Abstract
We characterized the kinetics and pharmacological properties of voltage-activated potassium currents in rat cerebellar Purkinje neurons using recordings from nucleated patches, which allowed high resolution of activation and deactivation kinetics. Activation was exceptionally rapid, with 10-90% activation in about 400 μs at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 μs near -80 mV. These rapid activation and deactivation kinetics are consistent with mediation by Kv3-family channels but are even faster than reported for Kv3-family channels in other neurons. The peptide toxin BDS-I had very little blocking effect on potassium currents elicited by 100-ms depolarizing steps, but the potassium current evoked by action potential waveforms was inhibited nearly completely. The mechanism of inhibition by BDS-I involves slowing of activation rather than total channel block, consistent with the effects described in cloned Kv3-family channels and this explains the dramatically different effects on currents evoked by short spikes versus voltage steps. As predicted from this mechanism, the effects of toxin on spike width were relatively modest (broadening by roughly 25%). These results show that BDS-I-sensitive channels with ultrafast activation and deactivation kinetics carry virtually all of the voltage-dependent potassium current underlying repolarization during normal Purkinje cell spikes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 563-571 |
| Number of pages | 9 |
| Journal | Journal of neurophysiology |
| Volume | 97 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2007 |
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ASJC Scopus subject areas
- Neuroscience(all)
- Physiology
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Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons : Inhibition by BDS-I toxin. / Martina, Marco; Metz, Alexia E.; Bean, Bruce P.
In: Journal of neurophysiology, Vol. 97, No. 1, 01.01.2007, p. 563-571.Research output: Contribution to journal › Article
TY - JOUR
T1 - Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons
T2 - Inhibition by BDS-I toxin
AU - Martina, Marco
AU - Metz, Alexia E.
AU - Bean, Bruce P.
PY - 2007/1/1
Y1 - 2007/1/1
N2 - We characterized the kinetics and pharmacological properties of voltage-activated potassium currents in rat cerebellar Purkinje neurons using recordings from nucleated patches, which allowed high resolution of activation and deactivation kinetics. Activation was exceptionally rapid, with 10-90% activation in about 400 μs at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 μs near -80 mV. These rapid activation and deactivation kinetics are consistent with mediation by Kv3-family channels but are even faster than reported for Kv3-family channels in other neurons. The peptide toxin BDS-I had very little blocking effect on potassium currents elicited by 100-ms depolarizing steps, but the potassium current evoked by action potential waveforms was inhibited nearly completely. The mechanism of inhibition by BDS-I involves slowing of activation rather than total channel block, consistent with the effects described in cloned Kv3-family channels and this explains the dramatically different effects on currents evoked by short spikes versus voltage steps. As predicted from this mechanism, the effects of toxin on spike width were relatively modest (broadening by roughly 25%). These results show that BDS-I-sensitive channels with ultrafast activation and deactivation kinetics carry virtually all of the voltage-dependent potassium current underlying repolarization during normal Purkinje cell spikes.
AB - We characterized the kinetics and pharmacological properties of voltage-activated potassium currents in rat cerebellar Purkinje neurons using recordings from nucleated patches, which allowed high resolution of activation and deactivation kinetics. Activation was exceptionally rapid, with 10-90% activation in about 400 μs at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 μs near -80 mV. These rapid activation and deactivation kinetics are consistent with mediation by Kv3-family channels but are even faster than reported for Kv3-family channels in other neurons. The peptide toxin BDS-I had very little blocking effect on potassium currents elicited by 100-ms depolarizing steps, but the potassium current evoked by action potential waveforms was inhibited nearly completely. The mechanism of inhibition by BDS-I involves slowing of activation rather than total channel block, consistent with the effects described in cloned Kv3-family channels and this explains the dramatically different effects on currents evoked by short spikes versus voltage steps. As predicted from this mechanism, the effects of toxin on spike width were relatively modest (broadening by roughly 25%). These results show that BDS-I-sensitive channels with ultrafast activation and deactivation kinetics carry virtually all of the voltage-dependent potassium current underlying repolarization during normal Purkinje cell spikes.
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U2 - 10.1152/jn.00269.2006
DO - 10.1152/jn.00269.2006
M3 - Article
C2 - 17065256
AN - SCOPUS:33846414373
VL - 97
SP - 563
EP - 571
JO - Journal of Neurophysiology
JF - Journal of Neurophysiology
SN - 0022-3077
IS - 1
ER -