青蒿素对心力衰竭兔窦房结超极化激活环核苷酸门控通道及起搏电流的影响

Effects of artemisinin on HCN channels and pacemaker currents in rabbits with heart failure

目的观察青蒿素对心力衰竭(心衰)兔超极化激活环核苷酸门控通道(HCN)及起搏电流(If)的影响.方法将30只健康雄性新西兰大白兔随机分为青蒿素组、心衰组和假手术组3组.选择主动脉瓣返流及腹主动脉缩窄法建立兔心衰模型,青蒿素组给予青蒿素75 mg·kg-1·d-1剂量灌胃每日3次,心衰组和假手术组灌喂等量的0.5%竣甲基纤维素钠溶液.4周后测量心率并行超声心动图检查,测量左心室舒张末期内径(LVEDD)、左心室收缩末期内径(LVESD)、左心室舒张末期容积(LVEDV)、左心室收缩末期容积(LVESV)、左心室射血分数(LVEF)及左心室短轴缩短率(LVFS).采用全细胞膜片钳技术,在电压钳模式下记录起搏电流If.应用Western blot方法检测窦房结HCN2和HCN4蛋白表达.结果与假手术组兔比较,心衰组兔的心率增快,LVEDD、LVESD、LVEDV和LVESV升高,LVEF和LVFS降低,差别有统计学意义(P均<0.05).与心衰组兔比较,青蒿素组兔的心率[(229.3±16.7)bpm比(193.2±18.8)bpm]下降,LVEDD[(18.6±1.8)mm比(15.4±1.2)mm]、LVESD[(14.2±1.7)mm比(11.3±1.6)mm]、LVEDV[(10.3±1.9)ml比(6.7±1.2)ml]和LVESV[(5.2±1.7)ml比(3.4±1.3)ml]降低,LVEF[(42.0±3.0)%比(57.0±4.0)%]和LVFS[(22.3±2.0)%比(28.9±2.7)%]升高,差别有统计学意义(P均<0.05).青蒿素组If电流由(1.40±0.24)nA下降至(0.76±0.11)nA(P<0.05),降低幅度为(51.2±2.3)%.青蒿素组窦房结中HCN2、HCN4蛋白表达下降(P均<0.05).结论青蒿素能使心衰兔窦房结If电流下降,HCN蛋白减少,降低心率,改善心脏结构和功能.

Objective To observe the effects of artemisinin on hyperpolarization activated cyclic nucleotide-gated(HCN)channels and pacemaker currents(If)in rabbits with heart failure(HF).Methods 30 healthy male New Zealand white rabbits were randomly divided into 3 groups:artemisinin group,HF group and sham group.The rabbit model with HF was established by experimental aortic valve regurgitation and abdominal aortic constriction.Arteminsinin group was given artemisinin 75 mg·kg-1·d-1 intragastrically three times a day,HF group and sham group were fed with 0.5%sodium methylcellulose solution.Heart rate(HR)was measured and echocardiography was performed 4 weeks later.Left ventricular end diastolic dimension(LVEDD),left ventricular end-systolic dimension(LVESD),left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular ejection fraction(LVEF)and left ventricular fractional shortening(LVFS)were measured.The whole cell patch clamp technique was used to record the If currents in the voltage clamp mode.The expressions of HCN2 and HCN4 proteins in sinus node were detected by Western blot.Results Compared with sham group,there were significant increases in HR,LVEDD,LVESD,LVEDV,LVESV and decreases in LVEF and LVSF in HF group(all P<0.05).Compared to HF group,significant decreases in HR[(229.3±16.7)bpm vs.(193.2±18.8)bpm],LVEDD[(18.6±1.8)mm vs.(15.4±1.2)mm],LVESD[(14.2±1.7)mm vs.(11.3±1.6)mm],LVEDV[(10.3±1.9)ml vs.(6.7±1.2)ml]and LVESV[(5.2±1.7)ml vs.(3.4±1.3)ml],and increases in LVEF[(42.0±3.0)%vs.(57.0±4.0)%]and LVFS[(22.3±2.0)%vs.(28.9±2.7)%]were observed in artemisinin group(all P<0.05).There was a significant decrease in If current from(1.40±0.24)nA to(0.76±0.11)nA(P<0.05).The expressions of HCN2,HCN4 protein in sinoatrial node decreased significantly in artemisinin group(both P<0.05).Conclusion Artemisinin can decrease If current,HCN protein expression and HR,improve cardiac function and structure in rabbits with HF.