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H Saito - One of the best experts on this subject based on the ideXlab platform.
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distinct characteristics of transcellular transport between nicotine and Tetraethylammonium in llc pk1 cells
Journal of Pharmacology and Experimental Therapeutics, 1998Co-Authors: Kenji Takami, Mikihisa Takano, Masahiro Okuda, H Saito, Kenichi InuiAbstract:To clarify the mechanisms of the renal tubular secretion of nicotine, we studied transport of nicotine in the kidney epithelial cell line LLC-PK1. The transcellular transport of nicotine from the basolateral side to the apical side of the LLC-PK1monolayers grown on membrane filters was much greater than that of Tetraethylammonium. The basolateral-to-apical transport of nicotine was stimulated by lowering the pH of the apical side, accompanied by a decrease in the accumulation of nicotine. The accumulation of nicotine from the basolateral side was inhibited by unlabeled nicotine, cotinine, Tetraethylammonium, cimetidine and quinidine. The uptake of nicotine across the apical membrane was inhibited by unlabeled nicotine and quinidine but not by Tetraethylammonium or cimetidine. Pretreatment with p -chloromercuribenzene sulfonate caused a decrease in the transcellular transport of Tetraethylammonium but not of nicotine. These results suggest that nicotine undergoes vectorial transport from basolateral side to the apical side of LLC-PK1 monolayers in a H+ gradient-dependent manner, corresponding to the secretion in the renal tubules. Nicotine transport in LLC-PK1 cells could be mediated by a transport system that is distinct from the transport system for Tetraethylammonium.
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transcellular transport of organic cation across monolayers of kidney epithelial cell line llc pk
American Journal of Physiology-cell Physiology, 1992Co-Authors: H Saito, K I Inui, M Yamamoto, R HoriAbstract:Transcellular transport and the accumulation of [14C]Tetraethylammonium, a typical organic cation, by LLC-PK1 cell monolayers grown on microporous membrane filters were studied. Tetraethylammonium was accumulated progressively in the monolayers from the basolateral side and was transported unidirectionally to the apical side. The transcellular transport of Tetraethylammonium was saturable, temperature dependent, and sensitive to the pH of the apical side of the monolayers. The apparent Michaelis constant and maximum velocity values for the transport were 67 microM and 222 pmol.mg protein-1.min-1, respectively. Unlabeled Tetraethylammonium, amiloride, procainamide, cimetidine, and choline inhibited the basolateral uptake and transcellular transport of [14C]Tetraethylammonium. The development of Tetraethylammonium transport activity was observed in the differentiating cells. A sulfhydryl reagent inhibited the Tetraethylammonium transport at both the basolateral and apical membranes of the LLC-PK1 cells. These findings suggest that these monolayers possess unidirectional transport systems for organic cations, corresponding to the secretion in the renal proximal tubules.
Krishna Nand Singh - One of the best experts on this subject based on the ideXlab platform.
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An efficient C-C bond cleavage of 1,2-diols using Tetraethylammonium superoxide
Indian Journal of Chemistry Section B-organic Chemistry Including Medicinal Chemistry, 2007Co-Authors: Krishna Nand Singh, Rajesh Kumar, Ajay Kumar ShuklaAbstract:Tetraethylammonium superoxide, generated in situ by the phase-transfer reaction of potassium superoxide and Tetraethylammonium bromide in DMF, brings about an easy cleavage of vicinal diols and related dihydroxy arenes under mild reaction conditions, at room temperature.
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Tetraethylammonium bromide catalysed phase transfer reaction of potassium superoxide with hydrazones and tosylhydrazones
IJC-B Vol.40B(07) [July 2001], 2001Co-Authors: Rajesh Kumar, Krishna Nand SinghAbstract:A variety of hydrazones and tosylhydrazones of carbonyl compounds have been investigated under the mild reaction conditions of potassium superoxide and Tetraethylammonium bromide in dry dimethylformamide. As a result, hydrazones are generally transformed to their corresponding azines whereas tosylhydrazones undergo facile fragmentation to give the olefinic products in fairly good yields. The study highlights the use of Tetraethylammonium bromide as an efficient and inexpensive catalyst for superoxide studies.
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Phase transfer catalysis by Tetraethylammonium bromide: Reaction of potassium superoxide with some acetylated compounds
Indian Journal of Chemical Technology, 2000Co-Authors: Sundaram Singh, Krishna Nand SinghAbstract:The reaction of Tetraethylammonium superoxide (Et 4 NO 2 ) with some acetylated aromatic and heteroaromatic compounds gives the corresponding carboxylic acids under significantly mild conditions. The investigation extends the applicability of Tetraethylammonium bromide (Et 4 NBr) as an efficient phase transfer catalyst.
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Phase transfer catalysis by Tetraethylammonium bromide : Oxidation of primary and secondary alcohols using potassium superoxide in aprotic medium.
Indian Journal of Chemical Technology, 2000Co-Authors: Ajay Kumar Shukla, Krishna Nand SinghAbstract:Tetraethylammonium superoxide, generated in situ by the phase transfer reaction of potassium superoxide and Tetraethylammonium bromide, readily oxidises the primary and secondary alcohols in dry dimethylformamide at room temperature. As a result, primary alcohols are transformed into their corresponding acids whereas secondary alcohols are converted to ketones in fairly good yields. The report demonstrates the applicability of Tetraethylammonium bromide as phase transfer catalyst for efficient superoxide studies.
Kenichi Inui - One of the best experts on this subject based on the ideXlab platform.
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distinct characteristics of transcellular transport between nicotine and Tetraethylammonium in llc pk1 cells
Journal of Pharmacology and Experimental Therapeutics, 1998Co-Authors: Kenji Takami, Mikihisa Takano, Masahiro Okuda, H Saito, Kenichi InuiAbstract:To clarify the mechanisms of the renal tubular secretion of nicotine, we studied transport of nicotine in the kidney epithelial cell line LLC-PK1. The transcellular transport of nicotine from the basolateral side to the apical side of the LLC-PK1monolayers grown on membrane filters was much greater than that of Tetraethylammonium. The basolateral-to-apical transport of nicotine was stimulated by lowering the pH of the apical side, accompanied by a decrease in the accumulation of nicotine. The accumulation of nicotine from the basolateral side was inhibited by unlabeled nicotine, cotinine, Tetraethylammonium, cimetidine and quinidine. The uptake of nicotine across the apical membrane was inhibited by unlabeled nicotine and quinidine but not by Tetraethylammonium or cimetidine. Pretreatment with p -chloromercuribenzene sulfonate caused a decrease in the transcellular transport of Tetraethylammonium but not of nicotine. These results suggest that nicotine undergoes vectorial transport from basolateral side to the apical side of LLC-PK1 monolayers in a H+ gradient-dependent manner, corresponding to the secretion in the renal tubules. Nicotine transport in LLC-PK1 cells could be mediated by a transport system that is distinct from the transport system for Tetraethylammonium.
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Cholesterol modulates organic cation transport activity and lipid fluidity in rat renal brush-border membranes
Biochimica et Biophysica Acta, 1996Co-Authors: Tomohiro Nabekura, Mikihisa Takano, Kenichi InuiAbstract:The role of cholesterol in organic cation transport was studied in rat renal brush-border membranes. H+ gradient-dependent uptake of the organic cation Tetraethylammonium in brush-border membrane vesicles was stimulated by cholesterol enrichment in a dose-dependent manner. The dissipation rate of the H+ gradient, a driving force for organic cation transport in brush-border membranes, was reduced by cholesterol enrichment. Tetraethylammonium uptake in the absence of H+ gradient was also stimulated by cholesterol enrichment. These findings indicate that cholesterol modulates Tetraethylammonium uptake by affecting the intrinsic activity of the organic cation transporter and the H+ gradient dissipation rate. Therefore, cholesterol content should be an important determinant for organic cation transport in renal brush-border membranes.
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Characteristics of organic cation transporter in rat renal basolateral membrane.
Biochimica et Biophysica Acta, 1993Co-Authors: TADAO KATSURA, Masato Yasuhara, Yoshiko Tomita, Mikihisa Takano, Kenichi Inui, Ryohei HoriAbstract:Abstract Characteristics of organic cation transport system were studied in rat renal basolateral membrane and compared with those in brush-border membrane. We first examined the effect of various chemical modifiers on Tetraethylammonium uptake by the membrane vesicles. Treatment with N , N ′-dicyclohexylcarbodiimide and phenylglyoxal (carboxyl groups and arginine residues specific reagent, respectively) resulted in inhibition of Tetraethylammonium transport in both basolateral and brush-border membranes. Tetraethylammonium uptake by brush-border, but not by basolateral, membrane vesicles was decreased by diethyl pyrocarbonate, histidine residues specific reagent, treatment. Treatment of sulfhydryl groups with HgCl 2 decreased Tetraethylammonium transport in both membranes. However, in contrast to brush-border membrane, unlabeled Tetraethylammonium failed to protect against the inhibition of [ 14 C]Tetraethylammonium uptake by p -chloromercuribenzene sulfonate in basolateral membrane. We next examined the inhibitory effect of various organic cations on Tetraethylammonium uptake. The order of inhibitory potency of organic cations was somewhat different between two membranes. These findings suggest that the characteristics of organic cation transport systems in basolateral and brush-border membranes were different in regard to essential amino acid residues and the affinity of substrates.
R Hori - One of the best experts on this subject based on the ideXlab platform.
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transcellular transport of organic cation across monolayers of kidney epithelial cell line llc pk
American Journal of Physiology-cell Physiology, 1992Co-Authors: H Saito, K I Inui, M Yamamoto, R HoriAbstract:Transcellular transport and the accumulation of [14C]Tetraethylammonium, a typical organic cation, by LLC-PK1 cell monolayers grown on microporous membrane filters were studied. Tetraethylammonium was accumulated progressively in the monolayers from the basolateral side and was transported unidirectionally to the apical side. The transcellular transport of Tetraethylammonium was saturable, temperature dependent, and sensitive to the pH of the apical side of the monolayers. The apparent Michaelis constant and maximum velocity values for the transport were 67 microM and 222 pmol.mg protein-1.min-1, respectively. Unlabeled Tetraethylammonium, amiloride, procainamide, cimetidine, and choline inhibited the basolateral uptake and transcellular transport of [14C]Tetraethylammonium. The development of Tetraethylammonium transport activity was observed in the differentiating cells. A sulfhydryl reagent inhibited the Tetraethylammonium transport at both the basolateral and apical membranes of the LLC-PK1 cells. These findings suggest that these monolayers possess unidirectional transport systems for organic cations, corresponding to the secretion in the renal proximal tubules.
Keiko Nishikawa - One of the best experts on this subject based on the ideXlab platform.
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effects of tetramethyl and Tetraethylammonium chloride on h2o calorimetric and near infrared spectroscopic study
Journal of Physical Chemistry B, 2013Co-Authors: Yoshikata Koga, Fumie Sebe, Keiko NishikawaAbstract:The effect of Tetraethylammonium chloride (TEAC) on H2O was investigated by the 1-propanol (1P) probing thermodynamic methodology developed by us earlier. It was found that TEAC is an amphiphile with a small hydrophobic and a dominant hydrophilic contribution. An earlier application of the same 1P-probing methodology to tetramethylammonium chloride (TMAC) indicated that the latter is as hydrophilic as urea without any hydrophobic contribution. The hydrophilic effect of TEAC was found to be about twice stronger than that of TMAC. To investigate further these surprising findings, we applied a new analysis method using the concept of the excess partial molar absorptivity of the solute on the ν2 + ν3 combination band of H2O in the near-infrared (NIR) range of their aqueous solutions. The results confirmed that both salts are indeed strongly hydrophilic toward H2O which manifests itself in the 5123 cm–1 chromophore of the NIR band of H2O. Furthermore, we suggest from the behavior of the 5263 cm–1 band that bot...