Decrease In Adenylate Energy Charge Research Articles

Implications of dietary phosphorus sources on zootechnical performance and stress response of the pacific white shrimp Litopenaeus vannamei

The phosphorous (P) is an essential element for several functions, including the synthesis of high energy compounds in cells like adenosine triphosphate (ATP) and arginine phosphate (ArgP). The dietary requirements of P could change according to physiological and environmental conditions, particularly if organisms are exposed to stress conditions. As the P availability could be related to its chemical form in the diet, the present study analyzed the influence of different P sources (KH2PO4, NaH2PO4, NH4H2PO4, Na5P3O10), on the stress response of the Pacific white shrimp Litopenaeus vannamei. Final weight was 8.5% higher (p < 0.01) in shrimp fed on tripolyphosphate (Na5P3O10) diet compared with the monophosphate diets. Weight gain and specific growth also trend to increase, whereas feed conversion ratio trend to decrease with this polyphosphate source, although not significantly. Stress response of shrimp exposed to handling followed by hypoxia was characterized by an overall increase of lactate and glucose levels in hemolymph, as well as a decrease in Adenylate Energy Charge (AEC) and ArgP in the muscle. No effect of dietary P sources was observed on baseline biochemical composition and overall indicators of stress response, except for higher carbohydrate levels in hepatopancreas and RNAm expression of arginine kinase (AK) in muscle with the NaH2PO4 diet, suggesting a potentially better energy status with this diet.

Energy metabolism of juvenile scallops Nodipecten subnodosus under acute increased temperature and low oxygen availability

High temperature increases energy demand in ectotherms, limiting their physiological capability to cope with hypoxic events. The present study aimed to assess the metabolic tolerance of juvenile Nodipecten subnodosus scallops to acute hyperthermia combined with moderate hypoxia. A previous study showed that juveniles exhibited a high upper temperature limit (32 °C), but the responses of juveniles to combined hyperthermia and low dissolved oxygen are unknown. Scallops were exposed to control conditions (treatment C: 22 °C, ∼7.1 mg O2 L−1 or PO2 156.9 mmHg), acute hyperthermia under normoxia (treatment T: 30 °C, ∼6.0 mg O2 L−1 or PO2 150.9 mmHg) or acute hyperthermia plus hypoxia (treatment TH: 30 °C, ∼2.5 mg O2 L−1 or PO2 62.5 mmHg) for 18 h. In T, juveniles exhibited an enhanced oxygen consumption, together with a decrease in adenylate energy charge (AEC) and arginine phosphate (ArgP), and with no changes in metabolic enzyme activity in the muscle. In TH, scallops maintained similar AEC and ArgP levels in muscle as those observed in T treatment. This response occurred along with the accumulation of inosine monophosphate and hypoxanthine. Besides, reduced citrate synthase and pyruvate kinase activities, enhanced hexokinase activity, and a higher octopine dehydrogenase/lactate dehydrogenase ratio in the mantle indicated the onset of anaerobiosis in TH. These responses indicate that juvenile scallops showed tissue-specific compensatory responses regarding their energy balance under moderate hypoxia at high temperatures. Our results give an insight into the tolerance limit of this species to combined hyperthermia and hypoxia in its northern limit of distribution.

Juvenile roach (Rutilus rutilus) increase their anaerobic metabolism in response to copper exposure in laboratory conditions.

This study aims to determine the potential impairment of cell energy synthesis processes (glycolysis and respiratory chain pathways) by copper in juvenile roach at different regulation levels by using a multi-marker approach. Juvenile roach were exposed to 0, 10, 50, and 100µg/L of copper for 7days in laboratory conditions. The glycolysis pathway was assessed by measuring the relative expression levels of 4 genes encoding glycolysis enzymes. The respiratory chain was studied by assessing the electron transport system and cytochrome c oxidase gene expression. Muscle mitochondria ultrastructure was studied, and antioxidant responses were measured. Furthermore, the main energy reserves-carbohydrates, lipids, and proteins-were measured, and cellular energy was evaluated by measuring ATP, ADP, AMP and IMP concentrations. This study revealed a disturbance of the cell energy metabolism due to copper exposure, with a significant decrease in adenylate energy charge in roach exposed to 10μg/L of copper after 1day. Moreover, ATP concentrations significantly decreased in roach exposed to 10μg/L of copper after 1day. This significant decrease persisted in roach exposed to 50µg/L of copper after 7days. AMP concentrations increased in all contaminated fish after 1day of exposure. In parallel, the relative expression of 3 genes encoding for glycolysis enzymes increased in all contaminated fish after 1day of copper exposure. Focusing on the respiratory chain, cytochrome c oxidase gene expression also increased in all contaminated fish at the two time-points. The activity of the electron transport system was not disturbed by copper, except in roach exposed to 100µg/L of copper after 1day. Copper induced a metabolic stress. Juvenile roach seemed to respond to the ensuing high energy demand by increasing their anaerobic metabolism, but the energy produced by the anaerobic metabolism is unable to compensate for the stress induced by copper after 7days. This multi-marker approach allows us to reach a greater understanding of the effects of copper on the physiological responses of juvenile roach.

Impaired cortical energy metabolism but not major antioxidant defenses in experimental bacterial meningitis

The loss of soluble brain antioxidants and protective effects of radical scavengers implicate reactive oxygen species in cortical neuronal injury caused by bacterial meningitis. However, the lack of significant oxidative damage in cortex [J. Neuropathol. Exp. Neurol. 61 (2002) 605–613] suggests that cortical neuronal injury may not be due to excessive parenchymal oxidant production. To see whether this tissue region exhibits a prooxidant state in bacterial meningitis, we examined the state of the major cortical antioxidant defenses in infant rats infected with Streptococcus pneumoniae. Adenine nucleotides were co-determined to assess possible changes in energy metabolism. Arguing against heightened parenchymal oxidant production, the high NADPH/NADP + ratio (∼3:1) and activities of the major antioxidant defense and pentose phosphate pathway enzymes remained unchanged at the time of fulminant meningitis. In contrast, cortical ATP, ADP and total adenine nucleotides were on average decreased by ∼25%. However, energy depletion did not lead to a significant decrease in adenylate energy charge (AEC). ATP depletion was likely a consequence of metabolic degradation, since it correlated with both the loss of total adenine nucleotides and accumulation of purine degradation products. Furthermore, the loss of ATP and decrease in AEC correlated significantly with the extent of neuronal injury. These results strongly suggest that energy depletion rather than parenchymal oxidative damage is involved in the observed cortical neuronal injury.

Is there a critical tissue oxygen tension for bioenergetic status and cellular pH regulation in solid tumors?

Bioenergetic and metabolic status have been correlated with tissue oxygenation in murine fibrosarcomas (FSaII) of varying sizes (44-600 mm3). Ratios of beta-nucleoside triphosphates to inorganic phosphate (beta NTP/P) and phosphocreatine to inorganic phosphate (PCr/P(i)) ratios derived from 31P nuclear magnetic resonance spectroscopy (NMR) were positively correlated to median tissue O2 tension (pO2) values using O2-sensitive needle electrodes. pH declined during growth with intracellular acidosis being evident in tumors > 350 mm3. Whereas lactic acid formation greatly contributed to this decline in small and medium-sized tumors, adenosine triphosphate (ATP) hydrolysis and slowing down of the activities of pumps involved in cellular pH regulation seem to be major factors responsible for intracellular acidification in bulky tumors. PCr levels decreased at an early growth stage, whilst ATP concentrations dropped in bulky malignancies only, coinciding with a decrease in adenylate energy charge and a substantial rise in the levels of total P(i). On average, median pO2 values of ca. 10 mmHg represent a critical threshold for energy metabolism. At higher median O2 tensions, levels of ATP, phosphomonoester (PME) and total P(i) were relatively constant. This coincided with intracellular alkalosis or neutrality and stable adenylate ratios. On average, median pO2 values < 10 mmHg coincided with intracellular acidosis, ATP depletion, a drop in energy charge and rising P(i) levels.

Energy metabolism of the mussel, Mytilus galloprovincialis, during long-term anoxia

In the mussel, Mytilus galloprovincialis, the pattern of metabolic adaptations to long-term anoxia was clearly biphasic. The first phase (transition stage) lasted 24 hr and was characterized by the decrease of adenylate energy charge, the consumption of aspartate and the accumulation of succinate and alanine. The second phase (stationary stage) was characterized by the depletion of glycogen stores, the production of propionate, which was subsequently excreted into incubation water, and the metabolic depression. The ATP turnover rate was reduced by a factor of 3.9 from short-term anoxia to long-term anoxia.

Intracellular acidosis in murine fibrosarcomas coincides with ATP depletion, hypoxia, and high levels of lactate and total Pi.

Bioenergetic and metabolic status of murine FSaII tumours were evaluated using 31P MRS, acid extracts ('global' techniques) and quantitative bioluminescence ('microregional' assay). Data obtained from s.c. tumours of varying sizes (44-600 mm3) have been correlated with the oxygenation status evaluated using O2-sensitive needle electrodes. beta-NTP/Pi and phosphocreatine (PCr)/Pi ratios derived from 31P MRS were positively correlated to the median tissue pO2 values. pH declined during growth with intracellular acidosis being evident in tumours > 350 mm3. Whereas lactic acid formation greatly contributed to this decline in small- and medium-sized tumours, ATP hydrolysis and slowing down of the activities of pumps involved in pHi regulation seem to be major factors responsible for intracellular acidification in bulky tumours. PCr levels decreased at an early growth stage, whilst ATP concentrations dropped in bulky malignancies only, coinciding with a decrease in adenylate energy charge and a substantial rise in the levels of total Pi. MRS observable (mobile) Pi was consistently lower than [Pi] measured in acid extracts. On average, median pO2 values of ca 10 mmHg represent a critical threshold for energy metabolism. At higher median O2 tensions, levels of ATP, phosphomonoester and total Pi were relatively constant. This coincided with intracellular alkalosis or neutrality and stable adenylate ratios. On average, median pO2 values < 10 mmHg coincided with intracellular acidosis, ATP depletion, a drop in energy charge and rising Pi levels.

Inorganic Phosphate (Pi) Enhancement of Dark Respiration in the Pi-Limited Green Alga Selenastrum minutum (Interactions between H+/Pi Cotransport, the Plasmalemma H+-ATPase, and Dark Respiratory Carbon Flow).

Inorganic phosphate (Pi) enrichment of the Pi-limited green alga Selenastrum minutum in the dark caused a 2.5-fold increase in the rate of O2 consumption. Alkalization of the media during Pi assimilation was consistent with a H+/Pi cotransport mechanism with a stoichiometry of at least 2 H+ cotransported per Pi. Dark O2 consumption remained enhanced beyond the period of Pi assimilation and did not recover until the medium was reacidified. This result, coupled with an immediate decrease in adenylate energy charge following Pi enrichment, suggested that respiration is regulated by the ATP requirements of a plasmalemma H+-ATPase that is activated to maintain intracellular pH and provide proton motive force to power Pi uptake. Concentrations of tricarboxylic acid cycle intermediates decreased following Pi enrichment and respiratory CO2 efflux increased, indicating that the tricarboxylic acid cycle was activated to supply reductant to the mitochondrial electron transport chain. These results are consistent with direct inhibition of electron transport by ADP limitation. Enhanced rates of starch breakdown and increases in glycolytic metabolites indicated that respiratory carbon flow was activated to supply reductant to the electron transport chain and to rapidly assimilate Pi into metabolic intermediates. The mechanism that initiates glycolytic carbon flow could not be clearly identified by product:substrate ratios due to the complex nature of Pi assimilation. High levels of triose-P and low levels of phosphoenolpyruvate were the primary regulators of pyruvate kinase and phosphofructokinase, respectively.

Effect of salinity on the plasma membrane ATPase from tomato ( Lycopersicon esculentum Mill.) leaves

Experiments were conducted to determine if salt-induced changes in the plasma-membrane H +-ATPase could account for decreased shoot growth in Lycopersicon esculentum Mill. cv Heinz 1350. The plasma membrane was isolated from mature and young leaves of untreated (control) and salt-stressed leaves using the aqueous polymer two-phase technique. Analysis of ATP hydrolytic activity showed that salt stress reduced the V max of H +-ATPase specific activity in mature leaves but had no effect in young, growing leaves. These findings are consistent with measurements of adenine nucleotide levels. We observed a large decrease in adenylate energy charge (AEC) in mature leaves following salt stress. AEC in young leaves remained unaffected. In addition, a dramatic increase in K, the adenylate kinase mass action ratio, from 0.18 to 1.53 was measured in mature leaves following salt stress. These results indicate that salt stress did not reduce growth of young, growing leaves by decreasing H +-ATPase activity and support our earlier hypothesis that salt stress affects mature leaves and, as a consequence, their ability to supply essential metabolites for growing regions of both shoot and roots.

Recovery after anaerobic metabolism in the leech (Hirudo medicinalis L.).

Medicinal leeches (Hirudo medicinalis L.) responded to self-induced hypoxia (72 h) with typical anaerobic metabolism characterized by a decrease in adenylate energy charge, utilization of the substrates glycogen and malate, and accumulation of the main anaerobic end-products succinate and propionate. Propionate was also excreted into the medium. Ammonia excretion was suppressed. Aerobic recovery resulted in a profound O2 debt. Resynthesis of ATP was completed within 30 min. Disposal of succinate and restoring of malate required 2-3 h, and clearance of propionate and recharging of glycogen 6-12 h. Ammonia excretion did not exceed normoxic rates and excretion of propionate during recovery accounted for only 10% of total propionate accumulated during hypoxia. It is postulated that the clearance of succinate and propionate involves oxidation but also resynthesis of malate and glycogen. During hypoxia and recovery blood osmolality remained constant. The Na+ and Cl- ion concentrations in blood, the decrease of which was nearly equimolar during hypoxia, were re-established following different time-courses. Na+ concentration returned to normoxic levels after 2-3 h. The delayed increase in Cl- concentration, however, correlating with 6-12 h necessary to clear blood propionate, is interpreted as an anion regulating effect.

Effects of arsenic on survival and metabolism of Crangon crangon

Metabolic changes and toxic effects in Crangon crangon (collected during summer 1989 near Helsingor, Denmark and at Kulhuse in the Isefjord) were observed during exposure to different arsenate concentrations. Survival, respiration, and concentrations of hemolymph glucose, muscle glycogen andadenine nucleotides were measured. C. crangon was very tolerant of arsenate; survival was only affected at arsenate concentrations >25 ppm. Small individuals (0.2 to 0.29 g wet weight) were less tolerant than medium-sized and large individuals (0.5 to 0.59 g and 0.8 to 0.89 g wet weight), e.g. at 50 ppm the LT50 for small individuals was 180 h compared to 343 h and 360 h in middle-sized and large individuals. The relation between size and toxicity is probably due to the change in surface/volume ratio. Under clean conditions the respiration of C. crangon showed a clear relation between routine MO2 (O2 in mlg-1 h-1) and wet weight (r2=0.89; P<0.001). During shortterm exposure to arsenate (10 and 50 ppm), the respiratory rates (MO2) seemed to decrease in a size-dependent manner. The concentrations of blood glucose and muscle glycogen did not change in response to arsenate exposure. The concentrations of adenylate phosphates were high and constant throughout the experiments. C. crangon had maximal adenylate energy charge (AEC) values of ca. 0.8. No decrease in AEC due to the exposure to arsenate was observed.

ホスホエノールピルビン酸による赤血球エネルギー状態（Ａｄｅｎｙｌａｔｅ Ｅｎｅｒｇｙ Ｃｈａｒｇｅ）の改善 細胞賦活剤としてのホスホエノールピルビン酸

Phosphoenolypyruvate inhibited the decrease in adenylate energy charge induced by A23187. It is proposed that this high energy compound penetrates the cell membrane and is metabolized to ATP inside the cells. Phosphoenolpyruvate may be an important agent for clinical use to consider in counteracting the reduction of adenylate energy charge under a variety of other conditions.

REGULATION OF THE CYTOSOL 5′-NUCLEOTIDASE OF THE HEART BY ADENYLATE ENERGY CHARGE: 93

5'-Nucleotidase was partially purified from chicken and rat heart by the similar procedure used for the purification of the cytosol 5'-nucleotidase from chicken and rat liver. Some kinetic properties of the enzymes from heart were similar to those of the cytosol 5'-nucleotidase from the liver.The heart enzymes from both species were activated by ATP. When AMP was used as a substrate, the substrate-velocity plot of the chicken heart enzyme was sigmoidal (h=1.8). ATP at the concentration of 5 mM converted the curve into hyperbolic one and decreased s0.5 from 40 mM to 8 mM. The substrate-velocity plot of the rat heart enzyme with AMP was hyperbolic even in the absence of ATP. ATP at the concentration of 5 mM activated the enzyme by decreasing Km from 21 mM to 7 mM.AMP-hydrolysing activity of these two enzyme preparations from cardiac tissue was markedly increased with the decrease in adenylate energy charge [(ATP + 0.5ADP)/(ATP + ADP + AMP)] in the physiological range. This suggests that the cytosol 5'-nucleotidase is important in production of a vasodilator, adenosine, from AMP during hypoxic condition of the heart.

MECHANISM OF INCREASED RATE OF DE NOVO PURINE BIOSYNTHESIS IN RAT LIVER AFTER BILATERAL ADRENALECTOMY: 92

In rat liver after bilateral adrenalectomy de novo purine biosynthesis was studied 24, 48 and 72 hours in comparison to sham-operated control. At these time points the rate of de novo purine biosynthesis assayed by [14C]glycine incorporation to hepatic purines significantly increased by 1.61, 1.95 and 2.01 folds respectively associated with comparable free glycine concentration in plasma or liver tissue. Hepatic concentration of 5-phosphoribosyl 1-pyrophosphate(PRPP) increased by 2.91, 1.50 and 1.75 folds at these 3 time points. 24 hours after bilateral adrenalectomy ATP and GTP concentration decreased by 33 and 24% respectively which were counterbalanced by the increased concentration of AMP(245%) and GMP(38%) associated with 18% decrease of adenylate energy charge. The replacement of corticosterone acetate to adrenal-ectomized animals for 24 hours partially reversed these changes. The results suggest that the increased rate of de novo purine biosynthesis in adrenal-ectomized rat liver is mediated by the increased concentration of PRPP and that it is compensatory against increased catabolism of purine ribonucleotides as a result of increased AMP concentration.

Changes in adenylate energy charge and total adenine nucleotide concentration in mouse testis induced by cadmium administration

Subcutaneous administration of CdCl 2 (3 mg/kg body weight) caused a decrease in adenylate energy charge, (ATP + 0.5ADP)/(ATP + ADP + AMP), and a depletion of the adenine nucleotide pool in the testis of mice. This preceded a decrease in LDH-X activity in the testicular extracts. These results biochemically support the hypothesis that the testicular damage induced by cadmium is secondary to anoxia caused by vascular lesion.

Adenylate energy charge in three marine bivalve species during anoxia

Abstract Influence of anoxia on adenylate energy charge (AEC) has been studied with three bivalve species from the Western Baltic Sea, Macoma calcarea, Cyprina islandica and Astarte borealis, which represent different levels of tolerance to anoxia, increasing in the order listed. Under normoxic conditions (10°C, 16.5%°S) the adenylate energy charge (a measure for the potentially available energy of an organism, ranging from 0 to a hypothetical maximum of 1.0) accounted to 0.80 for M. calcarea, 0.79 for C. islandica and 0.55 for A. borealis. A subsequent exposure to anoxia resulted in a decrease of AEC in all three species, with the lowest AEC measured in A. borealis, the species with the best tolerance to anoxia. To investigate the influence of temperature, experiments with M. calcarea and A. borealis were also conducted at 5 and 15 °C. It was found that an increase of temperature leads to increased AEC values in M. calcarea, but to decreased levels in A. borealis. The adaptive value of being able to lowe...

In vivo nuclear magnetic resonance spectroscopy of a transplanted brain tumour.

In vivo nuclear magnetic resonance 31P spectroscopy was used to demonstrate different patterns of high energy phosphate metabolism in a group of malignant tumours of glial origin. In some of the more malignant tumours a decrease in adenylate energy charge was found. This was associated with a decline in phosphocreatine and an increase in sugar phosphate and inorganic phosphorus.

Influence of blood glucose concentration on brain lactate accumulation during severe hypoxia and subsequent recovery of brain energy metabolism.

The effects of hypoxaemia on regional cerebral blood flow (CBF) and brain cortical metabolite concentrations were investigated at different blood glucose concentrations in rats under nitrous oxide anaesthesia. Tissue hypoxia of 15-min duration was induced by a combination of arterial hypoxaemia, hypotension, and clamping of the right carotid artery. Blood glucose concentrations were manipulated by varying the food intake in the 24 h before the experiment, and by glucose administration. Cortical CBF doubled during hypoxia on the intact side, but did not differ significantly from control values on the clamped side. In the clamped hemisphere there was a substantial decrease in adenylate energy charge. At brain tissue glucose concentration of 1 mumol g-1 and above, there was an inverse correlation between adenylate energy charge and brain lactate concentration. In starved animals with mean brain glucose of 0.32 +/- 0.00 mumol g-1, lactate concentration was significantly lower, in spite of equally severe disruption of energy state. Recovery of brain adenylate energy charge was worse in fed and glucose-infused groups than in the fasted group. These results demonstrate that limitation of substrate supply during severe hypoxia in the rat allows enhanced recovery of brain energy metabolism following the hypoxic episode.

Transport of 2-deoxy-D-[3H]glucose in microvessels isolated from bovine cerebral cortex.

Microvessels were isolated from a bovine cortex and the transport of glucose was investigated by using 2-deoxy-D-[3H]glucose (2-DG). The apparent Km for 2-DG transport was 118 microM and therefore indicates a significant high affinity for the substrate. The inhibition of 2-DG uptake by D-glucose showed an apparent Ki of 222 microM. Other sugars, e.g., 3-methyl-D glucose and D-fructose, also inhibited the 2-DG uptake by 60.6 and 36.0%, respectively. Phloretin (1 X 10(-3) M) inhibited the 2-DG transport more than phlorizin (83.7 vs. 53.8%). Ouabain (1 and 5 X 10(-4) M) did not inhibit the uptake of 2-DG but 2,4-dinitrophenol (1 X 10(-4) M) did (78.0%). The uptake of 2-DG could not be demonstrated in homogenized microvessels. Adenine nucleotides (conc. 2 mM) had various effects on the 2-DG uptake by microvessels. ATP inhibited the uptake by 20.7%, ADP was virtually without effect, and AMP stimulated the uptake of 2-DG by 8.5%. It was also found that the decrease of adenylate energy charge favors the uptake of 2-DG. All these findings suggest that, in cerebral microvessels of a bovine cortex, 2-DG is apparently transported by a specific, carrier-mediated transport system.

Release-induced changes in adenine nucleotide metabolism of human blood platelets

Human platelets incubated in platelet-rich plasma (PRP) accumulated [ 14C]5-hydroxytryptamine (5-HT) with a Kt of 2.3/uM and [ 3H]adenine with a K t of 1.1μM. Preincubation with 1.8μM adenine decreased 5-HT uptake by 20%. The incorporated adenine was mainly converted to ATP and ADP. Tyramine, tryptamine, imipramine, reserpine, 1-aminoadamantane (D 1) and its 3.5-dimethyl derivative (D 145) released more than 65% of previously accumulated [ 14C]5-HT. In addition D 145, reserpine,and imipramine also reduced endogenous ATP and ADP within platelets by more than 40% part of which was recovered extracellularly. In[ 14C]adenine-labeled platelets the same 3 drugs caused a marked decrease in adenylate energy charge and [ 14C]ATP which was metabolized mainly to hypoxanthine + inosine. The results indicate that release of 5-HT plus ATP/ADP from platelet storage organelles requires energy which is supplied by the metabolically active adenine nucleotide pool whereas 5-HT alone is liberated rather by passive transport.