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BACKGROUND AND PURPOSE Prostacyclin mimetics express potent vsoactive effects via prostanoid receptors which are not defined unequivocally, as to date no study has considered sex as a factor. The aim of this study was to determine the contribution of IP and EP3 prostanoid receptors to prostacyclin mimetic Iloprost mediated responses, whether KV 7.1-5 channels represent downstream targets of selective prostacyclin-IP-receptor agonist MRE-269 and the impact of the oestrus cycle on vascular reactivity. EXPERIMENTAL APPROACH Within 2nd order mesenteric arteries (MAs) from male and female Wistar rats, we determined; 1.) relative mRNA transcripts for EP1-4 (Ptger1-4 ), IP (Ptgi) and TXA2 (Tbxa) prostanoid receptors via RT-qPCR; 2.) The effect of Iloprost, MRE-269, isoprenaline and ML277 on pre-contracted arterial tone in the presence of inhibitors of prostanoid receptors, potassium channels and molecular interreference of KV 7.1 via wire-myograph; 3.) Oestrus cycle stage via histological changes in cervical cell preparations. KEY RESULTS Iloprost evoked a bi-phasic response in male MAs, at concentrations ≤100nmol-L-1 relaxing, then contracting the vessel at concentration ≥300nmol-L-1 in a process attributed to IP and EP3 receptors respectively. Secondary contraction was absent in the females, which was associated with a reduction in Ptger3. Pharmacological inhibition and molecular interference of KV 7.1 significantly attenuated relaxations produced by the selective IP-receptor agonist MRE-269 in male and female Wistar in Diestrus /Metoestrous, but not Pro-oestrus/Oestrus. CONCLUSIONS AND IMPLICATIONS Stark sexual dimorphisms in Iloprost mediated vasoactive responses are present within MAs. KV 7.1 is implicated in IP-receptor mediated vasorelaxation and is impaired by the Oestrus cycle.

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.’

Kcnq-encoded KRT-qPCR, immunocytochemistry, proximity ligation assay and wire myography were performed in renal and mesenteric arteries. Circulating sex hormone concentrations were determined by liquid chromatography-tandem mass spectrometry. Whole-cell electrophysiology was undertaken on cells expressing KThe KGPER1 signalling decreased K

Prostacyclin mimetics express potent vasoactive effects via prostanoid receptors that are not unequivocally defined, as to date no study has considered sex as a factor. The aim of this study was to determine the contribution of IP and EPWithin second-order mesenteric arteries from male and female Wistar rats, we determined (1) relative mRNA transcripts for EPIloprost evoked a biphasic response in male mesenteric arteries, at concentrations ≤100 nmol·LStark sexual dimorphisms in iloprost-mediated vasoactive responses are present within mesenteric arteries. K