Effects of insulin and atrial natriuretic peptide on renal tubular sodium handling in sickle cell disease

We assessed the effect of insulin and atrial natriuretic peptide (ANP) on renal sodium handling in eight patients with sickle cell disease (SCD), who are characterized by loss of vasa recta and long loops of Henle, and matched control subjects. During insulin infusion (50 mU.kg(-1).h(-1)), fractional sodium excretion decreased by 0.44 +/- 0.72% (P = 0.13) in patients with SCD and by 0.57 +/- 0.34% (P = 0.002) in control;subjects, whereas fractional distal sodium reabsorption increased by 4.1 +/- 1.5% (P <0.001) and 3.0 +/- 1.5% (

Effects of insulin on glucose uptake and leg blood flow in patients with sickle cell disease and normal subjects

The hemodynamic concept of insulin resistance assumes that vasodilatory effects of insulin determine glucose uptake. Sickle cell disease (SCD) is characterized by microangiopathy and microvascular occlusion. Therefore, we hypothesized that patients with SCD have a reduced insulin-mediated glucose uptake. In 8 patients with SCD and 8 matched normal controls, we studied the effects of a 4-hour insulin infusion (50 mU/kg/h) on glucose uptake and leg blood flow (LBF) using the euglycemic clamp technique and venous occlusion plethysmography. Time-control experiments were performed in the same subjects. Insulin-mediated glucose uptake (M value, mg/kg/min) did not differ between patients with SCD and control subjects during the second (6.3 +/- 4.6 and 7.6 +/- 2.6, P = .5), third (7.5 +/- 4.6 and 9.3 +/- 3.4, P = .4) and fourth hour (8.6 +/- 4.7 and 11.0 +/- 2.9, P = .2) of the clamp. At baseline, LBF was higher in the patients with SCD than in the controls (3.28 +/- 1.68 and 1.37 +/- 0.47 mL/min/dL, respectively; P = .005). Insulin-induced increases in LBF in patients with SCD and in normal subjects were not different (P = .9). Respectively, 56% and 24% of the changes in glucose uptake could be explained from changes in LBF in the course of the insulin infusion in the patients with SCD and controls. We suppose that the comparable insulin sensitivity between both groups is due to a compensatory hemodynamic state in SCD characterized by vasodilation and increased flow. Copyright (C) 2001 by W.B. Saunders Company