[Activation of delta-opioid receptors increases resistance of isolated heart to ischemia/reperfusion: role of cAMP and intracellular calcium].

Activation of cardiac delta-opioid receptors (ORs) by their selective agonist DPDPE (154 nM) increased the resistance of perfused rat heart to ischemia/reperfusion. Decreased release of creatine phosphokinase to the perfusate and decreased occurrence of arrhythmia were observed during reoxygenation. At the same time, opioidergic decrease in left ventricular developed pressure took place both during the preischemic period and after restoring the coronary circulation. All these effects could be prevented by blocking delta-ORs by naltrindole or inhibition of Ca2+ -ATPase of sarcoplasmic reticulum by cyclopiazonic acid. Delta-OR agonist DPDPE had no effect on cAMP levels in myocardial tissue during the whole experiment. The obtained data suggest that the antiarrhythmic and cytoprotective effects observed after delta-OR stimulation can be realized through the changes in Ca2+ transport at the level of the sarcoplasmic reticulum.