Marked oestrous cycle-dependent regulation of rat arterial KV7.4 channels driven by GPER1

Background and purposeKcnq-encoded KV7 channels (termed KV7.1-5) regulate vascular smooth muscle cell (VSMC) contractility at rest and as downstream targets of receptor mediated responses. However, the current literature focuses predominantly on males. Considering the known impact of sex, the oestrus cycle and sex-hormones on vascular reactivity, the aim of this investigation was to characterise the molecular and functional properties of KV7 within renal and mesenteric arteries from female Wistar rats separated into Di-oestrus and Met-oestrus (F-D/M) and Pro-oestrus and Oestrus (F-P/E).Experimental approachRT-qPCR, immunocytochemistry, proximity-ligation assay and wire myography were performed in renal and mesenteric arteries. Circulating sex-hormone concentrations was determined by liquid chromatography tandem mass-spectrometry. Whole-cell electrophysiology undertaken on cells expressing KV7.4 in association with G-protein coupled Oestrogen receptor 1 (GPER1).Key resultsThe KV7.2-5 activators S-1/ML213 and the pan-KV7 inhibitor Linopirdine were more effective in arteries from F-D/M compared to F-P/E animals. In VSMCs isolated from F-P/E rats, the membrane abundance of KV7.4 but not KV7.1, KV7.5 and Kcne4 was reduced compared to F-D/M cells. Plasma oestradiol was significantly higher in F-P/E compared to F-D/M and progesterone showed the converse pattern. Oestradiol/GPER1 agonist G-1 diminished KV7.4 currents in heterologous expression system and reduced KV7.4 membrane abundance, ML213 relaxations, and interaction between KV7.4 and the molecular chaperone protein, heat shock protein 90 (HSP90), in arteries from F-D/M but not F-P/E.Conclusions and implicationsGPER1 signalling decreases KV7.4 membrane abundance in conjunction with diminished interaction with HSP90, giving rise to a ‘pro-contractile state.’