Loading...
Please wait, while we are loading the content...
Similar Documents
Gating of Recombinant Small-Conductance Ca-activated K+ Channels by Calcium
| Content Provider | Scilit |
|---|---|
| Author | Hirschberg, Birgit Maylie, James Adelman, John P. Marrion, Neil V. |
| Copyright Year | 1998 |
| Description | Journal: The Journal of general physiology Small-conductance Ca-activated $K^{+}$ channels play an important role in modulating excitability in many cell types. These channels are activated by submicromolar concentrations of intracellular $Ca^{2+}$, but little is known about the gating kinetics upon activation by $Ca^{2+}$. In this study, single channel currents were recorded from Xenopus oocytes expressing the apamin-sensitive clone rSK2. Channel activity was detectable in 0.2 μM $Ca^{2+}$ and was maximal above 2 μM $Ca^{2+}$. Analysis of stationary currents revealed two open times and three closed times, with only the longest closed time being Ca dependent, decreasing with increasing $Ca^{2+}$ concentrations. In addition, elevated $Ca^{2+}$ concentrations resulted in a larger percentage of long openings and short closures. Membrane voltage did not have significant effects on either open or closed times. The open probability was ∼0.6 in 1 μM free $Ca^{2+}$. A lower open probability of ∼0.05 in 1 μM $Ca^{2+}$ was also observed, and channels switched spontaneously between behaviors. The occurrence of these switches and the amount of time channels spent displaying high open probability behavior was $Ca^{2+}$ dependent. The two behaviors shared many features including the open times and the short and intermediate closed times, but the low open probability behavior was characterized by a different, long $Ca^{2+}$-dependent closed time in the range of hundreds of milliseconds to seconds. Small-conductance Ca- activated $K^{+}$ channel gating was modeled by a gating scheme consisting of four closed and two open states. This model yielded a close representation of the single channel data and predicted a macroscopic activation time course similar to that observed upon fast application of $Ca^{2+}$ to excised inside-out patches. |
| Related Links | http://jgp.rupress.org/content/111/4/565.full.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217120/pdf http://jgp.rupress.org/content/jgp/111/4/565.full.pdf |
| ISSN | 00221295 |
| DOI | 10.1085/jgp.111.4.565 |
| Journal | The Journal of general physiology |
| Issue Number | 4 |
| Volume Number | 111 |
| Language | English |
| Publisher | Rockefeller University Press |
| Publisher Date | 1998-04-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: The Journal of general physiology Potassium Channel Calcium-activated Single Channel Afterhyperpolarization |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physiology |
