CHANGE IN OPIOID PEPTIDE LEVEL IN THE HEART AND BLOOD-PLASMA DURING ACUTE MYOCARDIAL-ISCHEMIA COMPLICATED BY VENTRICULAR-FIBRILLATION

1. The influence of acute myocardial ischaemia (AMI) complicated by ve ntricular fibrillation (VF) on opioid peptide level in myocardium and blood plasma of rats has been studied. 2. Leu-enkephalin level in myoc ardium of rats with AMI and VF has been found to be significantly lowe r than in animals with AMI but without VF. 3. Met-enkephalin level has been found to be significantly increased in both animals with VF and without it. We have not found a significant difference in met-enkephal in level in myocardium of animals with VF and without it. 4. AMI was i nduced to increase the enkephalin and beta-endorphin level in blood pl asma of all the animals, whether VF had occurred or not. 5. Preliminar y administration of D-Ala(2), Leu(5), Arg(6)-enkephalin, a synthetic a nalogue of leu-enkephalin, has prevented a decrease of ventricular fib rillation threshold in experimental coronary occlusion. 6. The obtaine d results allow us to conclude that enkephalins of myocardium but not opioid peptides of blood plasma play an important role in VF occurrenc e.