| Objective:To investigate the protective effects of sodium nitrite in isolated rat hearts with ischemia-reperfusion injury and explore the mechanism.METHODS: The Langendorff-perfused rat hearts models was established.40 mature male SD rats were divided into 5 groups randomly(n=8) :control group (C group):the isolated hearts were continuous infused 100min with Krebs-Henseleit(K-H) solution ;ischemia reperfusion group (I / R group): the isolated hearts were infused with K-H solution for 40 min, and subjected to global myocardial ischemia by St.Thomasâ…¡cardioplegic solution for 30 min and were reperfused with K-H solution for 60min;the low, middle and high concentration of sodium nitrite group (LN group, MN group, HN group) : the treatment was the same as I/R group,but the St.Thomasâ…¡cardioplegic solution was added with 0.01mg/L,0.1mg/L,1mg/L sodium nitrite respectively. Hemodynamic parameters were measured before ischemia and 10,30,60 min after reperfusion . The activity of creatine kinase (CK)and lactate dehydrogenase(LDH) of coronary flow ,the contents of NO and the activity of NOS in heart tissue were detected at time points of 60min after reperfusion,and the morphological changes of myocardium were observed under optical microscope.RESULTS: The difference of baseline values of cardiac function in each groups had no sense in statistics (P> 0.05); Compared with baseline values, The values of CF, LVSP, + dp / dtmax and -dp/dtmax in I / R group decreased at each time point during reperfusion (P <0.05); The trends of values of CF, LVSP, + dp / dtmax and -dp/dtmax in LN group and in LN group were the same as that I / R group(P <0.05),but were not as good as that I / R group significantly (P <0.05 or P <0.01), and the descending trends of MN group were lower than that LN group (P <0.05). Compared with C group, The activity of CK and LDH of coronary effluent in I / R group, LN group, MN group, HN group were increased (P <0.01 or P <0.05). The change of LN group were more prominent than that in MN group (P<0.0 5).While the HN group were significantly higher than the other four groups (P <0.01).The contents of NO and the activity of NOS in heart tissue in I/R group, LN group, MN group, HN group were increased(P <0.01 or P <0.05) compared with that C group . The activity of cNOS in MN group, HN group were higher than that I/R group,and MN group was more prominent (P<0.05). The difference of activity of iNOS in three groups had no sense in statistics (P> 0.05). The activity of iNOS in HN group was significantly higher than the other four groups (P<0.01), while the activity of cNOS lower than the other four groups (P<0.01). The microscopy showed seriously damaged structure of cardiac myocytes during ischemia-reperfusion ,disorderly arrayed myofibril,cell swelling, interstitial edema, vacuolar degeneration and the point of dissolution stove sheet .Using sodium nitrite,the changes in the structure of cardiocyte in LN group and MN group were mild and MN group was more prominent, but HN group were serious.CONCLUSION: Adding sodium nitrite in cardioplegic solution increased coronary blood flow , reduced the activity of CK and LDH, and protected the myocardium against ischemia-reperfusion injury . The mechanism may be related to the synthesis of cNOS induced. |
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