Impairment of sodium pump and Na/H exchanger in erythrocytes from non-insulin dependent diabetes mellitus patients: effect of tea catechins.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Rizvi
Syed Ibrahim
SI
Department of Biochemistry, University of Allahabad, Allahabad - 211 002, India.
Zaid
Mohammad Abu
MA
D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000209:etiology; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015394:Molecular Structure; D017923:Sodium-Hydrogen Exchangers / Q000187:drug effects / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013662:Tea / Q000737:chemistry*
D017923:Sodium-Hydrogen Exchangers; D013662:Tea; D002392:Catechin; D000254:Sodium-Potassium-Exchanging ATPase