The successful transplantation of a human kidney between 24-year-old male identical twins has made possible the study of the function of a homotransplanted kidney. The purposes of the study were twofold: 1) to evaluate the functional capacity of the transplanted kidney; 2) more specifically, to investigate the capacity of a transplanted, and therefore totally denervated, kidney to regulate renal hemodynamics and electrolyte and water excretion.Studies were performed on both the recipient (R) and the donor (D). All but one of the experiments on R were performed after his own two kidneys had been surgically removed; thus, the majority of the data obtained specifically de- Association.preliminary study, during which time the twins were shown to be identical, D's left kidney was transplanted retroperitoneally into the right iliac fossa of R. End to end anastomoses were effected between the renal artery of the transplanted organ and the recipient's right hypogastric artery and between the renal vein and the right common iliac vein. The ureter was implanted directly into the urinary bladder. Clinical improvement began in the immediate postoperative period and continued until all the apparent stigmata of both uremia and hypertension regressed. Bilateral nephrectomy was performed in a two-stage procedure at three and at five and one-half months following transplantation, leaving R with only the transplanted organ. To date he has enjoyed over a year of total well being on an unrestricted regimen. Detailed accounts of the clinical course and operative procedure have been previously described (1).
ProcedureTwenty-three clearance studies and several miscellaneous experiments were performed over an eighteen-month period. Control studies were obtained on D prior to transplantation. The majority of observations on R was made during a four-month interval beginning six months after transplantation.Except where indicated, all studies were performed in the morning with the subjects postprandial and recumbent. In ten studies (six on R and four on D) glomerular filtration rate (GFR) was measured by the clearance of inulin (C,3) using standard renal clearance techniques as previously described (2). In nine of these ten studies, effective renal plasma flow (ERPF) was measured by the clearance of p-aminohippurate (ClAN). In six of the studies in which C,3 was measured, urine was collected through an inlying soft rubber multiholed catheter, and urine collection periods (15 to 20 minutes in duration) were concluded with two washouts of distilled water and two or more injections of air. In the control and early postoperative studies on D and the postoperative (left nephrectomy) and osmotic diuresis studies on R, bladder catheterization was not performed.In an additional ten studies (six on R and four on D) endogenous creatinine clearance (Cc,) was employed to estimate trends in GFR. These studies were carried out using voided specimens. In the majority of individual 1364