Examination of Growth-Mediated Changes in Hemodynamics and Tubular Transport of Sodium, Glucose and Hippurate after Nephrectomy

Abstract

BUGGE-ASPERHEIM, B. & KIIL, F. Examination of Growth-Mediated Changes in Hemodynamics and Tubular Transport of Sodium, Glucose and Hippurate after Nephrectomy. Scand. J. din. Lab. Invest. 22, 255-265, 1968.Mitotic activity in renal cortical tubules of dogs was not significantly different from controls after peritoneal drainage of one of the kidneys, but increased more than five-fold after nephrectomy. In order to examine which functional changes were growth-mediated, clearance studies were performed on four unanesthetized dogs under control conditions (stage I), in the 3-4 weeks after ureteroperitoneostomy of the left kidney (stage 11) and for a similar period after removal of the left kidney (stage Ill). Glomerular filtration rate (GFR) of the right kidney increased by an average of 50 per cent after ureteroperitoneostomy and did not change further after nephrectomy. Both during conditions of water diuresis and during loading with hypotonic saline, GFR, para-aminohippurate (PAH) clearance and tubular sodium reabsorption were as high in experiments performed after ureteroperitoneostomy as after nephrectomy. In contrast, tubular transport capacities of glucose (Tmc,) and para-aminohippurate (Tm,,,) of the right kidney did not rise during stage 11, whereas the increments in stage 111 were similar to those observed in two dogs directly subjected to nephrectomy. In two other dogs with half of the right kidney resected, Tm, and Tmp,,did not increase during stage I1 but increased rapidly in stage 111. It isconcluded that the increments in TmG and TmpA are growth-dependent, whereas the increments in GFR, PAH-clearance and tubular sodium reabsorption and the regulation of sodium excretion are not dependent on renal growth.

Compensatory Growth and Other Growth Responses of the Kidney

“…Glucose Tn" as a proximal tubular func tion believed to vary mainly with mass of the kidney, was increased by 2-4 days, with an apparently maximum increase attained by 1-2 weeks [60]. In another study, however, no change in glucose Tm was seen at I week but a 37% increase by 15 and a 50% increase by 30 days were reported [73]. PAH Tm in these same studies increased by 70%.…”

“…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].…”

“…Following UNX in rats, GFR at first may increase more slowly than mass but later outstrip it [150,215,260]. Ureteral diversion to perito neum or vena cava in dogs or rats is followed by signifi cant increases in contralateral and probably also ipsilateral GFR but with no significant change in the masses of either over days or weeks [73,150,472,500]. The concen tration of Na/K-ATPase [154] and rate of DN A synthesis [458] do not change.…”

Effects of Sera from Uninephrectomized Rats on Renal Slices: PAH and TEA Uptake and QO₂

“…For example, PAH and glucose transport are augmented after uni nephrectomy [4,5] and changes in renal sodium handling occur [6][7][8][9][10][11]. However, the findings concerning renal so dium handling postuninephrectomy are not consistent.…”

Mechanism of Glomerulotubular Balance: The Whole Kidney Approach

“…This tailoring of filtering and reabsorptive capacities in each nephron for nu merous solutes was emphasized by Smith [40] and was called glomerular-tubular bal ance. After removal of most of the kidney mass, GTB for sodium and water applies immediately for the remaining nephrons be fore any mitotic activity has started, but tubular growth signified by increased capac ity for glucose reabsorption requires several weeks to develop [6], How glomerular and tubular growth processes are coordinated remains unknown. Evidently glomerulartubular balance is a prerequisite for measur ing GTB in the whole kidney.…”