Micropuncture Studies of Sodium Tranport in the Remnant Kidney of the Dog THE EFFECT OF GRADED VOLUME EXPANSION

Wen, Sung-Feng; Wong, Norman L.M.; Evanson, Raphael L.; Lockhart, Earle A.; Dirks, John H.

doi:10.1172/jci107195

Cited by 37 publications

(17 citation statements)

References 32 publications

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“…This was carried out by infusion of calcium chloride in saline-loaded normal dogs or administration of highly purified parathyroid hormone to saline-loaded TPTX dogs. Saline-loaded animals were used because it has been shown that proximal tubule FR sodium in the dog, once suppressed by saline infusion, tends to remain unaffected by further inhibitory maneuvers such as graded volume expansion (56,57). Indeed, neither calcium infusion nor parathyroid hormone administration, both of which have been shown to reduce proximal tubule sodium reabsorption (12,18,58), significantly altered proximal TF/P inulin in the saline-loaded animals in the present studies.…”

Section: Discussionmentioning

confidence: 74%

Micropuncture Studies of Phosphate Transport in the Proximal Tubule of the Dog THE RELATIONSHIP TO SODIUM REABSORPTION

Wen¹

1974

J. Clin. Invest.

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A B S T R A C T Micropuncture studies were performed in the dog to examine the relationship between sodium and phosphate transport in the proximal tubule. In hydropenic, thyroparathyroidectomized animals, administration of parathyroid extract, saline, or acetazolamide resulted in a fall in proximal tubule fluid-to-plasma (TF/P) inulin ratio as well as a rise in tubule fluid-toplasma ultrafilterable (TF/UF) phosphate ratio. A correlation was found between the changes in fractional reabsorption of sodium and phosphate but the phosphate changes were generally greater than those of sodium. Also, a high distal phosphate delivery in the face of low fractional excretion of phosphate in the urine in thyroparathyroidectomized dogs suggests significant phosphate reabsorption in the distal nephron. On the other hand, calcium chloride infusion to saline-loaded, normal dogs to suppress endogenous parathyroid hormone reduced proximal TF/UF phosphate without change in TF/P inulin, while both parameters remained unchanged in saline-loaded, thyroparathyroidectomized dogs after calcium infusion. An increase in proximal TF/UF phosphate associated with unchanged TF/P inulin was also demonstrated by administration of highly purified parathyroid hormone to saline-loaded, thyroparathyroidectomized dogs. It was concluded that although proximal tubule phosphate transport is generally closely related to that of sodium, the two can dissociate under certain experimental conditions, especially under the influence of parathyroid hormone. These observations also indicate that the effect of parathyroid hormone on proximal tubule phosphate transport is not solely dependent upon its effect on sodium transport.

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Section: Discussionmentioning

confidence: 74%

Micropuncture Studies of Phosphate Transport in the Proximal Tubule of the Dog THE RELATIONSHIP TO SODIUM REABSORPTION

Wen¹

1974

J. Clin. Invest.

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“…In chronic renal disease, the excretion of sodium by the kidney is known to change during the course of the disease process [1][2][3]. A number of factors have been evoked to explain this adaptation.…”

Section: Introductionmentioning

confidence: 99%

Increased Release of Atrial Natriuretic Peptide by the Atria of Rats with Experimental Renal Failure

Wong

Wong²

1991

Nephron

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Indirect evidence suggests that atrial natriuretic peptide (ANP) secretion is augmented in chronic renal disease. The object of our present study is to examine the release of ANP from isolated atria obtained from chronic renal failure rats to directly determine whether ANP secretions are increased under these conditions. Experiments were conducted on male Wistar rats (200–225 g) who were subjected to 5/6 nephrectomy of sham operation. Plasma blood urea nitrogen was significantly elevated in 5/6 nephrectomized rats (65 ± 7 vs. 16 ± 1 mg%). Overall glomerular filtration rate was 2.36 ± 0.06 ml/min in sham-operated animals, as opposed to 0.55 ± 0.11 ml/min in 5/6 nephrectomized rats. Fractional excretion of sodium was significantly higher in 5/6 nephrectomized rats (0.52 ± 0.01 vs. 1.68 ± 0.21%). Plasma ANP was 102 ± 4 pg/ml in normal rats and 161 ± 14 pg/ml in 5/6 nephrectomized ones. We have also measured immunoreactive ANP in the atria of normal and 5/6 nephrectomized rats. ANP content and concentration in the atria were lower in 5/6 nephrectomized rats. (652 ± 34 vs. 515 ± 46 ng/mg of tissue). Right atria from normal and nephrectomized animals were superfused with a modified Langendorff preparation. Spontaneous release of ANP was significantly higher from the nephrectomized rats (17.5 ± 0.6 pg/min/mg) than from the normal rats (9.8 ± 0.3 pg/min/mg). These results suggest that ANP may play a role in sodium homeostasis in rats with reduced renal mass.

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“…Thus, changes in fractional water excretion in these animals may not be influenced by plasma ANF levels. Increases in fractional excretion of water in renal failure animals were reported before [25,26], This could be due to changes in intrarenal blood flow and inability to respond to vasopres sin. Preliminary studies in 5/6 nephrectomized rats showed that cyclic AMP generation by inner medullary collecting duct cells in response to vasopressin was impaired [27].…”

Section: Discussionmentioning

confidence: 79%

Effect of Dietary Sodium on Atrial Natriuretic Factor Released in Rats with Chronic Renal Failure

Wong

Wong²

1992

Nephron

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Studies were done in partially nephrectomized rats to examine the effect of dietary sodium intake on atrial natriuretic factor (ANF) released by the atria. Experiments were done in four groups of male Wistar rats. Group 1 (n = 10) and 3 (m = 10) rats were sham-operated. Group 2 and 4 were 5/6 nephrectomized. Group 1 and 2 were fed a sodium-supplemented diet. Group 3 and 4 received a sodium-deficient diet. Renal functions were similar between group 2 and 4. Plasma ANF level was raised in group 2 (182 ± 17 pg/ml). Circulating ANF levels in group 1,3 and 4 were 95 ± 5,90 ± 5 and 95 ± 4 pg/ml, respectively. Atrial ANF contents were higher in partially nephrectomized rats after receiving a sodium-supplemented diet. A reduction in atrial ANF contents occurred when fed a sodium-deficient diet. In vitro studies were done to assess the rate of ANF released. ANF secretory rates were highest in group 2 (11 ± 1.5 pg/min/mg). There was no difference between group 1,3 and 4. A positive correlation was found between plasma ANF and ANF released in all groups examined. Thus, plasma ANF levels were a good reflection of ANF secretory rates. A significant correlation existed between plasma ANF and sodium excretion in chronic renal failure rats (r = 0.78; p < 0.01). A dissociation between plasma ANF and water excretion was seen. These results suggest that in chronic renal failure rats, ANF played a role in sodium adaptation.

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Micropuncture Studies of Sodium Tranport in the Remnant Kidney of the Dog THE EFFECT OF GRADED VOLUME EXPANSION

Cited by 37 publications

References 32 publications

Micropuncture Studies of Phosphate Transport in the Proximal Tubule of the Dog THE RELATIONSHIP TO SODIUM REABSORPTION

Micropuncture Studies of Phosphate Transport in the Proximal Tubule of the Dog THE RELATIONSHIP TO SODIUM REABSORPTION

Increased Release of Atrial Natriuretic Peptide by the Atria of Rats with Experimental Renal Failure

Effect of Dietary Sodium on Atrial Natriuretic Factor Released in Rats with Chronic Renal Failure

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