Calcium stimulates opioid receptor agonism in rat cardiac sarcolemma.

Abstract

We have found that calcium stimulates, in a dose-dependent manner, the binding of opioid to kappa and delta receptors in sarcolemma from rat's ventricles isolated by hypotonic lithium bromide shock. Opioid binding was measured using [3H]-diprenorphine as a radioligand. The delta-selective agonist [D-Ala2, D-Leu5]-enkephalin and the kappa-selective agonist U-50, 488H both inhibited control and Ca(2+)-stimulated [3H]-diprenorphine binding to the sarcolemma, whereas [D-Ala2,MePhe4,Gly-(ol)5]-enkephalin was ineffective. The stimulatory effect of calcium increased the maximal binding capacity without affecting the affinity of the receptor for the ligand.

• Authors: C Ventura, C Guarnieri, L Bastagli, P Bernardi, P Puddu, C M Caldarera
• Journal: Cardioscience (Cardioscience) Vol. 1 Issue 2 Pg. 151-4 (Jun 1990) ISSN: 1015-5007 [Print] Italy
• PMID: 1966375 (Publication Type: Journal Article)

Chemical References

• Receptors, Opioid
• Receptors, Opioid, delta
• Receptors, Opioid, kappa
• Tritium
• Diprenorphine
• Calcium

Topics

• Animals
• Calcium (pharmacology)
• Diprenorphine
• Dose-Response Relationship, Drug
• Myocardium (metabolism)
• Radioligand Assay
• Rats
• Receptors, Opioid (drug effects, metabolism)
• Receptors, Opioid, delta
• Receptors, Opioid, kappa
• Sarcolemma (metabolism)
• Stimulation, Chemical
• Tritium