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Calcium influx via L- and N-type calcium channels activates a transient large-conductance Ca2+-activated K+ current in mouse neocortical pyramidal neurons.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Sun, Xiaolu Gu, Xiang Qun Haddad, Gabriel G. |
| Copyright Year | 2003 |
| Abstract | Ca2+-activated K+ currents and their Ca2+ sources through high-threshold voltage-activated Ca2+ channels were studied using whole-cell patch-clamp recordings from freshly dissociated mouse neocortical pyramidal neurons. In the presence of 4-aminopyridine, depolarizing pulses evoked transient outward currents and several components of sustained currents in a subgroup of cells. The fast transient current and a component of the sustained currents were Ca2+ dependent and sensitive to charybdotoxin and iberiotoxin but not to apamin, suggesting that they were mediated by large-conductance Ca2+-activated K+ (BK) channels. Thus, mouse neocortical neurons contain both inactivating and noninactivating populations of BK channels. Blockade of either L-type Ca2+ channels by nifedipine or N-type Ca2+ channels by omega-conotoxin GVIA reduced the fast transient BK current. These data suggest that the transient BK current is activated by Ca2+ entry through both N- and L-type Ca2+ channels. The physiological role of the fast transient BK current was also examined using current-clamp techniques. Iberiotoxin broadened action potentials (APs), indicating a role of BK current in AP repolarization. Similarly, both the extracellular Ca2+ channel blocker Cd2+ and the intracellular Ca2+ chelator BAPTA blocked the transient component of the outward current and broadened APs in a subgroup of cells. Our results indicate that the outward current in pyramidal mouse neurons is composed of multiple components. A fast transient BK current is activated by Ca2+ entry through high-threshold voltage-activated Ca2+ channels (L- and N-type), and together with other voltage-gated K+ currents, this transient BK current plays a role in AP repolarization. |
| Starting Page | 3891 |
| Ending Page | 3895 |
| Page Count | 5 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.jneurosci.org/content/jneuro/23/9/3639.full.pdf |
| PubMed reference number | 12736335v1 |
| Volume Number | 23 |
| Issue Number | 9 |
| Journal | The Journal of neuroscience : the official journal of the Society for Neuroscience |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Action Potentials Apamin BK Virus Calcium Channel Calcium ion Charybdotoxin Conotoxin N-type calcium channels Nifedipine Potassium Pyramidal Cells Subgroup A Nepoviruses dalfampridine iberiotoxin omega-Conotoxin GVIA omega-Conotoxins |
| Content Type | Text |
| Resource Type | Article |
