| Summary: | 碩士 === 國防醫學院 === 藥理學研究所 === 98 === Baicalein is a major flavonoid extracted from the root of Scutellaria baicalensis Georgi (also called Huangqin), a traditional oriental medicine widely used in treating allergic and inflammatory diseases. It has been reported to demonstrate potent antioxidant and anti-inflammatory effects. The aim of this study is to investigate whether baicalein can protect against myocardial ischemia/reperfusion (MI/R) injury by improving calcium homeostasis in rats. Isolated hearts were perfused by the Langendorff apparatus, baicalein (10 mg/kg, i.p.) was pretreated 24 hr and 40 min before MI. Global ischemia/reperfusion model was induced by stopping perfusion for 15 min and recover perfusion for 1 hr. The diastolic [Ca2+]i calcium levels in isolated single cardiomyocytes were significantly reduced by baicalein, whereas the amplitude of Ca2+ transients were significantly enhanced by baicalein, when compared with the MI/R levels. The protein expression of sodium-calcium exchanger (NCX) in the baicalein-treated group was significantly increased when compared with that of the MI/R group, which may contribute to reduce diastolic [Ca2+]i calcium levels. Furthermore, in regional ischemia/reperfusion model, which was induced by left coronary artery occlusion for 45 min and 2 h of reperfusion, the levels of lactate dehydrogenase, creatine kinase-muscle-brain fraction and tumor necrosis factor- were significantly reduced in the baicalein-treated group. The protein expression of NCX and phospho-extracellular signal-regulated kinases (p-ERK) after MI/R was significantly elevated, but the protein expression of phospho-phospholamban (p-PLB) was significantly reduced by baicalein. In conclusion, the cardioprotective effect of baicalein can be attributed to the improvement of calcium homeostasis after MI/R injury by elevating the protein expression of NCX, activation of the ERK pathway and inhibition of PLB phosphorylation.
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