Insulin Effect on Renal Sodium Reabsorption in Adolescent Offspring of Essential Hypertensive Parents

Abstract We previously showed that children and adolescent offspring of patients with essential hypertension have an increased proximal renal sodium reabsorption as measured by lithium fractional excretion. Insulin has been shown to have antinatriuretic properties and to be increased (hyperinsulinemia) in essential hypertension. The aim of this study was to evaluate the role of insulin on the increased proximal renal sodium reabsorption previously reported. Lithium and sodium fractional excretions were measured 3 hours before and 3 hours after an intravenous glucose tolerance test in 20 normotensive adolescents with a family history of essential hypertension (F+, 14.8±0.5 years) and 10 normotensive control subjects without a family history of hypertension (F−, 15.2±0.9 years). Results are mean±SEM. Lithium fractional excretion before glucose loading was 16.1±1.8% in F+ versus 23.5±2.0% in F− ( P P =NS). Lithium fractional excretion did not change after intravenous glucose loading in either group. The insulin area under the curve was 2815±499 in F+ versus 2290±418 μU/mL per hour in F− ( P =NS). There was no correlation between lithium fractional excretion and insulin area under the curve. Fractional excretion of sodium before glucose loading was 0.99±0.1% in F+ versus 0.99±0.1% in F− ( P =NS) and after glucose loading was 0.77±0.1 in F+ versus 0.85+0.1% in F− ( P