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Rat supraoptic magnocellular neurones show distinct large conductance, Ca$ ^{2+}$ ‐activated K$ ^{+}$ channel subtypes in cell bodies versus nerve endings
| Content Provider | Scilit |
|---|---|
| Author | Dopico, Alejandro M. Widmer, Hélène Wang, Gang Lemos, José R. Treistman, Steven N. |
| Copyright Year | 1999 |
| Description | Journal: The Journal of physiology 1 Large conductance, $Ca^{2+}$-activated $K^{+}$ (BK) channels were identified in freshly dissociated rat supraoptic neurones using patch clamp techniques. 2 The single channel conductance of cell body BK channels, recorded from inside-out patches in symmetric 145 mM $K^{+}$, was 246.1 pS, compared with 213 pS in nerve ending BK channels (P < 0.01). 3 At low open probability $(P_{o}$), the reciprocal of the slope in the $ln(NP_{o}$)-voltage relationship (N, number of available channels in the patch) for cell body and nerve ending channels were similar: 11 vs. 14 mVper e-fold change in $NP_{o}$, respectively. 4 At 40 mV, the [Ca^{2+}$]_{i}$ producing half-maximal activation was 273 nM, as opposed to > 1.53 μM for the neurohypophysial channel, indicating the higher $Ca^{2+}$ sensitivity of the cell body isochannel. 5 Cell body BK channels showed fast kinetics (open time constant, 8.5 ms; fast closed time constant, 1.6 and slow closed time constant, 12.7 ms), identifying them as ‘type I’ isochannels, as opposed to the slow gating (type II) of neurohypophysial BK channels. 6 Cell body BK activity was reduced by 10 nM charybdotoxin $(NP_{o}$, 37 % of control), or 10 nM iberiotoxin $(NP_{o}$, 5 % of control), whereas neurohypophysial BK channels are insensitive to charybdotoxin at concentrations as high as 360 nM. 7 Whilst blockade of nerve ending BK channels markedly slowed the repolarization of evoked single spikes, blockade of cell body channels was without effect on repolarization of evoked single spikes. 8 Ethanol reversibly increased neurohypophysial BK channel activity $(EC_{50}$, 22 mM; maximal effect, 100 mM). In contrast, ethanol (up to 100 mM) failed to increase cell body BK channel activity. 9 In conclusion, we have characterized BK channels in supraoptic neuronal cell bodies, and demonstrated that they display different electrophysiological and pharmacological properties from their counterparts in the nerve endings. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2269476/pdf |
| Ending Page | 114 |
| Page Count | 14 |
| Starting Page | 101 |
| ISSN | 00223751 |
| e-ISSN | 14697793 |
| DOI | 10.1111/j.1469-7793.1999.0101o.x |
| Journal | The Journal of physiology |
| Issue Number | 1 |
| Volume Number | 519 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 1999-08-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: The Journal of physiology Cell Body Bk Channels Ending Bk |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physiology Sports Science |
