It is the purpose of this study to 1) determine the distribution of TxA2 synthase within the kidneys of patients with chronic transplant rejection, 2) determine whether over-production of TxA2 restrains renal blood flow and glomerular filtration rate and electrolyte excretion, and maintains elevated levels of blood pressure in patients with chronic renal transplant rejection, and 3) characterize the pharmacokinetics of cyclosporine in the presence of aspirin and the pharmacodynamics of aspirin as a cyclooxygenase inhibitor.