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PubMed1972

Effects of fatty acids on growth and envelope proteins of Bacillus subtilis.

Fatty acids of different chain lengths were added to cultures of Bacillus subtilis growing in nutrient sporulation medium, and the effects of these fatty acids on growth, oxygen uptake, adenosine triphosphate (ATP) concentration, and membrane protein composition were examined. All fatty acids inhibited growth, the effect being reduced in the presence of glycolytic compounds and reversed by transfer to medium without fatty acids. The inhibition of growth was correlated with a reduction in both the rate of oxygen consumption and the concentration of ATP per cell. The concentration required to obtain a certain degree of inhibition increased with decreasing molecular weight of the fatty acid. However, the reduced nicotinamide adenine dinucleotide oxidation system of cell envelope preparations (i.e., the electron transport system) was not inhibited. Submaximal growth inhibition was accompanied by the relative increase of a membrane protein band revealed by urea-acetic acid gel electrophoresis. This increase was blocked by actinomycin or chloramphenicol. All of the above changes could also be produced by 2,4-dinitrophenol. The inhibition results are best explained by assuming that the fatty acids reversibly react with the cell membrane or proteins in it; they could either alter the membrane structure or uncouple the electron transport chain from two types of proteins, those used for ATP regeneration and others needed for the transport of certain compounds into the cells.

Acetates↗
PubMed1991

Cardiothyreosis.

In the present study: (a) physiopathology, (b) clinics, and (c) therapy of cardiothyreosis are discussed. (a) The hyperkinetic syndrome, the earliest clinical sign in thyrotoxicosis (vasodilatation, increase in inotropism, automatism, etc.), is mediated by a two-fold increase in the number of beta-receptors, and supported by an adequate synthesis of ATP and creatinphosphate (CP) in the young and, to a lesser extent, in the elderly. Genetical heart reserves are mobilized, thus significantly increasing the number and the size of mitochondria and also the enzymatic equipment (such as: the alpha-glycerophosphate-dehydrogenase, malic, pentosic cycles, etc.), a.s.o. Due to an excessive adrenergic action (glycogenolysis, an excessive oxygen consumption, up to necrosis, the ATP and CP syntheses dramatically drop; the phosphorus/oxygen ratio decreases to 2 (normal = 4). In this condition, the high functional cardiovascular performances are also impaired (the submaximal effort capacity is attained at a smaller and smaller oxygen consumption; Propranolol 2 mg i.v. decreased the cardiac output by above 30% (vs 10%--normal); electrocardiogram presents aspects of "coronary disease", tachycardia, etc.). An ultrastructural damage occurs: from "mitochondrial disease", partial lysis of myofibrils, to myofibrosis (revealed postmortem), in spite of a reduced degree of coronary atherosclerosis. Ultrastructural and biochemical experimental data support this point of view. (b) The incidence, precocity and severity of the thyrotoxic heart increase with age and the existence of a previous cardiovascular pathology. Cardiothyreosis is not present under 27 years; in 4,353 patients its incidence is of 25% (arrhythmia--21%, heart failure--12%, coronary insufficiency--1-3%). Of a major interest are tachyarrhythmias which may lead to a high mortality by hypodiastolic congestive heart failure, heart failure with secondary hyperaldosteronism, thromboembolic episodes and ventricular fibrillation. Thyrotoxicosis favours the disease of papillary muscles--mitral prolapse and insufficiency, reversible especially in children. (c) The treatment of thyrotoxic heart is an etiologic one (medical, surgical, radioactive--the last two being preferable after the adequate medical therapy). In particular, cardiothyreosis requires a reinforced irradiation (10,000 rads instead of 7,000 rads) in smaller 131I doses. The protection against the increased nocivity of catechols in thyrotoxicosis is very important (which explains the high mortality in the thyrotoxic "storm") and requires propranolol; doses above 2 mg/kilo body/day are recommended. In the elderly, the sensitivity to propranolol decreases: verapamil i.v. is more efficient in paroxysmal tachyarrhythmias (flutter, atrial fibrillation) and in those occurring intra-operatively during halothane narcosis. The anticoagulant therapy is administered in tachyarrhythmias with high ventricular rate, especially in the elderly, to avoid the embolic risk, higher in defibrillation condition.(ABSTRACT TRUNCATED AT 400 WORDS)

Angina Pectoris↗
PubMed1988

Reversibility of acute alcohol cardiac depression: 31P NMR in hamsters.

Isolated hamster hearts were perfused with 2% ethanol for 30 min and then reequilibrated with control medium. One group of hamsters was pretreated with verapamil. Another group received diltiazem. Myocardial verapamil levels were 9.5 +/- 0.7 mg/g dry wt; diltiazem levels were 22 +/- 7 mg/g dry wt. Energy metabolites were assessed by using 31P NMR standardized with high-pressure liquid chromatography of freeze-clamped tissue. Intracellular calcium was measured by atomic absorption spectrophotometry, marking the extracellular space with K(CoEDTA). After 30 min of perfusion, untreated hamster hearts showed a 74% decrease in developed pressure, a marked increase in end-diastolic pressure, a decrease of ATP from 9.8 to 8.8 mmol, and an increase of Pi from 6.7 to 9.8 mmol, but no change of phosphocreatine (PCr) or intracellular pH (pHi). Verapamil pretreatment partially prevented cardiac depression during alcohol perfusion. Whereas diltiazem had no protective effect. After reequilibration, developed pressure and oxygen consumption significantly exceeded control values. ATP decreased to 8 mmol; pHi, PCr, and Pi showed no significant change. Verapamil-pretreated hearts showed better performance than untreated hearts without change in PCr and Pi, whereas ATP dropped slightly to 8.7 mmol. Thus, functional cardiac depression resulting from acute alcohol exposure is reversible. Increased intracellular calcium levels during alcohol exposure normalized after the removal of alcohol. There was no major change in high-energy phosphates during alcohol exposure or after the removal of alcohol. Verapamil protects the heart from functional depression during alcohol exposure without affecting energy resources.

Adenine Nucleotides↗
PubMed1973

Control of phosphoenolpyruvate synthesis in guinea-pig mitochondria.

1. The synthesis of phosphoenolpyruvate and the O(2) consumption from the tricarboxylic acid-cycle intermediates citrate, alpha-oxoglutarate, malate and succinate by guinea-pig mitochondria were compared. Malate was the most effective of these precursors; there was no synthesis of phosphoenolpyruvate from succinate. 2. The addition of palmitate, acetoacetate and ATP enhanced the synthesis of phosphoenolpyruvate from citrate and alpha-oxoglutarate. Palmitate and ATP increased the O(2) consumption, whereas acetoacetate had no effect on this parameter. 3. Octanoate depressed the synthesis of phosphoenolpyruvate from citrate, alpha-oxoglutarate and malate and increased the O(2) consumption. Pentenoic acid had no effect on phosphoenolpyruvate synthesis from any of the substrates used, although it increased the uptake of O(2). These findings might be relevant to the control of gluconeogenesis in vivo.

Acetoacetates↗
PubMed1985

Gonadotropin-induced inhibition of oxygen consumption in rat oocyte-cumulus complexes: relief by adenosine.

In the cumulus-oocyte complex (COC), as well as in the whole ovarian follicle, gonadotropins stimulate glycolysis, measured as lactate accumulation. In contrast to this, COC oxygen consumption is decreased by gonadotropins. One possible explanation for this inhibition is a competition for a limited supply of cofactors, common for both the glycolytic pathway and the respiratory chain. In the present study, addition of adenosine to COCs cultured with gonadotropins restored the oxygen consumption to basal levels. This effect was specific for metabolizable adenosine. Other nucleosides or non-metabolizable 2-chloro-adenosine had no effect. Adenosine also increased ATP and decreased lactate accumulation by the COC. The nucleoside transport inhibitor dipyridamol abolished the effects of adenosine on oxygen consumption and ATP accumulation. Taken together, these results support the hypothesis that a relative lack of adenosine-derived cofactors is probably involved in the decrease of oxygen consumption in vitro by gonadotropin-stimulated cumulus cells.

Adenosine↗
PubMed2006

Redox regulation of endogenous substrate oxidation by cardiac mitochondria.

Reactive oxygen species (ROS) play important roles in regulating mitochondrial function, as well as in ischemia-reperfusion injury and cardioprotection. Here we show that, in the absence of exogenous substrates, cardiac mitochondria have a surprisingly large capacity to phosphorylate ADP by oxidizing endogenous substrates, provided that H2O2 is removed from the extramitochondrial environment and a reduced environment is maintained in the matrix. In isolated mitochondria without exogenous substrates, addition of catalase and the membrane-permeant reducing agent N-acetylcysteine (Nac) or the ROS scavenger mercaptopropionyl glycine significantly increased the ability to phosphorylate added ADP, as demonstrated by 1) full recovery of membrane potential (Deltapsi) and matrix volume from ADP-induced dissipation and shrinkage, 2) ADP-dependent increase in O2 consumption, and 3) enhanced rate of ATP synthesis. Removal of extramitochondrial H2O2 by catalase was required to stimulate endogenous substrate oxidation, as shown by the increase in O2 consumption and Deltapsi. This effect was greatly enhanced by addition of Nac or mercaptopropionyl glycine to suppress oxidation-induced ROS increases in the matrix. Theoretical considerations, as well as reversible inhibition of O2 consumption with 3-mercaptopropionic acid and pyruvate in state 3, indicate that these substrates are fatty acids. Under in vivo conditions in which powerful antioxidant conditions are maintained, this mechanism may be important in stimulation of beta-oxidation and ATP production at low levels of extramitochondrial fatty acids. Incapacitation of this mechanism may potentially contribute to mitochondrial dysfunction during oxidative stress.

3-Mercaptopropionic Acid↗
PubMed1986

The mechanism of the hormonal activation of respiration in isolated hepatocytes and its importance in the regulation of gluconeogenesis.

The effects of hormones on the cytochrome spectra of isolated hepatocytes were recorded under conditions of active gluconeogenesis from L-lactate. Glucagon, phenylephrine, vasopressin and valinomycin, at concentrations that caused stimulation of gluconeogenesis, increased the reduction of the components of the cytochrome bc1 complex, just as has been observed in liver mitochondria isolated from glucagon-treated rats [Halestrap (1982) Biochem. J. 204, 37-47]. The effects of glucagon and phenylephrine were additive. The time courses of the increased reduction of cytochrome c/c1 and NAD(P)H/NAD(P)+ caused by hormones, valinomycin, A23187 and ethanol were measured by dual-beam spectrophotometry and fluorescence respectively. Ethanol (14 mM) produced a substantial rise in NAD(P)H fluorescence, beta-hydroxybutyrate/acetoacetate and lactate/pyruvate ratios, no change in cytochrome c/c1 reduction, a 10% decrease in O2 consumption and a 60% decrease in gluconeogenesis. Glucagon, phenylephrine and vasopressin caused a substantial and transient rise in NAD(P)H fluorescence, but a sustained increase in cytochrome c/c1 reduction and the rates of O2 consumption and gluconeogenesis. The transience of the fluorescence response was greater in the absence of Ca2+, when the cytochrome c/c1 response also became transient. The fluorescence response was smaller and less transient, but the cytochrome c/c1 response was greater, in the presence of fatty acids. Both responses were greatly decreased by the presence of 1 mM-pent-4-enoate. Valinomycin (2.5 nM) caused a decrease in NAD(P)H fluorescence coincident with an increase in cytochrome c/c1 reduction and the rate of gluconeogenesis and O2 consumption. A23187 (7.5 mM) caused increases in both NAD(P)H fluorescence and cytochrome c/c1 reduction. The effects of hormones and valinomycin on the time courses of NAD(P)H fluorescence, cytochrome c/c1 reduction and light-scattering by hepatocytes were compared with those of 0.5 microM-Ca2+ or 1 nM-valinomycin on the same parameters of isolated liver mitochondria. It is concluded that hormones increase respiration by hepatocytes in a biphasic manner. An initial Ca2+-dependent activation of mitochondrial dehydrogenases rapidly increases the mitochondrial [NADH], which is followed by a volume-mediated stimulation of fatty acid oxidation and electron flow between NADH and cytochrome c. 10. Amytal (0.5 mM) was able to reverse the effects of hormones on the reduction of cytochromes c/c1 and the rates of gluconeogenesis and O2 consumption without significantly lowering tissue [ATP].(ABSTRACT TRUNCATED AT 400 WORDS)

Amobarbital↗
PubMed1984

Comparative use of fructose and glucose in human liver and fibroblastic cell cultures.

The effect of fructose as a substitute for glucose in cell culture media was investigated in human skin fibroblast and liver cell cultures. Cells were grown for between 2 and 10 days in identical flasks in four different media, containing 5.5 mmol X 1-1 and 27.5 mmol X 1-1 glucose and fructose, respectively. In the presence of fructose, cell growth was stimulated, but less in liver cells than fibroblasts. At Day 6, increases were observed in [3H]thymidine incorporation, protein levels, and amino acid consumption, and a reduction was noted in ATP levels. In media containing 5.5 mmol X 1-1 glucose or fructose, consumption of fructose was four times lower than that of glucose at Day 3 and did not rise until Day 6. In fructose media, the lactate production was very low (four to five times less than that of glucose) and the pH values were always higher. Some findings were different for the fibroblasts and liver cells, owing to the specific characteristics of these two cell types in culture; this applied especially to the effects of glucose and fructose concentrations of 27.5 mmol X 1-1. Several possible explanations for the stimulation of cell growth in fructose medium were discussed.

Adenosine Triphosphate↗
PubMed2006

Hyperlipidemic mice present enhanced catabolism and higher mitochondrial ATP-sensitive K+ channel activity.

BACKGROUND & AIMS: Changes in mitochondrial energy metabolism promoted by uncoupling proteins (UCPs) are often found in metabolic disorders. We have recently shown that hypertriglyceridemic (HTG) mice present higher mitochondrial resting respiration unrelated to UCPs. Here, we disclose the underlying mechanism and consequences, in tissue and whole body metabolism, of this mitochondrial response to hyperlipidemia. METHODS: Oxidative metabolism and its response to mitochondrial adenosine triphosphate (ATP)-sensitive K+ channel (mitoK(ATP)) agonists and antagonists were measured in isolated mitochondria, livers, and mice. RESULTS: Mitochondria isolated from the livers of HTG mice presented enhanced respiratory rates compared with those from wild-type mice. Changes in oxygen consumption were sensitive to adenosine triphosphate (ATP), diazoxide, and 5-hydroxydecanoate, indicating they are attributable to mitochondrial ATP-sensitive K+ channel (mitoK(ATP)) activity. Indeed, mitochondria from HTG mice presented enhanced swelling in the presence of K+ ions, sensitive to mitoK(ATP) agonists and antagonists. Furthermore, mitochondrial binding to fluorescent glibenclamide indicates that HTG mice expressed higher quantities of mitoK(ATP). The higher content and activity of liver mitoK(ATP) resulted in a faster metabolic state, as evidenced by increased liver oxygen consumption and higher body CO(2) release and temperature in these mice. In agreement with higher metabolic rates, food ingestion was significantly larger in HTG mice, without enhanced weight gain. CONCLUSIONS: These results show that primary hyperlipidemia leads to an elevation in liver mitoK(ATP) activity, which may represent a regulated adaptation to oxidize excess fatty acids in HTG mice. Furthermore, our data indicate that mitoK(ATP), in addition to UCPs, may be involved in the control of energy metabolism and body weight.

Animals↗
PubMed2005

Pharmacology of new agents for acute heart failure syndromes.

Current therapies for acute heart failure syndromes (AHFS) target hemodynamics by decreasing congestion or increasing myocardial contraction. Several new agents for AHFS use novel mechanisms of action that focus on new treatment targets, such as those providing anti-ischemic and anti-stunning effects, blocking vasopressin receptors, or blocking endothelin-1 receptors. For example, levosimendan acts as a calcium sensitizer and adenosine triphosphate-dependent potassium (K(ATP)) channel opener that increases contraction, causes vasodilation, and provides cardioprotective effects. This is accomplished by its dual mechanism of action. Levosimendan binds to cardiac troponin C, thereby enhancing calcium myofilament responsiveness and increasing myocardial contraction without increasing intracellular calcium levels. Thus, contraction is increased with no significant increase in myocardial oxygen consumption. The opening of K(ATP) channels by levosimendan causes vasodilation and exerts anti-ischemic and anti-stunning effects on the myocardium. Other new agents target neurohormonal pathways. Tezosentan is an antagonist of endothelin-1 receptors A and B. By inhibiting endothelin-1 receptors, tezosentan may counteract the activities of endothelin-1, which include vasoconstriction, proarrhythmic activities, potentiation of other neurohormones, and mediation of increased vascular permeability. Tolvaptan is a vasopressin V2-receptor antagonist that functions as an aquaretic (ie, it increases urine volume and serum sodium with little or no sodium loss). Therefore, by using novel mechanisms of action, these agents may provide new opportunities for helping patients with AHFS.

Acute Disease↗
PubMed1980

[Cause of the appearance of cyanide-resistant respiration in the yeast Candida lipolytica].

Changes in the activity of the cell respiration of the yeast Candida lipolytica and its ATP, ADP, NADH, NAD+ pools during the development of the cyanide-resistant respiration were studied. A change-over of the yeast culture to the stationary growth phase conditioned by glucose exhaustion or aerobic incubation of the resting cells in the exponential growth phase without the exogenous carbon source were shown to be accompanied by: 1) decrease of the rate of oxygen consumption; 2) appearance of the cyanide-resistant respiration; 3) appearance of the benzhydroxamic acid-sensitive respiration; 4) appearance of stimulating dinitrophenol action on the rate of oxygen consumption; 5) increase in the ATP content and decrease of the ADP content in the cells. It was concluded that the appearance of the cyanide-resistant respiration is induced by the decrease of the activity of the respiratory chain due to the increase of the ATP concentration and the decrease of the ADP concentration in yeast cells. The functioning of the cyanide-resistant pathway of the electron transfer is one of the ways of NAD+ pool regulation in yeast cells.

Adenosine Diphosphate↗
PubMedDate not supplied

Oxygen uptake occurs faster than sodium pumping in bee retina after a light flash.

When neurones are active there is an entry of Na+, which must subsequently be pumped out, and an increase in their oxygen consumption rate (Qo2). The Na+ pump derives its energy from ATP, splitting it into ADP and Pi, and it has reasonably been proposed that the changes in concentrations of ATP, ADP and Pi lead to a stimulation of the O2 consumption by the mitochondria and hence to a restoration of the stock of ATP. Here we present evidence suggesting that Qo2 must be controlled differently in the retinal photoreceptor cells of the honeybee drone. Stimulation of drone photoreceptors with a flash of light causes an entry of Na+ (ref. 4) and a transient increase in Qo2 that indicates respiration of the right order of magnitude to provide ATP to pump the Na+ out. We report intracellular recordings of changes in intracellular sodium (Nai+) and potassium (Ki+) in response to single light flashes and have compared the time course of extra oxygen consumption (delta Qo2) with these ion changes and other indices of Na+ pumping. We found that the time course of pumping seems to lag behind the time course of delta Qo2. It follows that the mitochondrial respiration must be stimulated by some signal which is generated earlier than the rise in ADP produced by the Na+ pump.

Adenosine Triphosphate↗
PubMed1977

Effect of acetylsalicylic acid on gastric mucosa. II. Mucosal ATP and phosphocreatine content, and salicylate effects on mitochondrial metabolism.

The effects of acetylsalicylic acid on gastric mucosal ATP and phosphocreatine and mucosal O2 consumption were studied using in vitro bullfrog gastric mucosa. Electrophysiological parameters (potential difference and resistance) changed rapidly after exposure to 10 or 20 mM acetylsalicylic acid at pH 3.0, 4.0, or 6.0 in the mucosal solution. ATP and phosphocreatine content decreased rapidly after exposure. Control mucosae contained 11.8 +/- 0.98 nmoles of ATP and 11.5 +/- 0.68 nmoles of phosphocreatine per mg of protein. ATP content decreased 21% and phosphocreatine decreased 45% after 15 to 30 min of exposure. Longer durations of exposure reduced both ATP and phosphocreatine to 10 to 15% of control levels. O2 consumption was increased during the first 15 to 30 min after exposure to acetylsalicylate. Longer durations of exposure reduced O2 consumption to near control levels. Study of isolated mitochondria confirmed that acetylsalicylate itself did not significantly affect mitochondrial respiration, respiratory control ratio, or ADP:O ratio. Salicylate had a biphasic effect which was concentration dependent. Salicylate initially stimulated and later inhibited mitochondrial respiration. Using various substrates the site of inhibition appeared to be located in the segment of the respiratory chain between coenzyme Q and cytochrome c1.

Adenosine Triphosphate↗
PubMed1990

Regulation of the oxidative phosphorylation rate in the intact cell.

The mechanisms that underlie the balance between the consumption and oxidative generation of ATP in the intact cell are not well-defined. Cytosolic inorganic phosphate (Pi) and ADP levels, the cytosolic ATP/ADP ratio, and the cytosolic phosphorylation potential (PP) have all been proposed as major regulatory variables, the latter as a component of a "near-equilibrium" thermodynamic regulatory scheme. Therefore, the potential regulatory roles of these variables in the intact cell were evaluated with 31P NMR and Langendorff perfused rat hearts; in this preparation, the tissue oxygen consumption rate (MVO2) can be varied over a wide range. When the exogenous carbon source was varied, none of the proposed regulatory parameters, i.e., the ATP/ADP ratio, PP, or cytosolic ADP level, were found to be uniquely related to MVO2. Rather, ADP levels at a given MVO2 decreased progressively for the exogenous carbon sources in the following order: glucose, glucose + insulin, palmitate + glucose, lactate, pyruvate + glucose, and octanoate + glucose. In the octanoate and pyruvate groups, MVO2(-1) was linearly dependent upon [ADP]-1 with apparent Km values being in the range previously observed in isolated mitochondria. A similar trend was observed in the MVO2-[Pi] relationship. The present findings suggest that exogenous carbon sources which effectuate deregulation of intramitochondrial NADH generation lower cytosolic ADP and Pi to levels which are limiting to the rate of oxidative phosphorylation. For other carbon sources, the processes controlling the rate of NADH generation also participate in determining the rate of oxidative ATP synthesis. However, this control must be exerted kinetically rather than through a near-equilibrium thermodynamic mechanism as indicated by the present data and prior kinetic studies of the ATP synthetic process in both isolated mitochondria and intact myocardium [La Noue, K. F., et al. (1986) Biochemistry 25, 7667-7675; Kingsley-Hickman, P., et al. (1987) Biochemistry 26, 7501-7510].

Adenosine Triphosphate↗
PubMedDate not supplied

31P nuclear magnetic resonance and saturation transfer studies of the isolated perfused rat kidney.

Previous studies using 31P nuclear magnetic resonance (NMR) saturation transfer techniques to quantitate the energy metabolism of the kidney have often resulted in estimates of adenosine triphosphate (ATP) turnover which are much lower than those predicted from the renal oxygen consumption and reasonable values of the P/O ratio. We measured the ATP turnover in isolated perfused kidneys of rats, using 31P NMR saturation transfer and a new procedure for quantitation of the intracellular Pi concentration. The estimated turnover rates of ATP were higher than previously reported. The P/O ratios calculated on the basis of these rates of ATP turnover and rates of renal oxygen consumption reported in the literature were within the range of theoretically possible values. Thus, 31P NMR saturation transfer can be used to quantitate the ATP turnover in the isolated perfused rat kidney.

Adenosine Triphosphate↗
PubMed1994

Energy metabolism of reticulocytes: two different sources of energy for Na+K(+)-ATPase activity.

Total energy production in rabbit reticulocytes amounted to 136.52 +/- 6.50 mumol ATP h-1 ml-1 of reticulocytes: 88.3 per cent was provided by oxidative phosphorylation, whereas only 11.7 per cent by aerobic glycolysis. Na+K(+)-ATPase accounted for 23 per cent, i.e. 27.65 +/- 2.55 mumol ATP h-1ml-1 of reticulocytes, in the overall energy consumption in reticulocytes of rabbits. Under basal conditions ATP for Na+K(+)-ATPase activity was derived exclusively from oxidative phosphorylation. However, when the activity of Na+K(+)-ATPase was increased due to the stimulation of adenylate cyclase by (-)-isoprenaline, the additional energy required was provided by aerobic glycolysis. These results indicate that two different compartments, one cytosolic and the other mitochondrial, provide energy for Na+K(+)-ATPase activity in reticulocytes.

Adenosine Triphosphate↗
PubMed1990

The abnormal-shaped mitochondria in thymus lymphocytes treated with inhibitors of mitochondrial energetics.

The effects of uncouplers (DNP, FCCP), oligomycin, and rotenone on the energetics and mitochondrial ultrastructure in lymphocytes have been studied. We confirmed the previous observations done on Ehrlich ascites and cardiomyocyte culture cells that uncouplers and respiratory inhibitors cause the appearance of ringlike and dumbbell-like mitochondria. It is shown that this effect does not correlate with decrease in ATP concentration, changes in oxygen consumption, or condensation of the mitochondrial matrix. FCCP (2 microM) is more effective in the induction of abnormal-form mitochondria than 240 microM DNP, oligomycin, or rotenone. Combined treatment with DNP, oligomycin, and rotenone or with DNP and rotenone produces an effect as strong as 2 microns FCCP. DNP (240 microM) and FCCP (2 microM) have a similar effect on respiration and intracellular ATP, but only the latter induces condensation of the mitochondrial matrix.

Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone↗
PubMed2003

Isoflurane alters energy substrate metabolism to preserve mechanical function in isolated rat hearts following prolonged no-flow hypothermic storage.

BACKGROUND: Isoflurane enhances mechanical function in hearts subject to normothermic global or regional ischemia. The authors examined the effectiveness of isoflurane in preserving mechanical function in hearts subjected to cardioplegic arrest and prolonged hypothermic no-flow storage. The role of isoflurane in altering myocardial glucose metabolism during storage and reperfusion during these conditions and the contribution of adenosine triphosphate-sensitive potassium (K(atp)) channel activation in mediating the functional and metabolic effects of isoflurane preconditioning was determined. METHODS: Isolated working rat hearts were subjected to cardioplegic arrest with St. Thomas' II solution, hypothermic no-flow storage for 8 h, and subsequent aerobic reperfusion. The consequences of isoflurane treatment were assessed during the following conditions: (1) isoflurane exposure before and during storage; (2) brief isoflurane exposure during early nonworking poststorage reperfusion; and (3) isoflurane preconditioning before storage. The selective mitochondrial and sarcolemmal K(atp) channel antagonists, 5-hydroxydecanoate and HMR 1098, respectively, were used to assess the role of K(atp) channel activation on glycogen consumption during storage in isoflurane-preconditioned hearts. RESULTS: Isoflurane enhanced recovery of mechanical function if present before and during storage. Isoflurane preconditioning was also protective. Isoflurane reduced glycogen consumption during storage under the aforementioned circumstances. Storage of isoflurane-preconditioned hearts in the presence of 5-hydroxydecanoate prevented the reduction in glycogen consumption during storage and abolished the beneficial effect of isoflurane preconditioning on recovery of mechanical function. CONCLUSIONS: Isoflurane provides additive protection of hearts subject to cardioplegic arrest and prolonged hypothermic no-flow storage and favorably alters energy substrate metabolism by modulating glycolysis during ischemia. The effects of isoflurane preconditioning on glycolysis during hypothermic no-flow storage appears to be associated with activation of mitochondrial K(atp) channels.

Adenosine Triphosphate↗