Studies Of Icariin On Anti-Myocardial Ischemia And Mechanisms

Objectives In this paper, the acute myocardial ischemia model was established by ligating left anterior descending branch on anaesthetized dog coronary artery to observe the protecting action of Icariin(ICA) for treating acute myocardial ischemia. And more these studies were performed to investigate the effects of icariin on hemodynamics in normal anesthetic chest-opened dogs and injured vascular endothelial cells. The possible mechanism of ICA was revealed in different aspects by different index such as holistic, biochemical and cellular levels.Methods The experimental myocardial infarction model was prepared by left anterior descending coronary artery ligated in anesthetic dogs, the myocardial infarction area was measured by nitroblue tetrazolium(NBT) dyeing, the epicardium electrocardiogram(EECG) was maped, the activity of serum enzyme and SOD, and the level of MDA were determined by corresponding kit. Parameters of cardiac hemodynamics were examined in anesthetic chest-opened dogs with various doses of ICA. The chemical hypoxia-ischemia model was established. The viability of cell was determined by MTT assay. MDA level and SOD activity of cell homogenate were measured by corresponding kit. Cells apoptosis was defined by flow cytometry and Hoechst 33342 staining.Results ICA decreased the infarct size dyed by NBT, attenuated the degree and range of myocardial ischemia in experimental myocardial infarction canine, and the activity of creatine phosphokinase(CPK), the MDA level were also decreased by ICA, but the activity of SOD was increased. ICA increased the myocardial blood flow(MBF) obviously, reduced its resistance to improve blood and oxygen supply. Lowered heart rate, oxygen consumption index andoxygen uptake rate to reduce the myocardial oxygen consumption. Went down total peripheral vascular resistance(TPR) to reduce the afterload, which made heart perfusion flow enhance. And ICA increased cardiac index and stroke index to improve cardiac pumping function. The viability of vascular endothelial cells were decreased in condition of hypoxia. The level of MDA in cell homogenate was increased and the activity of SOD decreased significantly. And endothelial cells apoptosis was induced by hypoxia. Incubation of vascular endothelia cells with various concentration of ICA significantly increased the viability of cell and the activity of SOD, decreased the level of MDA and the ratio of cell apoptosis.Conclusion All results mentioned above demonstrated that ICA could protect myocardial cell from ischemic injury, the mechanisms of ICA may be related to reduce the myocardial oxygen consumption, increase myocardial blood and oxygen supply, improve cardiac pumping function, prevent apoptosis, inhibit the formation of free radicals and the lipid peroxidation. It is suggested that ICA may play a role in prevention and treatment of ischemic heart disease. In the future, the more effects of ICA and its mechanisms are value to be further investigated.