Gating properties of single SK channels in hippocampal CA1 pyramidal neurons.
The activation of small-conductance calcium-activated potassium channels (SK) has a profound effect on membrane excitability. In hippocampal pyramidal neurons, SK channel activation by Ca2+ entry from a preceding burst of action potentials generates the slow afterhyperpolarization (AHP). Stimulation of a number of receptor types suppresses the slow AHP, inhibiting spike frequency adaptation and causing these neurons to fire tonically. Little is known of the gating properties of native SK channels in CNS neurons. By using excised inside-out patches, a small-amplitude channel has been resolved that was half-activated by approximately 0.6 microM Ca2+ in a voltage-independent manner. The channel possessed a slope conductance of 10 pS and exhibited nonstationary gating. These properties are in accord with those of cloned SK channels. The measured Ca2+ sensitivity of hippocampal SK channels suggests that the slow AHP is generated by activation of SK channels from a local rise of intracellular Ca2+.
Hirschberg
B
B
Vollum Institute, Oregon Health Sciences University, Portland, Oregon 97201 USA.
Maylie
J
J
Adelman
J P
JP
Marrion
N V
NV
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D004553:Electric Conductivity; D006624:Hippocampus / Q000166:cytology*; D015640:Ion Channel Gating / Q000187:drug effects; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051640:Small-Conductance Calcium-Activated Potassium Channels
D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D051640:Small-Conductance Calcium-Activated Potassium Channels; D002118:Calcium