Phenylephrine and Pulse Pressure Variability

Inclusion Criteria: * 18 to 45 years of age * Non-obese (Body Mass Index less than 30 kg/m2) * Baseline systolic blood pressure between 80-140 mmHg * Baseline diastolic blood pressure \<90 mmHg Exclusion Criteria: * Participants who have cardiac, vascular, respiratory, neurological and/or metabolic illness * Current or previous use of anti-hypertensive medications * Any known history of renal or hepatic insufficiency/disease * Pregnancy (verified by negative urine test on the experimental days) or breast-feeding * Current smokers, as well as individuals who regularly smoked within the past 3 years * Sulfite allergy, as this is a contraindication to intravenous phenylephrine * Serious mental illness including claustrophobia * History of use of recreational drugs including cocaine or amphetamines * Peripheral vascular disease * Subject on anticoagulant treatment * Subjects with a baseline systolic blood pressure \<80 mmHg