Interactions between gluconeogenesis and sodium transport in rabbit proximal tubule

1984 ◽  
Vol 246 (6) ◽  
pp. F859-F869 ◽  
Author(s):  
S. R. Gullans ◽  
P. C. Brazy ◽  
V. W. Dennis ◽  
L. J. Mandel
Keyword(s):  
Proximal Tubule ◽  
Sodium Transport ◽  
Acid Metabolism ◽  
Renal Proximal Tubule ◽  
Active Sodium ◽  
Atp Production ◽  
Cellular Energy ◽  
Glucose Synthesis ◽  
And Control ◽  
Gluconeogenic Substrate

Gluconeogenesis and sodium transport are ATP-requiring functions of the renal proximal tubule. Previously observed interactions between these processes indicated that they may compete for cellular energy. We have reevaluated this interaction in the rabbit proximal tubule using two preparations: suspensions of cortical tubules and isolated perfused tubules. In the presence of lactate and alanine, net glucose synthesis was 22.3 +/- 1.3 nmol X mg protein-1 .30 min-1. Additions of valerate, butyrate, or succinate increased this rate by factors of 2-3 without affecting cellular ATP levels or net fluid absorption (Jv). Inhibition of ATP production with rotenone, which we have previously shown to inhibit Jv [Am. J. Physiol. 243 (Renal Fluid Electrolyte Physiol. 12): F133-F140, 1982], greatly decreased the gluconeogenic rate, but this was modulated by the type of gluconeogenic substrate used. Increasing Na-K-ATPase activity with nystatin or decreasing it with ouabain had widely differing effects, which also depended on the substrate regimen. We conclude that the interaction between gluconeogenesis and active sodium transport cannot be described by a simple competition for ATP. Rather, under normal circumstances, the renal proximal tubule can meet the energetic demands of both gluconeogenesis and sodium transport, and control of these processes is multifactorial and sensitive to fatty acid metabolism.

Na-HCO3 cotransport and Na-H antiporter in chronic respiratory acidosis and alkalosis

1989 ◽  
Vol 256 (3) ◽  
pp. F414-F420 ◽  
Author(s):  
O. S. Ruiz ◽  
J. A. Arruda ◽  
Z. Talor
Keyword(s):  
Proximal Tubule ◽  
Respiratory Acidosis ◽  
Renal Proximal Tubule ◽  
Transport Systems ◽  
Acid Base ◽  
Basolateral Membranes ◽  
Two Systems ◽  
22Na Uptake ◽  
And Control

Renal acidification in renal proximal tubule is thought to be mediated by luminal Na-H antiporter and the HCO3- generated by this antiporter is removed from the cell by a basolateral Na-HCO3 cotransporter. To study the effect of respiratory acid-base disorders on these transport systems, we have measured the Na-HCO3 cotransport in basolateral membranes and Na-H antiporter in luminal membranes in control rabbits, rabbits exposed to 10% CO2 (chronic hypercapnia), and rabbits exposed to 10% O2-90% N2 (chronic hypocapnia). The Vmax of HCO3(-)-dependent 22Na uptake was significantly higher in chronic hypercapnia than controls (2.54 +/- 0.03 vs. 1.18 +/- 0.21 nmol.mg protein-1.3 s-1, P less than 0.001). Likewise, the Vmax of the Na-H antiporter was also increased compared with controls (924.9 +/- 42.1 vs. 549.1 +/- 62.8 fluorescence units (FU).300 micrograms protein-1.min-1). In chronic hypocapnia, the Vmax of Na-HCO3 cotransport was lower than controls (0.72 +/- 0.11 vs. 1.18 +/- 0.21 nmol.mg protein-1.3 s-1, P less than 0.05). There was no difference, however, in the Vmax of the Na-H antiporter between hypocapnia and control (524.2 +/- 24.3 vs. 549.1 +/- 62.8, FU.300 micrograms protein-1.min-1). The Vmaxs of the Na-HCO3 cotransport and of the Na-H antiporter in hypocapnic, control, and hypercapnic rabbits were linearly related (r = 0.81), suggesting a simultaneous adaptation of the two systems in respiratory acid-base disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

Transepithelial sulfate transport by avian renal proximal tubule epithelium in primary culture

2002 ◽  
Vol 283 (6) ◽  
pp. R1354-R1361 ◽  
Author(s):  
Paul L. Dudas ◽  
J. Larry Renfro
Keyword(s):  
Proximal Tubule ◽  
Primary Cultures ◽  
Renal Proximal Tubule ◽  
Proximal Tubules ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Electrophysiological Properties ◽  
Ussing Chambers ◽  
And Control ◽  
Inorganic Sulfate

The mechanisms and control of transepithelial inorganic sulfate (Si) transport by primary cultures of chick renal proximal tubule monolayers in Ussing chambers were determined. The competitive anion, S2O3 2− (5 mM), reduced both unidirectional reabsorptive and secretory fluxes and net Sireabsorption with no effect on electrophysiological properties. The carbonic anhydrase (CA) inhibitor ethoxzolamide decreased net Si reabsorption ∼45%. CAII protein and activity were detected in isolated chick proximal tubules by immunoblots and biochemical assay, respectively. Cortisol reduced net Sireabsorption up to ∼50% in a concentration-dependent manner. Thyroid hormone increased net Si reabsorption threefold in 24 h, and parathyroid hormone (PTH) acutely stimulated net Sireabsorption ∼45%. These data indicate that CA participates in avian proximal tubule active transepithelial Si reabsorption, which cortisol directly inhibits and T3 and PTH directly stimulate.

Stimulatory effect of insulin on renal proximal tubule sodium transport is preserved in type 2 diabetes with nephropathy

2015 ◽  
Vol 461 (1) ◽  
pp. 154-158 ◽  
Author(s):  
Motonobu Nakamura ◽  
Nobuhiko Satoh ◽  
Masashi Suzuki ◽  
Haruki Kume ◽  
Yukio Homma ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Proximal Tubule ◽  
Sodium Transport ◽  
Renal Proximal Tubule

Anion permeabilities of the isolated perfused rabbit proximal tubule

1982 ◽  
Vol 242 (4) ◽  
pp. F395-F405 ◽  
Author(s):  
D. G. Warnock ◽  
V. J. Yee
Keyword(s):  
Proximal Tubule ◽  
Sodium Transport ◽  
Permeability Coefficient ◽  
Negative Charge ◽  
Ion Selectivity ◽  
Proximal Tubules ◽  
Active Sodium ◽  
Chloride Permeability ◽  
Per Se ◽  
Two Populations

Electrophysiologic and isotopic techniques were used to characterize the anion permeabilities of isolated perfused rabbit proximal tubules (S2 segments). Tubules were differentiated into chloride- and sodium-selective populations by electrophysiologic rather than by anatomic criteria. The tubules were studied under conditions that inhibited active sodium transport. The isotopic chloride permeability coefficient was 5.5 +/- 0.6 X 10(-5) cm/s (n = 19) for chloride-selective tubules and 3.2 +/- 0.6 X 10(-5) cm/s (n = 15) for sodium-selective tubules. The isethionate permeability coefficient was 1.1 +/- 0.2 X 10(-5) cm/s (n = 23) and did not vary with sodium or chloride selectivity. The variation of oxyanion permeability (bicarbonate, isethionate, and cyclamate) relative to chloride resulted from changes in chloride permeability, per se, rather than any change in the oxyanion permeability. A consistent relation between bicarbonate and isethionate permeability permitted the permeability of bicarbonate ion to be estimated at 1.3 X 10(-5) cm/s. The mechanism of ion selectivity appears to be different for the two populations of tubules. Chloride-selective tubules appear to hve relatively small pathways that do not contain fixed-charge sites. In contrast, sodium-selective tubules may have permeation pathways that contain fixed negative-charge sites.

scholarly journals Dopamine and Angiotensin Type 2 Receptors Cooperatively Inhibit Sodium Transport in Human Renal Proximal Tubule Cells

Hypertension ◽  
2012 ◽  
Vol 60 (2) ◽  
pp. 396-403 ◽  
Author(s):  
John J. Gildea ◽  
Xiaoli Wang ◽  
Neema Shah ◽  
Hanh Tran ◽  
Michael Spinosa ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Sodium Transport ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells ◽  
Angiotensin Type

scholarly journals The Effects of Insulin Resistance and Inflammation on Renal Proximal Tubule Sodium Transport and Hypertension

2013 ◽  
Vol 03 (05) ◽  
pp. 34-41
Author(s):  
Shoko Horita ◽  
Motonobu Nakamura ◽  
Masashi Suzuki ◽  
Hideomi Yamada ◽  
George Seki
Keyword(s):  
Insulin Resistance ◽  
Proximal Tubule ◽  
Sodium Transport ◽  
Renal Proximal Tubule

The Fine Structure of Rat Renal Microbodies and Cytoplasmic Bodies Following Perfusion Fixation

1973 ◽  
Vol 31 ◽  
pp. 620-621
Author(s):  
J. M. Barrett ◽  
P. M. Heidger
Keyword(s):  
Fine Structure ◽  
Proximal Tubule ◽  
Rat Kidney ◽  
Renal Proximal Tubule ◽  
Convincing Evidence ◽  
Cytoplasmic Bodies ◽  
Rat Renal Proximal Tubule ◽  
Renal Proximal Tubule Cells ◽  
Perfusion Fixation

Microbodies have received extensive morphological and cytochemical investigation since they were first described by Rhodin in 1954. To our knowledge, however, all investigations of microbodies and cytoplasmic bodies of rat renal proximal tubule cells have employed immersion fixation. Tisher, et al. have shown convincing evidence of fine structural alteration of microbodies in rhesus monkey kidney following immersion fixation; these alterations were not encountered when in vivo intravascular perfusion was employed. In view of these studies, and the fact that techniques for perfusion fixation have been established specifically for the rat kidney by Maunsbach, it seemed desirable to employ perfusion fixation to study the fine structure and distribution of microbodies and cytoplasmic bodies within the rat renal proximal tubule.

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