NA+ H+ ANTIPORTER PROPERTIES IN PERIPHERAL-BLOOD LYMPHOCYTES FROM NORMOTENSIVE OBESE AND TYPE-2 DIABETIC-PATIENTS DO NOT DIFFER SIGNIFICANTLY FROM CONTROLS/

It has been hypothesized that some genetic factors link different cond itions characterized by the presence of insulin resistance: among them , obesity, type 2 (non-insulin-dependent) diabetes mellitus and arteri al hypertension. A good candidate could be the Na+/H+ exchanger, the i ncreased activity of which is considered a genetic marker of essential hypertension. In this study we looked at whether the Na+ dependence o f the Na+/H+ antiporter is modified in obese and type 2 diabetic patie nts, in the absence of arterial hypertension. The activity of this ion exchanger was measured in peripheral blood lymphocytes by acidifying them in Na+-free buffer and then monitoring the recovery of intracellu lar pH after Na+ addition. Quiescent lymphocytes were used because the y do not have insulin receptors, thus ruling out the effects of the el evated insulin concentrations on the Na+/H+ exchanger activity. Antipo rt activity, measured as the ability to extrude H+ in the presence of external Na+, showed no differences in normotensive obese and type 2 d iabetic patients when compared with healthy subjects. Our data therefo re suggest that an altered Na+/H+ exchange activity cannot be consider ed a common feature of insulin-resistant states.