Stenotic glomerulotubular necks in radiation nephropathy.

Fibrosis of the renal interstitium is well correlated with kidney function and a greater extent of fibrosis predicts renal failure. Recent work has shown striking fibrotic constrictions at the glomerulotubular neck in porcine radiation nephropathy and in Wegener's granulomatosis in man. The present studies were designed to identify stenotic necks in a third species and to evaluate the effect of captopril treatment. Experimental radiation nephropathy was established with 17 Gy total body irradiation of barrier-maintained rats. Kidneys were obtained at 99 and 203 days for histology, using perfusion fixation. There was renal injury, with a rise in BUN, as expected, which was attenuated by captopril treatment. There was stenotic neck formation at 99 and 203 days. Captopril did not influence the absolute fraction of necks that were stenotic but it did prevent the evolution of glomeruli with necks to atubular glomeruli. It is concluded that stenosis of the glomerulotubular neck is a general phenomenon of any scarring kidney disease; that stenotic necks are probably an intermediate step in the evolution towards atubular glomeruli; and that timely use of captopril may prevent the progression of a stenotic neck towards an atubular glomerulus.