Hypoglycemia and Autonomic Nervous System Function- B2

Participants are admitted for two days and two nights to an inpatient clinical research center for performance of study procedures. On Day 1, two hyperinsulinemic hypoglycemic (50 mg/dl) clamps are performed - an AM clamp from about 9 to 11 am and a PM clamp from about 1 to 3 pm.. Modified Oxford procedures are performed in duplicate at five time points -- before the AM clamp, during the AM clamp, before the PM clamp, during the PM clamp, and the morning of Day 2 (about 16 hrs after completion of the the PM clamp). The Modified Oxford procedure involves the sequential intravenous administration of nitroprusside and phenylephrine with assessment of blood pressure and heart rate by finapress. Baroreflex sensitivity is the relationship of changes in heart rate to changes in blood pressure. .