Ferrous ion diminished the antiarrhythmic effect of naloxone in myocardial ischemia of isolated rat hearts.
This investigation was to examine the effect of ferrous ion (a prooxidant) on the antiarrhythmic effect of naloxone (an endogenous opioid receptor antagonist) in isolated rat hearts. Isolated Sprague-Dawley rat hearts were perfused in the Langendorff mode and myocardial ischemia was performed by ligating the left descending coronary artery. Cardiac rhythm was recorded. Heart alpha-tocopherol concentrations were analyzed. Naloxone (1.2 micromol/heart) was effective in reducing the severity of arrhythmia (arrhythmia score; mean+/-S.E.M: 2.82+/-0.69 for naloxone vs. 5.18+/-0.38 for control, p<0.01). Fe2+ (100 nmol/heart) alone did not significantly affect the arrhythmia score (5.63+/-0.32) when compared with the control, however, Fe2+ administration did cause significant early onset of ventricular premature contraction and ventricular tachycardia. Additionally, Fe2+ administration diminished the naloxone's antiarrhythmic effect (arrhythmia score 4.12+/-0.40). Alpha-tocopherol, a major free radical scavenger that exerts protective functions on heart tissues during myocardial ischemia/reperfusion, was significantly higher in the naloxone-treated group (59.05+/-3.00 nmol/g wet wt) than in the control group (43.84+/-4.17 nmol/g wet wt, p<0.05). These results suggest that endogenous opioid peptides and reactive oxygen species might be related to ischemia-induced arrhythmia.
Department of Education and Research, Taichung Veterans General Hospital, Taiwan, ROC.
J S
JS
Kuo
J P
JP
Wu
P J
PJ
Tsai
C S
CS
Yang
D000704:Analysis of Variance; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D008297:Male; D017202:Myocardial Ischemia / Q000188:drug therapy; D009206:Myocardium / Q000378:metabolism; D009270:Naloxone / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014810:Vitamin E / Q000378:metabolism
D000889:Anti-Arrhythmia Agents; D005296:Ferrous Compounds; D009292:Narcotic Antagonists; D014810:Vitamin E; D009270:Naloxone