Washout of renal countercurrent Na gradient by osmotic diuresis

Malvin, Richard L.; Wilde, Walter S.

doi:10.1152/ajplegacy.1959.197.1.177

Cited by 67 publications

(19 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Certainly, on the basis of present micropuncture evidence in the dog, it is hazardous to draw any definite conclusions about the function of the loop of Henle from measured changes in TCH20. Our data which suggest that large inhibitory effects occur within the loop, moreover, seem more consistent with the finding that strong osmotic diuresis leads to almost total dissipation of the osmotic gradient in the papilla (20)(21)(22). Clearly, further studies specifically designed to correlate intratubular events with over-all measurements of CH20 or T'i2o under the appropriate experimental conditions are needed.…”

Section: Discussionsupporting

confidence: 91%

“…In view of the lesser permeability to water in the ascending limb, it seems likely that most of the water reabsorption in the loop takes place in the descending limb, and therefore, the inhibitory action of mannitol is largely manifested at this point in the nephron. This would readily result from both the osmotic effect of mannitol within the tubular lumen and to dissipation of the medullary osmotic gradient which occurs during mannitol diuresis (20)(21)(22).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Micropuncture study of hypertonic mannitol diuresis in the proximal and distal tubule of the dog kidney

Seely¹,

Dirks²

1969

J. Clin. Invest.

View full text Add to dashboard Cite

A B S T R A C T Fractional reabsorption of water, sodium, and potassium at proximal and distal tubular sites within the nephron was studied by recollection-micropuncture experiments on dogs undergoing hypertonic mannitol diuresis. After an initial control hydropenic phase, 16% mannitol in modified Ringer's solution was administered intravenously, resulting in marked increases in fractional excretion of water (28.7%), sodium (12.6%), and potassium (63.9%). Inulin clearance decreased significantly from 35.1 to 25.2 ml/min. Analysis of paired micropuncture data revealed a significant decrease in tubule fluid to plasma (TF: P) inulin ratios in both the proximal tubule (1.63-1.45) and distal tubule (5.38-1.94). There was also a significant decrease in proximal TF: P sodium ratios (0.99-0.93) and potassium ratios (1.05-0.98). Distal TF: P sodium ratios, in contrast, rose significantly (0.38-0.59), while TF: P potassium ratios tended towards unity whether initially greater or less than one. Fractional reabsorption of sodium and water decreased by 5% and 10% respectively in the proximal tubule, but to a lesser extent than the resulting increases in fractional urinary excretion. The nonreabsorbed fraction, however, had increased sharply at the point of distal puncture for water (32%), sodium (26%), and potassium (26%), indicating a large inhibitory effect within the loop of Henle in addition to the smaller proximal effects.

show abstract

Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Micropuncture study of hypertonic mannitol diuresis in the proximal and distal tubule of the dog kidney

Seely¹,

Dirks²

1969

J. Clin. Invest.

View full text Add to dashboard Cite

show abstract

“…This proposal is supported by the observation that medullary solute content is reduced under these conditions (26). Such a change in medullary hemodynamics, when sufficient in magnitude, might prevent further retention of medullary solute and limit TCHO despite increasing sodium transport at the ascending limb.…”

Section: Mc20mentioning

confidence: 85%

The Effects of Salt Restriction on the Renal Concentrating Operation in Normal, Hydropenic Man*

Stein¹,

Levitt²,

Goldstein³

et al. 1962

J. Clin. Invest.

View full text Add to dashboard Cite

In the presence of antidiuretic hormone, the elaboration of a concentrated urine by the absorption of solute-free water depends upon the osmotic gradient established between collecting duct fluid and the hypertonic medullary interstitium (1-3). The quantity of solute deposited within the meIuilla depends, in large part, upon the rate at which sodium is presented to the ascending limb of the loop of Henle (2, 4, 5).Considerable evidence indicates that prolonged salt restriction results in a decreased extracellular fluid volume and glomerular filtration rate (GFR) coincident with a sharp reduction in sodium excretion (6-8). It might be anticipated that such changes could affect medullary salt supply and thereby influence the renal concentrating operation. The reported effects of salt restriction on the concentrating operation appear to vary depending upon the species studied. Experiments in the dog have demonstrated that dietary salt restriction reduces maximal urine osmolality (9, 10), whereas similar studies in man (4) and the rat (11) have failed to reveal any such alteration.The present studies were undertaken in order to elucidate further the effects of prolonged salt restriction on the concentrating operation in normal man under conditions of maximal hydropenia. METHODS

show abstract

“…In the dog, much of the change in solute concentrations is attributable to increased water content (RuizGuinazu, Arrizurietta & Yelinek, 1964;Goldberg & Ramirez, 1967) and to a profound depletion of medullary urea content (Goldberg & Ramirez, 1967), with smaller reductions in medullary sodium content (Malvin & Wilde, 1959;Dell & Winters, 1967;Goldberg & Ramirez, 1967).…”

Section: Discussionmentioning

confidence: 99%

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

Atherton¹,

Hai²,

Thomas³

1968

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. The time course and extent of changes in the composition of renal tissue slices in osmotic diuresis were determined by sacrificing groups of rats before and during the intravenous infusion of mannitol (15 g/100 ml.) for up to 71 hr.2. Very rapid changes in tissue water and solute contents occurred within 15 min, preceding the times of maximal diuresis, with little subsequent change even up to 7-hr.3. The main changes were: (a) an increase in water content in all slices, particularly the papilla; (b) a very profound decrease in papillary and medullary urea content in the first 15 min, with a small, but significant, further decrease, subsequently; (c) a small, but significant, rapid decrease in papillary sodium, and small non-significant increases in the outer medulla and cortex. Subsequent changes in any segment were small and non-significant; (d) apart from small changes in the first 15 min ammonium and potassium contents remained fairly constant.4. The rates of change in papillary and urinary urea concentrations were similar, so that after 30 min, any differences between tip and urinary concentrations were small and non-significant.5. The findings are discussed in terms of factors influencing countercurrent mechanisms. It is concluded that altered medullary blood flow is mainly responsible for the rapid changes in medullary composition.6. The relation between papillary and urinary urea concentrations is explicable in terms of passive handling, with equilibration across a freely permeable collecting duct membrane.

show abstract

Washout of renal countercurrent Na gradient by osmotic diuresis

Cited by 67 publications

References 1 publication

Micropuncture study of hypertonic mannitol diuresis in the proximal and distal tubule of the dog kidney

Micropuncture study of hypertonic mannitol diuresis in the proximal and distal tubule of the dog kidney

The Effects of Salt Restriction on the Renal Concentrating Operation in Normal, Hydropenic Man*

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

Contact Info

Product

Resources

About