Inhibitor of NOS2 improves rat cardiac function after myocardial infarction

Objective:To explore the function of NOS2 in the development of cardiac dysfunction after myocardial infarction.Method:Rats with myocardial infarction induced by left coronary ligation received S-methylisothiourea(SMT)or saline for 4 weeks. The hemodynamic studies were performed. Infarct size, heart weight, plasma NO, heart NOS2 were quantified.Result:Long term administration of SMT could decrease plasma NO level[( 26.6± 2.2)vs ( 46.6± 4.2)μmol/L,P 0.05], heart weight, infarct size, and ameliorate cardiac dysfunction[LVEDP ( 6.1± 0.7) vs ( 11.0± 1.2) mmHg,P 0.05; CVP ( 0.8± 0.1) vs ( 1.6± 0.2) mmHg,P 0.05]. Four weeks after myocardial infarction, NOS2 level in noninfarct myocardium was much higher than controls[( 0.261± 0.025) vs ( 0.092± 0.011 )A·μm -2,P 0.05)].Conclusion:These findings demonstrate that induction of NOS2 after myocardial infarction exerts negative effects on cardiac function and structure. Long term administration of a selective NOS2 inhibitor SMT may prove to be beneficial in the treatment of cardiac dysfunction after myocardial infarction.