title: Effects of prostaglandins and thromboxane analogues on bullock and dog iris sphincter preparations.
abstract: 1 The bullock iris sphincter was contracted by low concentrations of prostaglandin E2 (PGE2), 16, 16-dimethyl PGE2 and 17,18,19,20-tetranor-16-p-chlorophenoxy PGE2. Other compounds with thromboxane-like actions, for example 11,9-epoxymethano PGH2, were also potent spasmogens, ZK 36374, a stable carbacyclin, was a partial agonist on the PGE-sensitive system of this tissue. 2 The thromboxane antagonist, EP 045, had little effect on the action of PGE2 and 16,16-dimethyl PGE2 on the bullock iris. 3 The dog iris sphincter was sensitive to PGF2 alpha but not to PGE2 and 11,9-epoxymethano PGH2. 4 16,16-dimethyl PGE2 had very low activity on the dog iris in contrast to its high activity on the bullock iris. The reverse was found with the 17,18,19,20-tetranor-16-m-trifluoromethylphenoxy analogue of PGF2 alpha (ICI 81008). This indicates a considerable selectivity of action of the two analogues. 5 The results are discussed in relation to the existing knowledge of prostanoid receptors.
mesh_terms: D000818:Animals; D002417:Cattle; D015232:Dinoprostone; D004285:Dogs; D011464:Epoprostenol / Q000494:pharmacology; D016285:Iloprost; D066298:In Vitro Techniques; D007498:Iris / Q000187:drug effects*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011453:Prostaglandins / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology; D011465:Prostaglandins, Synthetic; D013045:Species Specificity; D013931:Thromboxanes / Q000494:pharmacology*
chemical_list: D011453:Prostaglandins; D011458:Prostaglandins E; D011465:Prostaglandins, Synthetic; D013931:Thromboxanes; C034549:EP 045; D011464:Epoprostenol; D016285:Iloprost; D015232:Dinoprostone