Changes In ATP Levels Research Articles

Chromosomal puff induction in salivary glands from Drosophila hydei by arsenite

During incubation of salivary glands from Drosophila hydei in the presence of arsenite (7.5 × 10 −5 M) the major temperature-sensitive puffs show essentially the same kinetics of development as after anaerobiosis followed by air or during temperature shock. Also the dose-response curve, the labeling intensity after a [ 3H]uridine pulse and the electronmicroscopic features of the temperature-sensitive chromosome regions are virtually the same during arsenite treatment as those obtained with other treatments. However, one major difference between incubation with arsenite and the other treatments is found in the changes in ATP level. During arsenite treatment the ATP level does not change, whereas during the other treatments the ATP level is reduced. In an attempt to correlate puff-inducing events with changes in the mitochondrial metabolism, the affinity of the α-glycerophosphate oxidase was measured and the related changes in the α-glycerophosphate concentration were studied. During all puff-inducing treatments studied so far, thus also during arsenite treatment, a decrease in affinity of the α-glycerophosphate oxidase and a decrease in α-glycerophosphate concentrations is found in the first 15–20 min of the incubation. Later the concentration of α-glycerophosphate increases again, possibly due to the further decrease in affinity of α-glycerophosphate oxidase.

ATP Levels and Energy Requirements of Ion Transport in Cells of Slices of Greening Barley Leaves

Leaf slices obtained from 6 days old etiolated barley seedlings at various time intervals during greening were kept for 1 h in experimental solutions under various conditions. Under N2 in the dark ATP levels are rather low and independent of the time of greening. Under N2 in the light ATP levels significantly increase from the low level during the first 4 h of greening and then remain constant. In air ATP levels are similar in the light and in the dark, and rather independent of the time of greening; they are similar to the levels obtained in light + N 2 after 4 h of greening or longer. These results are compared with earlier experiments on ion uptake and photosynthesis of greening barley leaves. Ion uptake rates appear to be highly correlated with ATP levels. In light + N2 changes of ATP levels, of 36 C1 − and 86 Rb + uptake and of photosynthetic O 2 evolution during greening have the same kinetics.

Changes in phospholipid susceptibility toward phospholipase induced by ATP depletion in avian and amphibian erythrocyte membranes

About half of the sphingomyelin content of fresh and ATP-depleted chicken erythrocytes is hydrolysed by sphingomyelinase. Removal of sphingomyelin exposes the rest of the membrane phospholipids to hydrolysis by phospholipase C only in ATP-depleted but not in fresh cells. Addition of both sphingomyelinase and phospholipase C to ATP-depleted cells causes about 60–70% hydrolysis of the total phospholipids accompanied by extensive (90%) hemolysis. The phospholipids of toad erythrocytes are partially available to phospholipase C activity in fresh cells (17–25% hydrolysis) without prior sphingomyelinase treatment. However, in ATP-depleted toad cells phospholipase C hydrolyses 66% of phospholipids and causes extensive lysis. Treatment of either fresh or ATP-depleted toad erythrocytes by sphingomyelinase together with phospholipase C induces hydrolysis of most of the phospholipids with complete lysis. Restoration of ATP to ATP-depleted cells endows them with resistance to the attack of phospholipase C. The correlation between changes in ATP level and membrane organization as revealed by increased susceptibility toward phospholipase is discussed.

Role of sialic acid in erythrocyte survival

The role of membrane sialic acid in erythrocyte survival is unclear, although there is evidence for a reduction in sialic acid and surface charge in older erythrocytes. We reduced the surface charge of human, rat, and rabbit erythrocytes by removing sialic acid with neuraminidase.Reduction in sialic acid correlated with decreases in electrophoretic mobility and loss of PAS staining of membrane glycoproteins on polyacrylamide gels. No changes in ATP levels or deformability were found. 51Cr erythrocyte survivals in rats and rabbits showed rapid clearance of desialylated erythrocytes with sequestration by the liver.These results suggest that reduction in erythrocyte sialic acid is a mechanism of erythrocyte destruction and may be important in erythrocyte senescence.

Role of Sialic Acid in Erythrocyte Survival

The role of membrane sialic acid in erythrocyte survival is unclear, although there is evidence for a reduction in sialic acid and surface charge in older erythrocytes. We reduced the surface charge of human, rat, and rabbit erythrocytes by removing sialic acid with neuraminidase. Reduction in sialic acid correlated with decreases in electrophoretic mobility and loss of PAS staining of membrane glycoproteins on polyacrylamide gels. No changes in ATP levels or deformability were found. 51Cr erythrocyte survivals in rats and rabbits showed rapid clearance of desialylated erythrocytes with sequestration by the liver. These results suggest that reduction in erythrocyte sialic acid is a mechanism of erythrocyte destruction and may be important in erythrocyte senescence.

Cerebral energy reserves and glycolysis in neural tissue of 6-aminonicotinamide-treated mice.

AbstractCerebral energy metabolism was studied in brains of mice treated with the nicotinamide analog, 6‐aminonicotinamide (6‐AN), which is converted to a potent inhibitor of 6‐phosphogluconate dehydrogenase in viro. Six hours after administration of 6‐AN, the level of cerebral 6‐phosphogluconate was increased at least 170‐fold, whereas substrates for other NADP +‐dependent dehydrogenases either did not change or increased only slightly. Large increases in 6‐phosphogluconate were observed in the cerebral cortex, three layers of the cerebellum, and the dorsal column and anterior horn regions of the spinal cord after administration of 6‐AN. Thus, glucose was metabolized via the oxidative enrymes of the pentose phosphate pathway in a wide variety of neuronal structures in vivo. Highest concentrations of 6‐phosphogluconate were observed in the cerebellar molecular layer.Energy use rates and glycolysis were studied by measuring the disappearance of the major energy reserves during periods of anoxic‐ischemia imposed on cerebral tissue of 6‐AN‐treated mice. Production of lactate and utilization of glycogen during anoxic‐ischemia were reduced in brain of 6‐AN‐treated mice, which is in accord with the suggestion that glycolysis is inhibited in cerebral tissue of 6‐AN‐treated animals. Levels and ratios of pyridine nucleotides in cerebral tissue were not altered by 6‐AN treatment. From changes in levels of ATP, phosphocreatine, glucose, and glycogen in brain during ischemia, the rate of energy use was calculated to be 21.7 mmol · kg wet tissue−1 · min−1, which was not significantly different from that observed in normal adult mouse brain. Therefore, despite an apparent slowing of hexose utilization in cerebral tissue 6‐AN‐treated mice, normal cerebral energy use was maintained during the initial period of anoxic‐ischemia.

ATP level and CO2 production of mast cells in anaphylaxis.

The short and long-term effects of the anaphylactic reaction on energy metabolism of rat mast cells were studied. The ATP content amounted to 12.1 ± 1.1 ×10<sup>––</sup><sup>16</sup> moles per mast cell in different experiments. Following antigen challenge (horse serum 0.6%), a significant decrease of the ATP level was obtained: 16% at 30 sec and 38% at 2 min with no further change up to 10 min. The decrease was evident in the absence of metabolic substrates as well as in the presence of pyruvate. However, glucose completely counteracted the fall in ATP level. The fall in ATP content and the release of histamine were both related to the antigen concentration. No change in ATP level was observed in controls or by antigen challenge of mast cells from nonsensitized rats. Pyruvate was metabolized by oxidative metabolism in the mast cell. The CO<sub>2 </sub>production amounted to 2.2 ×10<sup>––16</sup> moles CO<sub>2</sub>/mast cell/min and was completely abolished by antimycin A. Antigen challenge of sensitized rat mast cells increased the CO<sub>2</sub> production by 30%, while no increase was observed with cells from non-sensitized rats. The increase in oxidative metabolism was not correlated to the histamine release. Thus, the same enhancement in CO<sub>2</sub> production was obtained with antigen concentrations over a great range. 2,4-Dinitrophenol mimicked the effects of antigen on the ATP level as well as on the oxidative metabolism of pyruvate. The results indicate that the antigen-antibody reaction exerts effects on the energy production in the mast cells consistent with an uncoupling of oxidative phospho-rylation.

Simultaneous Measurement of Oxygen Evolution and Endogenous Adenosine-Triphosphate Levels in Isolated ‘Intact’ Chloroplast Suspensions

Simultaneous continuous polarographic estimation of oxygen evolution and measurement of ATP levels by the firefly luciferase method were made in suspensions containing predominantly intact spinach chloroplasts. Measurements were made during light to dark and dark to light transitions in the presence and absence of bicarbonate, 3-phosphoglycerate and ribose-5-phosphate and following the addition of these compounds during steady state conditions. Absolute levels of ATP were usually in the range 3.7 μmol ATP per g chlorophyll and the results of kinetic experiments are interpreted within the established concepts of photophosphorylation and the carbon reduction cycle. In experiments involving dark to light transitions in the absence of added bicarbonate, light to dark transitions in the presence of 3-phosphoglycerate and during photosynthesis in the presence of bicarbonate, 3-phosphoglycerate and ribose-5-phosphate rapid transient changes in ATP levels were observed.

Effect of 6-benzylaminopurine on ATP levels and Me− 14C incorporation into neutral and polar lipids during the release of dormant buds of Nicotiana tabacum

1. 1. This work was ddne to correlate changes in ATP levels with lipid metabolism during the breaking of vegetative dormancy of Nicotiana tabacum var. Maryland Catterton. 2. 2. 6-Benzylaminopurine-treated axillary buds contained higher levels of free ATP than the controls during the release of buds from dormancy. 3. 3. The rate of Me− 14C incorporation from methionine into polar and neutral lipids is enhanced by cytokinin between 6 and 18 h after bud treatment.

Thymidine Salvage Pathway in Normal and Leukemic Leukocytes with Effects of ATP on Enzyme Control

Abstract The enzymes of the "salvage" pathway for thymidine in normal and leukemic leukocytes separated on glass-bead-columns were studied. Levels of thymidine kinase activity in blast cells were high, but were low in granulocytes, normal and leukemic lymphocytes, and in RBC. Phosphatase and thymidine phosphorylase activity was high in granulocytes and in normal and leukemic lymphocytes, but became apparent in blast cells only in the absence of ATP. All the cells studied could phosphorylate TMP to some extent, but the amount of TTP formed depended greatly on the presence of an optimum ATP concentration. Without added ATP breakdown to thymine was at its peak, while phosphorylation of TMP was negligible. Excess ATP reduced or inhibited the activity of most of the enzymes, preventing both phosphorylation and breakdown. Concentrations of Mg equimolar with the ATP gave maximum TTP production, while inhibition by high ATP concentrations occurred despite equimolar Mg concentrations. Both TTP and thymine production ceased in the absence of Mg. Changes in ATP levels in cell loci may function in regulating thymidine metabolism.

Factors influencing the utilization of reduced nicotinamide adenine dinucleotide by pigeon heart mitochondria.

Pigeon heart mitochondria that were studied exhibited ADP:O and respiratory control ratios of 2.3–3.1 and 6–20 respectively with glutamate as substrate. This coupled respiration of glutamate was reversibly inhibited by ATP. In polarographic and photometric experiments at 28° in a medium containing 0.23 M mannitol, 0.07 M sucrose, 0.02 M Tris, and 0.02 mM EDTA at pH 7.2 such mitochondria oxidized 15–150 μM NADH with essentially zero order kinetics and an apparent Kmof approximately 4 μM. NADH oxidation, which was not coupled to phosphorylation, was increased 50% by the addition of 5 mM orthophosphate (Pi) but was inhibited by albumin, NAD, ATP, and ADP. The effect of NAD became marked only at concentrations of 2–5 mM. However, ATP in concentrations (5–10 mM) similar to those found in heart, inhibited by 50–75% the oxidation of physiological levels (~ 10 μM) of NADH. These and other findings are compatible with the view that the oxidation of cytoplasmic NADH is a normal property of heart mitochondria, and that the control of this process by changes in the intracellular levels of ATP and Pimay influence myocardial carbohydrate utilization.

Changes in the intracellular levels of ATP, ADP, AMP and P1 and regulatory function of the adenylate system in leaf cells during photosynthesis.

1. 1. Leaves were exposed to periods of light and dark, killed in liquid air and freeze-dried. The dry material was fractionated by a non-aqueous method into a chloroplastic and a residual fraction. These were analyzed for ATP, ADP, AMP, pyruvate and orthophosphate and for adenylate kinase (EC 2.7.4.3). 2. 2. The concentrations of the adenylates in chloroplasts vary between 1.5 · 10−4 and 5 · 10−4M. ATP shows a rapid increase in the light and a rapid decrease in the dark in both chloroplasts and cytoplasm. The changes in ADP are opposite to those in ATP. The changes in AMP are the same as those for ADP in Spinacia and Beta, while in Coleus an increase is observed even in the light. This may be explained by a low activity of adenylate kinase in Coleus and by high activities in Spinacia and Beta. Less than 50% of the adenylate kinase is located in the chloroplasts of the investigated species. 3. 3. The levels of inorganic phosphate in chloroplasts are relatively high (4 · 10t3 to 25 · 10−3M); they decrease rapidly in the light, sometimes by as much as 30% of the initial value, and increase slowly in a subsequent dark period. 4. 4. Pyruvate decreases in the light and increases in the dark. 5. 5. From the results it is concluded that the controlling factor in the inhibition of glycolysis and respiration by light is the increased ratio of ATP to ADP rather than a drop in the orthophosphate. 6. 6. Mass action ratios and the behaviour of AMP point to the existence of a photosynthetic reaction generating AMP.