Abstract
Palytoxin stimulated a cation-dependent short-circuit current (Isc) in rat distal and proximal colon in a concentration-dependent fashion when applied to the mucosal surface of the tissue. The distal colon exhibited a higher sensitivity to the toxin. The palytoxin-induced Isc was blocked by vanadate but was resistant to ouabain or scilliroside, suggesting the conversion of a vanadate-sensitive H+/K+-ATPase into an electrogenic cation transporter. Cation substitution experiments with basolaterally depolarized tissues suggested an apparent permeability of the palytoxin-induced conductance of Na+>K+>Li+. Immunohistochemical control experiments confirmed the absence of the Na+/K+-ATPase in the apical membrane. Consequently, the pore-forming action of palytoxin is not restricted to Na+/K+-ATPase but is also observed with the colonic H+/K+-ATPase.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acrylamides / pharmacology*
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Animals
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Borates / pharmacology
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Bufanolides / pharmacology
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Cell Membrane Permeability / drug effects*
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Cnidarian Venoms / pharmacology*
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Colon / drug effects*
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Colon / enzymology
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Enzyme Inhibitors / pharmacology
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H(+)-K(+)-Exchanging ATPase / drug effects*
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Intestinal Mucosa / drug effects
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Intestinal Mucosa / enzymology
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Ion Channels / drug effects*
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Ion Transport / drug effects*
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Lithium / metabolism
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Membrane Potentials / drug effects*
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Ouabain / pharmacology
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Potassium / metabolism
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Proton Pumps / drug effects*
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Rats
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Rats, Wistar
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Sodium / metabolism
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Sodium-Potassium-Exchanging ATPase / analysis
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Vanadates / pharmacology
Substances
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Acrylamides
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Borates
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Bufanolides
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Cnidarian Venoms
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Enzyme Inhibitors
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Ion Channels
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Proton Pumps
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scilliroside
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Vanadates
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Ouabain
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Lithium
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Sodium
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H(+)-K(+)-Exchanging ATPase
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Sodium-Potassium-Exchanging ATPase
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palytoxin
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Potassium