Pertussis toxin inhibits endothelium-dependent relaxations evoked by fluoride

Fluoride is a direct activator of G-proteins. In isolated rings of canine coronary artery, fluoride caused relaxation of rings with endothelium, but only slight contraction of rings denuded of endothelium. The endothelium-dependent relaxations to fluoride were inhibited by pertussis toxin, an inhibitor of G-proteins, or by methylene blue, an inhibitor of soluble guanylate cyclase. Therefore, fluoride causes endothelium-dependent relaxations in part by activating a pertussis toxin-sensitive G-protein in the endothelial cells.