Effects Of Aldehyde Dehydrogenase 2 On Myocardial Protection

Aldehyde dehydrogenase 2(ALDH2) is a major protein on the mitochondrion which plays a key role in the oxidation of acetaldehyde and its derivates.Myocardial cells filled with mitochondria are sensitive to ischemia due to its distinctive physiological functions.The reactive oxygen species(ROS) produced after ischemia does a great harm to the tissue and body.ALDH2 eliminate the ROS and other harmful substances to protect cells from further damage.We observed that over-expression of ALDH2 in heart failure mice can inhibit cell apoptosis and improve the cardiac function.On this basis,the drug enhancing ALDH2 enzyme activity was applied to the ischemia-reperfusion and heart failure rats.The positive conclusions help us to provide a safe and effective drug target to the cardiac protection.Part 1 Gene Transfer of Aldehyde Dehydrogenase 2 Attenuates Postinfarction Heart FailureAim:To observe the effects of ALDH2 gene transfection on cardiac function and myocardial apoptosis in postinfarction C57BL/6 mice.Methods:Use left ventricle liquid injection model and acute myocardial infarction(AMI) model to investigate the effects of ALDH2 over-expression on C57BL/6 mice.Normal saline group(NS 0.1ml 0.9%Sodium Chloride) and Blank Vector group(BV 2.0×10⁸pfu/μ10.Iml GFP adenovirus) are set as controls.Ultrasonic cardiogram(UCG) parameters,including left ventricular end-diastolic diameter(LVEDD),ejection fraction(EF) and fractional shortening(FS) were measured 2 and 4 weeks after operation to evaluate the cardiac function of all the mice.Heart failure mice were sacrificed for further investigation.Apoptosis was measured by TUNEL assay.The expression level of p53 protein was detected by Immuno -histochemistry.Results:The UCG data showed that EF and FS of ALDH2 group increased 15.01% and 13.85%respectively while LEVDD decreased 14.86%compared to NS group (all P＜0.05).Meanwhile,the data measured 2 weeks after operation have no significant difference.The number of apoptotic cardiac cells in ALDH2 group was much less than NS and BV group(both P＜0.001).Besides,the expression of p53 protein in ALDH2 group was enhanced greatly compared to both controls(P＜0.001).Conclusions:Over-expression of ALDH2 reduces myocardial apoptosis and improves cardiac function in heart failure mice,which shows a protective role of ALDH2 in heart failure.Part 2 Cardioprotection Role of Drug on Myocardial Ischemia followed by ReperfusionAim To evaluate the effects of drug,which can increase the activity of ALDH2 enzyme,on the way of cardiac protection,we applied the rat ischemia followed by reperfusion heart model to observe the possible changes in the drug administrated rats.Methods The suitable dosage(0.3g/kg weight all n=12) are determined according to mice drug tolerance and human dosage.Sprague-Dawley rats were randomized to receive either 0.9%Sodium Chloride(0.2ml intragastric administration),activated simvastatin(1mg/kg intraperitoneal injection) or drug(0.3g/kg weight intragastric administration) 3 days before myocardial ischemia and reperfusion.After reperfusion,6 rats form each group were used to calculate the infarction ratio by Evan's blue and triphenyltetrazolium chloride(TTC) staining. Myocardial apoptosis was evaluated by TUNEL assay;the expression of 4-HNE combined proteins was detected by fluo immunofluorescence.ALDH2 activity was measured by the method of acetaldehyde metabolism between drug and normal rats without I/R injury.Results The ratio of infarction size calculated through TTC and Evan's Blue staining was 29.41%±8.39%in SIM group vs.57.72±6.52%in NS group (P＜0.001),significantly reduced by 28.31%;While only 35.58%±5.77% infarction size detected in Drug group,show a reduction of 22.14%(P＜0.001).Risk areas showed no difference among 3 groups(P＞0.01). HE staining showed cell injure by I/R in three groups.The apoptosis detected in ischemia region is 71.7±11.9 per scan in NS group while 45.1±7.8 and 51.7±9.0/scan in SIM and Drug group,both P＜0.05 when compared to NS group.ALDH2 activity showed no significant difference between NS and Drug groups.The expression level of 4-HNE combined protein in cardiac myocytes is mainly concentrated on cell membrane and myofilaments,interestingly,the blood vessel endothelium have more 4-HNE combined proteins than that is in cardiac myocytes.Conclusions Drug can greatly inhibit the accumulation of 4-HNE and reduce the cell apoptosis induced by ischemia/reperfusiono Methods The suitable dosage(0.3g /kg weight,all n=6) are determined according to mice drug tolerance and human dosage.Sprague-Dawley rats were randomized to receive 0.9%Sodium Chloride(0.2ml intragastric administration),Enalapril(lmg/kg intragastric administration),drug (0.3g/kg weight intragastric administration) or drug and enalapril combination(1mg/kg enalapril and 0.3g/kg drug intragastric administration) alone.4 weeks after acute myocardial infarction injury. Rats weight were record every week after operation.Ultrasonic cardiogram (UCG) parameters,including interventricular septum thickness(IVS), posterior wall thickness(PW),left ventricular end-diastolic diameter (LVEDD),left ventricular end-systolic dimension(LVESD),ejection fraction(EF) and fractional shortening(FS) were measured 4 weeks after operation to evaluate the cardiac function of all the heart failure rats. Results Body weight of rats in each group showed an upward trend after declining at the 1^st week,rats in drug group have the lowest body weight while ENL group have the highest.The UCG data showed significant difference between drug group and NS group.Conclusions Long-term drug treatment may improve the cardiac function in heart failure rats.