Role of Opioid Receptors in Cardioprotection of Cold-Restraint Stress and Morphine

• Published in: Journal of biomedical science Vol. 11; no. 6; pp. 726 - 731
• Main Authors: Wu, S., Wong, M.C.Y., Chen, M., Cho, C.H., Wong, T.M.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland 01.01.2004
• Subjects: Original Paper; ĸ-Opioid receptor; Protein kinase C; Cardioprotection; Cold; Restraint; Infarct size; Morphine; KATP channel
• ISSN: 1021-7770; 1423-0127
• DOI: 10.1159/000081818

Since cold exposure confers cardioprotection, the present study attempted to determine the role of opioid receptors (OR). Stress with cold exposure and restraint for 3 h, shown previously to induce peptic ulcer in a synergistic manner, attenuated infarct size induced by myocardial ischemia and reperfusion in the isolated perfused rat heart from 36.64 ± 1.8 to 22.85 ± 2.6%. This is similar to protecting the rat with morphine at 8 mg/kg, which also attenuated the infarct size from 36.26 ± 1.6 to 20.30 ± 2.1%. The effects of cold-restraint or morphine were abolished by naloxone, a non-selective OR antagonist; nor-binaltorphimine, a selective ĸ-OR antagonist; naltrindole, a selective δ-OR antagonist, or CTOP, a selective µ-OR antagonist. The effects were also attenuated by blockade of protein kinase C or the mitochondrial K ATP channel. The finding is first evidence that all three OR subtypes mediate cardioprotection of cold-restraint stress in the rat.