Rat vas deferens: a specific bioassay for endogenous opioid peptides.
The electrically-evoked contractions of the rat vas deferens were selectively inhibited by beta-endorphin, the preparation being much less sensitive to enkephalins and narcotic analgesic drugs. However, introduction of D-Ala in position 2 of [Leu]-enkephalin enhanced the activity of the opioid peptide to the order of that of beta-endorphin. It is concluded that the rat vas deferens preparation constitutes a specific bioassay for endogenous opioid peptides and related compounds.
D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D011817:Rabbits; D051381:Rats; D014649:Vas Deferens / Q000187:drug effects*
D004723:Endorphins; D004745:Enkephalins