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Background Shensong Yangxin (SSYX) is one of the compound recipe of Chinese materia medica.This study wasconducted to investigate the effects of SSYX on sodium current (I_(Na)),L-type calcium current (I_(Ca,L)),transient outwardpotassium current (I_(to)),delayed rectifier current (I_K),and inward rectifier potassium currents (I_(K1)) in isolated ventricularmyocytes.Methods Whole cell patch-clamp technique was used to study ion channel currents in enzymatically isolated guinea pigor rat ventricular myocytes.Results SSYX decreased peak I_(Na) by (44.84±7.65)% from 27.21±5.35 to 14.88±2.75 pA/pF (n=5,P<0.05).Themedicine significantly inhibited the I_(Ca,L).At concentrations of 0.25,0.50,and 1.00 g/100 ml,the peak I_(Ca,L) was reduced by(19.22±1.10)%,(44.82±6.50)% and (50.69±5.64)%,respectively (n=5,all P<0.05).SSYX lifted the Ⅰ-Ⅴ curve of both I_(Na)and I_(Ca,L) without changing the threshold,peak and reversal potentials.At the concentration of 0.5%,the drug blocked thetransient component of I_(to) by 50.60% at membrane voltage of 60 mV and negatively shifted the inactive curve anddelayed the recovery from channel inactivation.The tail current density of I_K was decreased by (30.77±1.11)% (n=5,P<0.05) at membrane voltage of 50 mV after exposure to the medicine and the time-dependent activity of I_K was alsoinhibited.Similar to the effect on I_K,the SSYX inhibited I_(K1) by 33.10% at the test potential of-100 mV with little effect onreversal potential and the rectification property.Conclusions The experiments revealed that SSYX could block multiple ion channels such as I_(Na) I_(Ca,L),I_k,I_(to) and I_(K1),which may change the action potential duration and contribute to some of its antiarrhythmic effects.Chin Med J 2007;120(12):1068-1074
Background Shensong Yangxin (SSYX) is one of the compound recipe of Chinese materia medica.This study wasconducted to investigate the effects of SSYX on sodium current (I_(Na)),L-type calcium current (I_(Ca,L)), Transient outward potassium current (I_(to)), delayed rectifier current (I_K), and inward rectifier potassium currents (I_(K1)) in isolated ventricular myocytes.Methods Whole cell patch-clamp technique was used to study ion channel currents in enzymatically isolated guinea Pigor rat ventricular myocytes.Results SSYX may peak I_(Na) by (44.84±7.65)% from 27.21±5.35 to 14.88±2.75 pA/pF (n=5, P<0.05).Themedicine significantly inhibited the I_(Ca,L ).At concentrations of 0.25,0.50,and 1.00 g/100 ml,the peak I_(Ca,L) was reduced by (19.22±1.10)%,(44.82±6.50)% and (50.69±5.64)%,respectively ( n=5, all P<0.05).SSYX lifted the I-V curve of both I_(Na)and I_(Ca,L) without changing the threshold,peak and reversal potentials.At the concentration of 0.5%,the drug blocked Thetransient Component of I_(to) by 50.60% at membrane voltage of 60 mV and negatively shifted the inactive curve and delayy the recovery from channel inactivation.The tail current density of I_K was decreased by (30.77±1.11)% (n=5,P< 0.05) at membrane voltage of 50 mV after exposure to the medicine and the time-dependent activity of I_K was alsoinhibited.Similar to the effect on I_K,the SSYX inhibited I_(K1) by 33.10% at the test potential of-100 mV with The little effect on reversal potential and the rectification property.Conclusions The experiments revealed that SSYX could block multiple ion channels such as I_(Na) I_(Ca,L),I_k,I_(to) and I_(K1),which may change the action Potential duration and contribute to some of its antiarrhythmic effects. Chin Med J 2007;120(12):1068-1074