Hemoglobin vesicle improves recovery of cardiac function after ischemia-reperfusion by attenuating oxidative stress in isolated rat hearts

Hemoglobin vesicle (HbV) could be a useful blood substitute in emergency medicine. The aim of this study was to clarify the effects of HbV on cardiac function after ischemia-reperfusion (I/R) ex vivo. Isolated rat hearts were perfused according to the Langendorff method. An ischemia-reperfusion group (n = 6) was subjected to 25 minutes of global ischemia and 30 minutes of reperfusion. HbV (hemoglobin, 0.33 g/dL) was perfused before ischemia-reperfusion for 10 minutes (HbV group, n = 6). Hemodynamics were monitored, and tissue glutathione contents were measured. The redox state of reactive thiols in cardiac tissues was assessed by the biotinylated iodoacetamide labeling method. Left ventricular developed pressure was significantly recovered in the HbV group after 30 minutes of reperfusion (56.3 ± 2.8 mm Hg vs. ischemia-reperfusion group 27.0 ± 8.0 mm Hg, P < 0.05). Hemodynamic changes induced by HbV were similar to those observed when N-nitro-L-arginine methyl ester was perfused for 10 minutes before ischemia-reperfusion (L-NAME group). The oxidized glutathione contents of cardiac tissues significantly decreased, and biotinylated iodoacetamide labeling of thiols was maintained in both the HbV and the L-NAME groups. HbV improved the recovery of cardiac function after ischemia-reperfusion in isolated rat hearts. This mechanism is dependent on functional protection against thiol oxidation.     

Microsomal and peroxisomal fatty acid oxidation in streptozotocin diabetic rat liver

Microsomal lauric acid hydroxylation and fatty acid peroxisomal β-oxidation were studied in hepatic subcellulant preparations from streptozotocin-induced diabetic and diabetic insulin-treated rats.

• 1.2. The liver microsomes of the streptozotocin diabetic rats displayed a similar activity to hydroxylate lauric acid as the control microsomes.
• 2.3. Diabetic insulin-treated rats showed lower (ω1) and ω-lauric acid hydroxylase activities than diabetic and control rats.
• 3.4. Streptozotocin-induced diabetes and diabetic insulin-treated rats exhibited no significant changes on peroxisomal palmitoyl CoA β-oxidation compared to the control rats.
• 4.5. Both microsomal and peroxisomal fatty acid oxidation responded in a similar way in this model of experimental diabetes.

     

Enhanced peroxisomal beta-oxidation of fatty acids and glutathione metabolism in rats exposed to phenoxyacetic acids

Peroxisomal beta-oxidation of fatty acids and the activities of glutathione-metabolizing enzymes in rat liver were measured after administration of 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), clofibrate [ethyl], 2-(p-chlorophenoxy)-2-methylpropionate], glyphosate (N-phosphonomethyl glycine, a herbicide not structurally related to phenoxy acids) or saline for 14 days. beta-Oxidation increased by 6-fold in the group given clofibrate, 3-fold in the 2,4-D-treated group, and 2-fold in the MCPA-treated group over the level in the controls (saline-treated). Glyphosate did not increase beta-oxidation. No significant change in reduced glutathione content from that in controls was found in any of the treated groups. Glutathione reductase activity increased by about 40% after administration of either 2,4-D or MCPA, and glutathione peroxidase activity increased by 30% in animals given MCPA. A slight decrease in glutathione S-transferase activity was found in the group treated with clofibrate. The marked increases in peroxisomal beta-oxidation of fatty acids were accompanied by only minor changes in the activities of enzymes involved in glutathione-dependent inactivation of organic hydroperoxides and other oxygen-centred reactive agents.     

A novel partial fatty acid oxidation inhibitor decreases myocardial oxygen consumption and improves cardiac efficiency in demand-induced ischemic heart

The benefits of inhibition of fatty acid oxidation (FOX) and stimulation of glucose oxidation (GOX) in ischemia are controversial. The objective of this study was to evaluate the effect of the FOX inhibitor CVT-4325 on the rates of FOX, GOX, myocardial oxygen consumption (MVO2), and cardiac efficiency in the absence and presence of palmitate during demand-induced ischemia of the rodent isolated hearts. Palmitate concentration-dependently increased FOX, decreased GOX, and increased MVO2. CVT-4325 inhibited FOX and increased GOX in the presence (but not the absence) of 1.2 mM palmitate, with EC50 values of 0.9 and 5.8 microM, respectively. The potency for CVT-4325 to inhibit FOX was 10-fold greater (0.9 versus 9.7 microM) in the presence of 1.2 mM compared with 0.4 mM palmitate. The increase in MVO2 caused by 1.2 mM palmitate was significantly reduced by 3 to 10 microM CVT-4325 in guinea pig hearts. In the presence of 1.2 mM palmitate, an increase in pacing rate of the guinea pig heart from 3.5 to 6.5 Hz caused a significant 50% increase in MVO2, a decrease in cardiac efficiency, and an increase in lactate concentration in the cardiac effluent from 0.04 +/- 0.01 to 0.10 +/- 0.02 mM (P < 0.01). CVT-4325 (3 microM) attenuated the increase (P < 0.05) in MVO2 while maintaining cardiac contractility, and decreased the lactate production to 0.05 +/- 0.01 mM (P < 0.01). Thus, the FOX inhibitor CVT-4325 decreased MVO2 and increased myocardial efficiency during demand-(pacing)-induced ischemia in the presence of palmitate in the rodent isolated hearts.     

Perfluoro-N-decanoic acid effects on enzymes of fatty acid metabolism

In vitro perfluorodecanoate (PFDA) effects on Pseudomonas acyl-CoA synthetase, Candida acyl-CoA oxidase and pigeon muscle carnitine acetyltransferase were examined. Synthetase made little PFDA-CoA from PFDA. It used palmitate, oleate, laurate and decanoate more extensively. PFDA inhibited acyl-CoA formation from these acids. Palmitoyl-CoA formation was affected most. That of decanoyl-CoA was affected least. Inhibitions appeared to be competitive. Acyl-CoA oxidase test substrates were palmitoyl-CoA, lauroyl-CoA and decanoyl-CoA. Oxidase preferred C-10 and C-12 acyl-CoAs. PFDA inhibited oxidation of C-10 and C-12 acyl-CoAs more than that of palmitoyl-CoA. Inhibitions with C-16 and C-10 acyl-CoAs were competitive, KIs 593 +/- 150 and 76 +/- 6.0 microM. Acetyl-CoA was the best acetyltransferase substrate. C-2 to C-8 transfer from acyl-CoAs was inhibited similarly by PFDA. Inhibitions of C-2 and C-8 transfer were competitive and non-competitive, respectively, KIs 111 +/- 15 and 76 +/- 28 microM.     

Food preservative sorbic acid deregulates hepatic fatty acid metabolism

Sorbic acid (SA) is one of the most commonly used food preservatives worldwide. Despite SA having no hepatotoxicity at legal dosages, its effect on hepatic lipid metabolism is still unclear. We investigated the effect of SA on hepatic lipid metabolism and its mechanism of action in C57BL/6 mice. Daily treatment with SA (1 g/kg in diet) for 4 weeks did not alter the body weight, organ weight, and blood lipids in mice. However, hepatic lipid accumulation, particularly that of triglycerides, fatty acids, and glycerol, but not cholesteryl ester and free cholesterol, was increased with SA treatment. Mechanistically, SA decreased the expression of proteins related to de novo fatty acid lipogenesis, fatty acid internalization, and very low-density lipoprotein (VLDL) secretion-related pathways, including sterol regulatory element-binding proteins, acetyl-coA carboxylase, fatty acid synthase, liver fatty acid-binding protein, CD36, and apolipoprotein E. In contrast, SA increased the expression of diacylglycerol O-acyltransferase 2, the key enzyme for triacylglycerol synthesis. Moreover, SA downregulated the protein expression of autophagy-related and β-oxidation-related pathways, the two major metabolic pathways for lipid metabolism, including LC-3, beclin-1, autophagy related protein 5 (ATG-5) and ATG-7, acyl-CoA synthetase long chain family member 1, carnitine palmitoyltransferase Iα, peroxisome proliferator-activated receptor α (PPARα), PPARγ, and PPARγ coactivator-1. Collectively, SA deregulates de novo lipogenesis and fatty acid internalization, VLDL secretion, autophagy, and β-oxidation in the liver, leading to impaired lipid clearance and ultimately, resulting in lipid accumulation in the liver.     

肝缺血再灌注损伤对大鼠心肾能量代谢的研究

目的研究肝缺血再灌注损伤后对心肾能量代谢指标的影响。方法按照体重将大鼠随机分为5组,每组10只:假手术组、模型-0 h组、模型-2 h组、模型-4 h组、模型-6 h组。用无损伤血管夹钳夹后造成缺血再灌注损伤模型。按再灌注后即刻和再灌注后2,4,6 h,立即处死动物,取材。用酶联免疫吸附法检测组织的钠钾ATP酶、钙镁ATP酶含量。结果假手术组、模型-2 h组、模型-4 h组的肝组织Ca²⁺-Mg²⁺-ATP酶含量分别为(343.84±22.11),(221.88±64.15),(235.02±58.84)μmol·g^-1,与假手术组比较,模型-2 h、4 h组的差异均有统计学意义(均P<0.05)。假手术组、模型-2 h、4 h组的肾组织Na^+-K^+-ATP酶含量分别为(79.46±10.84),(67.28±3.39),(69.09±1.47)μmol·g^-1;这3组的Ca²⁺-Mg²⁺-ATP酶含量分别为(345.68±21.68),(227.39±50.63),(246.38±64.31)μmol·g^-1,与假手术组比较,这3组差异均有统计学意义(均P<0.05)。假手术组和模型-0,2,4,6 h组的心肌组织Na^+-K^+-ATP酶含量分别为(68.16±12.17),(71.92±9.91),(61.62±7.96),(59.23±3.86),(79.72±9.91)μmol·g^-1;这5组的Ca²⁺-Mg²⁺-ATP酶含量分别为(261.05±40.52),(279.13±34.12),(243.62±23.59),(244.66±17.79),(291.78±36.38)μmol·g^-1,与假手术组比较,这5组的差异均无统计学意义(均P>0.05),表明心肌组织能量代谢指标无明显变化。结论肝缺血再灌注损伤时,心、肾功能同时受损,但肾损伤早于心肌损伤。     

多不饱和脂肪酸与肝脏脂质代谢的调控

多不饱和脂肪酸(PUFA)通过调控转录因子的活性及含量调节多种基因的转录。PUFA能够激活过氧化物酶体增殖物激活受体α(PPARα),上调参与肝脏脂肪酸氧化的基因转录,抑制固醇调节元件结合蛋白-1c(SREBP-1c),下调参与肝脏脂肪合成的基因表达。PPARα与SREBP-1c在非酒精性脂肪肝(NAFLD)的发病过程中发挥重要作用。本文就PUFA对PPARα、SREBP-1c及其他参与脂质代谢的核转录因子如肝脏X受体、肝脏核因子-4等的调控加以综述,为NAFLD的治疗提供新思路。     

Comparative effects of oxygen and sulfur-substituted fatty acids on serum lipids and mitochondrial and peroxisomal fatty acid oxidation in rat.

Feeding tetradecyloxyacetic acid (a 3-oxa fatty acid) to rats led to decreased serum cholesterol and decreased serum triacylglycerol, resembling the effects of the corresponding 3-thia fatty acid (tetradecylthioacetic acid). The 3-oxa fatty acid inhibited strongly the mitochondrial fatty acid oxidation and led to the development of fatty liver, while the 3-thia fatty acid stimulated the mitochondrial fatty acid oxidation. Feeding tetradecyloxypropionic acid (a 4-oxa fatty acid) had less effect on the serum lipids. It stimulated fatty acid oxidation in the mitochondria and lowered the hepatic level of triacylglycerol. The corresponding 4-thia fatty acid (tetradecylthiopropionic acid) inhibited mitochondrial fatty acid oxidation and induced development of fatty liver. All these compounds, both the oxa and the thia fatty acids, induced some increase in the activity of the peroxisomal acyl-CoA oxidase. Repeated administration of 3-oxadicarboxylic acid to rats resulted in no lipid lowering effects, and marginal changes of fatty acyl-CoA oxidase activity. Oxidation of the S-atom of the 3-thia fatty acid to the corresponding sulfoxide or sulfone eliminated the metabolic effects of the thia fatty acid. The study has shown that the effects of 3- and 4-oxa fatty acids are in some ways opposite to those of the 3- and 4-thia fatty acids. The possibility that the lipophilicity of the fatty acid analogues may be an important factor behind the differences observed are discussed. It is suggested that these oxa- and thia-analogues of fatty acids may be useful in studies on the regulation of fatty acid metabolism.     

Effect of clofibric acid and tiadenol on peroxisomal β-oxidation and fatty acid binding protein in intestinal mucosa of rats

Rats were fed a diet containing clofibric acid or tiadenol. The treatment of rats with clofibric acid caused an increase in the activity of cyanide-insensitive palmitoyl-CoA oxidation and in the concentration of a polypeptide with a molecular weight of about 80,000 in the light mitochondrial fraction in intestinal mucosa. Treatment of rats with tiadenol increased the activity of cyanide-insensitive palmitoyl-CoA oxidation more markedly than with clofibric acid. The induced activity in intestinal mucosa was about $\text{1}\text{10}\text{th}$ that in liver. Treatment of rats with either of the two peroxisome proliferators increased both [1-¹⁴C]oleic acid binding capacity and the concentration of FABP in intestinal mucosa of rats. The treatment of rats with clofibric acid did not seem to alter the properties of FABP found in intestinal mucosa.     

Methylated eicosapentaenoic acid and tetradecylthioacetic acid: effects on fatty acid metabolism.

We introduced methyl or ethyl groups to the 2- or 3-position of the eicosapentaenoic acid (EPA) molecule to investigate whether the branching of EPA could influence its hypolipidemic effect in rats. The most effective branching involved two methyl groups in the 2-position and one methyl group in the 3-position. These EPA derivatives increased hepatic mitochondrial and peroxisomal beta-oxidation and decreased plasma lipids concomitant with suppressed acetyl-coenzyme A (CoA) carboxylase (EC 6.4.1.2) and fatty acid synthase (EC 2.3.1.85) activities. This was followed by elevated activities of camitine O-palmitoyltransferase (EC 2.3.1.21) and possibly 2,4-dienoyl-CoA reductase (EC 1.3.1.34), as well as induced mRNA levels of these enzymes and fatty acyl-CoA oxidase. The fatty acid composition in liver changed, with an increased 18:1 n-9 content, whereas the expression of delta9-desaturase remained unchanged. We investigated the flux of fatty acids in cultured hepatocytes, and found that oxidation of [1-14C]-labeled palmitic acid increased but the secretion of palmitic acid-labeled triglycerides decreased after addition of 2-methyl-EPA. The fatty acyl-CoA oxidase (EC 1.3.3.6) activity in these cells remained unchanged. A significant negative correlation was obtained between palmitic acid oxidation and palmitic acid-labeled synthesized triglycerides. To investigate whether the hypolipidemic effect occurred independently of induced peroxisomal beta-oxidation, we fed rats 2-methyl-tetradecylthioacetic acid. This compound increased the peroxisomal but not the mitochondrial beta-oxidation, and the plasma lipid levels were unchanged. In conclusion, EPA methylated in the 2- or 3-position renders it more potent as a hypolipidemic agent. Furthermore, this study supports the hypothesis that the mitochondrion is the primary site for the hypolipidemic effect.     

Chlorogenic acid exhibits anti-obesity property and improves lipid metabolism in high-fat diet-induced-obese mice

This study investigated the efficacy of chlorogenic acid on altering body fat in high-fat diet (37% calories from fat) induced-obese mice compared to caffeic acid. Caffeic acid or chlorogenic acid was supplemented with high-fat diet at 0.02% (wt/wt) dose. Both caffeic acid and chlorogenic acid significantly lowered body weight, visceral fat mass and plasma leptin and insulin levels compared to the high-fat control group. They also lowered triglyceride (in plasma, liver and heart) and cholesterol (in plasma, adipose tissue and heart) concentrations. Triglyceride content in adipose tissue was significantly lowered, whereas the plasma adiponectin level was elevated by chlorogenic acid supplementation compared to the high-fat control group. Body weight was significantly correlated with plasma leptin (r = 0.894, p < 0.01) and insulin (r = 0.496, p < 0.01) levels, respectively. Caffeic acid and chlorogenic acid significantly inhibited fatty acid synthase, 3-hydroxy-3-methylglutaryl CoA reductase and acyl-CoA:cholesterol acyltransferase activities, while they increased fatty acid β-oxidation activity and peroxisome proliferator-activated receptors α expression in the liver compared to the high-fat group. These results suggest that caffeic acid and chlorogenic acid improve body weight, lipid metabolism and obesity-related hormones levels in high-fat fed mice. Chlorogenic acid seemed to be more potent for body weight reduction and regulation of lipid metabolism than caffeic acid.     

醒脑静注射液对脑缺血再灌注损伤家兔花生四烯酸代谢的影响

目的：观察醒脑静注射液(XNJI)对脑缺血再灌注家兔花生四烯酸代谢的影响，并探讨其脑保护机制。方法：将健康家兔20只以“四管闭塞法”及再开放颈动脉建立家兔急性全脑缺血及缺血再灌注动物模型，造模后分为生理盐水组(n=10)和醒脑静组(n=10)，于缺血前和再灌注前，生理盐水组家兔静脉注射生理盐水1ml·kg~(-1)，醒脑静组静脉注射醒脑静注射液1ml·kg~(-1)。观察血浆、脑组织中血栓素B_2(TXB_2)、6-酮-前列腺素F_(1α)(6-Keto-PGF_(1α))含量与比值的变化，并观察脑超微结构变化。结果：醒脑静组与生理盐水组同时相相比血浆和脑组织TXB_2含量、TXB_2／6-Keto-PCF_(1α)比值明显降低(P＜0．05)，醒脑静组脑组织超微结构病理改变不明显。结论：XNJI通过抑制TXB_2合成、促进6-Keto-PGF_(1α)生成而下调两者比值，这可能是其减轻脑缺血再灌注损伤的又一作用机制。     

Microsomal and peroxisomal fatty acid oxidation in bile duct ligated rats: A comparative study between liver and kidney

• 1.1. Microsomal cytochrome P-450 and peroxisomal fatty acid oxidation was studied in the kidney of rats 7 days after bile duct ligation (BDL) and a comparative study between kidney and liver was done.
• 2.2. Only in the liver did cholestasis decrease the cytocrome P-450 content and the peroxisomal fatty acid (3-oxidation, the catalase activity, and the microsomal metabolism of lauric acid and aminopyrine.
• 3.3. In contrast, cholestasis did not influence these activities in the kidney. The microsomal and peroxisomal activities studied responded in a coordinate way to cholestasis.
• 4.4. These results could suggest the possibility of a cause-and-effect relationship between microsomal cytochrome P-450 and peroxisomal activity.

     

Physiologically tolerable insulin reduces myocardial injury and improves cardiac functional recovery in myocardial ischemic/reperfused dogs

This study was designed to examine whether physiologically tolerable insulin, which maintains lower blood glucose, can protect the myocardium against ischemia/reperfusion (I/R) injury in a preclinical large animal model. Adult dogs were subjected to 50 minutes of myocardial ischemia (80% reduction in coronary blood flow) followed by 4 hours of reperfusion and treated with vehicle, glucose-insulin-potassium (GIK; glucose, 250 g/L; insulin, 60 U/L; potassium, 80 mmol/L), GK, or low-dose insulin (30 U/L) 10 minutes before reperfusion. Treatment with GIK exerted significant cardioprotective effects as evidenced by improved cardiac function, improved coronary blood flow, reduced infarct size, and myocardial apoptosis. In contrast, treatment with GK increased blood glucose level and aggravated myocardial I/R injury. It is interesting that treatment with insulin alone at the dose that reduced blood glucose to a clinically tolerable level exerted significant cardioprotective effects that were comparable to that seen in the GIK-treated group. This low-dose insulin had no effect on coronary blood flow after reperfusion but markedly reduced coronary reactive hyperemia and switched myocardial substrate uptake from fat to carbohydrate. Our results suggest that lower glucose supply to the ischemic myocardium at early reperfusion may create a "metabolic postconditioning" and thus reduce myocardial ischemia/reperfusion injury after prolonged reperfusion.     

Effects of dietary treatment with 11 dicarboxylic acids, diethylcarboxylic esters and fatty acids on peroxisomal fatty acid beta-oxidation, epoxide hydrolases and lauric acid omega-hydroxylation in mouse liver.

C57B1/6 male mice were exposed through their diet to 11 dicarboxylic acids, carboxylic acids and diethyldicarboxylesters for 10 days. For the diacids and diethylesters this treatment resulted in a chain length-dependent induction of lauryl-CoA oxidase and cyanide-insensitive palmitoyl-CoA oxidation activities. A chain length of 12 carbon atoms or more seemed to be necessary for induction of these two activities. In addition, the same chain length dependence was observed for induction of lauric acid omega + omega-1 hydroxylase activity and increase in the protein content of the mitochondrial fraction. Treatment with two "natural" fatty acids, i.e. lauric and palmitic acid gave no effect at all on these various parameters. In no case was induction of cytosolic and mitochondrial epoxide hydrolase activities observed. Instead, a slight decrease in these activities was observed after administration of diacids with a chain length of 4-8 carbon atoms, whereas microsomal epoxide hydrolase activity was concurrently induced.     

Alpha-lipoic acid attenuates insulin resistance and improves glucose metabolism in high fat diet-fed mice

Aim:

To investigate whether alpha-lipoic acid (ALA) could attenuate the insulin resistance and metabolic disorders in high fat diet-fed mice.

Methods:

Male mice were fed a high fat diet (HFD) plus ALA (100 and 200 mg·kg⁻¹·d⁻¹) or HFD plus a positive control drug metformin (300 mg·kg⁻¹·d⁻¹) for 24 weeks. During the treatments, the relevant physiological and metabolic parameters of the mice were measured. After the mice were euthanized, blood samples and livers were collected. The expression of proteins and genes related to glucose metabolism in livers were analyzed by immunoblotting and real time-PCR.

Results:

HFD induced non-alcoholic fatty liver disease (NAFLD) and abnormal physiological and metabolic parameters in the mice, which were dose-dependently attenuated by ALA. ALA also significantly reduced HFD-induced hyperglycemia and insulin resistance in HFD-fed mice. Furthermore, ALA significantly upregulated the glycolytic enzymes GCK, HK-1 and PK, and the glycogen synthesis enzyme GS, and downregulated the gluconeogenic enzymes PEPCK and G6Pase, thus decreased glucose production, and promoted glycogen synthesis and glucose utilization in livers. Moreover, ALA markedly increased PKB/Akt and GSK3β phosphorylation, and nuclear carbohydrate response element binding protein (ChREBP) expression in livers. Metformin produced similar effects as ALA in HFD-fed mice.

Conclusion:

ALA is able to sustain glucose homeostasis and prevent the development of NAFLD in HFD-fed mice.