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cAMP-activation of amiloride-sensitive Na+ channels from guinea-pig colon expressed in Xenopus oocytes.
Liebold KM
,
Reifarth FW
,
Clauss W
,
Weber W
.
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Guinea-pig distal colonic mRNA injection into Xenopus laevis oocytes resulted in expression of functional active epithelial Na+ channels in the oocyte plasma membrane. Poly(A)+ RNA was extracted from distal colonic mucosa of animals fed either a high-salt (HS) or a low-salt (LS) diet. The electrophysiological properties of the expressed amiloride-sensitive Na+ conductances were investigated by conventional two-electrode voltage-clamp and patch-clamp measurements. Injection of poly(A)+ RNA from HS-fed animals [from hereon referred to as HS-poly(A)+ RNA] into oocytes induced the expression of amiloride-sensitive Na+ conductances. On the other hand, oocytes injected with poly(A)+ RNA from LS-fed animals [LS-poly(A)+ RNA] expressed a markedly larger amount of amiloride-blockable Na+ conductances. LS-poly(A)+ RNA-induced conductances were completely inhibitable by amiloride with a Ki of 77 nM, and were also blocked by benzamil with a Ki of 1.8 nM. 5-(N-Ethyl-N-isopropyl)-amiloride (EIPA), even in high doses (25 "mu"M), had no detectable effect on the Na+ conductances. Expressed amiloride-sensitive Na+ channels could be further activated by cAMP leading to nearly doubled clamp currents. When Na+ was replaced by K+, amiloride (1 "mu"M) showed no effect on the clamp current. Single-channel analysis revealed slow gating behaviour, open probabilities (Po) between 0.4 and 0.9, and slope conductances of 3. 8 pS for Na+ and 5.6 pS for Li+. The expressed channels showed to be highly selective for Na+ over K+ with a permeability ratio PNa/PK > 20. Amiloride (500 nM) reduced channel Po to values < 0.05. All these features make the guinea-pig distalcolon of LS-fed animals an interesting mRNA source for the expression of highly amiloride-sensitive Na+ channels in Xenopus oocytes, which could provide new insights in the regulatory mechanism of these channels.
Asher,
NaCl-dependent expression of amiloride-blockable Na+ channel in Xenopus oocytes.
1992, Pubmed,
Xenbase
Asher,
NaCl-dependent expression of amiloride-blockable Na+ channel in Xenopus oocytes.
1992,
Pubmed
,
Xenbase
Canessa,
Amiloride-sensitive epithelial Na+ channel is made of three homologous subunits.
1994,
Pubmed
,
Xenbase
Canessa,
Epithelial sodium channel related to proteins involved in neurodegeneration.
1993,
Pubmed
,
Xenbase
Cathala,
A method for isolation of intact, translationally active ribonucleic acid.
1983,
Pubmed
Clauss,
Modulation of Na and Cl transport by mineralocorticoids.
1988,
Pubmed
Clauss,
Characterization of conductive pathways in guinea pig distal colon in vitro.
1985,
Pubmed
Dumont,
Oogenesis in Xenopus laevis (Daudin). I. Stages of oocyte development in laboratory maintained animals.
1972,
Pubmed
,
Xenbase
Garty,
Characteristics and regulatory mechanisms of the amiloride-blockable Na+ channel.
1988,
Pubmed
Garty,
Mechanisms of aldosterone action in tight epithelia.
1986,
Pubmed
Goldman,
POTENTIAL, IMPEDANCE, AND RECTIFICATION IN MEMBRANES.
1943,
Pubmed
Hamill,
Amiloride: a molecular probe for mechanosensitive channels.
1992,
Pubmed
Kleyman,
Amiloride and its analogs as tools in the study of ion transport.
1988,
Pubmed
Lingueglia,
Expression cloning of an epithelial amiloride-sensitive Na+ channel. A new channel type with homologies to Caenorhabditis elegans degenerins.
1993,
Pubmed
,
Xenbase
Merlin,
Ca2+ and cAMP activate different K+ conductances in the human intestinal goblet cell line HT29-Cl.16E.
1995,
Pubmed
Palmer,
Amiloride-sensitive Na channels from the apical membrane of the rat cortical collecting tubule.
1986,
Pubmed
Palmer,
Epithelial Na channels: function and diversity.
1992,
Pubmed
Palmer,
Ion selectivity of epithelial Na channels.
1987,
Pubmed
Rechkemmer,
Effects of a low-sodium diet on electrolyte transport in the proximal and distal colon of the guinea pig (Cavia porcellus).
1992,
Pubmed
Reifarth,
Voltage- and Ca(2+)-dependence of the K+ channel in the vacuolar membrane of Chenopodium rubrum L. suspension cells.
1994,
Pubmed
Renard,
Localization and regulation by steroids of the alpha, beta and gamma subunits of the amiloride-sensitive Na+ channel in colon, lung and kidney.
1995,
Pubmed
Schild,
A mutation in the epithelial sodium channel causing Liddle disease increases channel activity in the Xenopus laevis oocyte expression system.
1995,
Pubmed
,
Xenbase
Smith,
Epithelial Na+ channels.
1991,
Pubmed
Towle,
Characterization of an endogenous Na+/H+ antiporter in Xenopus laevis oocytes.
1991,
Pubmed
,
Xenbase
Weber,
Amiloride-sensitive Na+ conductance in native Xenopus oocytes.
1995,
Pubmed
,
Xenbase
Weber,
Endogenous D-glucose transport in oocytes of Xenopus laevis.
1989,
Pubmed
,
Xenbase
Weber,
The Ca(2+)-induced leak current in Xenopus oocytes is indeed mediated through a Cl- channel.
1995,
Pubmed
,
Xenbase
Weber,
Influence of extracellular Ca2+ on endogenous Cl- channels in Xenopus oocytes.
1995,
Pubmed
,
Xenbase
Weber,
Regulation of electrogenic Na+ transport across leech skin.
1995,
Pubmed
Weber,
Comparison of a Na+/D-glucose cotransporter from rat intestine expressed in oocytes of Xenopus laevis with the endogenous cotransporter.
1991,
Pubmed
,
Xenbase
Weber,
Expression of amiloride-sensitive Na+ channels of hen lower intestine in Xenopus oocytes: electrophysiological studies on the dependence of varying NaCl intake.
1992,
Pubmed
,
Xenbase
Yang,
Block of stretch-activated ion channels in Xenopus oocytes by gadolinium and calcium ions.
1989,
Pubmed
,
Xenbase