Abstract
Several opioid peptides and narcotic drugs reduced transepithelial potential difference (PD) and short circuit current (Isc) in guinea-pig ileal mucosa measured in vitro in Ussing chambers. [D-Ala2,D-Leu5]enkephalin was the most potent peptide tested. Enkephalin analogues with altered C-terminal amino acids were less potent, as were ß-endorphin and dermorphin. Etorphine produced potent effects whereas morphine and SKF 10,047 were inactive. Ethylketazocine produced a biphasic dose-response curve. When added by themselves diprenorphine and naloxone produced small increases in Isc. This effect was not seen when Cl- and HCO3- in the Ringer were replaced by SO42-. Diprenorphine and naloxone were able to shift the dose response curves for all agonists to the right, with the exception of that for ethylketazocine. Diprenorphine was a more potent antagonist than naloxone. SKF 10,047 also acted as a pure antagonist. Morphine and ethylketazocine had no antagonist effects. It is concluded that the opiate receptor in the guinea-pig ileal mucosa is similar to a δ-opiate receptor as defined by ligand binding studies, but that some differences also exist.
Original language | English (US) |
---|---|
Pages (from-to) | 177-183 |
Number of pages | 7 |
Journal | European Journal of Pharmacology |
Volume | 81 |
Issue number | 2 |
DOIs | |
State | Published - Jul 9 1982 |
Keywords
- Enkephalins
- Ileal mucosa
- Intestinal secretion
- Opiate antagonists
- δ-Receptor
ASJC Scopus subject areas
- Pharmacology