Cloxyquin has been reported as a specific activator of TRESK [TWIK-related spinal cord K1 channel (also known as K2P18.1)] background potassium channel. In this study, we have synthe-tized chemically modified analogs of cloxyquin and tested their effects on TRESK and other K2P channels. The currents of murine K2P channels, expressed heterologously in Xenopus oocytes, were measured by two-electrode voltage clamp, whereas the native background K1 conductance of mouse dorsal root ganglion (DRG) neurons was examined by the whole-cell patch-clamp method. Some of the analogs retained the activator character of the parent compound, but, more interestingly, other derivatives inhibited mouse TRESK current. The inhibitor analogs (A2764 and A2793) exerted state-dependent effects. The degree of inhibition by 100 mM A2764 (77.8% 6 3.5%, n 5 6) was larger in the activated state of TRESK (i.e., after calcineurin-dependent stimulation) than in the resting state of the channel (42.8% 6 11.5% inhibition, n 5 7). The selectivity of the inhibitor compounds was tested on several K2P channels. A2793 inhibited TWIK-related acid-sensitive K1 channel (TASK)-1 (100 mM, 53.4% 6 13, 5%, n 5 5), while A2764 was more selective for TRESK, it only moderately influenced TREK-1 and TWIK-related alkaline pH-activated K1 channel. The effect of A2764 was also examined on the background K1 currents of DRG neurons. A subpopulation of DRG neurons, prepared from wild-type animals, expressed background K1 currents sensitive to A2764, whereas the inhibitor did not affect the currents in the DRG neurons of TRESK-deficient mice. Accordingly, A2764 may prove to be useful for the identification of TRESK current in native cells, and for the investigation of the role of the channel in nociception and migraine.
ASJC Scopus subject areas
- Molecular Medicine