ relationship was decreased by palmatine 10 μM and 100 μM.But the reverse potential of I_(CRAC)occurred at Voltage=0 mV in all cells.Palmatine 0.3- 100 μM failed to have any significant effect on either inward or outward components of I_(K1)at any membrane potential examined. CONCLUSION:The inhibitory effects on I_K and I_(CRAC)could be one of the mechanisms that palmatine exerts protective effect on hepatocytes.

关 键 词：掌叶防己碱 肝实质细胞 钙离子电流 钾离子电流 细胞培养 作用机制 

分 类 号：R975[医药卫生—药品] R965[医药卫生—药学]