Potential receptors through which PUFA-lactone molecules act in endothelial cell

The arterioles of the microvascular system are the primary site of blood pressure regulation. Microvascular dysfunction is a known contributor to cardiovascular diseases, the leading cause of death. Under these conditions, the loss of nitric oxide-induced dilation is compensated by an alternative regulating pathway mediated by endothelial-derived hyperpolarizing factors (EDHF). Previously we discovered that lactone derivatives of polyunsaturated fatty acids (PUFA-L) initiate hyperpolarization and relaxation of peripheral blood vessels. Inhibition of G-protein-coupled receptors (GPCR) subunits impaired the PUFA-L endothelial-signaling reaction. Free fatty acid receptors (FFARs) are GPCRs known for binding fatty acids and their derivatives as ligands and activating intracellular signaling leading to hyperpolarization Thus, we aim to investigate and characterize the potential receptors by which PUFA-L molecules mediate cellular hyperpolarization.

In human endothelial cells, EPA-L induced a dose-dependent calcium influx. and further potassium efflux was reduced by the GPR40 inhibitor (GW1100). Patch clamp analyses revealed EPA-L increased whole-cell K+ currents that were significantly inhibited by the GPR40 inhibitor. In addition, there is no significant difference in the whole-cell K+ currents between HEK cells with or without GPR40 overexpression. Further experiments will evaluate the GPR40 as a mediator of the EPA-L, using molecular inhibition via siRNA, in addition to other potential receptors that might also mediate this reaction.

By revealing the specific mechanism of PUFA-L in regulating endothelial hyperpolarization, we expect our findings to shed light on the involvement of the novel EDHF lipid mediators in regulating microvascular dilation.