Abstract: OBJECTIVE: To examine the microvascular pathological characteristics and changes in related injury factors in a rat model of acute blood stasis.METHODS: A total of 75 Sprague-Dawley rats were divided randomly and equally into a control group and four experimental groups assessed at different times after the induction of stasis(0, 1, 3 or 6 h after stasis)(n = 15). The acute blood stasis model was established through rat tail-vein injection of high-molecular-weight dextran. After Electrocardiograph(ECG) detection at predetermined times(0,1, 3 and 6 h after induction of stasis), the rats were sacrificed and blood and cardiac samples were harvested for analysis. Hematoxylin-eosin(HE) staining and transmission electron microscopy were used for histopathological detection; an enzyme linked immunosorbent assay(ELISA) was used to detect thromboxane B2(TXB2) and 6-keto-prostaglandin F1α(6-Keto-PGF1α) concentrations; a real-time polymerase chain reaction(PCR) reaction system was used to detect intercellular adhesion molecule1(ICAM-1) and vascular cell adhesion molecule1(VCAM-1) m RNA expression; western blotting was used to detect vascular endothelial cadherin(VE-cadherin) protein expression.RESULTS: The ST segment in the ECG showed gradual elevation after induction of stasis and continued elevation at a high level at 3 and 6 h. The HE staining showed changes in myocardial cell necrosis and tissue dissociation after the induction of stasis, along with inflammatory infiltration. Results of transmission electron microscopy showed immediate changes in blood stasis and lumen occlusion in the microvasculature, along with endothelial cell swelling. After the induction of stasis, TXB2 concentrations gradually increased while 6-Keto-PGF1αconcentrations were immediately significantly reduced. The TXB2/6-Keto-PGF1αratio was maintained at a high level. ICAM-1 m RNA expression showed an unstable elevation while VCAM-1 m RNA expression was significantly reduced after the induction of stasis. Compared with the control group, VE-cadherin protein expression increased at 0 and 3 h after the induction of stasis, while no change occurred at 1 and 6 h.CONCLUSION: The pathological manifestations of acute blood stasis are microvascular blood retention, lumen stenosis and even occlusion. The condition is also called "blood coagulation and weep" in Traditional Chinese Medicine. The blood stasis model resulted in the injury and necrosis of endothelial cells and cardiomyocytes, along with the presence of an imbalance of vasomotor factor levels, platelet activation, and increases in the expression of adhesion molecules and endothelial barrier dysfunction,which corresponds to "blood failed to nourish" in Traditional Chinese Medicine.

Key words: Blood stasis, Acute-phase reaction, Microvessels, Endothelial cells, Medicine, Chinese traditional