The high yield of prostacyclin biosynthesis by the iris and its effects on the intraocular muscles.
Iris, and to a lesser extent ciliary body, from cat and rabbit produce considerable amounts of prostacyclin (PGI2) after incubation of the tissue with 1-14C arachidonic acid. These tissues also generate PGI2-like material after gentle squeezing. It is likely that major metabolites found previously in iris and aqueous humor actually were 6-keto-PGF1alpha. It is concluded that PGH2 and PGI2 are synthetized at the same location. PGI2 induces a contraction of the sphincter and dilator and a relaxation of the ciliary muscle if the tissues had been previously exposed to indomethacin. Thromboxane A2 (TxA2) has either no effect or may cause a slight relaxation of the sphincter.
D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D002415:Cats; D002924:Ciliary Body / Q000187:drug effects* / Q000378:metabolism; D011464:Epoprostenol / Q000096:biosynthesis* / Q000494:pharmacology; D066298:In Vitro Techniques; D007498:Iris / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D011453:Prostaglandins / Q000096:biosynthesis*; D011460:Prostaglandins F / Q000494:pharmacology; D011680:Pupil / Q000187:drug effects*; D011817:Rabbits; D013928:Thromboxane A2 / Q000494:pharmacology
D001095:Arachidonic Acids; D011453:Prostaglandins; D011460:Prostaglandins F; D013928:Thromboxane A2; D011464:Epoprostenol