title: A characterization of dynorphin-(1-13) on the guinea pig ileal longitudinal muscle.
abstract: Using naloxone as the antagonist, a comparison of pA2 values obtained from the guinea pig ileal longitudinal muscle preparation revealed that the pA2 value for dynorphin-(1-13) was significantly different from that of the pure narcotic agonists such as morphine, beta h-endorphin, Leu- and Met-enkephalin and that of the mixed agonist-antagonists such as nalorphine. In addition, no cross-tolerance to dynorphin-(1-13) could be demonstrated whereas a pronounced cross-tolerance existed for other opioid peptides on a ileal strip made tolerant to morphine by implantation of morphine pellets to the guinea pig for 72 h. Thus, dynorphin-(1-13) would appear to have a unique pharmacology on this peripheral opioid receptor preparation quite distinct from that of other known opioid peptides.
mesh_terms: D000818:Animals; D004361:Drug Tolerance; D004399:Dynorphins; D004723:Endorphins / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009294:Narcotics / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000187:drug effects
chemical_list: D004723:Endorphins; D009294:Narcotics; D010446:Peptide Fragments; D011957:Receptors, Opioid; C026843:dynorphin (1-13); D004399:Dynorphins