Investigation of changing and significance of connexin43,[Ca~(2+)]_i and apoptosis in early phase of acute myocardial ischemia

Objective To investigate the variations of connexin43(Cx43),[Ca2+]i and apoptosis of ventricular myocardium in acute ischemic condition,and elucidate the underlying mechanisms of acute ischemic arrhythmias.Methods Thirty male SD rats were randomly divided into the sham group,acute myocardial ischemia for 15 min group(Is1) and for 30 min group(Is2) respectively(all group,n = 10).The incidences,durations and number of the ventricular arrhythmias,the expressions of Cx43 dephosphorylation,[Ca2+]i and apoptosis of myocardium were all studied.Then,we analyzed the corresponding relations between ventricular arrhythmias and other values.Results Ventricular arrhythmia significantly of Is1 group increased comparing with the sham group;after 30 min of ischemia,the arrhythmias were more serious.Cx43 dephosphorylation of Is1 group was higher than the sham group,but without significance.After coronary artery being ligated for 30 min,this value was significantly raised(P 0.01).Compared to the sham group,[Ca2 +]i and apoptotic rate were increased from 15 min of ischemia(P 0.01 for all).Correlation analysis revealed that severity score of arrhythmias of Is1 group was significantly correlated with Cx43 dephosphorylation,[Ca2 +]i,but not apoptotic rate,while in Is2 group,the severity score of arrhythmias was significantly correlated with all of them.Conclusion Intracellular calcium and apoptosis may be the main mechanism of ventricular arrhythmias in the early phase of myocardial ischemia,and in the later phase Cx43 may also be involved.