A transient outward cationic current activated by Na+ influx into frog visual neurones in vitro.
Whole cell patch clamp recording from neurones of a slice preparation of the frog optic tectum showed that depolarizing step commands from -70 mV holding potential generated a fast inward current always followed by a fast outward current. The fast outward current was blocked by tetrodotoxin (TTX) or 4-aminopyridine (4-AP), or by replacing external Na+ with Li+. When the patch pipette contained Cs+ instead of K+ the outward current was fully preserved, suggesting that the membrane channels responsible for this response were relatively non-selective in their permeability properties. This current (termed Icat) is a novel example of a non-specific cationic current dependent on influx of Na+ and presumably important to control the firing characteristics of these cells.
Zaykin
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Biophysics Laboratory, International School for Advanced Studies (S.I.S.S.A.) Trieste, Italy.
Nistri
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D000818:Animals; D002412:Cations / Q000378:metabolism*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011896:Rana temporaria; D012964:Sodium / Q000378:metabolism*; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014795:Visual Pathways / Q000502:physiology*
D002412:Cations; D013779:Tetrodotoxin; D012964:Sodium