Osmolality of distal tubular fluid in the dog.

Clapp, James R.; Robinson, Roscoe R.

doi:10.1172/jci105488

Cited by 71 publications

(39 citation statements)

References 16 publications

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“…This difference implies that the distal tubule of the dog is less permeable to water than that of the rat. This conclusion is also supported by the finding that tubule fluid remains hypotonic to plasma throughout the distal tubule of the dog (23). The fact that sodium ratios were significantly higher after mannitol loading in the dog indicates an additional effect on sodium transport apart from its osmotic action within the tubular lumen.…”

Section: Discussionmentioning

confidence: 57%

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

Seely¹,

Dirks²

1969

J. Clin. Invest.

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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.

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Section: Discussionmentioning

confidence: 57%

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

Seely¹,

Dirks²

1969

J. Clin. Invest.

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“…The marked abnormality in TCH2O formation (including the excretion of CH2o) during hydropenia could have been due to a limitation to the rate of medullary sodium accumulation as a consequence of two factors: (a) a reduced load of sodium to the loop of Henle, and (b) the inability of the sodium pump in the loop to respond normally to even small increments of sodium from the proximal tubule. If complete isosmotic equilibration does not occur in the late distal tubule in man, as is the case in the dog (22), then the reduced rate of osmotic water reabsorption from the collecting duct would account for the observations in sodium-depleted hypertensive man.…”

Section: Studies During Water Diuresismentioning

confidence: 98%

Mechanism of exaggerated natriuresis in hypertensive man: impaired sodium transport in the loop of henle

Buckalew¹,

Puschett²,

Kintzel³

et al. 1969

J. Clin. Invest.

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A B S T R A C T To evaluate the effects of saline loading on distal sodium reabsorption in hypertensive man, studies were performed during both water deprivation and water diuresis in eight hypertensive subjects, and the results were compared to data obtained from similar studies in normal subjects. All hypertensive patients exhibited an enhanced excretion of filtered sodium (Ca/CIn) at any level of distal delivery of sodium compared to normal controls. Free water reabsorption (TCH2o) during hypertonic saline loading was quantitatively abnormal in the hypertensives at high levels of osmolar clearance (Co.m), and also the curve of TCHIo vs. Co.m leveled off above a Co.m of 18 ml/min per 1.73 m' in the hypertensive group in contrast to the normal controls in whom TCH,0o showed no evidence of achieving an upper limit. Sodium depletion exaggerated the abnormality in T'Ho in hypertensives, and resulted in a positive free water clearance (CH2o) during hydropenia.During hypotonic saline loading in water diuresis, changes in free water clearance per 100 ml of glomerular filtrate (CIo0/CI.) were less at any given increment in urine flow per 100 ml of glomerular filtrate (V/CG.) in the hypertensives compared to normal controls (P < 0.001). This abnormality in CH2o/CI. in the hypertensives in conjunction with the defect in T'H2o observed during hydropenia indicates that sodium reabsorption in the loop of Henle was abnormal at any given rate of distal delivery of sodium in hypertension. Furthermore, these abnormalities in TCH2o and CH20 coincided temporally with the development of the exaggerated natriuresis. Although the distal defect in sodium transport, in large part, accounted for the augmented natriuresis in hyperThis work was presented in part at the 1st Annual Meeting of the

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“…In the dog, as well as monkey, fluid was always hypotonic along the entire distal tubule (6,7,14). The cat was clearly different from the dog and monkey with regards to this pattern of the distal tubular fluid.…”

Section: Discussionmentioning

confidence: 91%

“…In the dog as well as in the monkey the tubular fluid was always hypotonic along the entire distal convolution (6)(7)(8). While, in the rodents, e.g.…”

Section: Discussionmentioning

confidence: 99%

Micropuncture Study of Distal Tubular Function of Cat Kidney

Suzuki¹

1971

Jpn.J.Pharmacol

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Osmolality of distal tubular fluid in the dog.

Cited by 71 publications

References 16 publications

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

Mechanism of exaggerated natriuresis in hypertensive man: impaired sodium transport in the loop of henle

Micropuncture Study of Distal Tubular Function of Cat Kidney

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