[The effect of dalargin and des-Tyr-dalargin on the functional state of intact and ischemized-reperfused myocardium].

Experiments on isolated perfused rat heart showed that dalargin, an antagonist of mu- and delta-opioid receptors, favors a decrease in the parameters of contractility of intact myocardium, while not influencing the pumping function (systolic and diastolic contractility) of reperfused myocardium. At the same time, des-Tyr-dalargin (the non-opioid analog of dalargin) suppresses the contractility of both the intact heart and the isolated myocardium subjected to global ischemia and reperfusion. Both dalargin and des-Tyr-dalargin reduced the incidence of reperfusion-induced arrhythmia, but did not affect the coronary flow before ischemia and after restoration of the coronary flow. It is suggested that the effect of dalargin is related to activation of the cardiac delta-opioid receptors, while the inotropic action of des-Tyr-dalargin involves other receptor mechanisms.