| Objective: A lot of investigation reported that myocardial ischemia reperfusion (I/R) injury correlated closely with cytokines produced during I/R. The recent study also suggested that myocardial cell apoptosis might play an important role in I/R injury. This study was designed to investigate the effects of I/R on expression of FAS protein in myocardium and changes of plasma IL-8 and TNF-α on plateau. Method: 40 New Zealand white rabbits were randomly divided into four groups: (1) Plain sham-operated group (group I, n=10): The sham operations were induced by opening chest without ligation of left coronary artery. (2) Plain I/R group (group II, n=10): Operations were induced by opening chest and ligating left coronary artery, leading to myocardial ischemia for 1 h followed by reperfusion for 24 h. (3) Plateau sham-operated group (group III, n=10): The rabbits were taken to Lhasa from Chongqing by air and fed for two months. The sham operations were performed by opening chest without ligation of left coronary artery. (4) Plateau I/R group (group IV, n=10): The rabbits were the same as group III. Operations were performed by opening chest and ligating left coronary artery for 1 h ischemia followed by 24 h reperfusion. Blood samples were taken before operation (T1), before ischemia (T2), 1 h after ischemia (T3), 4 h after reperfusion (T4) and 24 h after reperfusion (T5). Plasma IL-8 and TNF-α were measured by radioimmunoasssay. Plasma cTnT were measured by ELISA method. Myocardial tissues were sampled from left ventricle at the start and the end of reperfusion respectively for ultrastructure observation. Myocardial FAS expression was detected by immunohistochemistry. The results were analyzed statistically.Results: 1. Plasma levels of cTnT in group III and group IV were higher than those in group I and group II at T1 (P<0.05). In group II and group IV, plasma levels of cTnT elevated after 1 h ischemia (P<0.01), and peaked at 4 h after reperfusion (P<0.01, vs preoperation), and were still at higher levels at 24 h after reperfusion (P<0.05). Both on plateuo and in plain, the plasma cTnT levels in I/R groups(II, IV) were higher than those in sham-operated groups(I,III) at T3, T4 and T5, respectively (P<0.01). Moreover, plasma levels of cTnT in group IV were higher than those in group II at T3, T4 and T5 (P<0.05).2. Plasma levels of IL-8 in group III and group IV were higher than those in group I and group II at T1 (P<0.05). In group II and group IV, plasma levels of IL-8 elevated after 1 h ischemia (P<0.01), and peaked at 4 h after reperfusion (P<0.01, vs preoperation), and were still at higher levels at 24 h after reperfusion (P<0.05). Both on plateuo and in plain, the plasma IL-8 levels in I/R groups(II, IV) were higher than those in sham-operated groups(I, III) at T3, T4 and T5, respectively(P<0.01). Moreover, plasma levels of IL-8 in group IV were higher than those in group II at T3, T4 and T5(P<0.05).3. Plasma levels of TNF-αin group III and group IV were higher than those in group I and group II at T1 (P<0.05).In group II and group IV, plasma levels of TNF-αelevated after 1 h ischemia(P<0.01), and peaked at 4 h after reperfusion (P<0.01, vs preoperation), and were still at higher levels at 24 h after reperfusion(P<0.05). Both on plateuo and in plain, the plasma TNF-αlevels in I/R groups(II, IV) were higher than those in sham-operated groups(I, III) at T3, T4 and T5, respectively(P<0.01). Moreover, plasma levels of TNF-αin group IV were higher than those in group II at T3, T4 and T5(P<0.05).4. Myocardial FAS expression was found in cardiac myocytes. Optical density (OD) value in group II and group IV were higher than those in group I and group III(P<0.01)respectively. OD value of group IV was slightly higher than that of group II, but had no statistical significance.Conclusion: Our preliminary results suggest that I/R injury on plateau is more severe than that in plain. In plateau I/R group, plasma cTnT elevated higher than those in plain I/R group and the myoc... |
PDF Full Text Request