The effects of nitric oxide on the cardiac function of ischemic and reperfused myocardium of rats in vivo at early reperfusion

Objective To determine the effects of nitric oxide on the cardiac function of ischemic and reperfused myocardium of rats in vivo at early reperfusion, and to investigate the mechanisms involved. Methods Thirty‐six male adult rats were randomly divided into three groups, sham, vehicle and L‐arginine group (n=12). MI/R was produced by ligating the left anterior descending coronary artery for 30min followed by 5 hours of reperfusion. Rats received vehicle (0.9% NaCl, 1 ml/kg, i.p.) or L‐arginine (100mg/kg, i.v.) at a bolus at 10 minutes before reperfusion. Sham‐operated animals underwent the same surgical procedures except that the suture that was passed under the left coronary artery was not tied. The following variables were measured: cardiac hemodynamic parameters, myocardial caspase3 activity. Results Compared with vehicle group, early treatment improved the cardiac function(LVSP: 99%±10% vs. 78%±10% at R2h, 93%±10% vs. 72%±9% at R3h; +dp/dt: 100%±10% vs. 82%±23% at R2h, 93%±11% vs. 75%±0.17% at R3h; −dp/dt: 119%±26% vs. 89%±19% at R2h, 113%±17% vs. 82%±19% at R3h. p<0.05), and reduced myocardial caspase3 activity (225 vs. 340μmol pNA/mg protein, p<0.05). Conclusion At early stage of myocardial reperfusion, cardiac function was improved by NO′s inhabiting apoptosis.