Aims: 

The Kv7 (KCNQ) potassium channels are involved in a generation of non-inactivating potassium current (I_M) and play a significant role in the regulation of excitability of different types of neurons, e.g. hippocampal pyramidal cells. The purpose of this study was to investigate the presence of Kv7 channels in GABAergic hippocampal interneurons and their ability to regulate functioning of these cells.

Methods: 

Experiments were carried out on GABAergic neurons of 18-27-day-old primary culture of hippocampi of newborn rats. Single-cell RT-PCR technique was used for identification of expression of KCNQ2-KCNQ5 genes, the whole cell patch-clamp method was performed for the recording of membrane currents or potentials.

Results: 

High level of expression of the genes coding Kv7.2 and Kv7.3 subunits was revealed in the any neuron studied. Small level of Kv7.5 subunits expression was detected in 38% of the cells. It was shown the non-inactivating current take major part (83 ± 1.7%) in the forming of total depolarization-evoked potassium current of the cells studied. Non – inactivating current revealed activation threshold about -60 mV and displayed biphasic kinetics of deactivation with fast (22 ± 3 ms) and slow (306 ± 40 ms) time constants. Retigabine (15 mcM) shifted its I-V plot to more negative values, increased current's amplitude at -20 mV by 66 ± 14% (P < 0.001) and prevented the ability of neurons to generate spike series.

Conclusion: 

These results demonstrated that Kv7 channels are highly involved in the providing of repolarisation and in the regulation of activity of inhibitory hippocampal interneurons.