Opioids in myocardial ischaemia: potentiating effects of dynorphin on ischaemic arrhythmia, bradycardia and cardiogenic shock following coronary artery occlusion in the rat.
The endogenous opioid peptide (EOP) dynorphin and opioid receptors have been found in the heart. This opioid system plays important roles in cardiovascular regulation and is involved in the pathophysiology of shock, heart failure and myocardial ischaemia. The aim of this study was to evaluate whether the EOP dynorphin modulates or potentiates ischaemia-induced arrhythmias and whether its effects are prevented by the opiate antagonist naloxone. Following coronary artery occlusion, all rats in the control group developed ischaemia-induced arrhythmias, bradycardia and hypotension, which were significantly potentiated by pre-treatment with dynorphin and attenuated by treatment with naloxone. The results clearly indicate that EOPs may be released when myocardial ischaemia occurs, thus causing arrhythmias, bradycardia and hypotension. Dynorphin and naloxone, by virtue of their opioid agonistic and antagonistic actions, respectively, potentiate and attenuate these fatal complications secondary to myocardial ischaemia. This suggests that EOPs play an important part in ischaemic heart disease.
Wu
J P
JP
Department of Medical Research, Taichung Veterans General Hospital, Taiwan, Republic of China.
Chen
Y T
YT
Lee
A Y
AY
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology* / Q000517:prevention & control; D001919:Bradycardia / Q000503:physiopathology / Q000517:prevention & control; D004399:Dynorphins / Q000037:antagonists & inhibitors / Q000502:physiology*; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects; D007022:Hypotension / Q000503:physiopathology; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology* / Q000517:prevention & control; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012770:Shock, Cardiogenic / Q000503:physiopathology* / Q000517:prevention & control
D009270:Naloxone; D004399:Dynorphins