Properties and expression of Kv3 channels in cerebellar Purkinje cells.
In cerebellar Purkinje cells, Kv3 potassium channels are indispensable for firing at high frequencies. In Purkinje cells from young mice (P4-P7), Kv3 currents, recorded in whole-cell in slices, activated at -30 mV, with rapid activation and deactivation kinetics, and they were partially blocked by blood depressing substance-I (BDS-I, 1 microM). At positive potentials, Kv3 currents were slowly but completely inactivating, while the recovery from inactivation was about eightfold slower, suggesting that a previous firing activity or a small change of the resting potential could in principle accumulate inactivated Kv3 channels, thereby finely tuning Kv3 current availability for subsequent action potentials. Single-cell RT-PCR analysis showed the expression by all Purkinje cells (n=10 for each subunit) of Kv3.1, Kv3.3 and Kv3.4 mRNA, while Kv3.2 was not expressed. These results add to the framework for interpreting the physiological function and the molecular determinants of Kv3 currents in cerebellar Purkinje cells.
Sacco
Tiziana
T
Rita Levi Montalcini Center for Brain Repair, Department of Neuroscience, University of Torino, Corso Raffaello 30 I-10125 Torino, Italy.
De Luca
Annarita
A
Tempia
Filippo
F
D000818:Animals; D002531:Cerebellum / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D003064:Cnidarian Venoms / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D018408:Patch-Clamp Techniques; D011689:Purkinje Cells / Q000502:physiology*; D012333:RNA, Messenger; D051670:Shaw Potassium Channels / Q000235:genetics* / Q000502:physiology*
C059796:BDS-I antiviral protein, Anemonia sulcata; D003064:Cnidarian Venoms; C490839:Kcnc1 protein, mouse; C085724:Kcnc3 protein, mouse; C115399:Kcnc4 protein, mouse; D012333:RNA, Messenger; D051670:Shaw Potassium Channels