Bidirectional effects of endogenous opioid peptides on endothelin release rates in porcine aortic endothelial cell culture: mediation by delta opioid receptor and opioid receptor antagonist-insensitive mechanisms.
The effects of opioid peptides on immunoreactive endothelin (ir ET) release from cultured porcine aortic endothelial cells over a 1-hr period (4-5 or 23-24 hr) were determined by radioimmunoassay and high-performance liquid chromatography after treatment for either 4 or 23 hr. Endogenous opioids, the synthetic delta opioid [D-Pen2,5]enkephalin and, for comparison, atrial and brain natriuretic peptides were added to the culture medium in concentrations ranging from 10(-12) to 10(-7) M. Thrombin (0.1-10 U/ml) served as a stimulatory reference. 1) Brain natriuretic peptide displayed only insignificant effects on ir ET release at 5 hr, but strongly inhibited ir ET release at 24 hr. 2) Opioids modulated release rates at 5 hr but did not display significant effects at 24 hr: metorphamide with predominant mu/kappa and weak delta opioid receptor activity stimulated release in a dose-dependent manner, whereas [Met5]enkephalin-Arg6-Phe7 with mu/delta activity and the delta agonists [Leu5]enkephalin, sulfated [Leu5]enkephalin and [D-Pen2,5]enkephalin decreased release rates; [Leu5]enkephalin was the most potent of the latter drugs. 3) Coincubation with either the nonselective opioid receptor antagonist naloxone (10(-5) M) or the delta receptor-selective antagonist ICI-174,864 (N,N-bisallyl-Tyr-D-Ala-Aib-Aib-Phe-Leu-OH) (10(-5) M) abolished all opioid-induced inhibitory effects, but rather potentiated or unmasked stimulatory effects of opioid peptides on ir ET release rates at 5 hr and also at 24 hr in the case of the delta agonists.(ABSTRACT TRUNCATED AT 250 WORDS)
Arendt
R M
RM
Department of Medicine I, Ludwig-Maximilian-University, Munich, Germany.
Schmoeckel
M
M
Wilbert-Lampen
U
U
Plasse
A
A
Heucke
L
L
Werdan
K
K
D000595:Amino Acid Sequence; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002478:Cells, Cultured; D016232:Endothelins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D004745:Enkephalins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009294:Narcotics / Q000494:pharmacology*; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D017465:Receptors, Opioid, delta / Q000502:physiology*; D013552:Swine; D013917:Thrombin / Q000494:pharmacology
D016232:Endothelins; D004745:Enkephalins; D009294:Narcotics; D009419:Nerve Tissue Proteins; D017465:Receptors, Opioid, delta; D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor; D013917:Thrombin