OBJECTIVE:To investigate the influence of acute blood stasis on nitric oxide (NO),angiotensin Ⅱ (Ang Ⅱ),angiopoietin-like protein 4 (ANGPTL4)mRNA,neuregulin 1 (NRG-1) mRNA,and platelet endothelial cell adhesion molecule-1 (PECAM-1) in rats with stasis induced by high-molecular-weight dextran (HMWD).METHODS:Seventy-five Sprague Dawley rats were divided randomly into five groups (n =15 in each group):control group,immediate group,1 h group,3 h group,and 6 h group.A model of acute blood stasis was established via injection of HMWD into the tail vein.After performing electrocardiogram at the predetermined times according to the grouping,we collected blood and cardiac samples for hematoxylin-eosin (HE) staining and histopathological examination via transmission electron microscopy.Enzyme-linked immunosorbent assay was used to detect plasma levels of NO,Ang Ⅱ,and fibrinogen.Real-time polymerase chain reaction was used to detect the expression of ANGPTL4 mRNA and NRG-1 mRNA.Immunohistochemical methods were used to detect PECAM-1 protein expression.RESULTS:The rat model of blood stasis showed blood retention in the capillary lumens.The ST segment showed gradual elevation,and was still elevated at 3 and 6 h after induction of blood stasis.HE staining showed myocardial cell necrosis and dissolution after modeling,along with basement membrane rupture and mitochondrial structural damage.Transmission electron microscopy showed endothelial cell swelling and an increase in absorption vesicles immediately after modeling.Endothelial cell apoptosis was increased at 3 and 6 h after modeling.Cardiac muscle fibers were disordered and intercalated discs were blurred immediately after modeling.There were massive numbers of dissolved cardiac muscle fibers,ruptured basement membranes,and mitochondrial structural damage at 3 and 6 h after modeling.NO plasma concentration was significantly reduced immediately and 1 h after modeling,while it was increased at 3 and 6 h.Ang Ⅱ plasma concentration was decreased immediately after modeling,but increased at 1,3,and 6 h.Fibrinogen plasma concentration was significantly increased at immediate,1,3,and 6 h after modeling.PECAM-1 protein expression was obviously increased immediately after modeling,at 1,6 h was found mild augment.Expression of AngPTL4 mRNA was increased at immediate,1,3,and 6 h after modeling,and was found further augment at 3,and 6 h.Expression of NRG-1 mRNA was increased at immediate,1,3,and 6 h after modeling,and the strongest expression was at 1 h.CONCLUSION:The pathological manifestation of acute blood stasis is characterized by microvascular blood retention.Prolonged blood stasis leads to worsening endothelial cell and cardiomyocyte damage,along with imbalances in the expression of vasomotor factors and increased vascular tone.The pathological damage caused by blood stasis also promotes the expression of cell protection factors.