title: The effect of vanadate on the electrogenic Na+/K+ pump, intracellular Na+ concentration and electrophysiological characteristics of mouse skeletal muscle fibre.
abstract: The present study reports a discrepancy between the effects of vanadate on the membrane Na+-K+-ATPase and the Na+/K+ pump of the skeletal muscle. Vanadate in concentration 4 X 10(-6) mol/l which is necessary to block the enzyme Na+-K+-ATPase activity of membrane fractions failed to inhibit the electrogenic Na+/K+ pump of intact muscle cells. The effect of vanadate on the electrophysiological parameters of the muscle fibre membrane required much higher vanadate levels, but again, Na+/K+ pump was still active. Vanadate in concentrations 4 X 10(-4) and 4 X 10(-5) mol/l depolarized the membrane potential and decreased the membrane resistance [apparently in consequence of enhanced passive membrane permeability for Na+ ions]. Action potentials and the electrical excitability of the muscle fibre membrane were reduced by these vanadate concentrations.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003964:Diaphragm / Q000378:metabolism; D004594:Electrophysiology; D005260:Female; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009132:Muscles / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
chemical_list: D014639:Vanadium; D014638:Vanadates; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium