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Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons: inhibition by BDS-I toxin.
J Neurophysiol. 2007 Jan; 97(1):563-71.JN

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 mus at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 mus 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.

Authors+Show Affiliations

Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA. m-martina@northwestern.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17065256

Citation

Martina, Marco, et al. "Voltage-dependent Potassium Currents During Fast Spikes of Rat Cerebellar Purkinje Neurons: Inhibition By BDS-I Toxin." Journal of Neurophysiology, vol. 97, no. 1, 2007, pp. 563-71.
Martina M, Metz AE, Bean BP. Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons: inhibition by BDS-I toxin. J Neurophysiol. 2007;97(1):563-71.
Martina, M., Metz, A. E., & Bean, B. P. (2007). Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons: inhibition by BDS-I toxin. Journal of Neurophysiology, 97(1), 563-71.
Martina M, Metz AE, Bean BP. Voltage-dependent Potassium Currents During Fast Spikes of Rat Cerebellar Purkinje Neurons: Inhibition By BDS-I Toxin. J Neurophysiol. 2007;97(1):563-71. PubMed PMID: 17065256.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons: inhibition by BDS-I toxin. AU - Martina,Marco, AU - Metz,Alexia E, AU - Bean,Bruce P, Y1 - 2006/10/25/ PY - 2006/10/27/pubmed PY - 2007/3/10/medline PY - 2006/10/27/entrez SP - 563 EP - 71 JF - Journal of neurophysiology JO - J Neurophysiol VL - 97 IS - 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 mus at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 mus 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. SN - 0022-3077 UR - https://www.unboundmedicine.com/medline/citation/17065256/Voltage_dependent_potassium_currents_during_fast_spikes_of_rat_cerebellar_Purkinje_neurons:_inhibition_by_BDS_I_toxin_ L2 - https://journals.physiology.org/doi/10.1152/jn.00269.2006?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -