Inclusion Criteria:

• * Men and women of all races and ethnicities
• * Capable of giving informed consent
• * Fluent in written and spoken English
• * Age 65-80 years
• * Body mass index (BMI) between 18.5 and 30 kg/m2
• * Normotensive defined as seated blood pressure \<130/80 mmHg and without hypertensive medications
• * Satisfactory history and physical exam

Exclusion Criteria:

• * Age \< 65 or \> 80 years
• * Women who are pregnant, nursing, or taking hormone replacement therapy
• * Decisional impairment
• * Prisoners
• * Current or recent (less than 6 months) recreational drug history or excessive alcohol abuse history (greater than 14 drinks per week)
• * Current smokers
• * Highly trained athletes
• * Evidence of type I or type II diabetes (fasting glucose \> 126 mg/dL or use of anti-diabetic medications)
• * Hypertension or history of serious cardiovascular disease (e.g., myocardial infarction within 6 months, symptomatic coronary artery disease, presence of angina pectoris, significant arrhythmia, congestive heart failure, deep vein thrombosis, pulmonary embolism, second or third degree heart block, mitral valve stenosis, aortic stenosis, hypertrophic cardiomyopathy) or cerebrovascular disease (e.g., cerebral hemorrhage, stroke, transient ischemic attack).
• * History or presence of immunological or hematological disorders
• * Impaired hepatic function \[aspartate aminotransferase (AST) or alanine aminotransferase (ALT) levels \>2 times upper limit of normal range\]
• * Impaired renal function (serum creatinine \>2.0 mg/dl)
• * Anemia
• * Taking drugs known to influence sympathetic activity (e.g. serotonin-norepinephrine reuptake inhibitors, norepinephrine transporter inhibitors, stimulants).
• * Treatment with anticoagulants (e.g. warfarin)
• * Treatment with chronic systemic glucocorticoid therapy (\>7 consecutive days in 1 month in the 1-month preceding the study)
• * Treatment with any investigational drug in the 1-month preceding the study
• * Known allergy or contraindication to angiotensin converting enzyme inhibitors or angiotensin receptor blockers, both of which increase endogenous angiotensin-(1-7) levels as part of their mechanism of action
• * Inability to give, or withdraw, informed consent