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目的:研究蜂毒肽对豚鼠心肌线粒体Na~+,K~+-ATP酶活性的影响。方法:应用光电比色法测定Na~+,K~+-ATP酶活性。以Line-weaver-burk双倒数作图法分析酶动力学参数。结果:蜂毒肽抑制心肌Na~+,K~+-ATP酶表现为浓度和时间依赖性,IC_(50)为2.60μmol/L。酶动力学研究表明,蜂毒肽对Na~+,K~+-ATP酶有抑制作用,对K~+表现为竞争性结合,对Na~+及ATP表现为非竞争性结合。结论:蜂毒肽对心肌Na~+,K~+-ATP酶有抑制作用,其抑制机制主要是与K~+竞争结合酶外侧的K~+结合位点。
Objective: To study the effect of melittin on mitochondrial Na~+, K~+-ATPase activity of guinea pig heart. Methods: The activity of Na~+, K~+-ATPase was measured by electro-optical colorimetry. The enzyme kinetic parameters were analyzed by Line-weaver-burk double reciprocal mapping. RESULTS: Methotrexate inhibited Na~+ and K~+-ATPase activity in myocardium in a concentration- and time-dependent manner, IC50 was 2.60 μmol/L. Enzymatic kinetic studies showed that melittin inhibited Na~+, K~+-ATPase, showed competitive binding to K~+, and exhibited non-competitive binding to Na~+ and ATP. CONCLUSION: Melittin has inhibitory effects on Na~+, K~+-ATPase in myocardium, and its inhibitory mechanism is mainly the K~+ binding site on the outside of K~+ competition binding enzyme.