Extracellular divalent ions modulate TREK-2-like channel conductance in prefrontal pyramidal neurons in rats

Background: The aim of the study was to investigate, with the use of the patch clamp technique, the dependence of the conductance of the TREK-2-like potassium leak channel in the medial prefrontal cortex pyramidal neurons on the presence of extracellular magnesium and calcium ions. It is suspected that TREK-2 channels regulate mood and may be associated with the pathophysiology of depression. Since magnesium and calcium deficiency contribute to depressive symptoms, we investigated how TREK-2- like channel pore propertie change in the absence of divalent cations. Results: Single-channel currents were recorded in a cell-attached configuration in enzymatically dispersed pyramidal neurons of the prefrontal cortex in rats. Spontaneous TREK-2-like channel activity was recorded either in the presence or absence of magnesium and calcium ions in extracellular solution. A significant increase in the inward channel conductance was observed when divalent cations were removed from the extracellular solution. Inward rectification was also increased when the bath temperature was raised to 34-37°C. Conclusions: The study confirmed that the activity of TREK-2-like channels is affected by the presence of magnesium and calcium ions in the extracellular solution. Therefore, in vivo, the TREK-2-like channel may possibly participate in the prefrontal cortex dysfunction associated with the deficiency of divalent cations.