Ba<sup>2+</sup>‐sensitive K<sup>+</sup> channels in luminal‐membrane vesicles from pars convoluta of rabbit proximal tubule

Jacobsen, Christian; Røigaard-Petersen, Hans; Sheikh, Mujeeb

doi:10.1016/0014-5793(89)80124-3

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…However, in the proximal tubule there is now direct evidence for the existence of K+ channels both in luminal and basolateral membranes [l-4]. Recently, also nonselective cation channels which discriminate poorly between Na + and K + ions have been observed in luminal membranes [5,6] as well as basolateral membranes [7-91. In a previous paper we characterized K + channels in luminal membranes of rabbit proximal straight tubule (pars recta) [3]. In the present communication we describe the properties of a K+ -selective channel in basolateral membranes from pars convoluta.…”

Section: Introductionmentioning

confidence: 82%

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Potassium channels in basolateral membrane vesicles from pars convoluta of rabbit proximal tubule

Jacobsen¹,

Blokkebak-Poulsen²,

Sheikh³

1990

FEBS Letters

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The characteristics of "Rb+ fluxes through conductive channels in basolateral-membrane vesicles isolated from pars convoluta of rabbit proximal tubule were investigated. In KC1 loaded vesicles a transient accmnulation of "Rb+ was observed which was inhibited by BaC4. The accumulation was driven by an electrical diffusion potential, as shown in experiments using membrane vesicles loaded with LixS04 and an outwardly directed Li+ gradient established with a Li+-ionophote. The vesicles containing the channel showed a cation selectivity with the order K+ = Rb+ > > Li+ 3 Na+ > choline+. The wRb+ flux was dependent on intravesicular Ca 2+ . Increasing concentrations of Ca2+ gradually decreased the =Rb+ uptake.

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Section: Introductionmentioning

confidence: 82%

“…Influx of ssRb+ was measured in K+ (55 mM)-loaded vesicles, analogous to flux-measurement procedures reported previously [3,15]. Dowex AGSOW-X8 columns were prepared in 1 ml tuberculin syringes.…”

Section: Assay Of Rb+ Transportmentioning

confidence: 99%

Potassium channels in basolateral membrane vesicles from pars convoluta of rabbit proximal tubule

Jacobsen¹,

Blokkebak-Poulsen²,

Sheikh³

1990

FEBS Letters

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“…To obtain further information on K ϩ conductances in both the apical and basolateral membranes, 86 Rb ϩ efflux experiments were performed on gill-cell monolayers grown on permeable filters. In various epithelial cells (1,20), 86 Rb ϩ has been shown to be a good indicator for K ϩ movement. Moreover, the substitution of KCl by RbCl in gill cells did not change the whole cell currents induced by the hypotonic shock (data not given).…”

Section: Discussionmentioning

confidence: 99%

Potassium channels in primary cultures of seawater fish gill cells. II. Channel activation by hypotonic shock

Duranton

Mikulovic

Tauc

et al. 2000

American Journal of Physiology-Regulatory, Integrative and Comp

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Previous studies performed on apical membranes of seawater fish gills in primary culture have demonstrated the existence of stretch-activated K(+) channels with a conductance of 122 pS. The present report examines the involvement of K(+) channels in ion transport mechanisms and cell swelling. In the whole cell patch-clamp configuration, K(+) currents were produced by exposing cells to a hypotonic solution or to 1 microM ionomycin. These K(+) currents were inhibited by the addition of quinidine and charybdotoxin to the bath solution. Isotopic efflux measurements were performed on cells grown on permeable supports using (86)Rb(+) as a tracer to indicate potassium movements. Apical and basolateral membrane (86)Rb effluxes were stimulated by the exposure of cells to a hypotonic medium. During the hypotonic shock, the stimulation of (86)Rb efflux on the apical side of the monolayer was inhibited by 500 microM quinidine or 100 microM gadolinium but was insensitive to scorpion venom [Leirus quinquestriatus hebraeus (LQH)]. An increased (86)Rb efflux across the basolateral membrane was also reduced by the addition of quinidine and LQH venom but was not modified by gadolinium. Moreover, basolateral and apical membrane (86)Rb effluxes were not modified by bumetanide or thapsigargin. There is convincing evidence for two different populations of K(+) channels activated by hypotonic shock. These populations can be separated according to their cellular localization (apical or basolateral membrane) and as a function of their kinetic behavior and pharmacology.

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“…In previous papers we have demonstrated K ÷ and Na ÷ ion channels in membrane vesicles isolated from outer cortex (pars convoluta) and outer medulla (pars recta) of rabbit proximal tubule [6][7][8][9].…”

Section: Introductionmentioning

confidence: 94%

GTP‐binding proteins in luminal and basolateral membranes from pars convoluta and pars recta of rabbit kidney proximal tubule

et al. 1992

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The GTP-binding proteins on luminal and basolateral membrane vesicles from outer cortex (pars convoluta) and outer medulla (pars recta) of rabbit proximal tubule have b~n examined. The membrane vesicles were highly purified, as ascertained by electron microscopy, by measurements of marker enzymes, and by investigating seganental-specifie transport systems. The [~SJGTP~,S binding to vesicles, and to sodium cholatc-cxtracted proteins from vesicles, indicated that the total content of GTP-binding proteins were equally distributed on pars convoluta, pars recta luminal and basolateral membranes. The m~mbranes were ADP-ribosylated with [~:P]NAD" in the presence of pertussis toxin and cholera toxin. Gel elec~ro-phoresis revealed, for all preparations, the presence of cholera toxin [~ZP]ADP.ribosylated 42 and 45 kDa Gct, proteins, and pertussis toxin [~:P]ADP-ribosylated 41 kDa G~, 40 kDa G0::. and 41 kDa G~ proteins. The 2D electrophoresis indicated that G,,'s were not present in luminal nor in basolateral membranes of pars convoluta or pars recta of rabbit proximal tubule. G-protein; Proximal tubule

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Ba²⁺‐sensitive K⁺ channels in luminal‐membrane vesicles from pars convoluta of rabbit proximal tubule

Cited by 6 publications

References 14 publications

Potassium channels in basolateral membrane vesicles from pars convoluta of rabbit proximal tubule

Potassium channels in basolateral membrane vesicles from pars convoluta of rabbit proximal tubule

Potassium channels in primary cultures of seawater fish gill cells. II. Channel activation by hypotonic shock

GTP‐binding proteins in luminal and basolateral membranes from pars convoluta and pars recta of rabbit kidney proximal tubule

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Ba2+‐sensitive K+ channels in luminal‐membrane vesicles from pars convoluta of rabbit proximal tubule

Cited by 6 publications

References 14 publications

Potassium channels in basolateral membrane vesicles from pars convoluta of rabbit proximal tubule

Potassium channels in basolateral membrane vesicles from pars convoluta of rabbit proximal tubule

Potassium channels in primary cultures of seawater fish gill cells. II. Channel activation by hypotonic shock

GTP‐binding proteins in luminal and basolateral membranes from pars convoluta and pars recta of rabbit kidney proximal tubule

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Ba²⁺‐sensitive K⁺ channels in luminal‐membrane vesicles from pars convoluta of rabbit proximal tubule