An immortalized myocyte cell line, HL-1, expresses a functional delta -opioid receptor.
The present study characterizes opioid receptors in an immortalized myocyte cell line, HL-1. Displacement of [(3)H]bremazocine by selective ligands for the mu (mu), delta (delta), and kappa (kappa) receptors revealed that only the delta -selective ligands could fully displace specific [(3)H]bremazocine binding, indicating the presence of only the delta -receptor in these cells. Saturation binding studies with the delta -antagonist naltrindole afforded a B(max)of 32 fmols/mg protein and a K(D)value for [(3)H]naltrindole of 0.46 n M. The binding affinities of various delta ligands for the receptor in HL-1 cell membranes obtained from competition binding assays were similar to those obtained using membranes from a neuroblastomaxglioma cell line, NG108-15. Finally, various delta -agonists were found to stimulate the binding of [(35)S]GTP gamma S, confirming coupling of the cardiac delta -receptor to G-protein. DADLE (D-Ala-D-Leu-enkephalin) was found to be the most efficacious in this assay, stimulating the binding of [(35)S]GTP gamma S to 27% above basal level. The above results indicate that the HL-1 cell line contains a functionally coupled delta -opioid receptor and therefore provides an in vitro model by which to study the direct effects of opioids on cardiac opioid receptors.
Neilan
C L
CL
Department of Cardiac Surgery, University of Michigan, B558 MSRB II, Ann Arbor, MI 48109-0686, USA.
Kenyon
E
E
Kovach
M A
MA
Bowden
K
K
Claycomb
W C
WC
Traynor
J R
JR
Bolling
S F
SF
D000700:Analgesics / Q000494:pharmacology; D001575:Benzomorphans / Q000494:pharmacology; D001667:Binding, Competitive; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016308:Enkephalin, Leucine-2-Alanine / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D007700:Kinetics; D008024:Ligands; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D013997:Time Factors; D014407:Tumor Cells, Cultured
D000700:Analgesics; D001575:Benzomorphans; D008024:Ligands; D009292:Narcotic Antagonists; D017465:Receptors, Opioid, delta; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D009271:Naltrexone; D016308:Enkephalin, Leucine-2-Alanine; C055382:naltrindole; C027248:bremazocine