Rizvi Syed Ibrahim, Zaid Mohammad Abu
Department of Biochemistry, University of Allahabad, Allahabad - 211 002, India.
Clin Chim Acta. 2005 Apr;354(1-2):59-67. doi: 10.1016/j.cccn.2004.11.008. Epub 2004 Dec 24.
Tea catechins (EGCG, EGC, ECG and EC) possess many important biological properties. We evaluated the effect of tea catechins on erythrocyte membrane Na(+)/K(+)-ATPase and sodium/hydrogen exchanger (NHE) activity in normal (control) and NIDDM subjects.
Erythrocyte membrane Na(+)/K(+)-ATPase and NHE activity were determined in normal and non-insulin dependent diabetes mellitus (NIDDM) patients. In vitro effect of tea catechins was studied by incubating membrane/intact erythrocytes in assay medium prior to Na(+)/K(+)-ATPase/NHE activity determination.
A 24.2% decrease in the activity of Na(+)/K(+)-ATPase (p<0.001) and 39.37% increase in activity of NHE (p<0.02) were observed in NIDDM subjects compared to normal. Tea catechins inhibited the activity of Na(+)/K(+)-ATPase and NHE in both normal and NIDDM erythrocytes, the effect was concentration-dependent. The inhibitory effect of EGCG and ECG at micromolar concentrations was greater compared to EGC and EC on Na(+)/K(+)-ATPase. On NHE the inhibition of tea catechins was in the order: EC>EGC>ECG>EGCG at concentrations up to 10 micromol/l.
This data may help to explain the anti-carcinogenic and cardioprotective effects of tea catechins. The effect of tea catechins on Na(+)/K(+)-ATPase and NHE may be explained due to a direct effect of these compounds on plasma membrane leading to a change in membrane fluidity.
茶儿茶素（表没食子儿茶素没食子酸酯、表儿茶素、儿茶素没食子酸酯和儿茶素）具有许多重要的生物学特性。我们评估了茶儿茶素对正常（对照）和非胰岛素依赖型糖尿病（NIDDM）受试者红细胞膜钠钾ATP酶和钠氢交换体（NHE）活性的影响。
测定正常人和非胰岛素依赖型糖尿病（NIDDM）患者红细胞膜钠钾ATP酶和NHE活性。在测定钠钾ATP酶/NHE活性之前，通过在测定培养基中孵育膜/完整红细胞来研究茶儿茶素的体外作用。
与正常人相比，NIDDM受试者的钠钾ATP酶活性降低了24.2%（p<0.001），NHE活性增加了39.37%（p<0.02）。茶儿茶素抑制正常和NIDDM红细胞中钠钾ATP酶和NHE的活性，其作用呈浓度依赖性。与表儿茶素和儿茶素相比，微摩尔浓度的表没食子儿茶素没食子酸酯和儿茶素没食子酸酯对钠钾ATP酶的抑制作用更强。在浓度高达10微摩尔/升时，茶儿茶素对NHE的抑制作用顺序为：儿茶素>表儿茶素>儿茶素没食子酸酯>表没食子儿茶素没食子酸酯。
这些数据可能有助于解释茶儿茶素的抗癌和心脏保护作用。茶儿茶素对钠钾ATP酶和NHE的作用可能是由于这些化合物对质膜的直接作用导致膜流动性改变所致。
