Glomerular capillary pressures in long-surviving rat renal allografts.

Many renal transplants undergo gradual deterioration in structure and function in the months or years after transplantation. The processes that underlie this progressive decline have not been defined, and may include immunological and nonimmunological mechanisms. The present experiments were designed to investigate the glomerular capillary hydrostatic pressure in long-surviving rat renal transplants with or without chronic rejection. Stop-flow glomerular pressures were measured in F344 renal allografts with chronic rejection, syngeneic F344 grafts, and long-surviving syngeneic and allogeneic LEW grafts without chronic rejection; control measurements were done in nontransplanted intact animals or after subtotal renal ablation. Renal ablation or transplantation resulted in increased glomerular pressure in F344 but not LEW kidneys; the glomerular pressure in syngeneic F344 grafts was not different from that in allogeneic F344 grafts. There was no correlation between the mean arterial pressure and the glomerular capillary pressure. Our data suggest that the glomerular capillary pressure is determined by local intrarenal factors. The glomerular capillary pressure in allotransplanted kidneys resembles that of the donor kidney after subtotal renal ablation. The importance of increased glomerular pressure in the progressive decline of graft function of chronic rejection remains to be established.