ABSTRACT
AIM:To establish a microthrombus model by carrageenan (Ca)/ lipopolysaccharides (LPS) intraperitoneal injection in rats with hyperhomocysteinemia (HHcy) and endothelial dysfunction induced by L-methionine intake. METHODS: ① Male Sprague Dawley rats were randomly divided into 2 groups: control and endothelial dysfunction (HHcy) groups. L-methionine was administered by gavage in HHcy group for total 4 weeks. Purified water was administered by gavage in control rats. Plasma Hcy, NO and vWF were examined and the thoracic aorta were excised after 4 weeks of L-methionine treatment to evaluate endothelial function. ② Male Sprague Dawley rats were randomly divided into 3 groups to establish a microthrombus formation model with Ca/ LPS: control, microthrombus formation (Ca/LPS) and endothelial dysfunction plus mitoarothrombus formation (HHcy+Ca/LPS) groups. Control rats were injected with normal saline (NS). Ca/LPS rats were intraperitoneally injected with carrageenan (Ca) and followed by lipopolysaccharides (LPS) 16 h later. HHcy+Ca/LPS rats were intragastric gavaged by L-methionine for total 4 weeks, and then were injected with Ca/LPS in the same way as Ca/LPS group. Cruor parameters and platelet count were detected at 20 h after LPS or NS injection and the mesentery microcirculation was monitored. Plasma NO and vWF were also detected at 24 h after LPS or NS injection. RESULTS: ① Plasma Hcy concentrations and vWF level were significantly increased in HHcy group, while plasma NO content was significantly decreased compared with that in control group. Endothelial dependent relaxation (EDR) of aortic rings was significantly decreased in HHcy group, suggesting endothelial damage/dysfunction was induced by HHcy. ② Mesentery capillary was obviously blocked by microthrombus in Ca/LPS rats and was blocked more seriously in HHcy+Ca/LPS rats. Cruor parameter results suggested that Ca/LPS rats were in hypercoagulable phase and HHcy+Ca/LPS rats were in hypocoagulable phase at 20 h after LPS injection. Platelet count and plasma NO content in HHcy+Ca/LPS group were significantly decreased, while plasma vWF level was significantly increased compared with Ca/LPS group. CONCLUSION: L-methionine intake induces severe HHcy and causes endothelial dysfunction in rats. Microcirculation dysfunction and microthrombosis can be caused by Ca/LPS intraperitoneal injection and may be aggravated by endothelial dysfunction.