Effect of leukocyte depletion on the function of the postobstructed kidney in the rat.

We have observed an influx of leukocytes, predominantly macrophages, into the cortex and medulla of the kidney following ureteral obstruction. To examine the potential contribution of these infiltrating cells to the decrease in GFR and RPF that occurs following ureteral obstruction, 16 male Lewis rats (wt 246.4 +/- 4.0 g) were studied in the awake state three hours after unilateral release of 24 hours of bilateral ureteral obstruction (BUO). Eight rats were not irradiated, and eight rats received 1315 rads one day prior to the obstruction. The leukocyte infiltrate following 24 hours of ureteral obstruction was quantified with and without prior irradiation in an additional eight rats. Irradiation reduced cortical infiltration (27.05 +/- 3.07 x 10(5) vs. 1.2 +/- 0.83 x 10(5) cells/g tissue) and medullary infiltration (13.6 +/- 1.79 x 10(5) vs. 0.86 +/- 0.45 x 10(5) cells/g tissue) of leukocytes following BUO (P less than 0.001 for both) and increased postobstruction GFR (1.58 +/- 0.12 vs. 2.97 +/- 0.15 ml/min/kg body wt, P less than 0.001). Eleven rats, six of which received irradiation, underwent sham laparotomy without BUO in order to assess the effect of irradiation alone on renal function. Irradiation had no effect on the renal function of non-obstructed rats. Urinary excretion of thromboxane B2 increased following BUO and this rise was significantly blunted by irradiation prior to BUO (9.53 +/- 2.14 vs. 32.46 +/- 4.95 vs. 19.03 +/- 1.94 pg/min). Fractional excretion of sodium and water was reduced by irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)