PGE2 and PGF2 alpha, cyclic nucleotides and reactivity of the rat femoral artery.

On isolated femoral artery strips of rats PGE2 produced a biphasic effect: relaxation at low concentrations (from 10(-14) to 10(-11) g/ml, and a contraction at higher concentrations (from 10(-11) to 10(-6) g/ml, while PGF2 alpha produced only contractions. The effects of both prostaglandins were influenced neither by alpha- nor by beta-adrenergic blockers. We established a dose-dependent increase of cyclic AMP levels during the first (relaxation) phase of the effect of PGE2 on isolated femoral artery strips of rats. During the second (contraction) phase of the PGE2 the cyclic levels were decreased. The results showed that, associated with the constriction produced by PGE2 alpha in the isolated femoral artery strips of rats, there was a dose-dependent rise in the cyclic GMP content. the results suggest that PGE might act on isolated smooth muscle through the cyclic AMP, and PGF--through the cyclic GMP.