Effects of activation of μ-, κ1-, δ1-, δ2-, and ORL1-receptors on heart resistance to the pathogenic action of delayed ischemia and reperfusion

Abstract

Different subtypes of opioid receptors (OR) were activated in rats in vivo to study the activation effect on the heart’s resistance to ischemia and reperfusion. It has been established that administration of deltorphin II, a selective δ2-OR agonist, lowered the infarct size/area at risk index (IS/AAR) by 23%. Naltrexone, naloxone methiodide (an OR inhibitor not penetrating the blood-brain barrier (BBB)), and naltriben (δ2-antagonist) eliminated the cardioprotective effect of deltorphin II, while BNTX (a δ1-antagonist) produced no effect on the cardioprotective action of the δ2-agonist. The infarct-reducing effect of deltorphin II was eliminated by administration of chelerythrine (a protein kinase C (PKC) inhibitor), glibenclamide (a KATP-channels inhibitor), and 5-hydroxydecanoate (a mitochondrial KATP-channel blocker). Administration of other opioids did not reduce the IS/AAR index. It has been established that all the deltorphins manifest antiarrhythmic potency. Other opioids do not produce any effect on the incidence of arrhythmia occurrences. The antiarrhythmic effect of deltorphin II was eliminated by preliminary administration of naltrexone, naloxone methiodide, and naltriben, but BNTX did not affect the δ2-agonist’s anti-arrhythmic effect. The preliminary administration of chelerythrine, a PKC inhibitor, eliminated the δ2 agonist’s antiarrhythmic action. However, glibenclamide and 5-hydroxydecanoate did not alter the antiarrhythmic effect by deltorphin II. Therefore, activation of the peripheral δ2-ORs reduces the infarct size and prevents the onset of arrhythmias. The antiarrhythmic effect of the δ2-OR stimulation is mediated by activating PKC and opening the mitochondrial KATP-channels. PKC participates in the antiarrhythmic effect of the δ2-OR activation, but this effect does not depend on the condition of KATP-channels.