Untersuchungen an wachen Hunden über die Einstellung der Natriumbilanz

Abstract

Sodium and potassium excretion, GFR (inulin clearance), ECF (inulin space) and TRBF (electromagnetic flowmeter) were determined in trained dogs 3 hrs after feeding either sodium poor (0.5 mEq/kg) or sodium rich (14 mEq/kg) meals.Low and high ECF's were induced by 1--4 months of low and high salt feeding, respectively. The animals could be divided into two groups according to prior dietary history.1.3 hrs after sodium rich meals animals with low ECF showed a delayed Na excretion (15°/0 of Na load) whereas animals with high ECF excreted Na at high rates (30°/0 of Na load) in the postprandial phase. The latter group received a low sodium diet a few days before the experimental period. This low sodium period was needed in order to make the two groups comparable.2. The postprandial potassium excretion was augmented in both groups, independently of the size of the ECF prior to the experiment.3. The postprandial ECF increased independently of dietary history or salt content of meals. However, the extent of increase was less after the salt poor meal (+ 12.7°/0) than after the salt rich meal (+ 25.5°/0). 4. GFR also increased postprandially. The maximum, observed on the first day of the salt rich period, amounted to 165°/0 of the preprandial value. It returned progressively during the salt rich period to the value seen in dogs with salt poor diet (131°/0). The return was accompanied by increased sodium excretion. Hence, no direct correlation between GX~R and sodium excretion was found in these experiments.5. TRBF increased postprandially up to 160°/0 of the value of the fasting animal, independently of dietary history and salt content of meals.6. Calculations of Na distribution revealed 20--144 mEq in the intracellular space in the third postprandial hour. A comparable amount of potassium was lost from this space. If a similar shift in renal cells occurs, then content of sodium within renal cells may be a regulatory factor in Na excretion.Wie unsere Untersuchungen an wachen Hunden zeigen [3,28], ist die 24 Std-Bilanz des Natriums selbst bei hoher Koehsalzzufuhr ausgeglichen, wenn der Extracellul/~rraum einen Grenzwert yon 22°/o des KSrpergewichtes erreicht hat. Bei einer t/~glichen Natriumzufuhr, die kleiner ist als der obligate renale und extrarenale Natriumverlust, verkleinert sich das ECF-Volumen im Laufe yon 16 Wochen bis auf 16°/o des KSrpergewich-

Impaired Autoregulation of Blood Flow and Glomerular Filtration Rate in the Isolated Dog Kidney Depleted of Renin

“…However, it is not clear from his paper whether the level of daily sodium intake was similar to or greater than that used in the present experiments. Dogs exhibit the capacity to rapidly excrete an oral sodium load (27). Since our dogs usually ingested their sodium load within the first 8 hours, it may be that they rapidly excreted the high-sodium intake and for a significant part of the day were in normal sodium balance.…”

The control of glomerular filtration rate and renal blood flow in chronically volume‐expanded rats.

“…However, the persistance of practically normal GFR and RPF is at variance with some but not all of those studies, in which volume expansion was achieved by DOCA (deoxycorticosterone acetate) administration and with NaCl in drinking water. The reason for increased RPF and GFR in some of those studies (Schnermann, Hermle, Schmidmeier & Dahlheim, 1975;Moore & Mason, 1986) but not in others (Sonnenberg, 1973;Hall, Guyton & Cowley, 1977;Fagard, (Behrenbeck & Reinhardt, 1967). In any case, the homogeneous results in chronic salt-and volume-loaded animals demonstrate that chronic volume expansion does not necessarily induce an increase of glomerular filtration rate, as has been frequently suggested in the past.…”

<i>In vitro </i>Production of a Natriuretic Material of Renal Origin

“…The absence of synthesis of the natriuret ic factor by cells removed from salt-depleted animals could be used as an argument that the kidney is influenced by the previous diet, as previously observed by Behrenbeck et al [13] and Nizet et al [10] in vivo. A simi lar effect is observed when any extrarenal influence has been disrupted by the culture.…”