To investigate the mechanisms of hepatic injury after biliary obstruction. After a rat model of complete biliary obstruction(CBO) was induced, hepatocyte mitochondria was isolated and the calcium content of mitochondria, the contents of liver malondialdyhyde (MDA) and superoxide dismutase (SOD), the levels of serum T-Bil, ALT, ALP and GGT were measured in each group. Results: After CBO, mitochondrial calcium content, liver MDA and serum T-Bil, ALT, ALP, GGT became increased progressively, compared with control group (Ｐ＜0.05); the liver SOD was decreased markedly (Ｐ＜0.05). Mitochondrial calcium content was highly positively correlated with liver MDA content, serum ALT and ALP, r values were 0.967, 0.924 and 0.919 respectively (Ｐ＜0.01). The liver MDA content was highly positively correlated with serum ALT and ALP, r values were 0.949 and 0.843 respectively (Ｐ＜0.01). Conclusions: Mitochondrial calcium overload and liver lipid peroxidation may be the important mechanisms of hepatic injury induced by biliary obstruction.
【Abstract】 Objective To analyze the correlations between the mt5351G and mt6680C genotypes in mitochondrial DNA ( mtDNA) haplogroup M and susceptibility to high altitude pulmonary edema ( HAPE)among the Hans. Methods Specimens from206 Hans cases of HAPE and 144 matched Hans controls were collected. Then PCR-RFLP method was used to determine haplogroup M and N of mtDNA, and PCR-LDR was used to genotype mt5351G and mt6680C in the haplogroup M in these samples. Results The frequencies of haplogroup Mand N were 49. 0% and 51.0% in the HAPE patients, and 47. 2% and 52. 8% in the controls, respectively, with no significant difference between the HAPE patients and the controls. In the haplogroup M, the genotype of mt6680C and mt5351G frequencies in the HAPE patients were both significantly higher than the controls ( both 12. 0% vs. 1. 5% , P = 0. 016) . Conclusion The existence of mt5351G and mt6680C genotypes in the haplogroup Mis a risk factor for HAPE among the Hans.
The main function of mitochondrial fusion protein 1 （Mfn1） and mitochondrial fusion protein 2 （Mfn2） was originally thought to be just regulating the fusion of mitochondrial outer membrane. But in recent years，many studies on these two proteins show that they are involved in many important cellular physiological processes including proliferation，apoptosis，necrosis and regulation of respiratory function and oxidative metabolism. There are many aspects of the influenceof Mfn1 and Mfn2 on cardiomyocyte，which have not been thoroughly studied yet，sometimes with even contradictoryconclusions. But these two proteins definitely have significant impact on the growth，development and physiological functionof cardiomyocyte. To investigate the function and mechanism of Mfn1 and Mfn2 in various physiological processes of cardiomyocyte is of great significance for in vitro studies of physiological functions of cardiomyocyte and technological development of myocardial tissue engineering and transplantation in vivo. This article mainly focuses on recent research progress of the influence of Mfn1 and Mfn2 on various physiological functions of cardiomyocyte.
Abstract： Objective To study the changes of the cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) expression of isolated rat hearts after diazoxide preconditioning (DPC), and to explore the possible mechanism of cAMP signaling pathway in myocardial protection by DPC. Methods Isolated working heart Langendorff perfusion models of 40 Wistar rats were set up and were divided randomly into four groups. For the ischemia reperfusion injury(I/R) group (n=10), 30 min of equilibrium perfusion was followed by a 60 min reperfusion of KrebsHenseleit (K-H) fluid. The DPC group (n=10) had a 10 min equilibrium perfusion and two cycles of 5 min of 100 μmol/L diazoxide perfusion followed by a 5 min diazoxidefree period before the 30 min ischemia and the 60 min reperfusion of K-H fluid. The blank control group (control group, n=10) and the Dimethyl Sulphoxide(DMSO) group (n=10) were perfused with the same treatment as in the DPC group except that diazoxide was replaced by natriichloridum and DMSO respectively. The activity of creatine kinase (CK) in coronary outflow, the activity of malonyldialdehyde (MDA) and superoxide dismutase (SOD) in myocardium were detected. And the scope of myocardial infarction and the concentrations of myocardial cAMP and PKA were also assessed. Results Compared with the I/R group, the level of MDA for the DPC group decreased significantly (8.28±2.04 nmol/mg vs. 15.52±2.18 nmol/mg, q=11.761,Plt;0.05), the level of SOD increased significantly (621.39±86.23 U/mg vs. 477.48±65.20 U/mg, q=5.598,Plt;0.05). After a 30 min reperfusion, compared with the I/R group, the content of CK decreased significantly (82.55±10.08 U/L vs. 101.64±19.24 U/L, q=5.598, Plt;0.05) and the infarct size reduced significantly (5.63%±9.23% vs.17.58%±5.76%, q=6.176,Plt;0.05) in the DPC group. The cAMP concentration in the DPC group was much higher than that in the I/R group (0.64±0.07 pmol/g vs. 0.34±0.05 pmol/g, q=14.738,Plt;0.05), and PKA concentration was also much higher than that in the I/R group ［17.13±1.57 pmol/(L·min·mg) vs. 12.85±2.01 pmol/(L·min·mg), Plt;0.05］. However, there were no significant differences between the I/R group, DMSO group and the control group in the above indexs (Pgt;0.05). Conclusion DPC significantly improves the releasing of cAMP and PKA, decreases oxygen free radicals, and relieves myocardial ischemia reperfusion injury. The cAMP signaling pathway may be involved in triggering the process of myocardial protection mechanisms of DPC.
Objective To investigate the role of mitochondrial adenosine triphosphatesensitive potassium channel(mitoKATP) in immature myocardial ischemic preconditioning, and to provide evidence for immature myocardial protection. Methods Langendorff isolated heart infused model was used in the experiment. Twentyfour rabbits (aged from 14 to 21 days) were randomly divided into 4 groups：ischemiareperfusion group（I/R group）, myocardial ischemic preconditioning group(E1 group), 5hydroxydecanoate(5-HD) group (E2 group) and Diazoxide (Diaz) group(E3 group). Hemodynamics recovery rate, myocardial water content(MWC), the leakage rates of serum creatine kinase and lactate dehydrogenase, adenosine triphosphate content, superoxide dismutase activity, malondialdehyde content, myocardial cell Ca2+ content and myocardial mitochondrial Ca2+ content, myocardial mitochondrial Ca2+-ATPase activity, the adenosine triphosphate(ATP) synthesizing ability of myocardial mitochondria were tested, and myocardial ultrastructure was observed via electron microscopy. Results The hemodynamics recovery rate, myocardial water content(P＜0.05), adenosine triphosphate content, superoxide dismutase activity, myocardial mitochondrial Ca2+-adenosine triphosphyatase(ATPase) activity and the ATP synthesizing ability of myocardial mitochondria of the rabbits in E1 and E3 group were significantly better than that in I/R group and E2 group(P＜0.05). Malondialdehyde content, the leakage rates of serum creatine kinase and lactate dehydrogenase, myocardial cell Ca2+ content and myocardial mitochondrial Ca2+ content of the rabbits in E1 group and E3 group were significantly lower than that in I/R group and E2 group (P＜0.05). The myocardial ultrastructure injury in E1 and E3 group were significantly reduced compared with that in I/R and E2 group. Conclusion Myocardial ischemic preconditioning has significant protective effects on immature myocardium. Its mechanism may be related to the activation of mitoKATP.
Objective To investigate the protective effects of ischemic postconditioning (IPo) on ischemiareperfusion (I/R) myocardium and the relationship with mitochondrial adenosine triphosphate (ATP) sensitive K+ channels (mitoKATP) and provide evidences to the development of druginduced postconditioning. Methods Langendorff models were established in 40 Wistar rats which were divided into 5 groups by random number table with 8 rats in each group. Normal control group(NC group): the rat hearts were continuously reperfused by KrebsHenseleit bicarbonate buffer (K-HB) for 100 min without any other treatment; I/R group: the rat hearts underwent a 40-min global ischemia followed by a 60-min reperfusion; IPo group: after a 40-min global ischemia, the process of 10-second reperfusion followed by a 10-second ischemia was repeated 6 times, then there was a continuous 58min reperfusion; 5-hydroxydecanoic acid(5-HD) group: after a 40min global ischemia, hearts with 5HD(100 μmol/L) K-HB were reperfused for 15min and then perfused without 5HD for 45min；IPo+5-HD group: after a 40-min global ischemia, the process that the isolated hearts with 5-HD(100 μmol/L) KHB were reperfused for 10second followed by a 10second ischemia was repeated 6 times, then the hearts with 5-HD(100 μmol/L) KHB were continuously [CM(159mm]perfused for 13-min followed by reperfusion without 5-HD(100 μmol/L) K-HB for 45-min. The cardiac function,coronary flow(CF), cardiac troponin I(cTnI) content in coronary effluent, the area of acute myocardial infarction (AMI) and myocardial ultrastructure were observed. Results Left ventricular developed pressure(74.3±3.3 mm Hg vs. 57.1±3.3 mm Hg,t=1300, P=0.000),+dp/dtmax(1 706.6±135.6 mm Hg/s vs. 1 313.3±96.2 mm Hg/s,t=6.28,P=0.000),－dp/dtmax(1 132.8±112.1 mm Hg/s vs. 575.7±67.7 mm Hg/s,t=13.48, P=0.000) and CF(6.49±0.30 ml/min vs. 3.70±0.24 ml/min,t=28.6,P=0.000) in IPo group were higher than those in I/R group. Left ventricular enddiastolic pressure(10.9±1.7mm Hg vs. 26.2±1.5 mm Hg,t=－19.21, P=0000)and cTnI content in coronary effluent (0.62±0.01 ng/ml vs. 0.71±0.01 ng/ml, t=-12.00,P=0.000) were lower than those in I/R group; the area of AMI decreased 20.8％ compared with that in I/R group (Plt;0.05). The myocardial protective effect in IPo+5HD group was similar with that in IPo group, but lower than that in IPo group. The electron microscope showed that IPo and IPo+5HD could reduce myocardial fiber damage and mitochondrial damage caused by I/R. Conclusion IPo can protect I/R myocardium, which is achieved mainly by activating mitoK-ATP channels.
Objective To investigate the effect of peroxisome proliferatoractivated receptor-γ coactivator-1α(PGC-1α) on early ischemic preconditioning (IPC) which may act as an important role in early IPC. Methods Building isolated working rat heart Langendorff model, thirty Wistar rats were divided randomly into three groups. Control group(CON group,n=10): a 120-min perfusion was performed without any intervension; ischemia and reperfusion group(I/R group,n=10): a 30-min equilibration period perfusion, a 30-min ischemia and a 60-min reperfusion were performed.; IPC group (n=10): a 10-min equilibration period perfusion was performed, then was elicited by two cycles of 5-min of ischemia interspersed with 5-min reperfusion prior to 30-min ischemia and a 60-min reperfusion. Frozen sections of myocardium at cardiac apex were made and immunohistochemical staining was used to detect expression and the intergrated optical density average (IODA) of PGC-1α. Ultrathin sections were made and the mitochondria under each specimen was evaluated according to Flameng score. Results PGC-1α expression in IPC group (IODA 10.94±5.23) was significantly higher than that in I/R group (IODA 3.88±1.72) and that in CON group (IODA 3.39±2.46; P=0.009, 0.007). The mitochondria changes in I/R group were significant edema and severe damage; but there were not so severe in CON group and IPC group.Flameng score of IPC group (0.44±0.13) and CON group (0.88±0.22) were lower than that in I/R group(1.78±0.14;P=0.003, 0.014) respectively. Conclusion IPC can protect myocytes mitochondria from ischemia and reperfusion.The cardioprotection may be related with the activation and the high expression of PGC-1α, which may act as one of the most important endogenous defence factors of the heart.
Objective\ To study the mechanism of myocardial protection of exogenous creatine phosphate (CP) against ischemia reperfused injury in modified isolated perfused working rat heart model.\ Methods\ Seventy two rats were divided into five groups.The rat hearts of five groups undergone Langendorff perfused were arrested and made totally ischemic for 40 minutes at 37℃ and reperfused for 20 minutes. St.Thomas cardioplegic solution wasn’t used in group A;It was used immediately after ischemia in group B and grou...
【Abstract】 Objective To detect the expression of Bcl-2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3)in cell death induced by nutrition deprivation in nucleus pulposus cells so as to further understand the mechanism of deathin nucleus pulposus cells. Methods Two adult Sprague Dawley rats, male or female, weighing 150-200 g, were involvedin this experiment. The cells isolated from rat caudal disc were cultured under the condition of L-DMEM culture media,10%FBS, and 21%O2 (control group) and under the condition of DMEM-free glucose culture media, no serum, and 1% O2(experimental group). The expressions of BNIP3 gene and protein were detected by real-time fluorescent quantitative PCR,immunofluorescence staining, and Western blot. The cell apoptosis rate and mitochondrial membrane potential were measuredby flow cytometry at 24, 48, and 72 hours after culture. Results The expression of BNIP3 decreased in the control group;the expressions of BNIP3 showed an increasing tendency with time in the experimental group, and BNIP3 combined withmitochondria. Significant differences were observed in the expressions of BNIP3 gene and protein between 2 groups at the othertime (P lt; 0.05) except that no significant difference was observed in the expression of BNIP3 gene at 24 hours (P gt; 0.05). Thecell apoptosis rate and mitochondrial membrane potential were significantly lower in the experimental group than those in thecontrol group (P lt; 0.05). Conclusion Upregulation of BNIP3 and translocation to mitochondria may be involved in nucleuspulposus cell death in nutrition deprivation.
Objective To investigate the preventive and therapeutic effects and the mechanisms of pyrrol idine dithiocarbamate (PDTC) on the atrophy of denervated skeletal muscle. Methods Thirty adult Wistar rats of either gender, weighing (200 ± 10) g were randomly divided into 3 groups: group A (n=6, control group), group B (n=12, denervation group), and group C (n=12, PDTC treatment group). The sciatic nerves of the rats were only exposed without cutting off in group A, and the rats were made denervated gastrocnemius models in groups B and C. PDTC of 100 mg/(kg•d) was injected peritoneally in group C and an intraperitoneal injection of the same amount normal sal ine was given in group B. After 14 and 28 days, the gastrocnemius was harvested to measure the ratio of muscle wet weight; the levels of nuclear factor of κB (NF-κB)p65 protein and the opening of the mitochondrial permeabil ity transition pore (MPTP) in the gastrocnemius were detectedrespectively by Western blot and laser confocal scanning microscope; and the apoptotic cells in atrophic muscle were measured with TUNEL. Results The ratio of muscle wet weight in group A was 1.039 ± 0.115, and it significantly decreased in groups B and C (P lt; 0.05); after 14 and 28 days of operation, the ratio of muscle wet weight in group C significantly increased when compared with those in group B (P lt; 0.05). The expression of NF-κB p65 protein in group A was 0.224 ± 0.041; the expressions of NF-κB p65 in groups B and C significantly increased when compared with that in group A (P lt; 0.05); however, the expression of NF-κB p65 in group C was significantly lower than that in group B (P lt; 0.05). The MPTP fluorescence intensity in group A was 31.582 ± 1.754; the MPTP fluorescence intensity was significantly lower in groups B and C than in group A (P lt; 0.05), and the MPTP fluorescence intensity in group C was significantly higher than that in group B (P lt; 0.05). The rate of apoptosis in group A was 4.542% ± 0.722%; after 14 and 28 days of operation, the rates of apoptosis significantly increased when compared groups B and C with group A, and signiticantly decreased when compared group C with group B (P lt; 0.05). Conclusion PDTC can retard denervated skeletal muscle atrophy, and the effect may have a relationship with its inhibition on NF-κB, the opening of the MPTP, and the ratio of apoptosis.