Properties and expression of Kv3 channels in cerebellar Purkinje cells

Abstract

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 μM). 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.

Differential Mechanisms of CRF1 and CRF2 Receptor Functions in the Amygdala in Pain-Related Synaptic Facilitation and Behavior

“…A very low concentration of TEA (50 M) broadened the spike and decreased the firing rate, occluding the effects of NBI27914, suggesting the contribution of a highly TEA-sensitive channel involved in action potential repolarization such as Kv3-type channels. Kv3 channels are blocked by low concentrations of TEA, and their blockade decreases the firing rate while broadening the spike Sacco et al, 2006). In contrast, blockade of other known K ϩ channels that could be affected by low TEA (although unlikely at 50 M) produced opposite or no effects Rudy and McBain, 2001;Faber and Sah, 2003;Kasten et al, 2007).…”

“…9 A, B). Kv3 channels, which are expressed in the amygdala, including the CeA (McDonald and Mascagni, 2006), can be distinguished pharmacologically because of their high sensitivity to extracellular TEA (Martina et al, 1998;Rudy et al, 1999;Sacco et al, 2006). Blockade of other known K ϩ channels that are sensitive to TEA would be expected to produce opposite or no effects on spike firing Rudy and McBain, 2001;Faber and Sah, 2003;Kasten et al, 2007).…”

Selection of Reference Genes for Quantitative Real-time RT-PCR Studies in Mouse Brain

“…In our study, the expression level of the target gene Kcnc3 in mouse cerebellum was used for this purpose. The Kcnc3 voltage-gated potassium channel subunit is expressed and functional since P7 in mouse cerebellar neurons (Goldman-Wohl et al 1994;Sacco et al 2006) and is indispensable for firing action potentials at high frequency (Rudy and McBain 2001). The developmental regulation of Kcnc3 transcript level is known: It was demonstrated to increase in parallel with the maturation of Purkinje cells during the postnatal development and to be expressed in all terminally differentiated Purkinje cells and in the adult deep cerebellar nuclei (Goldman-Wohl et al 1994).…”

The Role of Kv3-type Potassium Channels in Cerebellar Physiology and Behavior

“…Adult Purkinje cells do not express detectable Kv3.1 protein or Kv3.1-mediated potassium current [50]. There is, however, a report showing expression of Kv3.1 messenger RNA (mRNA) at postnatal day 7 [59]. The large glutamatergic neurons in deep cerebellar nuclear (DCN) neuron express Kv3.1, Kv3.2, and Kv3.3 subunits [70].…”