Suppression of reperfusion induced arrhythmias in the isolated rat heart: pretreatment with 7-oxo prostacyclin in vivo

Objective: The aim was to investigate the late effect of pretreatment with 7-oxo prostacyclin on reperfusion induced arrhythmias in the isolated rat heart. Methods: Forty eight hours after intramuscular administration of drug in vivo (50 µg·kg–1 body weight), isolated Langendorff perfused rat hearts were subjected to 30 minutes of regional ischaemia and 5 minutes of reperfusion. Incidence and duration of ventricular arrhythmias in both pretreated and control groups were evaluated on reperfusion. Morphological examination was also performed. Results: In the untreated group reperfusion induced 75% of sustained ventricular fibrillation. Incidence of ventricular fibrillation, its duration, and arrhythmia score were significantly lower in the pretreated group. Pretreatment with 7-oxo prostacyclin had no effect on heart rate and coronary flow throughout the whole course of perfusion. Neither was the occluded zone size affected. Ultrastructure of ischaemic and reperfused myocardium was better preserved in the pretreated group. Conclusions: Antiarrhythmic action of 7-oxo prostacyclin was unrelated to changes in haemodynamics, thus suggesting the direct influence of the myocardium. The possible mechanism of action may involve maintenance of intracellular cation homeostasis (particularly of Na+ and Ca2+) due to a stimulation of sarcolemmal Na+ pump activity. Cardiovascular Research 1993;27:1051-1055