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Alterations in renal tubular sodium and water reabsorption in chronic renal disease in man

1972; Elsevier BV; Volume: 2; Issue: 3 Linguagem: Inglês

10.1038/ki.1972.87

1523-1755

Thomas Kahn, G Mohammad, Richard Marlon Stein,

Renal function and acid-base balance

Alterations in renal tubular sodium and water reabsorption in chronic renal disease in man.Clearance studies were performed on subjects with GFR from 4 to 127 mI/mm under conditions of maximal hydration and hypotonic mannitol loading, Nonelectrolyte solute excretion per GFR (UNESV/GFR) was calculated as [UOsm-2 (UNa + UK)] V/GFR.Fractional sodium excretion (CNa/GFR) per level of UNESV/GFR in the low GFR group (GFR<35 mI/mm) was higher initially and increased at a steeper rate than noted in subjects with normal GFR.Thus subjects with low GFR appear to have an increased fractional excretion of sodium in response to a solute load.Fractional distal tubular sodium load (CH2O/GFR + CNa/GFR) was also higher initially in the low GFR group at every level of UNESV/ GFR and increased at a more rapid rate in response to a solute load.Thus azotemic subjects have a decreased fractional reabsorption of sodium in the proximal tubule independent of fractional solute load.Nevertheless, an increase in solute load provokes a greater inhibition of fractional proximal tubular sodium reabsorption in these subjects than in normals.Fractional distal tubular sodium reabsorption (CH2o/GFR) in the low GFR group appeared to be lower at every level of fractional distal sodium load.The higher CNa/GFR in the low GFR group appears to be consequent to decreased fractional sodium reabsorption in the proximal tubule and an alteration in the capacity of the distal tubule to reabsorb sodium.Alterations de Ia reabsorption tubulaire du sodium dans les affections rénales chroniques chez l'homme.Des etudes de clearance ont été réalisées chez des sujets dont les debits de filtration glomérulaire (GFR) étaient compris entre 4 et 127 mI/mm.dans des conditions d'hydratation maximale et au cours d'une charge de mannitol hypotonique.L'excrétion de substances dissoutes non electrolytiques par unite de filtrat glomérulaire (UNESV/ GFR) a été calculCe par [Uosm-2(UNa+UK)]V/GFR.L'excrétion fractionnelle du sodium (CNa/GFR) rapportée a UV/ GFR dans le groupe des GFR bas (GFR<35 mi/mm) était initialement plus élevCe et augmentait de facon plus abrupte que chez les sujets ayant un GFR normal.Par consequent les sujets a GFR bas semblent avoir une natriurése exagérée en réponse a une charge de substances dissoutes.La charge fractionnelle distale du sodium (CHZO/GFR + CNa/GFR) était