Ultracytochemical localisation of Na+, K+-ATPase in cerebral endothelium in acute hypertension

Nag, S.

doi:10.1007/bf00294215

Cited by 28 publications

(8 citation statements)

References 26 publications

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“…Alkaline phosphatase was asymmetrically distributed and enriched predominantly in the 30% membrane fraction (17‐fold). Mg 2+ ‐ATPase was enriched uniformly in both the 30% and the 38% fractions (2.5‐ and 1.6‐fold, respectively), whereas low‐ouabain affinity Na + ,K + ‐ATPase was selectively enriched in the 30% fraction (16‐fold), as reported earlier (Nag, 1990; Sanchez del Pino et al, 1995). With the exception of succinic dehydrogenase (a mitochondrial marker) in the 38% fraction, the subfractions were minimally contaminated by lysosomes (acid phosphatase), endoplasmic reticulum (glucose 6‐phosphatase), and mitochondria (30% fraction).…”

Section: Expression Of Gsh Uptake In Xenopus Laevis Oocytessupporting

confidence: 83%

GSH Transport in Immortalized Mouse Brain Endothelial Cells

Kannan¹,

Mittur²,

Bao³

et al. 1999

Journal of Neurochemistry

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Abstract:We have previously shown GSH transport across the blood-brain barrier in vivo and expression of transport in Xenopus laevis oocytes injected with bovine brain capillary mRNA. In the present study, we have used MBEC-4, an immortalized mouse brain endothelial cell line, to establish the presence of Na ϩ -dependent and Na ϩ -independent GSH transport and have localized the Na ϩ -dependent transporter using domain-enriched plasma membrane vesicles. In cells depleted of GSH with buthionine sulfoximine, a significant increase of intracellular GSH could be demonstrated only in the presence of Na ϩ . Partial but significant Na ϩ dependency of [ 35 S]GSH uptake was observed for two GSH concentrations in MBEC-4 cells in which ␥-glutamyltranspeptidase and ␥-glutamylcysteine synthetase were inhibited to ensure absence of breakdown and resynthesis of GSH. Uniqueness of Na ϩ -dependent uptake in MBEC-4 cells was confirmed with parallel uptake studies with Cos-7 cells that did not show this activity. Molecular form of uptake was verified as predominantly GSH, and very little conversion of [35 S]cysteine to GSH occurred under the same incubation conditions. Poly(A) ϩ RNA from MBEC expressed GSH uptake with significant (ϳ40 -70%) Na ϩ dependency, whereas uptake expressed by poly(A) ϩ RNA from HepG2 and Cos-1 cells was Na ϩ independent. Plasma membrane vesicles from MBEC were separated into three fractions (30, 34, and 38% sucrose, by wt) by density gradient centrifugation. Na ϩ -dependent glucose transport, reported to be localized to the abluminal membrane, was found to be associated with the 38% fraction (abluminal). Na ϩ -dependent GSH transport was present in the 30% fraction, which was identified as the apical (luminal) membrane by localization of P-glycoprotein 170 by western blot analysis. Localization of Na ϩ -dependent GSH transport to the luminal membrane and its ability to drive up intracellular GSH may find application in the delivery of supplemented GSH to the brain in vivo. Key Words: Blood-brain barrier-Mouse brain endothelial cells-Glutathione -Transport-Membrane vesiclesSodium dependence.

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Section: Expression Of Gsh Uptake In Xenopus Laevis Oocytessupporting

confidence: 83%

GSH Transport in Immortalized Mouse Brain Endothelial Cells

Kannan¹,

Mittur²,

Bao³

et al. 1999

Journal of Neurochemistry

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“…The electrogenic Na + /K + ATPase contributes ≈−8 mV to the resting potential of ECs (30, 103,120). Pump activity may also modulate oscillations in intracellular free Ca 2+ because blockade of the pump facilitates agonist-induced, synchronized Ca 2+ oscillations in confluent ECs (81).…”

Section: Membrane Potential and Electrogenic Pumpsmentioning

confidence: 99%

Ion Channels in Vascular Endothelium

Nilius

Viana

Droogmans

1997

Annu. Rev. Physiol.

266

194

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The functional impact of ion channels in vascular endothelial cells (ECs) is still a matter of controversy. This review describes different types of ion channels in ECs and their role in electrogenesis, Ca2+ signaling, vessel permeability, cell-cell communication, mechano-sensor functions, and pH and volume regulation. One major function of ion channels in ECs is the control of Ca2+ influx either by a direct modulation of the Ca2+ influx pathway or by indirect modulation of K+ and Cl- channels, thereby clamping the membrane at a sufficiently negative potential to provide the necessary driving force for a sustained Ca2+ influx. We discuss various mechanisms of Ca2+ influx stimulation: those that activate nonselective, Ca(2+)-permeable cation channels or those that activate Ca(2+)-selective channels, exclusively or partially operated by the filling state of intracellular Ca2+ stores. We also describe the role of various Ca(2+)- and shear stress-activated K+ channels and different types of Cl- channels for the regulation of the membrane potential.

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“…These transport systems play important role in the active secretion of fluid from blood to brain and in maintaining a constant concentration of ions in the brain's interstitial fluid [ 120 ]. Further, to perform major physiological functions, exchange of important metal ions such as K + and Na + takes place very fast from blood to tissues, but it shows slow rate when entered into the brain [ 41 , 121 ]. More specifically, Na + exchange across the blood brain barrier takes place by carrier-mediated transport [ 120 ], mainly by brain capillary Na + , K + ATPase system [ 122 ].…”

Section: Endothelial Transportmentioning

confidence: 99%

Transendothelial Transport and Its Role in Therapeutics

Upadhyay

2014

International Scholarly Research Notices

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Present review paper highlights role of BBB in endothelial transport of various substances into the brain. More specifically, permeability functions of BBB in transendothelial transport of various substances such as metabolic fuels, ethanol, amino acids, proteins, peptides, lipids, vitamins, neurotransmitters, monocarbxylic acids, gases, water, and minerals in the peripheral circulation and into the brain have been widely explained. In addition, roles of various receptors, ATP powered pumps, channels, and transporters in transport of vital molecules in maintenance of homeostasis and normal body functions have been described in detail. Major role of integral membrane proteins, carriers, or transporters in drug transport is highlighted. Both diffusion and carrier mediated transport mechanisms which facilitate molecular trafficking through transcellular route to maintain influx and outflux of important nutrients and metabolic substances are elucidated. Present review paper aims to emphasize role of important transport systems with their recent advancements in CNS protection mainly for providing a rapid clinical aid to patients. This review also suggests requirement of new well-designed therapeutic strategies mainly potential techniques, appropriate drug formulations, and new transport systems for quick, easy, and safe delivery of drugs across blood brain barrier to save the life of tumor and virus infected patients.

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Ultracytochemical localisation of Na+, K+-ATPase in cerebral endothelium in acute hypertension

Cited by 28 publications

References 26 publications

GSH Transport in Immortalized Mouse Brain Endothelial Cells

GSH Transport in Immortalized Mouse Brain Endothelial Cells

Ion Channels in Vascular Endothelium

Transendothelial Transport and Its Role in Therapeutics

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