Non-renin dependent hypertension in renal allograft rejections. A structural and functional analysis

A 25-year-old recipient of a cadaveric renal allograft underwent three acute rejection episodes within the first 40 days after transplant, the final episode necessitating nephrectomy. The saralasin acetate infusion test and plasma renin activity (as measured by radioimmunoassay of angiotensin I) were used as functional tests of the renin-angiotensin axis. Biopsy specimens of the allograft one hour after implantation and sections of the nephrectomy specimen were fixed and stained with hematoxylin-eosin for structural analysis. On three separate dates, during the final rejection episode, saralasin acetate infusion of up to 20 micrograms/kg/min failed to lower BP significantly. The final two trials were preceded by furosemide administration the previous day to reduce fluid volume. Plasma renin activity was low on all three dates. On nephrectomy, the allograft was noted grossly to be infarcted. Histologic examination revealed cortical necrosis, markedly narrowed or occluded intrarenal vessels, and extremely narrowed large vessels within the renal pelvis. The allograft renal artery was thickened and narrowed. From our structural and functional analysis we conclude that (1) hypertension, in this case, was probably volume dependent and was clearly renin independent; and (2) the low renin levels are explainable on the basis of extensive vascular occlusion producing renal infarction and resulting in a kidney incapable of producing significant amounts of renin (autonephrectomy).