The effect of insulin on Na+-H+ antiport activity of obese and normal subjects erythrocytes

Background/Aims: The exact mechanism that links insulin resistance and vasc ular disease remains unknown. A significantly increased Na+-H+ exchanger (N HE 1) activity and a different effect of insulin on obese individuals eryth rocyte NHE 1 has been suggested. These observations may provide a link betw een obesity, hyperinsulinemia and vascular disease. Methods: The intracellu lar pH and sodium influx were measured before and after addition of insulin in erythrocyte suspensions from normal and obese individuals. Amiloride, a specific NHE 1 inhibitor, and staurosporine a protein kinase C inhibitor w ere used to inhibit erythrocyte NHE 1. Results: Erythrocytes from normal individuals showed increased pH and incre ased sodium influx after insulin stimulation. This effect of insulin was in hibited by amiloride and by staurosporine as well. In contrast insulin had no effect on NHE 1 activity of erythrocytes from obese individuals. Conclusion: These ex vivo data indicate that erythrocyte NHE 1 activity in obese individuals is "insulin resistant". Erythrocytes may provide a simple system for the study of insulin resistance pathways in obesity. Copyright (C) 2001 S. Karger AG, Basel.