Naloxone Inhibits Early Arrhythmias Resulting From Acute Coronary Ligation

Abstract

The intravenous administration of naloxone 15 min before acute coronary artery ligation in both anaesthetized and conscious male rats markedly reduced the incidence and severity of the ventricular arrhythmias that occur within 30 min of the onset of myocardial ischaemia. The incidence of ventricular fibrillation was especially reduced and, in conscious rats, the survival 16 h after ligation was increased from 27% (in the controls) to 58 and 73% after 2 and 4 mg/kg naloxone respectively. One possible explanation of these results implies a detrimental effect of released endorphin in the early stages of myocardial ischaemia.

Anti‐arrhythmic activities of opioid agonists and antagonists and their stereoisomers

“…The opioid antagonist, naloxone, has been shown previously to reduce the incidence and severity of cardiac arrhythmias resulting from coronary ligation in rats (Fagbemi et al, 1982). Similar antiarrhythmic activity of naloxone was later described in other species with various experimental models (Huang et al, 1986;Lee et al, 1986).…”

Effects of morphine on cardiovascular responses to acute myocardial ischaemia in rats

“…Therefore, it is possible that the reduced and delayed occurrence of ventricular arrhythmias in chronically morphine-treated animals, as observed in the current study, may be secondary to the decreased responses to sympathetic overactivity during the early stage of acute myocardial ischaemia. However, evidence has shown that the release of other endogenous substances such as catecholamines (Riemersma, 1982), prostaglandins and thromboxanes (Coker, 1982), cyclic AMP (Podzuweit, 1982), endorphins (Fagbemi et al, 1982) and histamine (Dai, 1986) may also be involved in the genesis of ventricular arrhythmias caused by myocardial infarction. Therefore, further studies are required before a firm conclusion can be drawn.…”

“…Based on the protective effects of naloxone, Fagbemi et al (1982) have also postulated that activation of opiate receptors by endorphins released during the early stages of myocardial ischaemia may have detrimental effects of cardiac rhythm. Therefore, it is conceivable that acute morphine administration may retard or aggravate the occurrence of ventricular arrhythmias following acute coronary artery ligation.…”

Myocardial and Peripheral Concentrations of .BETA.-Endorphin Before and Following Myocardial Ischemia and Reperfusion During Coronary Angioplasty

“…[2][3][4] There is substantial evidence that cardiac opioid receptors are activated during myocardial ischemia and reperfusion, supporting the hypothesis that EOP are involved in the pathophysiology of ischemic heart disease. 12) We have shown that in patients with acute myocardial infarction, there was an increased plasma concentration of β-endorphin.…”

“…4) In humans, it has been shown that opioid receptors are present in the heart and that they play an important role in myocardial ischemia. 5) We have shown that in patients with acute myocardial infarction, there was an increased plasma concentration of β-endorphin.…”