The effects of 7-ethyl-8-methylf1avin (7-Et) and 7-methyl-8-ethyl-flavin (8-Et) on rat hepatic monoamine oxidase (MAO), brain MAO activity and 5-hydroxytryptamine (5-HT or serotonin) in rat brain were investigated. In the study of hepatic MAO activity, kynur-amine a nonphysiological substrate for both A and B type MAO, was used for a spectro-photometric method, and [14C]-labeled amines were also used for a radiometric procedure for camparison with MAO activity determined by the spectrophotometric method. The rate of change in MAO activity of hepatic mitochondria from rats receiving Rb-def and 7-Et and 8-Et flavin showed the activity was severely reduced during 8 weeks. Rapid reduction of enzyme activity (50% in def-group, 35% in 7-Et group and 8% 8-Et flavin group) was observed at the end of 2 weeks. The enzyme activity lasted with slow decre-ment of enzyme level from 4 weeks to the end of 8 weeks as low as 16% in def, 18% in 7-Et and 3% in 8-Et flavin group. The trend of decrement of MAO activity when kynura-mine was used as a substrate appears to be similar with the small variation of MAO activity when [14C]-labelled tyramine, dopamine, serotonin and tryptamine respectively were used as substrate. The rate of decay of brain mitochondrial MAO activity in rats receiving each respective f1avin was not rapid and severely depressed as the MAO activity we have found in liver mitochondrial MAO of rats during the 8 week experimental time, but a similar tendency of decay of MAO in each group was observed. The potent inhibitory effect of 8-Et on brain MAO was confirmed by the study of the simultaneous measure-ment of MAO activity in each experimental group. when the reduction Of brain MAO activity in rats receiving 8-Et after 6 weeks was approximately 80% of normal and in the same rats the concentration of brain 5-HT showed a 60% increment of that of the normal mts. During the experimental period there is no absolute parallelism between the MAO inhibition and 5-HT increase. However when the reduction of MAO activity reached 80% of normal value, the concentration of 5-HT increased dramatically as much as 60% of normal value. The results so far suggest clearly that 8-Et produces a much more potent inhibitory effect on the hepatic MAO a s well as brain MAO in rats. Therefore our present and previous results suggest that 7-Et and 8-Et flavin should bind itself to hepatic, brain MAO apoenzyme in the condition of total absence of riboflavin in these animals, and the holenzyme is catalytically inactive.
Animal ; Brain/enzymology* ; Brain/metabolism ; Comparative Study ; Male ; Mitochondria/enzymology* ; Mitochondria, Liver/enzymology* ; Monoamine Oxidase/metabolism* ; Rats ; Serotonin/metabolism*

OBJECTIVETo investigate the effects of seawater immersion on the function of myocardium and hepatocyte mitochondria in experimental hemorrhagic shock rats.

METHODSTwenty-four male Wistar rats were divided into three groups (n=8 in each group): control group, HSL group (hemorrhagic shock group on land) and HSS group (hemorrhagic shock group in seawater). The hemodynamic parameters, activities of H(+)-ATPase (adenosinetriphosphatase), succinate dehydrogenase (SDH) and Ca(2+)-Mg(2+)-ATPase, the calcium contents in myocardium and hepatocyte mitochondria were measured and the changes of proton translocation across the inner mitochondrial membrane were analyzed.

RESULTSThe hemodynamic indexes and the activities of H+-ATPase, SDH, Ca(2+)-Mg(2+)-ATPase in HSS group were significantly lower than those in control group and HSL group (P<0.05). In HSS group the calcium levels in tissue and mitochondria of myocardium and hepatocyte were elevated significantly compared with control group and HSL group (P<0.05). There was no significant difference in proton translocation among three groups.

CONCLUSIONSThis investigation demonstrates that seawater immersion can aggravate the conditions of hemorrhagic shock rats.

Animals ; Calcium ; metabolism ; Immersion ; Male ; Mitochondria, Heart ; enzymology ; Mitochondria, Liver ; enzymology ; Proton-Translocating ATPases ; metabolism ; Random Allocation ; Rats ; Rats, Wistar ; Seawater ; Shock, Hemorrhagic ; enzymology ; physiopathology

Methylation catalyzed by methyltransferases is a major metabolic pathway for an inactivation of some catecholamines, niacinamide as well as aliphatic sulfhydryl drugs and toxic hydrogen sulfides. To investigate the effects of obstructive jaundice in an animal model, common bile duct ligation (CBDL) was performed in the rat and enzyme activities of S-adenosyl-L-methionine-dependent arylamine N-methyltransferase and thiol methyltransferase were examined in liver cell fractions and serum for a period of 42 d after CBDL. Both mitochondrial and microsomal arylamine N-methyltransferase showed significant increases in their activities between the 1st through the 7th day (P < or = 0.05 to 0.001), and between the 1st through the 28th day (P X or = 0.01 to 0.001) post-ligation, although the cytosolic arylamine N-methyltransferase activity did not show a significant change compared to the activities from the sham-operated control. The mitochondrial as well as microsomal thiol methyltransferase showed significant increases in their activities between the 1st through the 28th day (P < or = 0.05 to 0.01 and P < or = 0.01 to 0.001, respectively) post-ligation, although the cytosolic thiol methyltransferase activity did not show a significant change compared to the activities from the sham-operated control. Arylamine N-methyltransferase and thiol methyltransferase in the serum from cholestatic rats also showed significant increases in their activities between the 1st through 28th day (P < or = 0.01 to 0.001), and between the 0.5th through the 42nd day (P < or = 0.05 to 0.001) post-ligation compared to the sham-operated control, respectively. Enzyme kinetic parameters (Km and Vmax) of hepatic membrane-bound arylamine N-methyltransferase and thiol methyltransferase were analyzed with the preparation from the 7th day post-ligation, using tryptamine or 4-chlorothiophenol as substrates and S-Adenosyl-L-[methyl-3H]methionine as co-substrate. The results indicate that although the Km values were about the same as the sham-operated control, the Vmax values of both enzymes increased significantly (P < or = 0.01 and 0.001, respectively). These results suggest that the biosynthesis of arylamine N-methyltransferase and thiol methyltransferase have been induced in response to obstructive jaundice.
Animal ; Bile Ducts/surgery ; Cholestasis/*enzymology ; Ligation ; Liver/*enzymology ; Methyltransferases/blood/*metabolism ; Microsomes, Liver/enzymology ; Mitochondria, Liver/enzymology ; Rats ; Rats, Sprague-Dawley ; Time Factors

OBJECTIVETo investigate the changes of proton transportation across the inner mitochondrial membrane (IMM) and H(+)-ATPase of hepatocytes in endotoxic shock rats.

METHODSEndotoxin from E. Coil of 5.0 mg/kg or saline of 1 ml/kg was injected into the femoral vein. The rats were sacrificed pre-injection and 1, 3, 5, 8 hours after injection, and plasma and liver tissue samples were collected respectively. The liver tissue samples were used for preparation of mitochondria and submitochondrial particles (SMPs). The proton-translocation of SMPs and H(+)-ATPase, phospholipase A(2) (PLA(2)) activities and malondialdehyde (MDA) content, membrane fluidities of different level of mitochondria membrane and plasma MDA content were assayed.

RESULTS(1) Five hours after E. Coli. O111B4 injection, the maximum fluorescence quenching ACMA after adding ATP, nicotinamide adenin dinucleoacid hydrogen (NADH), and the succinate were significantly decreased (P<0.05). The time of maximum fluorescent quenching and the half time of fluorescent quenching were significantly prolonged (P<0.01), especially when NADH was used as a substrate. (2) The mitochondrial H(+)-ATPase activity was significantly increased at early stage of endotoxic shock (P<0.05), and significantly decreased at late stage of endotoxic shock (P<0.01). (3) The mitochondrial membrane bound PLA(2) activity, plasmal and mitochondrial MDA content were significantly increased and succinate dehydrogenase (SDH) activity of mitochondria decreased markedly in endotoxic shock rats (P<0.05). (4) The mitochondrial membrane fluidity of different lipid regions was decreased, especially in the head of phospholipid.

CONCLUSIONSProton transportation across IMM and mitochondrial H(+)-ATPase activity are significantly decreased in endotoxic shock.

Animals ; Microscopy, Electron ; Mitochondria, Liver ; metabolism ; Proton-Translocating ATPases ; metabolism ; Rats ; Rats, Wistar ; Shock, Septic ; enzymology

Acute myocardial infarction is one of the major causes of mortality worldwide. Reperfusion in a timely fashion is the most effective way to limit infarct size. However, reperfusion can itself prompt further myocardial injury. This phenomenon is commonly known as myocardial ischemia-reperfusion (IR) injury. Mitochondrial aldehyde dehydrogenase (ALDH2) is an enzyme metabolizing acetaldehyde and toxic aldehydes. Increasing evidence has revealed a cardioprotective role of ALDH2 in myocardial IR injury. Evidence from animal studies has shown that ALDH2 diminishes acute myocardial infarct size, ameliorates cardiac dysfunction and prevents reperfusion arrhythmias. The activity of ALDH2 is severely compromised if it is encoded by the mutant ALDH2*2 gene, with an incidence of approximately 40% in Asian populations. Epidemiological surveys in the Asian population have depicted that ALDH2 polymorphism is closely associated with higher prevalence of acute myocardial infarction and coronary artery disease. Therefore, targeting ALDH2 may represent a promising avenue to protect against IR injury. This review recapitulates the underlying mechanisms involved in the protective effect of ALDH2 in cardiac IR injury. Translational potential of ALDH2 in the management of coronary heart disease is also discussed.
Aldehyde Dehydrogenase ; metabolism ; Animals ; Heart ; physiopathology ; Humans ; Mitochondria, Heart ; enzymology ; Myocardial Reperfusion Injury ; Myocardium ; pathology

OBJECTIVETo explore the mitochondrial toxicities induced by zidovudine (AZT) and adefovir dipivoxil (ADV) antiviral drugs using a rat model system.

METHODSTwelve healthy Sprague-Dawley rats were randomly divided into three equal groups and treated by oral gavage with zidovudine (125 mg/kg/day), adefovir (40 mg/kg/day), or saline (equal volume) for 28 days. The rats' body weights were measured once a week, and blood was collected every two weeks for blood and biochemical tests. All animals were sacrificed at the end of treatment, and liver, kidney, skeletal muscle, and cardiac muscle were collected by necropsy. Mitochondria were isolated from the respective tissue samples, and the activities of respiratory chain complexes were measured. DNA was purified from each sample and the mitochondrial DNA (mtDNA) content was monitored by quantitative real time PCR. Mitochondrial morphology was analyzed under electron microscope.

RESULTSNo significant adverse effects, including body weight loss, abnormal blood or biochemistry, were observed in rats treated with AZT or ADV. The activities of mitochondrial cytochrome c oxidase in liver and cardiac muscle were slightly decreased in rats treated with AZT (liver: 9.44+/-3.09 vs. 17.8+/-12.38, P?=?0.21; cardiac muscle: 32.74+/-5.52 vs. 24.74+/-20.59, P?=?0.28; kidney: 4.42+/-1.53 vs. 14.45+/-13.75, P?=?0.18; skeletal muscle: 33.75+/-8.74 vs. 40.04+/-2.49, P?=?0.45). The mtDNA content was significantly decreased in cardiac muscle of AZT-treated rats (cardiac muscle: 0.15+/-0.13 vs. 0.32+/-0.42, P?=?0.85). The morphology of mitochondria in liver, kidney, skeletal muscle, and cardiac muscle was significantly altered in the AZT-treated rats and included disappearance of the outer membrane, severely damaged structure, and swollen or completely absent cristae. No obvious effects were noted in the ADV- or saline-treated rats.

CONCLUSIONSignificant adverse effects related to mitochondrial toxicity were observed in rats treated with AZT. The slightly decreased mtDNA content in ADV-treated rats may suggest that this antiviral drug can also cause mitochondrial toxic effects.

Adenine ; adverse effects ; analogs & derivatives ; Animals ; DNA, Mitochondrial ; drug effects ; Electron Transport Complex IV ; metabolism ; Female ; Kidney ; enzymology ; Liver ; enzymology ; Mitochondria ; drug effects ; metabolism ; Mitochondria, Heart ; drug effects ; Mitochondria, Liver ; drug effects ; Mitochondria, Muscle ; drug effects ; Muscle, Skeletal ; enzymology ; Myocardium ; enzymology ; Organophosphonates ; adverse effects ; Rats ; Rats, Sprague-Dawley ; Zidovudine ; adverse effects

The mitochondrial respiratory chain supercomplex (mitoSC) is a complex super-assembly formed by free complexes on the mitochondrial inner membrane respiratory chain through the interaction between their subunits, mainly including mitoSCI+III+IV, mitoSCI+III, mitoSCIII+IV, high molecular weight mitoSC (HMW mitoSC) and mitochondrial metacomplex (mitoMC). mitoSC has been shown to improve the efficiency of electron transport in the respiratory chain and reduce the production of reactive oxygen species. The species and content of mitoSC change in different tissues in aging and many mitochondria-related diseases. By summarizing the structure and function of mitoSC in different tissues of human and mammals, and the changes of mitoSC under conditions of aging, heart disease, type 2 diabetes, cancer and genetic defects, this review focuses on the effects of exercise on mitoSC and its related regulation mechanisms in order to offer an insight for exercise interventions in mitochondria-related diseases.
Animals ; Electron Transport ; Exercise ; Humans ; Mitochondria ; Mitochondrial Diseases ; Mitochondrial Membranes ; enzymology

Apoptosis ; Calcineurin ; metabolism ; Chymotrypsin ; metabolism ; Humans ; Lysosomes ; enzymology ; Mitochondria ; metabolism ; pathology ; Mitochondrial Dynamics ; Neuroblastoma ; metabolism ; pathology

Mitochondrial adenosine triphosphate (ATP) synthase is the key enzyme of mitochondrial oxidative phosphorylation reaction. The down-regulation of the mitochondrial ATP synthase is a hallmark of most human carcinomas, which is the embodiment of the bioenergetic signature of cancer in the performance of the decreased oxidative phosphorylation and increased aerobic glycolysis. Combining with the bioenergetic signature of cancer, studies showed that mitochondrial ATP synthase and multidrug resistance and adverse prognosis of tumor were closely related. Its mechanisms are related to post-transcriptional regulation of the ATP synthase, the hypermethylation of the ATP synthase gene and the inhibitor peptide of the mitochondrial ATP synthase, called ATP synthase inhibitory factor 1 (IF1). In this review, we stress the biological characteristics of mitochondrial ATP synthase and the relationship between ATP synthase and multidrug resistance and prognosis of Malignant tumor, in order to find a new way for tumor therapy.
Adenosine Triphosphate ; Carcinoma ; enzymology ; Down-Regulation ; Energy Metabolism ; Humans ; Mitochondria ; enzymology ; Mitochondrial Proton-Translocating ATPases ; metabolism ; Neoplasms ; enzymology ; Nitric Oxide Synthase ; Oxidative Phosphorylation

OBJECTIVETo study the effect of cerebral mild hypothermia on cerebral mitochondrial ATPase activities in neonatal rats with hypoxic-ischemic brain damage (HIBD).

METHODSEighty-four seven-day-old Wistar rats were randomly assigned into four groups: sham-operated normothermic, sham-operated mild hypothermic, HIBD normothermic and HIBD mild hypothemic. HIBD was induced by left common carotid artery ligation, followed by 8% hypoxia exposure. At each time interval of 2, 6, and 12 hrs post-hypoxia-ischemia (HI), 7 rats were sacrificed and the brain tissues were sampled for detecting the activities of mitochondrial Na+K+ATPase and Ca2+ATPase.

RESULTSThe activities of mitochondrial Ca2+ATPase decreased significantly in the two HIBD groups compared with those of the two sham-operated groups at 2, 6, and 12 hrs post-HI. The HIBD mild hypothemic group had higher mitochondrial Ca2+ATPase activities compared with the HIBD normothermic group at 2, 6, and 12 hrs post-HI (5.25 +/- 0.61 micromol/mgPr.h vs 3.17 +/- 0.81 micromol/mgPr.h 4.59 +/- 0.81 micromol/mgPr.h vs 2.26 +/- 0.53 micromol/mgPr.h4.61 +/- 0.62 micromol/mgPr.h vs 1.31 +/- 0.78 micromol/mgPr.H, respectively) (P < 0.01). The activities of mitochondrial Na+K+ATPase decreased significantly in the two HIBD groups compared with those of the two sham-operated groups at 6 and 12 hrs post-HI. A significant difference was observed in the mitochondrial Na+K+ATPase activities between the HIBD mild hypothemic and HIBD normothermic groups at 6 and 12 hrs post-HI (5.25 +/- 0.66 micromol/mg Pr.h vs 3.76 +/- 0.78 micromol/mgPr.h, 4.74 +/- 0.80 micromol/mgPr.h vs 3.12 +/- 0.53 micromol/mgPr.h; P < 0.01).

CONCLUSIONSMild hypothermia following HIBD inhibits the decline in cerebral mitochondrial Ca2+ and Na+K+ ATPase activities in neonatal rats, thus providing protective effects against HIBD.

Animals ; Animals, Newborn ; Brain ; enzymology ; Calcium-Transporting ATPases ; metabolism ; Female ; Hypothermia, Induced ; Hypoxia-Ischemia, Brain ; enzymology ; therapy ; Male ; Mitochondria ; enzymology ; Rats ; Rats, Wistar ; Sodium-Potassium-Exchanging ATPase ; metabolism