Classification of 2-pore domain potassium channels based on rectification under quasi-physiological ionic conditions

Abstract

(2014) Classification of 2-pore domain potassium channels based on rectification under quasiphysiological ionic conditions, Channels, 8:6,[503][504][505][506][507][508]

Lateral Fenestrations in K+-Channels Explored Using Molecular Dynamics Simulations

“…17 The third and final channel studied belongs to the two pore domain potassium (K2P) channels, which generate leak potassium currents, and thus plays an essential role in cell excitability. K2P channels have been proposed to show weak inward rectification, [18][19] suggesting resemblance with/to inward-rectifying (Kir) potassium channels. 19 Six subfamilies, TWIK, TREK, TALK, TASK, THIK, and TRESK have been identified, primarily implicated in a range of cardiovascular and neurological disorders.…”

Non-trivial dynamics in a model of glial membrane voltage driven by open potassium pores

“…Quantitative studies summarizing the properties of macroscopic currents through the glial Kir4.1 (Seifert G., 2018) and K2P-TREK channels (Schewe et al, 2016), (Chen, 2014) suggest that apart from K2P activation there is no other channel kinetics critical to extend (13) with additional dynamical variable. Whole-cell Kir4.1 currents were showing rise times of less than 2 ms and negligible difference between the peak and steady current levels, in the mid-range voltages V m where the interaction of different currents is dynamically interesting.…”

“…Figure 5A shows pharmacologically isolated K2P current, using quinine , at [ K + ] o , = 5 mM (black circles), as well as at drastically elevated external potassium at [ K + ] o = 50 mM (blue dots) in our data from (Seifert et al, 2009). Both I-V recordings were fitted (solid lines) with the standard GHK current equation (Chen, 2014), even though the permeation studies suggest multi-ion occupancy of the pore and some form of pseudo gating (Schewe et al, 2016). Adding a small Na + permeability (Chen, 2014), P Na /P K = 0.06, within nominally non-conductive range (below −50 mV ) improves the fit at 5 mM , solid purple line.…”

“…Both I-V recordings were fitted (solid lines) with the standard GHK current equation (Chen, 2014), even though the permeation studies suggest multi-ion occupancy of the pore and some form of pseudo gating (Schewe et al, 2016). Adding a small Na + permeability (Chen, 2014), P Na /P K = 0.06, within nominally non-conductive range (below −50 mV ) improves the fit at 5 mM , solid purple line. That effect of Na + on passive K + conductivity in glia is known (Ransom & Goldring, 1973), but we didn’t use the correction within the numerical simulations due to a lack of recordings to verify P Na /P K dependence itself on [ K + ] o for notably elevated levels above 5 mM.…”

“…Along with these observations we model the astrocytic K2P-TREK1 currents using the GHK current model (Chen, 2014), extended with electrochemically dependent activation n K 2 P – coupling the voltage-dependent activation and electrochemical driving force into a mechanism named ion-flux gating (Schewe et al, 2016): …”