Investigation into the role of ω-3 polyunsaturated fatty acids and their structural analogues on the Kv7 channel function and vasodilator mechanisms

Fatty acids are essential components of cellular membranes. ω-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), exert significant influence on the cardiovascular, central nervous and immune systems, among others. In the vascular system, PUFAs have been shown to induce vasodilation. Nonetheless, most research focuses on their long-term effects within a single artery, primarily emphasising the effects of PUFAs on the endothelial layer. This PhD project characterised not only the underlying vasodilation mechanisms associated with the acute application of PUFAs in two distinct tissue types, but also achieved a more comprehensive understanding of the structure-activity relationship (SAR) between PUFAs and their vascular targets. Wire myography was used to examine the vasodilatory effects of PUFAs in rat arteries by testing the impact of the intact endothelium on the results observed, utilising pharmacological inhibitors, and applying a variety of structurally distinct compounds to elucidate the SAR. Furthermore, stable cell lines expressing voltage-gated potassium channels, KV7.4 and KV7.5, under the control of an inducible promoter, were developed, along with plasmid DNA encoding their heterodimers and tetramers, which were used for transient transfection. The activation of KV7 homotetramers and heterotetramers by DHA was examined in cell lines using whole-cell patch clamp recordings. PUFAs induced vasodilation in the aorta and the mesenteric arteries through their activity on KV7 channels, whilst also exhibiting tissue-specific heterogeneity in their mechanism of action. The SAR study highlighted important structural properties in the PUFAs that are crucial for KV7 channel activation. Furthermore, these findings propose a new hypothesis regarding the activity of DHA on KV7 channels by which they cause loss of voltage-gating sensitivity in KV7.4 and KV7.5 channels, while simultaneously increasing potassium currents and conductance, thereby rendering the channels akin to leak channels.