Activity of prostaglandin E, F, A and B on sphincter, dilator and ciliary muscle preparations of the cat eye.

Both sphincter and dilator muscle preparations of the cat iris contract to prostaglandins; F-2alpha and E-2 are the most potent and A-1 and B-1 the least. Ciliary muscle strips relax to PG'S provided that the strips are precontracted. E-1, E-2 and often F-2alpha are more potent relaxants than the remaining PG's. The effects of PG'S ARE NOT ALTERED BY ALPHA OR BETA BLOCKADE NOR BY ATROPINE; HOWEVER, PROPRANOLOL BLOCKS THE PG induced relaxation of the ciliary muscle. The effects of PG's on the sphincter are antagonized by catecholamines; but the latter act synergistically in contracting the dilator and in relaxing the ciliary muscle. Indomethacin markedly potentiates the effects of PG's on all three muscle preparations.