Ca2+ -activated nonselective cation channels in rat neonatal atrial myocytes.
A nonselective cation channel activated by intracellular Ca(2+) was identified in inside-out membrane patches taken from cultured rat atrial myocytes. Ca(2+) (0.01-1.00 m M) reversibly activated the channel in a concentration-dependent manner. The channel often showed a quick and irreversible rundown within a few minutes after patch excision. The I-V relationship of the channel was linear between -100 and +100 mV. The single channel conductance was 26.0 +/- 0.5 pS and its open probability was weakly voltage-dependent. Ion-substitution experiments showed that the channel was permeable to monovalent cations (P(x)/P(Cs): Li(+) (1.5) = K(+) (1.5) > Na(+) (1.2) > Rb(+) (1.1) > Cs(+) (1.0)) but not to Cl(-) (P(Cl)/P(Cs) < 0.01) and Ca(2+) (P(Ca)/P(Cs) = 0.02 +/- 0.01).
Zhainazarov
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AB
Department of Cardiology, Children's Hospital, 320 Longwood Avenue, Boston, MA 02115, USA. abz@ufbi.ufl.edu
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D002478:Cells, Cultured; D002586:Cesium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D006325:Heart Atria / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D008672:Metals, Alkali / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats
D002412:Cations; D002712:Chlorides; D007473:Ion Channels; D008672:Metals, Alkali; D002586:Cesium; D002118:Calcium