Effects of prostanoids on isolated feline cerebral arteries

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Abstract
The effects of various prostanoids on isolated feline basilar arteries (BA) were studied. Contractions were induced with the following order of potency: U 46619 [(15-S)-hydroxy-9.alpha.,11.alpha.-(epoxymethano)prosta-5Z,13E-dienoic acid] .apprxeq. U44069 [(15-S-hydroxy-11.alpha.,9.alpha.-(epoxymethano)prosta-5Z,13E-dienoic acid] > [prostaglandin] PGB2 > PGF2.alpha. .apprxeq. PGA2 .apprxeq. PGB1 .gtoreq. PGA1 .apprxeq. PGE2 = PGD2 > PGF1.alpha. .apprxeq. TXB2 [thromboxane B2] .apprxeq. PGE1 .apprxeq. PGD1. Distinct bimodal responses with a relaxation at low concentrations followed by a contraction at high concentrations, were induced by PGA1, PGA2, PGD and PGE2. None of the tested prostanoids relaxed K+-contracted arteries, and a sizable relaxant effect in PGF2.alpha.-contracted arteries could be induced only by PGE1. As judged by the relative order of potency, PG-induced contractions of the feline BA seem mediated by a thromboxane sensitive receptor. PGF2.alpha.-induced contractions apparently do not involve the release of noradrenaline [norepinephrine] from perivascular nerves since phentolamine failed to affect contractions induced by this agent.