Unexpected antagonism in the rat vas deferens by benzomorphans which are agonists in other pharmacological tests.
The benzomorphans, ethylketazocine, bremazocine and MR 2034 are pure agonists in the guinea-pig ileum and mouse vas deferens but are competitive antagonists without agonist activity in the rat vas deferens.
D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology*; D001665:Binding Sites; D006168:Guinea Pigs; D008297:Male; D051379:Mice; D009019:Morphinans / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects*; D013045:Species Specificity; D014649:Vas Deferens / Q000187:drug effects*
D001575:Benzomorphans; D009019:Morphinans; D011957:Receptors, Opioid