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

Abstract

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 un-anesthetized dogs under control conditions (stage I), in the 3–4 weeks after ureteroperitoneostomy of the left kidney (stage II) and for a similar period after removal of the left kidney (stage III). 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 (Tm_G) and para-aminohippurate (Tm_PAH) of the right kidney did not rise during stage II, whereas the increments in stage III were similar to those observed in two dogs directly subjected to nephrectomy. In two other dogs with half of the right kidney resected, Tm_G and Tm_{pA H}did not increase during stage II but increased rapidly in stage III. It is concluded that the increments in Tm_G and Tm_pAH 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.

Key Words:

• Diuresis
• glomerular filtration rate
• homeostasis
• kidney function tests
• kidney tubules
• mitosis
• natriuresis
• nephrectomy
• ureteroperitoneostomy
• water-electrolyte balance