Variance Of Ito After Acute Myocardial Infarction In Rat And Pravastatin Effects

Objective The abnormal activity of cadiocyte ion channel probably leads to arrhythmia after acute myocardial infarction (AMI). Transient outward current (Ito) plays an important role during repolarization of myocardium action potential (MAP). The decrease or absence of Ito prolongs platform-stage of MAP and makes repolarization abnormal. Ito is encoded by Kv1.4 ,Kv4.2 and Kv4.3 in rat. Current density of Ito in rat cadiocyte decreased after AMI 8 weeks, but the variance tendency is not clear. Now statins is widespread besides lowering lipids effect, some research showed statins resisted arrhythmia but the mechanism was not clear.furthermore, there is no report between statins and Ito in cadiocyte. Our research aimed to investigate variance of Ito after AMI in rat and pravastatin effects.Methods AMI model induced by the left anterior descending coronary artery (LAD )ligation in Sprague-Dawley rats ,randomly divided into 24-hour group, 1-week group, 4-week group and pravastatin group(20 mg·kg-1·d-1),5 ones in each group. Accordingly,the sham-operation groups was established at 3 time-points above, 5 ones in each group too. mRNA and protein of Kv1.4 ,Kv4.2 and Kv4.3 were measured with free right ventricular wall of each group using real-time polymerase chain reaction (real time-PCR) and western blot.Results 3 sham-operation groups were merged as sham group because of no difference. The expression of Kv1.4 mRNA and protein was up-regulated after 24 hours in AMI, pravastatin group was lower than 4-week group. the expression of Kv4.2 and Kv4.3 mRNA and protein was down-regulated, the former lowest in 4-week group and the latter lowest in 24-hour group, pravastatin group was higher than 4-week group.Conclusions The expression of Kv1.4 mRNA and protein increased while Kv4.2 and Kv4.3 mRNA and protein depressed after AMI in rat. pravastatin may reverse the variance of Ito after AMI .