Effect of Alkali Therapy on Vascular and Graft Function in Kidney Transplant Recipients

Inclusion Criteria: * Age 18-80 years * Serum bicarbonate 16-24 mEq/L on 2 separate measurements (at least 1 day apart) * Kidney transplant received 1 year prior to randomization * eGFR ≥ 45 ml/min/1.73m2 by CKD-EPI equation * Blood pressure \<130/80 mm Hg prior to randomization * BMI \< 40 kg/m2 (FMD measurements can be inaccurate in severely obese patients). * Able to provide consent * Immunosuppression regimen consisting of tacrolimus, mycophenolate mofetil and prednisone (95% of patients at University of Colorado are on this regimen) * Stable immunosuppression regimen for at least three months 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 * Nephrotic range proteinuria (urine complement activation fragment measurements may not be accurate with severe proteinuria) * 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 * Use of anticoagulants