scholarly journals Sodium-dependent transport of sugars and iodide from the cerebral ventricles of the rabbit

1973 ◽  
Vol 234 (1) ◽  
pp. 127-143 ◽  
Author(s):  
M. W. B. Bradbury ◽  
Hans E. Brøndsted
Keyword(s):  
Cerebral Ventricles ◽  
Sodium Dependent ◽  
Dependent Transport

scholarly journals Sodium-dependent transport of ascorbic acid in U937 cell mitochondria

IUBMB Life ◽  
2013 ◽  
Vol 65 (2) ◽  
pp. 149-153 ◽  
Author(s):  
Catia Azzolini ◽  
Mara Fiorani ◽  
Liana Cerioni ◽  
Andrea Guidarelli ◽  
Orazio Cantoni
Keyword(s):  
Ascorbic Acid ◽  
U937 Cell ◽  
Sodium Dependent ◽  
Dependent Transport

scholarly journals Perfluoroalkyl Carboxylic Acids Interact with the Human Bile Acid Transporter NTCP

Livers ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 221-229
Author(s):  
Melissa J. Ruggiero ◽  
Haley Miller ◽  
Jessica Y. Idowu ◽  
Jeremiah D. Zitzow ◽  
Shu-Ching Chang ◽  
...  
Keyword(s):  
Competitive Inhibition ◽  
Enterohepatic Circulation ◽  
Human Bile ◽  
Human Embryonic Kidney Cells ◽  
Elimination Half ◽  
Sodium Dependent ◽  
Km Value ◽  
Bile Acid Transporter ◽  
Dependent Transport ◽  
Chain Lengths

Na+/taurocholate cotransporting polypeptide (NTCP) is important for the enterohepatic circulation of bile acids, which has been suggested to contribute to the long serum elimination half-lives of perfluoroalkyl substances in humans. We demonstrated that some perfluoroalkyl sulfonates are transported by NTCP; however, little was known about carboxylates. The purpose of this study was to determine if perfluoroalkyl carboxylates would interact with NTCP and potentially act as substrates. Sodium-dependent transport of [3H]-taurocholate was measured in human embryonic kidney cells (HEK293) stably expressing NTCP in the absence or presence of perfluoroalkyl carboxylates with varying chain lengths. PFCAs with 8 (PFOA), 9 (PFNA), and 10 (PFDA) carbons were the strongest inhibitors. Inhibition kinetics demonstrated competitive inhibition and indicated that PFNA was the strongest inhibitor followed by PFDA and PFOA. All three compounds are transported by NTCP, and kinetics experiments revealed that PFOA had the highest affinity for NTCP with a Km value of 1.8 ± 0.4 mM. The Km value PFNA was estimated to be 5.3 ± 3.5 mM and the value for PFDA could not be determined due to limited solubility. In conclusion, our results suggest that, in addition to sulfonates, perfluorinated carboxylates are substrates of NTCP and have the potential to interact with NTCP-mediated transport.

scholarly journals Renal and small intestinal sodium-dependent symporters of phosphate and sulphate.

1994 ◽  
Vol 196 (1) ◽  
pp. 167-181
Author(s):  
H Murer ◽  
D Markovich ◽  
J Biber
Keyword(s):  
Apical Membrane ◽  
Transport Systems ◽  
Expression Cloning ◽  
Control Mechanisms ◽  
Intestinal Epithelial ◽  
Physiological Conditions ◽  
Sodium Dependent ◽  
Proximal Tubular ◽  
Small Intestinal ◽  
Dependent Transport

Homeostasis of inorganic phosphate (P(i)) and sulphate (Si) is largely achieved by absorption in the mammalian small intestine and by reabsorption in the proximal tubule of the kidney. Under normal physiological conditions, the kidney appears to play the major role in maintaining the extracellular concentration of these anions. In both epithelia, reabsorption of P(i) and to some extent also of Si underlie a variety of regulatory acute and chronic control mechanisms. Acute regulatory mechanisms are predominantly found in renal P(i) reabsorption, whereas chronic regulation of transepithelial P(i) transport is observed in both tissues. Also, in both epithelia, apically located sodium-dependent transport systems (Na+/P(i) and Na+/Si symport) represent major targets for known regulatory factors. By expression cloning using oocytes of Xenopus laevis, renal and small intestinal Na(+)-dependent phosphate and sulphate transport systems have been identified. Evidence has been obtained that cloned Na+/P(i) and Na+/Si symporters are localized in the apical membrane of proximal tubular or small intestinal epithelial cells respectively. Furthermore, recent results indicate that one of the cloned Na+/P(i) symporters is involved in the physiological and pathophysiological regulation of proximal tubular P(i) reabsorption.

Cystine dimethyl ester reduces the forces driving sodium-dependent transport in LLC-PK1 cells

1992 ◽  
Vol 263 (2) ◽  
pp. C516-C520 ◽  
Author(s):  
A. Ben-Nun ◽  
N. Bashan ◽  
R. Potashnik ◽  
R. Cohen-Luria ◽  
A. Moran
Keyword(s):  
Potassium Concentration ◽  
Dimethyl Ester ◽  
Maximal Velocity ◽  
Intact Cells ◽  
Sodium Gradient ◽  
Sodium Dependent ◽  
Rubidium Influx ◽  
Significant Change ◽  
Dependent Transport ◽  
Intracellular Potassium Concentration

Cystinosis is an inherited metabolic disease characterized by accumulation of lysosomal cystine and renal impairment. In an attempt to better understand the link between cystine accumulation and renal functions, we studied the effects of cystine loading on the Na(+)-H+ antiporter and the sodium pump in renal epithelial cells (LLC-PK1) in culture. Incubation of LLC-PK1 with 1 mM cystine dimethyl ester (CDME) for 48 h caused lysosomal cystine loading and reduced by 22 +/- 2% the maximal velocity of sodium-hydrogen antiport with no significant change in the affinity of sodium for the transporter. Rubidium influx decreased to 46 +/- 5% of control. Ouabain binding experiments revealed a 10% reduction in the number of Na(+)-K(+)-ATPase units in the intact cells. Na(+)-K(+)-ATPase activity in the particulate fraction of the cells homogenate declined to 50 +/- 7.5% of controls. No significant change was observed in the activity of ouabain-insensitive phosphatases. The intracellular concentration of sodium increased from 20.6 +/- 3.7 to 64.8 +/- 10 mM, and potassium concentration decreased from 103 +/- 6 to 80 +/- 13 mM. In addition to the observed reduction in the sodium gradient and in agreement with the reduction in the intracellular potassium concentration, the membrane potential changed from -80.8 +/- 7.5 to -69.9 +/- 7.0 mV. The results suggest that intracellular accumulation of cystine is associated with reduction in the number and the activity of membrane transporters. The consequence of the changes in the activity of Na(+)-K(+)-ATPase is a reduction in the electrochemical forces that drive transport in the renal cells tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Brush border membrane proteins in experimental Fanconi's syndrome induced by 4-pentenoate and maleate

1992 ◽  
Vol 70 (9) ◽  
pp. 1247-1253 ◽  
Author(s):  
Jean-François Pouliot ◽  
André Gougoux ◽  
Richard Béliveau
Keyword(s):  
Protein Phosphorylation ◽  
Brush Border ◽  
Time Course ◽  
Brush Border Membrane ◽  
Transport Systems ◽  
Molecular Defect ◽  
Fanconi’S Syndrome ◽  
Sodium Dependent ◽  
Dependent Transport ◽  
Fanconi's Syndrome

Fanconi's syndrome was investigated using brush border membrane (BBM) vesicles isolated from dog kidney. Sodium-dependent uptake of glucose, phosphate, and amino acids and protein phosphorylation were studied in BBM isolated from normal and from 4-pentenoate- and maleate-treated animals. The time course of D-glucose and phosphate uptake, in BBM vesicles, remained unchanged, indicating that both treatments had no effect on carrier properties, and that permeabilities to these substrates and to sodium were not modified. Furthermore, sodium-dependent transport of alanine, phenylalanine, proline, glycine, and glutamate into vesicles remained unaltered by either treatment. 4-Pentenoate treatment caused modifications of the phosphorylation pattern of BBM proteins: the phosphorylation of two proteins (61 and 74 kDa) was increased and that of two others (48 and 53 kDa) was decreased. Maleate treatment caused an increase in the phosphorylation for the same 61-kDa protein, which was also affected by 4-pentenoate treatment, suggesting that phosphorylation of this protein could be related to a mechanism involved in both 4-pententoate- and maleate-induced Fanconi's syndrome. These changes were also observed in the presence of sodium fluoride and L-bromotetramisole, indicating that the modification of phosphorylation was not due to a difference in phosphatase activities. These results suggest that Fanconi's syndrome induced by 4-pentenoate or maleate is not caused by an inhibition of BBM Na+-dependent transport systems. Our results also suggest that protein phosphorylation may play an important role in the molecular defect involved in Fanconi's syndrome.Key words: Fanconi's syndrome, 4-pentenoate, maleate, transport, phosphorylation.

Sodium-dependent transport activity for l-DOPA in Xenopus laevis oocyte injected with polya+ RNA from rabbit intestinal epithelium

1998 ◽  
Vol 31 ◽  
pp. S90
Author(s):  
Hiroyuki Ishii ◽  
Yoshio Goshima ◽  
Yukio Sasaki ◽  
Dai Ayusawa ◽  
Yosikatsu Kanai ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Intestinal Epithelium ◽  
Xenopus Laevis Oocyte ◽  
Transport Activity ◽  
Sodium Dependent ◽  
Dependent Transport
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