Preserved Relative Dispersion but Blunted Stimulation of Mean Flow, Absolute Dispersion, and Blood Volume by Insulin in Skeletal Muscle of Patients With Essential Hypertension

Abstract
Background —We examined the integrity of the effects of insulin on mean muscle blood flow, flow heterogeneity, and blood volume in essential hypertension. Methods and Results —Positron emission tomography, combined with [ 15 O]H 2 O and [ 15 O]CO as tracers for direct measurement of blood flow and volume in skeletal muscle, and a new bayesian iterative reconstruction algorithm allowing pixel-by-pixel quantitation of blood flow and flow dispersion, were used. Measurements were performed basally after an overnight fast and under normoglycemic hyperinsulinemic conditions in 11 newly diagnosed, untreated mildly hypertensive men (age, 35±1 years; body mass index, 25.2±0.4 kg/m 2 , blood pressure 141±4/96±2 mm Hg, mean±SE) and 11 matched normotensive men. Insulin-stimulated whole body glucose uptake was significantly decreased in the hypertensive men (41±4 μmol/kg per minute) compared with the normotensive (59±4 μmol/kg per minute, P P P P P P P P Conclusions —True flow heterogeneity, as judged from the coefficients of variation (relative dispersion), was comparable between the groups basally and during hyperinsulinemia. We conclude that mean flow, its absolute dispersion, and blood volume exhibit insulin resistance in patients with essential hypertension.