Impact of Dopamine Infusion on Insulin Secretion in Healthy Subjects

Each subject will receive a priming dose of dextrose 20% to increase their glucose concentration by 125 mg/dl in the first 15 minutes. Then they will receive variable rates of dextrose 20% infusion to maintain glucose level at 180-220 mg/dl. Then, dopamine (200mg/250ml) will be titrated up to 5 mcg/kg/min with care not to increase blood pressure greater than 160 systolic. Dopamine will be infused for 3 hours.