Figure 8.

PGE₂ induced relaxation of rings of canine meningeal artery, pre-contracted with phenylephrine and antagonism by the EP₄ receptor antagonist, BGC20-1531. (A) Typical concentration-dependent relaxant responses to PGE₂ (1 nmol·L⁻¹ to 30 µmol·L⁻¹) in phenylephrine pre-contracted canine middle meningeal artery rings in vitro. Representative data are shown from one of four independent experiments. (B) Concentration-dependent rightward shift of relaxant concentration-effect curves to PGE₂. Rings of meningeal artery were pre-incubated for 60 min with vehicle, 0.1 µmol·L⁻¹, 0.3 µmol·L⁻¹ or 1 µmol·L⁻¹ BGC20-1531, then cumulatively concentration-dependently relaxed with PGE₂. Data are expressed as percentage of the relaxation produced by prostacyclin (1 µmol·L⁻¹) and are expressed as mean ± SEM derived from four dogs.