The Role Of Endothelial Progenitor Cells And Nitric Oxide Induce By Physiologic Ischemic Training In Circulation Formation In Remote Ischemic Myocardium

Objective:①To research the role of endothelial progenitor cells (EPCs) in rabbits with ischemic myocardium in association with collateral circulation formation induced by physiological ischemic training (PIT).②To research the role of nitric oxide (NO) during this process.Methods:Controlled myocardial ischemia was modeled by a water balloon constrictor implanted on the left ventricular branch in a rabbit. The models were assigned randomly into six groups:sham-operation group (SO)、training only group(TO)、myocardial ischemic group (MI)、remote physiological ischemic training group (RIT)、RIT with pretreatment with the EPCs promoter (ProEPCs-RIT)、RIT with pretreatment with the EPCs inhibitor (InhiEPCs-RIT). TO was induced by three cycles of3-minute ischemic followed by5minutes of reperfusion using tourniquets on the hind limbs; MI was induced by two cycles of2-minute myocardium ischemic followed by10minutes of reperfusion by deflation and inflation of the water balloon; remote physiological ischemic training group (RIT) was induced by two cycles of myocardium ischemic training as MI plus three cycles of limb ischemic training as TO; ProEPCs-RIT and InhiEPCs-RIT were induced by RIT with the EPCs promoter and EPCs inhibitor, respectively. After4weeks’training, collateral capillary density (CD), NO level and EPCs count in regional ischemic myocardium and peripheral circulation were assessed by immunohistochemistry, nitrate reductase method, fluorescence-activated cell sorter. Results:①Compared with the other three training groups (SO, TO, MI), RIT had the highest CD (P<0.05), the effect was enhanced by EPCs promoter (P<0.05), but restrained by EPCs inhibitor (P<0.05),while results of InhiEPCs-RTT and TO had no difference with SO.②The EPCs count both in blood and ischemia myocardium was significantly higher in the RIT than in the SO(P<0.05), TO(P<0.05) and MI(P<0.05). RIT had more EPCs than InhiEPCs-RIT (P<0.05), but less than ProEPCs-RIT (P<0.05). InhiEPCs-RIT and TO had no difference with SO (P>0.05).③RIT had higher NO level than MI(P<0.05),LIT(P<0.05) or SO(P<0.05), but the effect was enhanced by EPCs promoter (P<0.05), but restrained by EPCs inhibitor (P<0.05),while results in InhiEPCs-RIT and TO had no difference with SO.④The number of EPCs in peripheral blood were highly correlated with the number of EPCs in ischemic myocardium (r=0.614,.P<0.05); the number of EPCs in ischemic myocardium were highly correlated with the number of CD in ischemic myocardium (r=0.764, P<0.05); EPCs count in ischemic myocardium were highly correlated with the level of NO in ischemic myocardium (r=0.70, P<0.05); the level of NO in ischemic myocardium were highly correlated with the number of CD in ischemic myocardium (r=0.917, P<0.05)Conclusions:Physiological ischemic training may promote the quantity and homing to the ischemic myocardium of EPCs and secrete NO, resulting in an increase in angiogenesis in remote ischemic myocardium.