Inclusion Criteria:  Aged 50 years or older; women must be post-menopausal Chronic kidney disease stage 3 or 4 (estimated glomerular filtration rate with the 4-variable MDRD prediction equation: 20-59 mL/min/1.73m^2; stable renal function in the past 3 months) History of inadequately controlled hypertension (systolic blood pressure 130-159 mmHg on two separate days) and on a stable antihypertensive regimen for the past 3 months Weight stable in the prior 3 months (<2 kg weight change) and willing to remain weight stable throughout the study Ability to provide informed consent  Exclusion Criteria:  Patients with advanced chronic kidney disease requiring chronic dialysis Significant pulmonary disorders including: chronic obstructive pulmonary disease, interstitial lung disease, cystic fibrosis, or uncontrolled asthma Significant co-morbid conditions with a life expectancy of < 1 year History of severe congestive heart failure (i.e., ejection fraction <35%) History of hospitalization within the last month Proteinuria > 5 g/day Current smoker Immunosuppressant agents taken in the past 12 months Known malignancy Inability to cooperate with or clinical contraindication for magnetic resonance imaging including: severe claustrophobia, implants, devices, or non-removable body piercings