The Effect Of Evodia Subine On Ion Channels In Rat Ventricular Myocytes

Objective:The effects of Rutaecarpine(Rut)on the major ion channel currents(INa,Ito)and I-V curves,activation kinetics,inactivation kinetics,and recovery kinetics after inactivation of rat ventricular myocytes were observed.Methods:A Langendorff perfusion device was used to separate rat heart from retrograde aortic aorta to obtain single ventricular myocytes;Perfusate with extracellular fluid containing Rut was used to perfuse INa,Ito and related kinetics of cells before and after administration with whole cell patch clamp technique.Learning parameters.Results:?.Effect of Rut on INa Channel1.In a single stimulus state,Rut inhibits INa in a time and concentration dependent manner.Inhibitory rates of 10 ?M,20 ?M,and 40 ?M rutacarpine on peak INa current were(22.37±2.42)%,(36.74±6.27)%,and(47.67±4.52)%,respectively(n=10,P<0.01).2.When the concentration is greater than 10?M,Rut can significantly increase the I-V curve of INa.The concentration of ruthenium at concentrations of 10?M,20?M,and 40?M reduced the peak sodium current density from(-32.53 ±5.12)pA/pF to(-25.13 ±2.7)pA/pF,(-18.71 ±5.2)pA/pF,and(-14.71 ±5.2)pA/pF(P<0.01,n = 10),but the IV curve shape,activation potential,peak potential,and reversal potential did not change.3.Rut concentration above 10?M can significantly shift the activation curve to the right,that is,move in the direction of depolarization.The activation voltage increases and the activation difficulty increases.4.In addition,Rut can significantly shift the inactivation curve of INa to the left,that is,to the hyperpolarization direction.10 ?M,20 ?M,and 40 ?M evodiamine decrease the V 1/2 from(-78.13 ±0.34)mV before administration,respectively.For(-94.22 ±1.32 mV),(-101.45 ±0.51)mV and(-112.56 ±0.72)mV(n=10,P<0.01),the slope factor k changes from 9.87±0.22to 12.12±0.32,13.16 ±0.76 and 5.23 1±0.43(P<0.01,n= 10).5.Not only that,Rut can also significantly shift rightward the inactivation curve of INa to ?from(16.19 ±0.71)ms before dosing to(25.41 ± 1.11)ms,(32.34 ±0.76)ms and(37.73)±0.27)ms(P<0.01,n=10),prolonged recovery duration and slower repolarization after inactivation.?.Effect of Rut on Ito Channel1.Rut inhibits Ito in a time-and concentration-dependent manner in a single stimulus state.Inhibitory rates of Ito peak currents by ruthenium at 10 ?M,20 ?M,and 40 ?M were(15.25±3.43)%,(33.45±6.58)%,and(57.46±7.72)%,respectively(n=10,P<0.01).2.10?M slightly inhibited the channel,but the effect was not significant,and 20?M and 40?M rutecarpine could significantly downshift the IV curve of Ito,and 20?M and 40?M ruthenium made the peak potassium current(41.16±3.65)pA./PF decreased to(28.97 ± 3.35)and(18.68±2.37)pA/pF(n=10,P<0.01)3.For the Ito activation curve,when the concentration was 20 ?M and 40?M,the activation curve shifted to the right,and half of the activation voltage(V1/2)increased from(14.45±0.96 mV)before administration to(27.69±4.35).mV and(28.89±3.74)mV(n=10,P<0.01);half of the activation voltage before and after administration increased,which means that the channel is more difficult to be activated under the same conditions.4.Rut can shift the inactivation curve to the left,ie,to the hyperpolarization direction.The half-maximal inactivation potential(V 1/2)for administration of 20 ?M and 40 ?MRut changes from(-36.34±0.76)mV before administration to(-).60.48 ± 0.96)mV and(-75.45 ± 0.78)mV(n = 10,P<0.01)accelerated the inactivation process.5.For the recovery curve after inactivation,Rut can shift the curve to the right.After inactivation,the activation parameter ? increases from(72.24 ± 1.32)ms before administration to(98.85 ±0.81)ms and(147.3 ±1.35)ms(n=10,P<0.01),prolonged recovery duration and slower repolarization after inactivation.Conclusion:The atrial and ventricular myocytes of rat shows a distinct electrophysiological characteristics.Besides,Rut can block INa and Ito with different degrees in ventricular myocytes when it reaches some concentration.