Effect Of Endogenous Nociceptin/Orphanin FQ On Arrhythmia Induced By Acute Myocardial Ischemia In Rats Through Connexin 43

Objective:To observe various ventricular arrhythmias induced by acute myocardial ischemia and the change of connexin 43(Cx43)protein content in myocardium in rats and effects of nociceptin/orphanin FQ receptor antagonist UFP-101 on the expression of arrhythmia and Cx43 protein.Methods:Sixty-four male SD rats,weighing 200~250 g,were randomly divided into control group(group C,each group was divided into three subgroups,which named CAO 15 min,CAO 60 min and CAO 120 min,n=8),N/OFQ receptor antagonist group(group U,each group was divided into three subgroups,which named CAO 15 min,CAO 60 min and CAO 120 min,n=8),Sham operation group(group S,each group was divided into two subgroups,which named thread without ligation 15 min and thread without ligation60 min,n=8).Group U was treatment with OFQ antagonist compound UFP-101 in the dosage of 1ul/g by caudal vein;group C was treatment with Equal volume of saline.Group C and U were administered 5 min before they were subjected to the coronary artery occlusion(CAO),group S only thread without ligation.Record the data of group C and U electrocardiogram which from 10 min before the injection to 15,60 min and 120 min after CAO,analysis and statistics of all kinds of ventricular arrhythmia.Determination of the content of phosphorylated Cx43(p-Cx43)protein and total Cx43 protein in all specimens by western blot.Results:15 minutes after CAO,the number of ventricular premature contraction(VPC)and ventricular diallelism of Group U,and the duration of ventricular tachycardia and ventricular fibrillation of Group U are lower than Group C obviously(P<0.05).60 minutes after CAO,the number of ventricular premature contraction(VPC)and ventricular diallelism and ventricular tachycardia and ventricular fibrillation of Group U are lower than Group C obviously(P<0.05).Expression of p-Cx43 protein : 15 minutes after CAO,the expression of p-Cx43 in group C was significantly lower than that in group S(P<0.05).The expression of p-Cx43 in group U was significantly higher than that in group C(P<0.01).60 minutes after CAO,the expression of p-Cx43 in group C and U were significantly lower than that in group S(P<0.05).Conclusion:Endogenous nociceptin/orphanin FQ antagonist UFP-101 can reduce the occurrence of arrhythmia in acute myocardial ischemia by promoting phosphorylation of Cx43 protein in rats.