RENAL-FUNCTION REMAINS AFTER UNILATERAL TOTAL AND CONTRALATERAL PARTIAL NEPHRECTOMY - AN EXPERIMENTAL-STUDY IN PIGS USING TC-99M-DTPA

Twelve nephrectomies (NEs) were performed in 12 pigs (11-17 kg). Total NE was performed on the left side and partial NE on the right side (l ower third of the kidney), thus two-thirds of the total kidney volume was removed. Renal function was studied;with Tc-99m-diethylenetriamine pentaacetic acid (DTPA) renography and serum urea and creatinine level s preoperatively, and 1 and 2 weeks postoperatively. The pigs were ima ged in each session for 30 min by collecting 10-s frames from a poster oanterior (PA) view of an anaesthesized animal. The injected activity was 37 MBq. Serial blood samples were taken from the subclavian vein a t 0, 1, 2, 3, 5, 15, 25, 40, 60 and 120 min (six animals) after Tc-99m -DTPA injection. The DTPA disappearance rate (DDR) was determined from these samples and in other cases (six animals) a blood sample at 20 m in was used. The DDR was also determined from the dynamic gamma imagin g data: Regions of interest (ROI) were upper body, spleen, heart and k idneys. The ROI analysis correlated well with the blood sampling data (r = 0.97, P < 0.0001). The reference values for pig DDRs were 0.99 +/ - 0.08%/min. These values were 0.71 +/- 0.08%/min at 1 week postoperat ively and 0.63 +/- 0.08%/min at 2 weeks. DTPA clearance rates were pre operatively 0.53 +/- 0.06 ml/s; at 1 week postoperatively 0.41 +/- 0.0 6 ml/s; and at 2 weeks 0.35 +/- 0.06 ml/s. There were no significant d ifferences pre- and postoperatively in creatinine and urea concentrati ons. The DTPA clearance (ml/s) and disappearance rates (%/min) when de termined per kidney area (cm(2)) increased significantly (P < 0.001 at both 1 and 2 weeks); in II of 12 animals the function of the resected right kidney was higher than the split function of the whole right ki dney preoperatively. Unilateral nephrectomy initiates a functional ada ptation or a growth response in the contralateral kidney to compensate for the loss of a renal mass. These data also indicate that two-third s of the kidney volume in young pigs can be removed without danger.