| Objective:To investigate mechanisms of the protective effect of angiotensinⅡtype-1 receptor (AT-1)blocker, valsartan, on congestive heart failure submitted to dilated cardiomyopathy.Methods:40 SD rats of health and maleness were divided randomly into 3 groups as follows:adriamycin group(the group M, n=15), valsartan group(the group V, n=15) and control group(the group C, n=10). The group M and the group V were injected adriamycin intraperitonealy at a dose of 2 mg·kg-1 once a week. Valsartan was administered by gavage at a dose of 30 mg·kg-1·d-1 in the group V.①After 8 weeks, the left ventricular dimension at end-diastole(LVEDD) and at end-systole(LVESD), the left ventricular ejection fraction (LVEF) and the left ventricular shortening fraction(LVFS) of hearts in different groups was measured with echocardiography.②The ultrastructure of cardiac mitochondia in different groups was detected with electron microscope.③The index of oxidative stress(MDA/T-SOD/CuZn-SOD/Mn-SOD) were measured by colorimetric method.④The Reactive Oxygen Species(ROS) were detected by using 2',7'-dichlorofluorescein diacetate(DCFH-DA) as a fluorescent probe.⑤membrane electrical potential (△Ψm) of cardiac mitochondria was evaluated by Rhodamine 123(Rh123).⑥Na+K+-ATPase and Ca2+Mg2+-ATPase were also measured by colorimetric method.⑦The swelling of heart mitochondria induced by Ca2+ was measured by colorimetric method.⑧The protein of second mitochondria-derived activator of caspase(Smac) was detected by The immunohistochemistry.⑨The protein levels of apoptosis inducing factor(AIF) and Smac were detected by western blot.Results:①The results of echocardiograghic measurements in different groups: Compared with the group C, LVEDD were significantly increased[(6.52±0.32)vs(5.83±0.45)mm, P＜0.05] in the group M. In group V, LVEDD was (6.08±0.54)mm, which was larger than that in the group C(P＞0.05) and smaller than that in group M(P>0.05). Compared with the group C, LVESD were significantly increased[(3.47±0.20)vs(2.55±0.19)mm, P＜0.05] in the group M. In group V, LVESD was (3.02±0.23)mm, which was significantly larger than that in the group C(P＜0.05) and significantly smaller than that in group M(P＜0.05). Compared with the group C, LVEF were significantly decreased[(83.00±1.31)vs(90.25±2.31)%, P＜0.05] in the group M. In the group V, LVEF was (86.13±1.36)%, which was significantly lower than that in the group C(P＜0.05) and significantly higher than that in group M(P＜0.05). Compared with the group C, LVFS were significantly decreased[(46.88±1.46)vs(56.13±3.64)%, P＜0.05] in the group M. In the group V, LVFS was (50.13±1.36)%, which was significantly lower than that in the group C(P＜0.05) and significantly higher than that in group M(P＜0.05).②The results of cardiac mitochondrial ultrastructure in different groups:Compared with the group C, cardiac mitochondria's volume was swelling obviously, their cristae were disrupted, and many of them were vacuolization in the group M. Compared with the group M, the ultrastructure of cardiac mitochondria were improved in group V.③The results of MDA and SOD measurements in different groups' cardiomyocyte:Compared with the group C, MDA was singnificant increased in the group M[(1.53±0.32) vs(0.86±0.29) nmol/mgprot, P＜0.05]. In the group V, MDA was (1.04±0.31) nmol/mgprot, which was higher than that in the group C(P＞0.05) and significantly lower than that in the group M(P＜0.05). Compared with the group C, the T-SOD were significantly decreased in the group M[(75.69±7.51)vs(99.13±11.64)U/mgprot, P＜0.05]. In the group V, T-SOD was (93.44±9.70) U/mgprot, which was lower than that in the group C(P＞0.05) and significantly higher than that in the group M(P＜0.05). Compared with the group C, CuZn-SOD were significantly decreased in the group M[(68.20±10.42)vs(91.06±14.37) U/mgprot, P＜0.05]. In the group V, CuZn-SOD was (85.38±5.57) U/mgprot, which was lower than that in the group C(P＞0.05) and significantly higher than that in the group M(P＜0.05). Compared with the group C, Mn-SOD was significantly decreased in the group M[(2.99±2.53)vs(6.42±1.75) U/mgprot, P＜0.05]. In the group V, Mn-SOD was (3.88±1.49) U/mgprot, which was significantly lower than that in the group C(P＜0.05) and little higher than that in the group M(P＞0.05). ④The results of ROS fluorescence intensity in different groups' cardiomyocyte:Compared with the group C, ROS fluorescence intensity was much stronger in the group M. ROS fluorescence intensity in the group V was stronger than that in the group C and weaker than that in the group M.⑤The results of△Ψm in different groups'cardiac mitochondria: Compared with the group C, Rh123 fluenrence intensity was significantly decreased in the group M[(386.93±67.92)vs(548.10±74.91), P＜0.05]. In the group V, Rh123 fluenrence intensity was (450.66±45.43), which was significantly lower than that in the group C(P＜0.05) and significantly higher than that in the group M(P＜0.05).⑥The results of ATPase measurements in different groups' cardiomyocyte:Compared with the group C, Na+K+-ATPase was significantly decreased in the group M[(18.77±1.63)vs(26.56±2.99) U/mgprot, P＜0.05]. In the group V, Na+K+-ATPase was (21.14±1.48) U/mgprot, which was significantly lower than that in the group C(P＜0.05) and significantly higher than that in the group M(P＜0.05). Compared with the group C, Ca2+Mg2+-ATPase was significantly decreased in the group M[(12.29±1.24)vs(19.44±2.75) U/mgprot, P＜0.05]. In the group V, Ca2+Mg2+-ATPase was (14.01±1.95) U/mgprot, which was significantly lower than that in the group C(P＜0.05) and little higher than that in the group M(P>0.05).⑦The results of cardiac mitochondria's swelling in different groups: Cardiac mitochondria's swelling induced by high concentration of Ca2+ was most obviously in the group C, and the swelling induced by high concentration of Ca2+ in the group V was much better than that in the group M.⑧The immunohistochemistry results of Smac in different groups' cardiomyocyte:In the group C, the majority were blue-stain negative myocytes, and could see a little Smac positive myocytes. In the group M and the group V, there were great more Smac positive myocytes than that in the group C, and there were lots of buffy particles in the endochylema. Compared with the group M, Smac positive myocytes were much less in the group V.⑨The western blot results of Smac and AIF in different groups' cardiomyocyte:Compared with the group C, RSmac/β-actin in the group M was significantly higher[(0.69±0.05) vs (0.23±0.08), P＜0.05]. RSmac/β-actin in the group V was (0.43±0.10), which was significantly higher than that in the group C(P＜0.05) and significantly lower than that in the group M(P＜0.05). Compared with the group C, RAIF/β-actin in the group M was significantly higher[(0.78±0.06) vs(0.41±0.12), P＜0.05]. RAIF/β-actin in the group V was (0.53±0.11), which was a little higher than that in the group C(P＞0.05) and significant lower than that in the group M(P＜0.05).Conclusion:Preadministration of valsartan can improve the impairement of rats'hearts induced by adriamycin. Its influence on the interity of the structure and function of cardiac mitochondria, the improvement of the generation of ROS and calcium homeostasis, and the antiapoptosis property maybe the mechanisms of its protective effect.
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