Effect of prostaglandin E2 on the isolated rabbit iris sphincter

Experiments on twenty-eight New Zealand albino rabbits have shown that prostaglandin E2 causes contraction of the isolated iris sphincter and is about five times as effective as acetylcholine. Prostaglandin E2 does not act on the cholinergic receptors; the effect of prostaglandin E2 was not increased by eserine, and not abolished by atropine. In high doses indomethacin (3 X 10(-4) M) reversed the prostaglandin effect, but lower concentrations (3 X 10(-5) M) left it unaffected.