Effect Of Myocardial Fibrosis And RAS After Early Bypass Operation Of Coronary Artery

ObjectiveAfter acute myocardial,heart generate ventricles remodeling,renin-angiotensin system of the myocardium is higher than normal,StAR is a regulatory protein of steroid hormone synthesis,which mainly effect acute stage of aldosterone synthesis. After acute myocardial infarction(AMI),express level of StAR mRNA is obviously higher than normal at myocard infracted zone,synthesis of aldosterone is augmentation and aggravate myocardial fibrosis.At present bypass operation of coronary artery(CABG) already is a therapeutic means of coronary heart disease.But coronary artery bypass graft (CABG) treat acute myocardial infarction(AMI) exist dispute about operation opportunity.After acute myocardial infarction (AMI),there is not clear between influence of coronary artery bypass graft (CABG) and level of renin angiotensin system,express level of StAR mRNA.myocardial fibrosis.To investigate the effect and significance of early coronary artery bypass graft (CABG) to collogen deposition.myocardial fibrosis.level of renin angiotensin system and express level of StAR protein at infracted zone of dog after acute myocardial infarction (AMI).MethodsThe anterior descending coronary of all thirty dogs randomly assigned into experimental group (n=22) and control group (n=8) were ligated into MI model. The diagnosis of MI model was ST-segment elevation of 0.2mv in I . II .avL electrocardiographic (ECG) leads, cardiac muscle turn darkening and patho-Q wave. T wave inversion or two-way.The experimental group included 1th week (n=6),2th week (n=4),4th week (n=6) and 6th week (n=6) CABG, completely imitate CABG of patients, obtain variant arteria cruralis as bridge blood vesse. and established control group (n=2) for every experimental group. We measured MI scope (TTC staining method),myocardial fibrosis(picric-sirius red staining method)at perimeter myocardial infarction zone,the level of renin activity and angiotensin II at myocardial infarction zone by radio-immunity,express level of StAR mRNA at myocardial infarction zone and normal myocardial zone by RT-PCR at eight weeks after surgery.ResultsFour dogs of every experimental group and all dogs of control group survived to the end of the study. 1.In Control Group, the area of myocardial infarction (P<0.05).the level of renin activity and angiotensin II (P<0.01)at myocardial infarction zone,express level of StAR mRNA at myocardial infarction zone (P<0.01) and content of myocardial collagen at myocardial infarction perimeter zone(P<0.05) are higher than 1.2experiment group (CABG at 1.2week) and normal myocardium.2.According to different time of early CABG, the area of myocardial infarction,the level of renin activity and angiotensin II at myocardial infarction zone,express level of StAR mRNA at myocardial infarction zone and content of myocardial collagen at infracted border zone (IBZ) of 3.4 experiment group (CABG at 4.6week) are higher than 1.2 experiment group (CABG at 1.2week) and normal myocardium.Conclusions1 .Early CABG for acute myocardial infarction(AMI) could obviously lessen the level of renin activity and angiotensin Hand decrease the area of myocardial infarctiona at myocardial infarction zone of dog with MI, which lessen the content of myocardial collagen at myocardial infarction perimeter zone and improve the myocardial collagen ratio of I type and III type and myocardial fibrosis, therapeutic efficacy of early CABG for acute myocardial infarction is best especially among two weeks.2.After acute myocardial infarction(AMI) of dog, express level of StAR mRNA at myocardial infarction zone is higher and increase synthesis of aldosterone, these aggravate myocardial fibrosis.Early CABG for acute myocardial infarction(AMI) could obviously lower express level of StAR mRNA at myocardial infarction zone,lessen myocardial fibrosis.therapeutic efficacy of early CABG for acute myocardial infarction is best especially among two weeks.