POTENTIATION OF NOREPINEPHRINE-INDUCED CONTRACTION BY PRIMARY PROSTAGLANDIN RECEPTOR ACTIVATION IN RAT AORTA

This study investigates the role of primary prostaglandin receptor act ivation in the modulation of agonist-induced vascular smooth muscle co ntraction. Prostaglandin F2alpha induced a concentration-dependent con traction of the rat aorta that was nearly abolished by the thromboxane A2 receptor antagonist, SQ29548. Prostaglandin F2alpha in the presenc e of SQ29548 induced leftward shifts of the norepinephrine and KCl con centration-response curves. Nifedipine abolished the leftward shift of the norepinephrine concentration-response curve observed in the prese nce of prostaglandin F2alpha and SQ29548. These results suggest that a function of primary prostaglandin receptor activation may be to poten tiate agonist-induced contraction. The potentiation is dependent upon the opening of dihydropyridine-sensitive Ca2+ channels.