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The influnce of volume expanison on renal function after relief of chronic unilateral ureteral obstruction

1974; Elsevier BV; Volume: 5; Issue: 6 Linguagem: Francês

10.1038/ki.1974.58

1523-1755

Douglas R. Wilson,

Pediatric Urology and Nephrology Studies

The influence of volume expansion on renal function after relief of unilateral chronic ureteral obstruction. Postobstructive diuresis was not observed after the relief of chronic partial ureteral obstruction in hydropenic rats with an intact contralateral kidney. However, when such animals were volume-expanded with hypotonic saline solution after relief of obstruction, urine flow from the hydronephrotic kidney was double that of the contralateral kidney, while urine osmolality was lower and fractional sodium excretion and free water clearance were higher from the postobstructive kidney. These differences were partly related to blunted diuresis from the contralateral normal kidney. Micropuncture measurements during volume expansion in normal and hydronephrotic kidneys showed no significant differences in surface nephron glomerular filtration rate (GFR) or proximal reabsorption, but there was a significant decrease in fractional water reabsorption in the distal nephron of hydronephrotic kidneys. Surface nephron GFR was increased in comparison to whole kidney GFR in both normal and hydronephrotic kidneys during volume expansion, suggesting that a change in distribution of nephron filtration rates was not responsible for the greater diuresis from the postobstructive kidney. Volume expansion could be an important factor in postobstructive diuresis by exaggerating a defect in water reabsorption in the distal nephron and/or in the deep nephrons or collecting ducts of the hydronephrotic kidney. Influence de l'expansion extracellulaire sur la fonction renale apres la levee d'une obstruction unilaterale chronique. La diurese post obstructive n'a pas ete observee apres la levee d'une occlusion ureterale partielle chez des rats hydropeniques dont le rein controlateral est intact. Cependant, quand ces animaux recoivent du solute sale hypotonique apres la levee de l'obstruction, le debit urinaire du rein hydronephrotique est le double de celui du rein controlateral alors que l'osmolalite urinaire est inferieure et l'excretion fractionnelle du sodium et la clearance de l'eau libre sont superieures du cote hydronephrotique. Ces differences sont en partie liees a la diurese attenuee du rein normal controlateral. Les determinations dans des echantillons de microponction obtenus pendant l'expansion extracellulaire dans les reins normaux et hydronephrotiques ne montrent pas de difference significative en ce qui concerne le debit de filtration glomerulaire des nephrons superficiels et leur reabsorption proximale. Par contre une diminution significative de la reabsorption fractionnelle d'eau est observee dans les tubes distaux des reins hydronephrotiques. Le debit de filtration glomerulaire des nephrons superficiels est augmente par rapport au debit de filtration du rein entier aussi bien dans les reins normaux qu'hydronephrotiques, ce qui suggere qu'une modification de la distribution des debits de filtration ne peut pas etre la cause de la plus grande diurese observee dans le rein ayant subi l'occlusion. L'expansion pourrait etre un facteur important dans la diurese post obstructive en exagerant un deficit de la reabsorption de l'eau par le tube distal et/ou les nephrons profonds et les canaux collecteurs de rein hydronephrotique.