Effect of parathyroid hormone on phosphate reabsorption in rat distal convolution

Pastoriza-Munoz, E; Colindres, Rómulo E.; Lassiter, WE; Lechène, C.

doi:10.1152/ajprenal.1978.235.4.f321

Cited by 27 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…], a maneuver which restores PTH-in duced phosphaturia in the hamster [21], Intact and PTH showed very similar effects at concentrations below 10~''AF without natriuresis and kaliuresis. This is consistent with the data of PasterizaMunez et al [22] that available biologically active PTH preparations have effects ini tially in the pars recta or more distal seg ments of the nephron rather than the earlier proximal segment of the rat kidney. The studies by Pusehett et al [23] in the dog are also compatible with this interpretation.…”

Section: Discussionsupporting

confidence: 92%

Differences in Effects of Amino-Terminal and Intact Parathyroid Hormone on Calcium, Phosphate, and cAMP Excretion by the Isolated Perfused Rat Kidney

Besarab¹,

Swanson²

1982

Kidney Blood Press Res

View full text Add to dashboard Cite

Urinary cAMP (UcAMP) reflects activation of renal adenylate cyclase by parathyroid hormone (PTH). UcAMP excretion and the phosphaturic, anticalciuretic responses to bovine PTH by a stable isolated perfused rat kidney were compared. Dose-response curves were obtained for two synthetic amino-terminal [1–34] PTH preparations and three highly purified intact [1–84] PTH preparations. With all preparations, anticalciuria occurred at lower concentrations ( < 10^-10 M) than those needed to produce a significant increase in UcAMP excretion or phosphate excretion. Maximal decreases in calcium clearance with [1–34] PTH were independent of concentrations between 10^-10 and 10^-7 M whereas cAMP and phosphate increased sigmoidally at PTH concentrations above 10^-10 M. The two synthetic [1–34] PTH preparations had identical anticalciuretic and phosphaturic dose-response curves despite their significantly different effects on cAMP excretion. Intact [1–84] PTH concentration-response curves were identical to those of [1–34] PTH at concentrations less than 3×10^-9 M. At higher concentrations, phosphaturia was greater and anticalciuria blunted compared to [1–34] PTH. These latter changes were associated with natriuresis and kaliuresis, effects not seen with [1–34] PTH. The isolated kidney may be a useful model for further studies of PTH action and also constitutes a bioassay system to evaluate hormone potency.

show abstract

Section: Discussionsupporting

confidence: 92%

Differences in Effects of Amino-Terminal and Intact Parathyroid Hormone on Calcium, Phosphate, and cAMP Excretion by the Isolated Perfused Rat Kidney

Besarab¹,

Swanson²

1982

Kidney Blood Press Res

View full text Add to dashboard Cite

show abstract

“…A surgical thyroparathyroidectomy (TPTX) was performed as previously described (7). To maintain their body temperature, rats were placed on a feedback-regulated heating table.…”

Section: Methodsmentioning

confidence: 99%

Parathyroid hormone decreases HCO3 reabsorption in the rat proximal tubule by stimulating phosphatidylinositol metabolism and inhibiting base exit.

Pastoriza-Munoz¹,

Harrington²,

Graber³

1992

J. Clin. Invest.

View full text Add to dashboard Cite

The mechanism of inhibition of HCO3 transport by parathyroid hormone (PTH) in the proximal tubule is not clearly defined. Previous studies in vitro have suggested that this effect is mediated via cAMP generation, which acts to inhibit Na/H exchange, resulting in cell acidification. To examine this question in vivo, intracellular pH (pH). was measured in the superficial proximal tubule of the rat using the pH-sensitive fluoroprobes 4-methylumbelliferone (4MU) and 2',7'-bis(carboxyethyl)-(5, and 6)-carboxyfluorescein (BCECF). PITH was found to alkalinize the cell. This alkalinization suggested inhibition of basolateral base exit, which was confirmed by in situ microperfusion studies: lowering HCO3 in peritubular capillaries acidified the cell, an effect blunted by PTH. Removal of luminal Na promoted basolateral base entry, alkalinizing the cell. This response was also blunted by PTH. Readdition of luminal Na stimulated the luminal Na/H exchanger, causing an alkalinization overshoot that was partially inhibited by PTH. cAMP inhibited luminal H secretion but did not alkalinize the cell. Stimulation of phosphatidylinositol-bis-phosphate turnover by PTH was suggested by the effect to the hormone to increase cell Ca. Blocking the PTH-induced rise in cell Ca blunted the effect of the hormone to alkalinize the cell, as did inhibition of phosphatidylinositol breakdown. Furthermore, stimulation of protein kinase C by a phorbol ester and a diacylglycerol applied basolaterally alkalinized the cell and inhibited luminal H secretion. The findings indicate that both arms of the phosphatidylinositol-bis-phosphate cascade play a role in mediating the effect of PlTH on the cell pH. The results are consistent with the view that PTH inhibits base exit in the proximal tubule by activation of the phosphatidylinositol cascade. The resulting alkalinization may contribute, with cAMP, to inhibit apical Na/H exchange and the PTH-induced depression of proximal

show abstract

“…A tracheostomy was performed and catheters were inserted in the external jugular vein for the administration of 0.85% NaCI solution at a rate of 40 Ml/ min, and in the femoral artery for blood pressure monitoring and arterial blood gas measurement. The left kidney was exposed for micropuncture as previously described (8) and catheters inserted in both ureters for urine collection.…”

Section: Methodsmentioning

confidence: 99%

Axial heterogeneity of intracellular pH in rat proximal convoluted tubule.

Pastoriza-Munoz¹,

Harrington²,

Graber³

1987

J. Clin. Invest.

View full text Add to dashboard Cite

In the proximal convoluted tubule (PT), the HCO3 reabsorptive rate is higher in early (EPS) compared with late proximal segments (LPS). To examine the mechanism of this HCO3 reabsorption profile, intracellular pH (pH) was measured along the superficial PT of the rat under free-flow and stationary microperfusion using the pH-sensitive fluorescence of 4-methylumbelliferone (4MU). With 4MU superfusion, pH1 was found to decline along the PT. Observation with 365-nm excitation revealed that EPS were brightly fluorescent and always emerged away from their star vessel. Midproximal segments were darker and closer to the star vessel which was surrounded by the darkest LPS. Decreasing luminal HCO3 from 15 to 0 mM lowered pH, in both EPS and LPS, but pH, remained more alkaline in EPS with both perfusates. Thus the axial decline in pH, along the PT is due to both luminal factors and intrinsic differences in luminal H+ extrusion in PT cells.

show abstract

Effect of parathyroid hormone on phosphate reabsorption in rat distal convolution

Cited by 27 publications

References 0 publications

Differences in Effects of Amino-Terminal and Intact Parathyroid Hormone on Calcium, Phosphate, and cAMP Excretion by the Isolated Perfused Rat Kidney

Differences in Effects of Amino-Terminal and Intact Parathyroid Hormone on Calcium, Phosphate, and cAMP Excretion by the Isolated Perfused Rat Kidney

Parathyroid hormone decreases HCO3 reabsorption in the rat proximal tubule by stimulating phosphatidylinositol metabolism and inhibiting base exit.

Axial heterogeneity of intracellular pH in rat proximal convoluted tubule.

Contact Info

Product

Resources

About