KV1 and KV3 Potassium Channels Identified at Presynaptic Terminals of the Corticostriatal Synapses in Rat

Abstract EN

In the last years it has been increasingly clear that K V -channel activity modulates neurotransmitter release.

The subcellular localization and composition of potassium channels are crucial to understanding its influence on neurotransmitter release.

To investigate the role of K V in corticostriatal synapses modulation, we combined extracellular recording of population-spike and pharmacological blockage with specific and nonspecific blockers to identify several families of K V channels.

We induced paired-pulse facilitation (PPF) and studied the changes in paired-pulse ratio (PPR) before and after the addition of specific K V blockers to determine whether particular K V subtypes were located pre- or postsynaptically.

Initially, the presence of K V channels was tested by exposing brain slices to tetraethylammonium or 4-aminopyridine; in both cases we observed a decrease in PPR that was dose dependent.

Further experiments with tityustoxin, margatoxin, hongotoxin, agitoxin, dendrotoxin, and BDS-I toxins all rendered a reduction in PPR.

In contrast heteropodatoxin and phrixotoxin had no effect.

Our results reveal that corticostriatal presynaptic K V channels have a complex stoichiometry, including heterologous combinations K V 1.1, K V 1.2, K V 1.3, and K V 1.6 isoforms, as well as K V 3.4, but not K V 4 channels.

The variety of K V channels offers a wide spectrum of possibilities to regulate neurotransmitter release, providing fine-tuning mechanisms to modulate synaptic strength.