Renal function in normal and kidney traumatized germfree rats

A comparative study was made between kidney-traumatized (unilateral nephrectomy, contralateral ligation of renal artery, and release after 120 min) germfree (GF) and conventional (CONV) rats, and normal control GF and CONV rats. In the kidney-traumatized animals the following trends were indicated. (i) Deaths in 3 to 5 days occurred approximately 25% of the time in GF and 60% in the CONV groups. (ii) Two to 4 days post-operation the renal blood flow was essentially unchanged in GF in comparison to normal controls, while it was 30% of the normal values in CONV rats. (iii) Blood urea nitrogen was approximately 4 times the normal values in GF and 28 times in CONV animals. (iv) The ratio of urine and blood plasma osmolality indicated that the concentrating ability of the kidneys was well maintained in GF while it was virtually lost in CONV traumatized rats. (v) The clearance of intravenously administered, labelled thiourea into the urine and caecal lumen of GF rats was markedly elevated in comparison to the low clearance of this label in CONV rats. No essential differences in kidney function were noted among normal (unoperated or sham-operated) GF and CONV groups. The results indicate that the absence of the intestinal flora is advantageous to the host. This effect might be caused by relief from microbial burden and by the enlarged caecum of GF rats acting as an auxiliary "dialysis membrane". Based on these data the role of oral antibiotic treatment in the management of human uraemia is worth investigating.