Inorganic phosphate homeostasis. Renal adaptation to the dietary intake in intact and thyroparathyroidectomized rats.

Tröhler, Ulrich; Bonjour, J.-P.; Fleisch, H.

doi:10.1172/jci108277

Cited by 182 publications

(47 citation statements)

References 31 publications

(32 reference statements)

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“…In contrast to the convoluted tubule, the proximal straight tubule has lower transport rates for glucose (17,22) and phosphate (23) and may be exposed to very low intraluminal concentrations of Pi in vivo (24,25). We measured Jv and glucose absorptive fluxes in five proximal straight tubules perfused from the outset with Pi-free solutions and bathed in normal rabbit serum.…”

Section: Resultsmentioning

confidence: 99%

Metabolic Requirement for Inorganic Phosphate by the Rabbit Proximal Tubule

Brazy¹,

Gullans²,

Mandel³

et al. 1982

J. Clin. Invest.

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A B S T R A C T These studies examine the effects of acute changes in the availability of inorganic phosphate on the function of isolated proximal renal tubules from rabbit kidney. We removed phosphate from the extracellular fluids and measured fluid absorption rates in isolated. perfused tubules and oxygen consumption rates in suspensions of cortical tubules. In proximal convoluted tubules, the selective removal of phosphate from the luminal fluid reduced fluid absorption rates from 1.11±0.12 to -0.01±0.08 nl/mmmin. This effect on fluid absorption was dependent on the presence of glucose transport and metabolism. The addition of phlorizin to the phosphate-free luminal fluid preserved fluid absorption rates (1.12±0.12 nl/ mm -min) as did the substitution of nonmetabolized a-methyl D-glucopyranoside for glucose (1.05±0.21 nl/mm min) or the addition of 2-deoxyglucose, an inhibitor of glycolysis, to the bathing medium (1.01±0.15 nl/mm -min). There was no effect on fluid absorption if phosphate was removed from the bath only. Additionally, removal of phosphate from the luminal fluid of proximal straight rather than convoluted tubules had no effect on fluid absorption rates. Oxygen consumption rates in suspensions of cortical tubules were reduced from 18.9±0.6 to 10.6±0.6 nmol O2/mg tubular protein * min by the removal of phosphate from the medium. This inhibition was prevented by the substitution of a-methyl D-glucopyranoside for glucose in the phosphate-free medium. The data indicate that under certain conditions, proximal convoluted tubules require the presence of phosphate in the luminal fluid to preserve tubular function. In the absence of intraluminal phosphate, glucose metabolism causes a reduction in both oxidative metab-

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Section: Resultsmentioning

confidence: 99%

Metabolic Requirement for Inorganic Phosphate by the Rabbit Proximal Tubule

Brazy¹,

Gullans²,

Mandel³

et al. 1982

J. Clin. Invest.

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“…This thesis is clearly reflected in the parallels between the renal handling of Pi in immature rats fed normal Pi diet and Pideprived adult rats. Both the immature rats (that have an increased demand for Pi due to an accelerated rate of growth) and Pi-deprived adult rats (that have a reduced supply of phosphate) exhibit an elevated tubular capacity to reabsorb Pi (2,15) and an apparent reduced sensitivity to PTH (6,16); adaptations that serve to facilitate the renal conservation of Pi.…”

Section: Discussionmentioning

confidence: 99%

Restoration of a Phosphaturic Response to Parathyroid Hormone in the Immature Rat

1989

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“…Phosphate depletion in rats is associated with hypophosphatemia, hypophosphaturia, hyperealcemia, and hypercalciuria (1)(2)(3)(4)(5)(6). Because renal tubular transport of calcium may share a common reabsorptive mechanism or pathway with magnesium (7)(8)(9), one might expect magnesuria with phosphate depletion.…”

Section: Introductionmentioning

confidence: 99%

Effect of Phosphate Depletion on Magnesium Homeostasis in Rats

Kreußer¹,

Kurokawa²,

Aznar³

et al. 1978

J. Clin. Invest.

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A B S T R A C T The effects of phosphate depletion on magniesiumni (NMg) homeostasis were evaluated in rats fed a diet containing 0.03% phosphorus for periods up to 8 wk. Plasma phosphorus fell signiificantly (P < 0.01) from 10.1+0.27 (SE) to 5.0±0.54 mgIl00 ml within 1 day and conitiniued to fall gradually to a level of 1.2±0.21 mg/100 ml by the end of the 8th wk. A signiificant (P < 0.01) increment in urinary Mg excretion (UMgV) from 46±2.7 to 126±24 ,ueq/24 h occurred during the 1st day of phosphate depletion; UMgV reached a peak of 300±+24 pieq/24 h by the 3rd day and remained high ranging between 150-300 ,ueq/24 h, thereafter. The magnittude of the magnesuria was related to the degree of hypophosphatemia and was not affected by lowering the calcium intake and reducing the hypercalciuria. The concentration of plasma Mg fell significantly (P < 0.01) from 1.2±0.02 to 0.79±0.10 meq/liter by the 1st day of the study and remained low throughout.Mg balance became negative during the 1st day of phosphate depletion and remained so during the entire study. This occurred despite a significant increment in the fraction of ingested Mg absorbed which becarmie evident by the 3rd wk of phosphate depletion. Mg contenit of muscle, kidney, and liver were not affected but bone Mg was reduced significantly. The change in bone Mg was not due to an overall reduction in bone mineral contenit because bone calcium content was not affected. Supplementation of large amounts of Mg (800-1,000 ,ueq/day) in the drinking water produced a normalization of serum Mg but did not bring about restoration of bone Mg despite a positive Mg balance. The disturbances in Mg metabolism were independent of the age or veight of the animals.Our results indicate that phosphate depletion is Dr. Kreusser is a Fellow of the Deutsche Forschungsgemeinschaft.Dr. Aznar is a Fellow of the Del Amo Foundation.

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Inorganic phosphate homeostasis. Renal adaptation to the dietary intake in intact and thyroparathyroidectomized rats.

Cited by 182 publications

References 31 publications

Metabolic Requirement for Inorganic Phosphate by the Rabbit Proximal Tubule

Metabolic Requirement for Inorganic Phosphate by the Rabbit Proximal Tubule

Restoration of a Phosphaturic Response to Parathyroid Hormone in the Immature Rat

Effect of Phosphate Depletion on Magnesium Homeostasis in Rats

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