The Effects of Infusion of Water on Renal Hemodynamics and the Tubular Reabsorption of Sodium*

Martino, Joseph A.; Earley, Laurence E.

doi:10.1172/jci105616

Cited by 25 publications

(11 citation statements)

References 21 publications

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“…With respect to the first point, there is little doubt that some water is reabsorbed beyond the diluting site (16). With regard to the second point, water loading itself may depress tubular sodium reabsorption (17), while the dilutional hyponatremia necessarily induced may enhance reabsorption (18,19 ments, subjects drank 20 ml/kg of water at the start of the study and control periods were not obtained until Uour was less than 75 mOsm/kg (Tables II and IV).…”

Section: Resultsmentioning

confidence: 99%

Tubular reabsorption of sodium during acute and chronic volume expansion in man

Alexander¹,

Doner²,

Auld³

et al. 1972

J. Clin. Invest.

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A B S T R A C T Renal hemodynamics and tubular fractional sodium reabsorption (FSR) were evaluated by clearance techniques during acute and chronic extracellular volume expansion in man.(1 -V/GFR) X 100 was used as an index of proximal and (CH20/V) X 100 as an estimate of distal fractional reabsorption. After acute loading with isotonic saline 37 mVkg body wt, proximal FSR decreased by 4.8% and distal FSR decreased by 4.4%. After comparable chronic expansion by mineralocorticoids ("escape"), proximal FSR also decreased by 3.9%, but distal reabsorption was not altered.In separate studies, subjects were progressively infused with saline to 57 (Ei) and to 80 (E2) ml/kg body wt, and appeared to divide into "excreters" (maximum UNaV > 1000 /AEq/min) and "nonexcreters" (maximum UNaV < 550 iAEq/min). In the excreters, GFR rose, proximal FSR decreased by 7.1% after E1 and only 0.9% further after E2. Distal FSR fell by 14.8% after E1 and by an additional 4.9% after Es. In the nonexcreters, GFR was stable and proximal FSR did not fall significantly after E1 or E2. Distal FSR decreased 4.5% after El and 1.3% further after E2. It is concluded that both acute and chronic extracellular expansion decrease proximal FSR in man, but only acute loading depresses distal FSR. Ability of some men to excrete sodium rapidly after acute infusion is related to larger increases in GFR and greater decreases in both proximal and distal FSR than occur in men in whom natriuresis is more limited.

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Section: Resultsmentioning

confidence: 99%

Tubular reabsorption of sodium during acute and chronic volume expansion in man

Alexander¹,

Doner²,

Auld³

et al. 1972

J. Clin. Invest.

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“…However, sustained expansion of body fluid volume might lead to an increased G.F.R. during the water loading phase, as can occur in dog (Martino & Earley, 1967). Increasing G.F.R.…”

Section: Discussionmentioning

confidence: 99%

“…caused increased sodium excretion in the rat (Atherton, Hai & Thomas, 1967). However, water loading can lead to depressed proximal tubular reabsorption ofsodium, by intrarenal mechanisms (Martino & Earley, 1967). Furthermore, expansion of extracellular fluid and plasma volumes would cause reduced aldosterone production (Bartter, Liddle, Duncan, Barber & Delea, 1956) and, therefore, reduced tubular reabsorption of sodium.…”

Section: Discussionmentioning

confidence: 99%

Effects of water diuresis and osmotic (mannitol) diuresis on urinary solute excretion by the conscious rat

Atherton¹,

Hai²,

Thomas³

1968

The Journal of Physiology

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SUMMARY1. The time course and extent of changes in urinary flow and in the outputs of urea, Na+, K+, and NH+ over a period of 71 hr in conscious rats during water and osmotic (mannitol) diuresis were determined, and compared with spontaneous changes in non-diuretic animals.2. In non-diuretic rats, a morning rise and subsequent decline in urinary osmolal, sodium, potassium and ammonium outputs occurred, possibly attributable to circadian rhythms.3. Water diuresis was accompanied by (i) a rapid increase in urea excretion during the phase of increasing urine flow, followed by a fall in later periods to values similar to those in non-diuresis, (ii) a slower increase in sodium output, continuing after the establishment of the constant water load, (iii) unchanged potassium excretion, but slightly increased ammonium outputs.

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“…(Grantham & Burg, 1966) the delivery of increased quantities of dilute fluid causes a loss of water from the collecting duct into the interstitium greater than that which occurs in hydropenia (Berliner & Bennett, 1967). Furthermore, the body fluid expanison caused by infusion of water is associated with increased glomerular filtration rate and decreased tubular reabsorption of sodium (Martino & Earley, 1967); this will also contribute to increased flow in the loop of Henle with possible effects on the medullary content of water and on countercurrent multiplication mechanisms (Ullrich, Kramer & Boylan, 1961).…”

Section: Discussionmentioning

confidence: 99%

The time course of changes in renal tissue composition during water diuresis in the rat

Atherton¹,

Hai²,

Thomas³

1968

The Journal of Physiology

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SUMMARY1. The time course and extent of changes in the composition of renal tissue slices in water diuresis were determined by sacrificing groups of rats before and during the intravenous infusion of dextrose (2.5 g/100 ml.) in amounts sufficient to administer over 2 hr, and subsequently to maintain for up to 74 hr, a positive fluid load of 4 % body weight.2. The corticomedullary osmolal gradient characteristic of the nondiuretic rats was progressively dissipated until, at 74 hr, only papillary tip concentrations were higher than those of other segments.3. The changes in individual constituents followed different time courses: (i) an increase in water content in all segments, particularly the papilla, was almost complete by 1 hr, preceding the maximal increases in urine flow; (ii) a marked decrease in papillary and medullary urea content in the first hour was followed by a slower, progressive decrease leading to an almost complete dissipation of the urea gradient by 74 hr; (iii) small, non-significant decreases in sodium content occurred in all segments in the first hr, followed by a further small, progressive decrease in papillary sodium content; (iv) changes in ammonium and potassium concentrations were mainly related to those in water content, since the contents of these solutes showed only small changes.4. By 2 hr, differences in the rates of decline of osmolal and urea concentrations in urine and papilla led to urinary concentrations significantly lower than papillary values. The steep papilla-urine urea concentration difference became smaller, but remained significant even at 74 hr.5. The findings are discussed in terms of changes in countercurrent mechanisms, particularly as influenced by anti-diuretic hormone.6. The development of papilla/urine urea concentration ratio greater than unity is also considered in terms of passive transport with changes in membrane permeability.

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The Effects of Infusion of Water on Renal Hemodynamics and the Tubular Reabsorption of Sodium*

Cited by 25 publications

References 21 publications

Tubular reabsorption of sodium during acute and chronic volume expansion in man

Tubular reabsorption of sodium during acute and chronic volume expansion in man

Effects of water diuresis and osmotic (mannitol) diuresis on urinary solute excretion by the conscious rat

The time course of changes in renal tissue composition during water diuresis in the rat

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