Flavored Ephedra Aconite Decoction Extract On Atrioventricular Conduction

Objective:To study the effects of Mahuang,Fuzi and Xixin Tang on the atrium -ventricle (A-V)conduction function in normal and A-V blockade New Zealand rabbits,and explore the possible mechanism involved.Methods:①Effects of Mahuang,Fuzi and Xixin Tang on A-V conduction in normal New Zealand rabbits:Mahuang,Fuzi,Xixin Tang- treated group:Mahuang,Fuzi,Xixin Tang 2ml/kg was given intragastrically after the animals have been fasted for 12h;the contrast group: 2ml/kg 0.9%saline was given intragastrically instead of Mahuang,Fuzi,Xixin Tang.The animals were medicated twice a day for 2 consecutive days.20 min after the last medication, animals were anaesthetized with intravenous injection of 20%urethane(1.2g/kg)through ear vein.Electrocardiogram electrodes were inserted into the four limbs and the electrodes were connected to bio-singal collecting computer system.The trachea was disconnected to perform the trachea intubatton.The left carotid artery was disconnected and a 4F dipolar pipe electrode (with 2mm interval)was inserted into the base of aorta.The electrode was adjusted until H-wave His Boundle electrocardiography between A-wave and V-wave appeared.The electrode was fixed and theⅡ- lead electroardiogram was recorded at 30,60,90,120 min after medication.②Effects of Mahuang,Fuzi and Xixin Tang on A-V conduction blockade in the rabbits with ischemia-reperfusion injury:The trachea was disconnected to perform the trachea intubatton and was connected to animal respiration machine.Animals were artificially ventilated with room air plus end-positive pressure oxygen.The chest cavity was opened to perform heart-bag hammock operation.The right coronary artery was disconjuncted at the base of aorta and a plastic tube coated surgical thread under the right coronary artery was placed.The right groin skin was incised and the right femoral artery was exposed and isolated.Right femoral artery intubatton (filled with 0.3%heparin sodium)was performed and the intubatton was connected to computer recording system through blood pressure transducer to monitor blood pressure.Incise the left groin skin and expose the left femoral vein to perform left femoral vein intubatton.0.9% saline was infused at constant speed to maintain animal blood pressure during the experiment.15 min after the surgery,the right coronary artery was ligated to induce myocardium ischemia. 15min(group A),60min(group B)and 120min(group C)later the thread was sniped to restore the coronary artery blood flow.Ⅱ-lead electroardiogram,His Boundle electrocardiography were recorded 0 min(before),1min,5min,10min,15min,20min,30min,60min,120min after ligation, and 1min,5min,10min,15min,30min 60min,120min,240min after reperfusion for every group.③Effects of Mahuang,Fuzi and Xixin Tang on A-V conduction blockade induced by verapamil:0.2%verapamil solution was injected into ear vein(2.0mg/kg,0.46～0.66ml/min)and injection was completed in 5-10 min.Ⅱ-lead electroardiogram,His Boundle electrocardiography were recorded 0 min(before),5min,15min,30min,60min,90min after verapamil injection. Cardioelectrogram and His Boundle electrocardiography in experiments②and③were recorded as experiment①.Observation parameters:heart rate,P-R interval,A-H interval.Results were expressed as(?)±s.Variance difference was used to compare differences between groups and X~2 test was used to compare heart rate.P＜0.05 is considered statistically significant.Results:Mahuang,Fuzi,Xixin Tang produced no significant effect on heart rate and A-V conduction function in normal New Zealand rabbits.When compared with contrast,no significant differences were observed in heart rate,P-R interval and A-H interval(P＞0.05). Coronary artery ischemia-reperfusion group had shortened P-R interval and A-H interval(P＜0.05).When compared with verapamil model group,the experimental group had increased heart rate(P＜0.05)and shortened P-R interval and A-H interval(P＜0.05).Conclusion:Mahuang,Fuzi and Xixin Tang had no effect on normal animals' heart rate and heart rhythm;Mahuang,Fuzi and Xixin Tang could improve A-V conduction blockade in rabbits with heart ischemis-reperfusion injury.Mahuang,Fuzi and Xixin Tang could increase the heart rate and improve the A-V conduction function in animal model with A-V blockade induced by verapamil.