Stimulatory actions of a novel thiourea derivative on large‐conductance, calcium‐activated potassium channels

Abstract

In this study, we examine whether an anti-inflammatory thiourea derivative, compound #326, actions on ion channels. The effects of compound #326 on Ca -activated K channels were evaluated by patch-clamp recordings obtained in cell-attached, inside-out or whole-cell configuration. In pituitary GH cells, compound #326 increased the amplitude of Ca -activated K currents (I ) with an EC value of 11.6 μM, which was reversed by verruculogen, but not tolbutamide or TRAM-34. Under inside-out configuration, a bath application of compound #326 raised the probability of large-conductance Ca -activated K (BK ) channels. The activation curve of BK channels was shifted to less depolarised potential with no modification of the gating charge of the curve; consequently, the difference of free energy was reduced in the presence of this compound. Compound #326-stimulated activity of BK channels is explained by a shortening of mean closed time, despite its inability to alter single-channel conductance. Neither delayed-rectifier nor erg-mediated K currents was modified. Compound #326 decreased the peak amplitude of voltage-gated Na current with no clear change in the overall current-voltage relationship of this current. In HEK293T cells expressing α-hSlo, compound #326 enhanced BK channels effectively. Intriguingly, the inhibitory actions of compound #326 on interleukin 1β in lipopolysaccharide-activated microglia were significantly reversed by verruculogen, whereas BK channel inhibitors suppressed the expressions of inducible nitric oxide synthase. The BK channels could be an important target for compound #326 if similar in vivo results occur, and the multi-functionality of BK channels in modulating microglial immunity merit further investigation.

Pioglitazone, a PPAR-γ Activator, Stimulates BKCa but Suppresses IKM in Hippocampal Neurons

“…They have been described to be functionally expressed in hippocampal neurons (Li et al, 2002; Huang et al, 2007; Wu et al, 2017). Another interesting paper has previously shown the function of Ca 2+ -activated K + channels in hippocampal pyramidal neurons (Storm, 1987).…”

Inhibitory Effective Perturbations of Cilobradine (DK-AH269), A Blocker of HCN Channels, on the Amplitude and Gating of Both Hyperpolarization-Activated Cation and Delayed-Rectifier Potassium Currents

“…In the experiments, we initially tested whether this compound had any perturbations on the amplitude and gating of this current identified in these cells. In order to preclude the contamination of most Ca 2+ -activated K + currents [22,27,28], we immersed the cells in Ca 2+ -free, Tyrode's solution, and during the measurements, we backfilled the recording pipette with a K + -containing solution. As the whole-cell current recordings were attained, we maintained the examined cell at −40 mV, and the 2-s hyperpolarizing voltage-clamp step to various potentials was later applied to elicit the slowly inwardly directed Ih, which displayed an inward-rectifying property.…”

Effectiveness of nalbuphine, a κ‐opioid receptor agonist and μ‐opioid receptor antagonist, in the inhibition of INa, IK(M), and IK(erg) unlinked to interaction with opioid receptors

“…Patch micropipettes (3–5 MΩ) were pulled from glass capillaries (Kimble, Vineland, NJ) on a PP‐830 puller (Narishige, Tokyo, Japan), and the tips were fire‐polished with MF‐83 microforge (Narishige). Ion currents were measured in either whole‐cell, cell‐attached, or inside‐out configuration of standard patch‐clamp technique with an RK‐400 amplifier (Bio‐Logic, Claix, France) (Wu et al, ). To correct junction potential, the current was zeroed with the electrode in the bath just before contact with cell surface.…”

“…Ion currents were measured in either whole-cell, cell-attached, or inside-out configuration of standard patch-clamp technique with an RK-400 amplifier (Bio-Logic, Claix, France) (Wu et al, 2017). To correct junction potential, the current was zeroed with the electrode in the bath just before contact with cell surface.…”