Coronary arterial remodeling and angiotensin Ⅱ type 2 receptor expression in ischemia-reperfusion injury rat after valsartan pretreatment / 重庆医学

ABSTRACT

Objective To observe the expression of angiotensin Ⅱ type 2 receptor (AT2R) and coronary arterial remodeling in ischemia-reperfusion(I-R) injury rat after the renin -angiotensin blocker valsartan pretreatment .Methods 123 rats were random-ly divided into 3 groups :sham -operation group(sham) ,control group and valsartan group(ARB) .The control group and the sham group received the gavage of normal saline and the ARB group received valsartan gavage 10 mg/(kg · d) for 4 weeks before surger-y .The I-R injury rat model was established by thoracotomy for ligating the left anterior descending (LAD) coronary artery and re-moving the ligation after 30 min .The sham group was performed the thoracotomy without ligation .At the 4 timepoints of postoper-ative 3 ,7 ,14 ,28 d ,the left ventricular diastolic and systolic pressures were measured ,then the rats were killed for collecting the rat heart sample .The section was stained by sirius red .The collagen deposition in coronary arterial remodeling and coronary arterial pe-ripheral area ,and the dynamic change of location and expression of AT2R in the coronary artery were observed by the immunohisto-chemical streptavidinbiotin peroxidase complex (SABC) .Results The immunohistochemical analysis revealed that AT 2R was local-ized in the adventitia of coronary arteries with the radial distribution ,showing the higher density especially in large coronary arterial peripheral area ,the partial expression existed in the coronary arterai intima .The expression of AT2R was transient ,which on 7 d af-ter I-R operation in the control group reached the peak value ,while the expression peak value of AT2R in the valsartan group was higher and earlier than that in the control group .The heart diastolic function on 3 d after I-R operation was impaired ;the left ven-tricular end diastolic presure (LVEDP) in the valsartan group was significantly lower than that in the control group .The collagen deposition of coronary peripheral mesenchyma on postoperative 28 d in the valsartan group was significantly lower than that in the control group;the coronary peripheral collagen deposition in the control group was gradually increased with the time progression , which on postoperative 14 ,28 d was significantly higher than that in the sham group .Conclusion Valsartan could inhibit the coronary arterial remodeling for protecting the heart function possible by the transient high AT 2R expression after myocardial I-R injury .