The functional state of the isolated rabbit kidney perfused with autologous blood

This report describes the technique and procedure for perfusing an isolated rabbit kidney with 25 ml heparinized autologous blood in a closed circuit including a pump and an oxygenator. The duration of the operative ischaemia was 5-8 min; the perfusion lasted 2.5 hours. An additional infusion was ma de to compensate for urinary losses. Renal blood flow increased progressive ly from 2.01+/-0.1 to 2.65+/-0.22* ml/g kidney weight (kw) per min (*P<0.05 ). Between the first (P1) and the last (P4) urine collection period the glo merular filtration rate (GFR) fell from 288+/-25 to 217+/- 38* mu l/g kw pe r min, urine flow from 5.58+/-1.13 to 4.91+/-0.75 mu l/g kw per min, Na+ ex cretion from 1.07+/-0.19 to 0.63+/-0.12* mu mol/g kw per min, K+ excretion from 0.46+/-0.03 to 0.28+/-0.05* mu mol/g kw per min, P excretion from 2.5/-0.2 to 2.0+/-0.5 mu g/g kw per min, Ca excretion from 0.4+/-0.1 to 0.12+/ -0.05* mu g/g kw per min, creatinine excretion from 6.94+/-0.32 to 5.68+/-0 .54 mu g/g kw per min, glucose excretion from 18.2+/-3.2 to 1.6+/-0.5* mu g /g kw per min, the free water clearance (CH2O) from -6.57+/-0.85 to -5.10+/ -1.31 mu l/g kw per min and urine osmolality from 600+/-52 to 590+/-105 mOs m/kg, urea excretion from 0.75+/-0.16 to 0.95+/-0.13 mu mol/g kw per min. E xcretion of glucose, P or Ca was observed only above a given plasma thresho ld value, and no transport maximum was found for glucose or P. Ca reabsorpt ion paralleled the Na reabsorption. The proximal tubule pressure, measured within the 1st h of perfusion, was 12.5+/-1.1 mm Hg. Histological examinati on at the end of the perfusion showed dilatation of the tubules as in the n on-perfused kidneys, and the presence of numerous bacteria. Hypertonic urin e (380-1110 mOsm/kg) was observed in the presence of vasopressin, in the la tter's absence the urine was hypotonic urine (206-278 mOsm/kg). There was n o correlation between renal plasma now and the GFR. CH2O increased with inc reasing filtered Na+ load. In conclusion, the blood-perfused, isolated rabb it kidney has a fairly constant functional capacity for approximately 2 h.