TY - JOUR
T1 - Control of guinea pig intestinal electrolyte secretion by a δ-opiate receptor
AU - Kachur, J. F.
AU - Miller, R. J.
AU - Field, M.
PY - 1980
Y1 - 1980
N2 - The effects of opioids on transepithelial potential difference and short-circuit current across guinea pig ileum stripped of one muscle layer were measured in vitro in Ussing chambers. Opioid peptides such as [DAla2, DLeu5]enkephalin and [DAla2, DMet5]enkephalin, which are primarily agonists at δ-opiate receptors, were able to reduce transepithelial potential difference and short-circuit current at concentrations as low as 1 nM. The narcotic drug etorphine was also very potent in reducing short-circuit current, but fentanyl and morphine, which are primarily agonists at μ-opiate receptors, were almost completely ineffective. Ketocyclazocine was relatively ineffective, and β-endorphin had intermediate potency. All opioid effects could be reversed by the opiate antagonist naloxone. Somatostatin also reduced short-circuit current, but its effect was not reduced by naloxone. Chloride flux measurements indicated that the effect of etorphine on short-circuit current is associated with an enhancement of active Cl- absorption. The relative effects of opioids in this system suggest that their actions are being mediated by a specific δ-opiate receptor. In contrast, opioid effects on guinea pig intestinal smooth muscle seem to be primarily mediated by a μ-opiate receptor.
AB - The effects of opioids on transepithelial potential difference and short-circuit current across guinea pig ileum stripped of one muscle layer were measured in vitro in Ussing chambers. Opioid peptides such as [DAla2, DLeu5]enkephalin and [DAla2, DMet5]enkephalin, which are primarily agonists at δ-opiate receptors, were able to reduce transepithelial potential difference and short-circuit current at concentrations as low as 1 nM. The narcotic drug etorphine was also very potent in reducing short-circuit current, but fentanyl and morphine, which are primarily agonists at μ-opiate receptors, were almost completely ineffective. Ketocyclazocine was relatively ineffective, and β-endorphin had intermediate potency. All opioid effects could be reversed by the opiate antagonist naloxone. Somatostatin also reduced short-circuit current, but its effect was not reduced by naloxone. Chloride flux measurements indicated that the effect of etorphine on short-circuit current is associated with an enhancement of active Cl- absorption. The relative effects of opioids in this system suggest that their actions are being mediated by a specific δ-opiate receptor. In contrast, opioid effects on guinea pig intestinal smooth muscle seem to be primarily mediated by a μ-opiate receptor.
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U2 - 10.1073/pnas.77.5.2753
DO - 10.1073/pnas.77.5.2753
M3 - Article
C2 - 6248864
AN - SCOPUS:0019222651
VL - 77
SP - 2753
EP - 2756
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 5 I
ER -