Antifibrillating effects of n-3 polyunsaturated fatty acids (PUFA) in aged hypertensive rats

Abstract

PUFA have been shown in clinical trials to reduce the incidence of cardiovascular disease and sudden death, while experimental studies suggest their antiarrhythmic effects. Hypertension-related cardiomyopathy accompanied by myocardial remodelling deteriorates with age and increases a risk for malignant arrhythmias. The aim of the study was to investigate effect of PUFA on inducible ventricular fibrillation (VF) in aged spontaneously hypertensive rats (SHR). Male and female 14 moth-old SHR were fed with PUFA (20 mg/day for 2 months). Age-matched controls were used as well. Results showed that PUFA supplementation resulted in significant blood pressure reduction in both male and female SHR, while no change in body weight was observed. There was a decrease of heart rate and an increase of coronary flow in female PUFA-treated rats as measured in isolated heart preparation, while no significant changes in male rats. All untreated SHR were susceptible to electrically induced sustained VF. In contrast, inducible VF was significantly suppressed by 57% and 67% in PUFA-treated male and female SHR. Interestingly, PUFA supplementation led to clear antifibrillating effects despite myocardial remodelling, i.e. fibrosis and hypertrophy were not eliminated. However, histochemistry revealed increase of selected membrane-bound enzyme activities in the ventricles of PUFA treated rats. There were also alterations in immunolabeling of gap junction channel protein, connexin-43, which need further analysis.