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 conditions characterized by the presence of insulin resistance: among them, obesity, type 2 (non-insulin-dependent) diabetes mellitus and arterial hypertension. A good candidate could be the Na⁺/H⁺ exchanger, the increased activity of which is considered a genetic marker of essential hypertension. In this study we looked at whether the Na⁺ dependence of the Na⁺/H⁺ antiporter is modified in obese and type 2 diabetic patients, 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 intracellular pH after Na⁺ addition. Quiescent lymphocytes were used because they do not have insulin receptors, thus ruling out the effects of the elevated insulin concentrations on the Na⁺/H⁺ exchanger activity. Antiport activity, measured as the ability to extrude H⁺ in the presence of external Na⁺, showed no differences in normotensive obese and type 2 diabetic patients when compared with healthy subjects. Our data therefore suggest that an altered Na⁺/H⁺ exchange activity cannot be considered a common feature of insulin-resistant states.