RADIATION-INDUCED CHANGES IN GLOMERULAR AND TUBULAR CELL-KINETICS ANDMORPHOLOGY FOLLOWING IRRADIATION OF A SINGLE KIDNEY IN THE PIG

Purpose: Radiation-induced changes in glomerular and tubular cell kine tics and morphology following irradiation of a single pig kidney were assessed. Methods and Materials: The right kidney of 13 adult female L arge White pigs was irradiated with a single dose of 9.8 Gy gamma rays , Animals were serially killed between 2 and 24 weeks postirradiation (PI); 1 h prior to postmortem each pig received 500 mg bromodeoxyuridi ne (BrdUrd), At postmortem, both kidneys were removed and tissue taken to prepare cell suspensions, The labeling index (LI) of these suspens ions was measured using flow cytometry; in vivo BrdUrd incorporation i n glomerular and tubular cells was determined immunohistochemically. T he kidneys were also assessed histologically. Results: Irradiation of the right kidney alone resulted in a significant increase in renal cel l LI in both the irradiated and the contralateral unirradiated kidney within 2 weeks of irradiation; peak values of 1.57 +/- 0.32% and 1.04 +/- 0.13%, respectively, were seen 4 weeks PI, significantly greater ( p < 0.001) than the preirradiation value of 0.18 +/- 0.01%. The LI val ues then declined with time, but remained greater than those seen prio r to irradiation, A similar pattern of response was determined from co unts of labeled glomerular and tubular cells identified immunohistoche mically. The increase in labeled glomerular cells was seen 2 weeks PI, whereas that for the tubular cells did not occur until 4 weeks PI, Th e irradiated kidney exhibited diffuse, progressive glomerular alterati ons, In contrast, tubular damage was focal; the irradiated kidney also exhibited a prominent vasculopathy, involving arteriolar and peripher al interlobular artery thickening, The contralateral unirradiated kidn ey appeared unchanged. Conclusion: These findings confirm the hypothes is that the morphologic and kinetic responses observed after irradiati on of a single kidney are similar to those observed after irradiation of both kidneys, Renal irradiation results in significant alterations in glomerular and tubular cell proliferation and morphology within 2-4 weeks of irradiation; glomerular changes appear predominant.