Serum Insulin, Insulin Sensitivity, and Erythrocyte Sodium Metabolism in Normotensive and Essential Hypertensive Subjects with and Without Overweight

Increased insulin circulating levels and perturbations of intracellular sodium metabolism have been reported in essential hypertensive patients, leading to postulate their involvement in the pathophysiology of the disease. In-vitro studies have shown that insulin modulates the activity of some transmembrane sodium transporters. The aim of this investigation was to assess in subjects with essential hypertension and/or overweight, the levels of fasting serum insulin, the activity of sodium transporters and their possible relationships. In 18 lean normotensive, 12 overweight normotensive, 18 untreated lean essential hypertensive, and 16 untreated overweight essential hypertensive subjects, we measured the fasting levels of blood glucose and serum insulin, and calculated the glucose/insulin ratio as an index of sensitivity to insulin. In addition, in the red blood cells of these subjects, we evaluated the maximal rate of ouabain-sensitive Na/K pump, furosemide-sensitive outward Na/K cotransport, Nai/Lio count...