Objective:To observe influence of matrine on cell action potential in guinea pig papillary muscles thus to clarify its antiarrhythmic mechanism. Method: Guinea pigs were divided into control group

matrine group(10

50

100 μmol·L-1)

aconitine group 1 μmol·L-1

aconitine 1 μmol·L-1＋matrine 50 μmol·L-1group

aconitine 1 μmol·L-1+matrine 100 μmol·L-1 group. Conventional microelectrode technique was used to record action potential duration(APD)

action potential amplitude (APA)

50 % and 90 % of APD repolarization(APD50 and APD90). Result: Matrine could prolong moderately APD50 and APD90 in a dose-dependent manner(10

50

100 μmol·L-1)and reduce APA. Aconitine could excessively prolong APD (vs control group

P<0.05)

APD50 and APD90. Matrine(100 μmol·L-1)could remedy for excessive elonggation of aconitine on APD

APD50 and APD90 (vs aconitine group

P<0.05 or P<0.01). Matrine(100 μmol·L-1)also could reduce APA(vs aconitine group

P<0.05). Conclusion: Matrine could remedy for excessive elonggation of aconitine on APD

APD50 and APD90 and reduce APA of aconitine-induced arrhythmia

which could maitain action potential in a normal range

and was probably one of matrine antiarrhythmic mechanisms.