Bicarbonate Administration in Kidney Transplant Recipients

Inclusion Criteria: * Age ≥ 18 years * Kidney transplant received at least 1 year ago * Serum bicarbonate 20-26 mEq/L on 2 separate measurements (at least 1 day apart) * eGFR \>45 ml/min/1.73m2 * Blood pressure \<140/90 mm Hg prior to randomization * BMI \< 40 kg/m2 (FMD measurements can be inaccurate in severely obese patients). * Able to provide consent * Stable kidney transplant medication regimen for at least 1 month prior to randomization * Stable anti-hypertensive regimen for at least one month prior to randomization * Not taking medications that interact with agents administered during experimental sessions (e.g. sildenafil interacts with nitroglycerin). Exclusion Criteria: * Significant comorbid conditions that lead the investigator to conclude that life expectancy is less than 1 year * Use of chronic daily oral alkali within the last 3 months (including sodium bicarbonate, calcium carbonate or baking soda) * Uncontrolled hypertension * Serum potassium \< 3.3 or ≥ 5.5 mEq/L at screening * New York Heart Association Class 3 or 4 heart failure symptoms, known EF ≤30%, or hospital admission for heart failure within the past 3 months · Factors judged to limit adherence to interventions * Current participation in another research study * Pregnancy or planning to become pregnant or currently breastfeeding * Chronic use of supplemental oxygen