Effects Of N-3 Polyunsaturated Fatty Acids On Ventricular Arrhythmia In Rats After Myocardial Infarction

Objective:To investigate the effects of n-3 Polyunsaturated Fatty Acids (n-3 PUFA) on cardiac neural remodeling after myocardial infarction.Methods:48 male rats were randomly divided into three groups:the n-3 PUFA group (MI+n-3 PUFA, n=18), receiving ligation of the left anterior descending branch with administration (0.70g/kg.d); the control group(MI+olive group, n=18), receiving ligation of the left anterior descending branch with olive oil administration (0.70g/kg.d); sham group (Sham group, n=12) receiving thoracotomy without ligation. After 4 weeks, electrophysiological recordings were carried out after the structural and function of the hearts are measured by ultrasound; TH and GAP43 level both in the imfarcted border and non imfarcted border were determined by immunohistochemical technique. ANP was detected by RT-PCR for the left ventricle.Results:The incidence of inducible ventricular arrhythmias (VAs) in the Ml+olive group was obviously higher than that in the sham group (p< 0.01). However, it was significantly decreased after n-3 PUFA treatment (p< 0.01). The densities GAP43 positive nerve fibers and TH at the border zone in the MI+olive group were significantly higher than that at the corresponding zone in the sham group (p< 0.05). Additionally, both the GAP43 and TH nerve fibers densities dropped significantly and were close to the sham group level after n-3 PUFA treatment compare with the MI+olive group. ANP mRNA level was not different between the MI+n-3 PUFA and MI+olive group. There was no different in the ventricular remodel. There was less incident of ventricular arrhythmia in the MI+n-3 PUFA groupConclusion:n-3 PUFA treatment is effective in reducing the occurrence of VAs in healed MI, partly by attenuating the heterogeneity of cardiac innervation and normalizing the appearance of cardiac nerve fibers. No effect on ventricular remodel was observed. Objective:To study the effect of n-3 polyunsaturated fatty acids (n-3 PUFA) on Cx 43 expression after myocardial infarction and its association with ventricular arrhythmiasMethods:Anterior descending coronary artery ligation produced myocardial infarction model,42 rats were divided into MI+ n-3 PUFA group (0.70g/kg.d, n= 15), MI+olive oil control group (MI+ olive Group) (0.70g/kg.d, n= 15), and sham operation (Sham groups, n= 12) groups.4 weeks later, cardiac structure and function were tested and isolated heart in Langendorff was used as programmed stimulation to nduced ventricular arrhythmia, ventricular effective refractory period measured (ERP); IECG QRS duration and QTc were measured and cardiac function, infarct size, collagen fibers were observed Cx 43 distribution were tested by mmunohistochemical. RT-PCR and Western-blot method were used to Cx43 mRNA and protein levels, Cx43 distribution was observed by electron microscope..Results:MI+n-3 PUFA group survived 14, MI+olive group survived 12 rats, Sham group survived 12 rats. MI+n3PUFA group QRS duration and QTc interval and the ERP were lower than those in MI+olive group (p<0.05). The rate of inducing in MI+n3PUFA group was significantly higher than Sham (60% higher than 11.1%, p<0.001) while MI+n3PUFA group induced less than MI+ olive group (P<0.05) using programmed stimulation. MI+n3PUFA group expression of Cx43 mRNA and Cx 43 protein levels were higher in the n3PUFA group than MI+olive group (p> 0.05). Gap junction structure and distribution was nearly normal in n-3PUFA group compared with MI+olive group by electron microscope.Conclusion:n-3 PUFA reduces myocardial infarction ventricular arrhythmias may has relation with increased ventricular expression of Cx43 protein...