| Heart failure is an important cardiovascular disease threatening human health in the 21st century. The five-year survival rate of patients with heart failure is about 50%, the risk of malignant arrhythmia significantly increased among stage D heart failure patients, and nearly 50% of heart failure patients died of sudden cardiac death caused by malignant arrhythmia. Malignant arrhythmia induced by myocardial electrophysiological remodeling is one of the most important reason of death in heart failure patients. Electrophysiological remodeling encompasses alterations in multiple electrogenic transport prosesses within the cardiac myocyte, involving a variety of functional changes of ion channels and cell signal transduction system, including changes of L-type calcium current and prolongation of the action potential duration. Since effective clinical drugs for cardiac electrophysiology remodeling is absent now, research of Traditional Chinese Medicine may be the breakthrough to solve this problem.TCM believes that heart qi deficiency is the basic pathogenesis of heart failure, which occurred throughout the progress. Promoting qi drugs are a sort of basis drugs for prevention and treatment of heart failure in TCM, which could effectively improve cardiac function in heart failure patients without adverse reactions. Astragalus, ginseng and codonopsis are three clinical conmmonly used promoting qi drugs. Previous studies discussed the mechanism of promoting qi drugs to improve cardiac function in heart failure animal models from the perspective of energy metabolism and sarcoplasmic reticulum calcium transport. But the mechanism of promoting qi drugs to improve the prognosis of heart failure form the perspective of electrophysiological remodeling has not yet been reported.This study established two kinds of mice model, pressure-overload-induced heart failure by thoracic aorta constrains and myocardial infarction induced heart failure by coronary artery ligation. Technique of animal echocardiography, electrocardiogram, whole cell patch clamp and Western Blot were used. Our research studied from the body level, cellular level and molecular level, to verify the hypothesis that promoting qi drugs could suppress the excessive expression of CaMK II, improve L-type calcium current and shorten the repolarization of heart, thus improve cardiac electrophysiology remodeling.Methods:1. Establish animal model:the coronary artery ligation, thoracic aorta constrains were used to establish myocardial infarction induced heart failure mice model and pressure-overload-induced heart failure mice model respectively.2. Group and intervention:(1) mice after coronary artery ligation were randomly divided into 4 groups of control, sham, YiQi (astragalus+codonopsis) and metoprolol, drug intervention for 4 weeks. (2)mice after thoracic aorta constrains were randomly divided into 6 groups of control, sham, astragalus, ginseng, codonopsis and metoprolol, drug intervention for 4 weeks.3. Detection technology:(1)4 weeks after coronary artery ligation and thoracic aorta constrains, general condition of mice including the body weight and death was recorded, cardiac systolic, diastolic function and ventricular remodeling were detected by echocardiography, ventricular repolarization time and incidence of ventricular arrhythmia were detected by dynamic electrocardiogram in consciousness. (2) 4 weeks after thoracic aorta constrains, mouse cardiac myocytes were isolated freshly. APD25, APD50, APD90 of myocytes in different frequencies (0.2Hz,2.0Hz) and in the intervention of ISO were recorded by current clamp mode of patch clamp. L-type calcium current density of myocytes in different frequencies and in the intervention of ISO, inactivation speed and voltage dependence activation-inactivation curve were recorded by whole-cell voltage clamp mode. (3) 4 weeks after thoracic aorta constrains, mice were killed and the myocardial tissues were removed and reserved, the protein expression level of L-type calcium channel and CaMK II were detected by Western Blot.Results:1. Evaluation of heart failure mice model:(1)4 weeks after coronary artery ligation, compared with sham group, LVEF of control group decreased significantly (p<0.01), left ventricular end-diastolic dimension increased significantly(p<0.01), corrected QT interval prolonged significantly(p<0.01). (2)4 weeks after thoracic aorta constrains, compared with sham group, LVEF of control group decreased significantly(p<0.01), left ventricular end-systolic diamension increased(p<0.05), left ventricular anterior wall thickness increased significantly(p<0.01), Ea reduced significantly(p<0.01), corrected QT interval prolonged significantly(p<0.01).2. Effect of promoting qi drugs on cardiac function and QT interval in heart failure mice: (1)4 weeks after coronary artery ligation, compared with control group, LVEF of YiQi group increased but without statistical significance, LVEF of metoprolol group had no statistical difference, corrected QT interval of YiQi gourp and metoprolol group shortened significantly(p<0.01); (2)4 weeks after thoracic aorta constrains, compared with control group, LVEF of astragalus group increased (p<0.05), Ea of astragalus group increased significantly (p<0.01), LVEF of codonopsis group increased significantly (p<0.01), corrected QT interval of astragalus group, ginseng group and codonopsis group shortened significantly (p<0.01).3. Effect of promoting qi drugs on action potentials and L-type calcium current in heart failure cells:(1) action potential duration:in 0.2Hz, compared with sham group, APD90 of control group prolonged significantly. Compared with control group, APD90 of astragalus group (p<0.05) and codonopsis group (p<0.01) shortened. In 2.0Hz, compared with sham group, APD90 of control group prolonged significantly. Compared with control group, APD90 of astragalus group (p<0.05) and codonopsis group (p<0.01) shortened. In the intervention of ISO, there were no statistical difference in APD90 between control group and sham group. Compared with control group, APD90 of codonopsis group shortened (p<0.05); (2) Current density of Ica,L^ in 0.1 Hz, compared with sham group, ICa,L density of control group increased significantly (p<0.01). Compared with control group, ICa,L density of codonopsis group decreased significantly (p<0.01). In 1.0Hz, compared with sham group, ICa,L density of control group increased significantly (p<0.01). Compared with control group, ICa,L density of astragalus group and codonopsis group decreased (p<0.05). In the intervention of ISO, there were no statistical difference in ICa,L density between control group and sham group. Compared with control gourp, the ICa,L density of codonopsis group lower (p<0.05); (3)Inactivation speed of Ica,L: compared with sham group, the Ï„1 and Ï„2 of control group prolonged significantly (p<0.01). Compared with control group, the Ï„1 and Ï„2 of astragalus group, ginseng group and codonopsis group reduced significantly (p<0.01). (4) voltage dependence activation-inactivation curve:compared with sham group, the half activation potential of control group reduced (p<0.01). Compared with control group, the half activation potential of astragalus group, ginseng group and codonopsis group were significantly higher (p<0.01).4. Effect of promoting qi drugs on protein expression level of L-type calcium channel and CaMK II:(1) there were no statistical difference in the expression level of CANCA1C between all groups. (2) Compared with sham group, the CaMK II expression level of control group was increased. Compared with control group, the CaMK II expression level of astragalus group, ginseng group and codonopsis group were down-regulated (p<0.01).Conclusion:1. Promoting qi drugs(astragalus+codonopsis) chould shorten the repolarization time of heart in myocardial infarction induced heart failure mice, but could not impove the cardiac function. Promoting qi drugs astragalus, ginseng, codonopsis could shorten the repolarization time of heart in pressure-overload-induced heart failure mice, improve the cardiac electrophysiology remodeling. Astragalus could improve cardiac systolic and diastolic function of heart failure simultaneously. Codonopsis could improve cardiac systolic function.2. Promoting qi drugs astragalus, ginseng, codonopsis could intervene L-type calcium current density, inactivation speed, voltage dependence activation-inactivation curve of heart failure cells in different degrees, impove L-type calcium current remodeling, shorten action potential duration of heart failure celles, intervene electrophysiological remodeling. The effects of astragalus and codonopsis were obvious, but the effect of Ginseng was not.3. The effect of astragalus, ginseng, codonopsis on regulation of L-type calcium channel may be mediated by suppression of CaMK II over-expression in heart failure.
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