Qiliqiangxin Affects L Type Ca2+ Current in the Normal and Hypertrophied Rat Heart

Qiliqiangxin capsule is newly developed Chinese patent drug and proved to be effective and safe for the treatment of patients with chronic heart failure. We compared the effects of different dose Qiliqiangxin on L type Ca(2+) current (I(Ca-L)) between normal and hypertrophied myocytes. A total of 40 healthy Sprague-Dawley rats were used in the study. The rats were randomly divided into two groups (control group and hypertrophy group). Cardiac hypertrophy was induced by pressure overload produced by partial ligation of the abdominal aorta. The control group was the sham-operated group. After 1 month, cardiac ventricular myocytes were isolated from the hearts of rats. Ventricular myocytes were exposed to 10 and 50 μmol/L Qiliqiangxin, and whole cell patch-clamp technique was used to study the effects of Qiliqiangxin on I(Ca-L). The current densities of I(Ca-L) were similar in control group (-12.70 ± 0.53 pA/pF, n = 12) and in hypertrophy group (-12.39 ± 0.62 pA/pF, n = 10). They were not statistically significant. 10 and 50 μmol/L Qiliqiangxin can decrease I(Ca-L) peak current 48.6%±16.8% and 59.0%±4.4% in control group. However, the peak current was only reduced 16.73%±8.03% by 50 μmol/L Qiliqiangxin in hypertrophied myocytes. The inhibited action of Qiliqiangxin on I(Ca-L) of hypertrophy group was lower than in control group. Qiliqiangxin affected L-type Ca(2+) channel and blocked I(Ca-L), as well as affected cardiac function finally. Qiliqiangxin has diphasic action that is either class IV antiarrhythmic agent or the agent of effect cardiac function.