Similarity between mu-opioid receptors in mouse vas deferens and guinea-pig ileum.
The effects of the opioid receptor agonist RX783006 and of the opioid receptor partial agonist (+)-meptazinol have been examined on electrically-induced twitch responses of the guinea-pig isolated ileum and of the mouse isolated vas deferens. Log10 concentration-tissue state curves were determined for (+)-meptazinol and for RX783006, alone, in combination and, when appropriate, in the presence of naloxone (30 nM). Analysis of these log10 concentration-tissue state curves using the null equations derived and verified in the previous paper allows quantitation of the characteristics of the interaction of (+)-meptazinol with the opioid receptors in these tissues. The results indicate that the apparent differences in the actions of (+)-meptazinol on isolated electrically-stimulated guinea-pig ileum and mouse vas deferens can be accounted for without the need to postulate differences between mu-opioid receptors in these two tissues.
Goodall
J
J
Hughes
I E
IE
Mackay
D
D
D000818:Animals; D004558:Electric Stimulation; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D006168:Guinea Pigs; D007082:Ileum / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008621:Meptazinol / Q000494:pharmacology; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D011957:Receptors, Opioid / Q000378:metabolism*; D017450:Receptors, Opioid, mu; D013045:Species Specificity; D014649:Vas Deferens / Q000378:metabolism*; D008083:beta-Lipotropin / Q000494:pharmacology
D010446:Peptide Fragments; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D008621:Meptazinol; D008083:beta-Lipotropin