MODULATION OF ERYTHROCYTE-MEMBRANE NA K-ATPASE ACTIVITY BY INSULIN INNORMAL AND TYPE-2 DIABETIC-PATIENTS - EVALUATION OF THE INSULIN-LIKE ROLE OF (-)EPICATECHIN/

An altered activity of erythrocyte membrane Na/K-ATPase has been repor ted in type 1 (insulin-dependent) and type 2 (non-insulin dependent) d iabetic condition. The present work deals with the study of the modula tion of red cell Na/K-ATPase activity by insulin in control and type 2 diabetic patients. We tried to evaluate the insulin-like role of (-)e picatechin, a benzopyran extracted from the bark of Pterocarpus marsup ium, traditionally used in Indian folk medicine for the treatment of d iabetes, on Na/K-ATPase. We report that (-)epicatechin inhibits Na/K-A TPase activity in both normal human and type 2 diabetic patient erythr ocytes, an effect which is similar to that of insulin. Insulin gives a typical dose responsive effect on Na/K-ATPase activity. The highest i nhibition of enzyme activity occurs at a 10(-9) M hormone concentratio n, with a lesser effect at higher and lower insulin concentrations. No dose responsive effect occurred with (-)epicatechin. Further work is needed to elucidate the mechanism of the insulin-like effect of (-)epi catechin on erythrocytes. (C) 1998 Lippincott-Raven Publishers.