Objective： To study the effects of gypenoside （Gyp） on the activity of microsomalNa^＋, K^＋-ATPase in rat＇s heart and brain in vitro. Methods： The microsomal Na^＋, K^＋-ATPase was prepared from rat＇s heart a...Objective： To study the effects of gypenoside （Gyp） on the activity of microsomalNa^＋, K^＋-ATPase in rat＇s heart and brain in vitro. Methods： The microsomal Na^＋, K^＋-ATPase was prepared from rat＇s heart and brain by differential centrifugation. The activity of microsomal Na^＋, K^＋-ATPase was assayed by colorimetric technique. Enzyme kinetic analysis method was used to analyze the effect of Gyp on the microsomal Na^＋, K^＋-ATPase of rats. Results： Gyp reversibly inhibited the brain and heart＇s microsomal Na^＋, K^＋-ATPase in a concentration-dependent manner, and showed a more potent effect on enzyme in the brain. The IC50 of Gyp for the heart and brain were 58.79± 8.05 mg/L and 52.07± 6.25 mg/L, respectively. The inhibition was enhanced by lowering the Na^＋, or K^＋-concentrations or increasing the ATP concentration. Enzyme kinetic studies indicated that the inhibitory effect of Gyp on the enzyme is like that of competitive antagonist of Na^＋, the counter-competitive inhibitor for the substrate ATP, and the mixed-type inhibitor for K^＋. Cenclusien： Gyp displays its cardiotonic and central inhibitory effects by way of inhibiting heart and brain＇s microsomal Na^＋, K^＋-ATPase activities in rats.展开更多
基金Supported by Guangdong Provincial Natural Science Foundation (No010742)
文摘Objective： To study the effects of gypenoside （Gyp） on the activity of microsomalNa^＋, K^＋-ATPase in rat＇s heart and brain in vitro. Methods： The microsomal Na^＋, K^＋-ATPase was prepared from rat＇s heart and brain by differential centrifugation. The activity of microsomal Na^＋, K^＋-ATPase was assayed by colorimetric technique. Enzyme kinetic analysis method was used to analyze the effect of Gyp on the microsomal Na^＋, K^＋-ATPase of rats. Results： Gyp reversibly inhibited the brain and heart＇s microsomal Na^＋, K^＋-ATPase in a concentration-dependent manner, and showed a more potent effect on enzyme in the brain. The IC50 of Gyp for the heart and brain were 58.79± 8.05 mg/L and 52.07± 6.25 mg/L, respectively. The inhibition was enhanced by lowering the Na^＋, or K^＋-concentrations or increasing the ATP concentration. Enzyme kinetic studies indicated that the inhibitory effect of Gyp on the enzyme is like that of competitive antagonist of Na^＋, the counter-competitive inhibitor for the substrate ATP, and the mixed-type inhibitor for K^＋. Cenclusien： Gyp displays its cardiotonic and central inhibitory effects by way of inhibiting heart and brain＇s microsomal Na^＋, K^＋-ATPase activities in rats.
