Gender Differences In Post-infarct Cardiac Rupture In A Mouse Model

Objective:To investigate gender differences in post-infarct cardiac rapture and early left ventricular remodeling in a mouse model and possible mechanisms.Methods:C57BL mice in two groups:males and females were divided into sham operation group and myocardial infarction(MI)group randomly.Following acute myocardial infarction(AMI) induced by open-chest surgery,the events of cardiac rupture were monitored,the echocar-diography and hemodynamics were performed at 7 days after surgery.Zymography and pathological staining were used to measure the activity of matrix metalloproteinases (MMPs),content of collagen and quantitate the inflammatory cells at 3 and 7 days after surgery.Results:1)A significantly higher incidence of cardiac rupture was observed in males than in females(26.7%versus 7.0%,P＜0.05).2)Males had a significantly higher number of inflammatory cells infiltrating at the infarct border at 3 days after surgery (P＜0.05).MMP-9 activity were higher in males than in females at 3 and 7 days after AMI. The collagen content were increased in females than in males after AMI.3)The MAP and LVSP in sham operation group were higher in male mice compared to female mice(both P＜0.05).And the severe infarct expansion,worse left ventricular(LV)remodeling and hemodynamics were showed in males compared to females at 7 days after surgery. Conclusion:The cardiac rupture rate during the first week after MI was significantly higher in male mice than in female mice.The mechanisms responsible for this gender-related difference in cardiac rapture were related to more infiltrating inflammatory cells,increased MMP-9 activity,premature collagen degradation,and aggravated early LV remodeling.