Effects of magnesium and nifedipine infusions on insulin action, substrate oxidation, and blood pressure in aged hypertensive patients.

Eight aged (70.1±2.1 years), nonobese (body mass index [BMI]=26.3±0.4), hypertensive (systolic blood pressure [SBP]=184±4.1; diastolic blood pressure [DBP]=105±2.4 mm Hg) subjects underwent a euglycemic hyperinsulinemic (7.1 pmol/ kg×min during 240 min) glucose clamp with four different infusions: a) 0.9% NaCl; b) 1.0 μg/kg×min nifedipine; c) 100 μmol/min magnesium; d) 1.0 μg/kg×min nifedipine plus 100 μmol/min magnesium. All tests were performed in random order. Simultaneous D-3-H glucose infusion and indirect calorimetry allowed us to determine glucose turnover parameters and substrate oxidation