Rapid non-genomic vasodilator actions of oestrogens and sex steroids

There is now convincing experimental evidence documenting acute and transient actions of steroid hormones in the vasculature. Steroids can rapidly activate signalling cascades within endothelial and smooth muscle cells that seem to bypass the classical, genomic receptor. Activation of these signalling cascades, involving alterations in intracellular Ca2+ and MAPK activity, leads to changes in membrane potential and/or Ca2+ fluxes through L-type channels. In addition to stimulating NO production acutely in endothelial cells, chronic exposure to 17beta-oestradiol may activate expression of eNOS via a genomic receptor(s).