Growth of rats' kidneys after unilateral uretero‐caval anastomosis.

Abstract

SUMMARY1. The relative significance of reduced excretion of urinary constituents and reduced renal mass, as stimuli to growth of one kidney after the other has been removed, has been investigated.2. To abolish the excretory function of one kidney without removing it, the right ureter was drained into the vena cava through a compound cannula for 6 weeks. Uretero-caval anastomoses, were performed in twenty-four male rats at 10 weeks of age: six survived without evidence of ureteric obstruction (and a further five with minimal obstruction).3. The rats with anastomoses. grew less than six other rats from which the right kidney had been removed or six which had been submitted to a sham operation, and their plasma urea and creatinine concentrations were higher.4. Relative to body weight, the dry weight of each kidney after ureterocaval anastomosis. without obstruction was 18 % greater than after sham operation; taking both kidneys together, the total increase was almost as much as in the left kidney alone after right nephrectomy (46%).5. Histologically and in terms of DNA concentration, the growth of both kidneys after uretero-caval anastomosis was of the same kind as in the left kidney after right nephrectomy.6. The return of urine from one kidney into the blood provided a powerful stimulus to renal growth in spite of the restraining effect of increased renal mass.

Compensatory Growth and Other Growth Responses of the Kidney

“…This doubling of the load has no effect on the size of either organ or on DN A synthesis [458] or Na/K-ATPase concentration [150]. The experiments are difficult since partial, low-grade ob struction of the diverted ureter apparently can impair function sufficiently to initiate slow contralateral growth [353], while peritonitis associated with diversion may prolong the growth-inhibitory effect of anorexia [429], The results of chronic urine reinfusion experiments pres ent an inexplicable contradiction to the unilateral diver sion and ligation studies. No obvious differences are evident between internal and external recirculation of urine.…”

“…Unilateral ureteral ligation, abruptly eliminating the function of one kidney, resulted in contralateral hypertrophy which was initially much slower than that following UNX and indicated that lost renal mass per se was at least partially responsible for growth. Return to the body of the output of one kidney in rats and dogs by way of ureteral diversion to duodenum [53,54], peritoneal space [73,150,154,264,336,458,472,500] or vena cava [145,353] also is the functional equiva lent of ureteral ligation or UNX. This doubling of the load has no effect on the size of either organ or on DN A synthesis [458] or Na/K-ATPase concentration [150].…”

“…Increased contralateral kidney growth begins almost immediately following the ligation [46,129,220,336,353,357,386], Mitotic activity peaks at 48 h but is half that of the ligated kidney [187], The pattern of growth up to 2 weeks resembles that following UNX, a principal difference being that the increases in weight during the first 2 or 3 weeks are about half as great [129,336]. The increases in RNA and DNA also are less than in the ligated kidney [46,129,357], While growth subsides and regresses in the ligated it continues in the contralateral with the result that by 24-42 days after ligation weight, total protein and RNA and DNA contents are close to those expected after UNX [336, 353,386].…”

Presence of renotrophic factor in plasma of unilaterally nephrectomized rats.

“…Though the role of a humoral factor in the mechanism of compensatory renal growth appears to be well established and though the compensatory hypertrophy has been repeatedly shown to occur independently from changes in renal function (Katz, 1970;Katz, Toback & Lindheimer, 1976 Obertop & Malt, 1977), the possibility that the early adaptation of the remaining kidney may play a contributory role in the onset of renal hypertrophy cannot definitely be ruled out (G. C. R. Morris, 1976).…”