ATP Values Research Articles

Effects of pH, temperature, and calcium concentration on the stoichiometry of the calcium pump of sarcoplasmic reticulum.

Coupling of Ca2+ transport to ATP hydrolysis by isolated skeletal muscle sarcoplasmic reticulum vesicles has been investigated by means of ATP pulse methods. The stoichiometric amounts of Ca2+ transported per pulse of ATP were measured by Ca2+-stat methods, using either a Ca2+ electrode or arsenazo III as end point detectors, or by means of 45CaCl2. Maximum coupling ratios (Ca2+/ATP), of 1.82 +/- 0.13 occurred at pH 6.8, 25 degrees C, and in the presence of saturating Ca2+ concentrations. Ca2+/ATP values decreased at alkaline pH, with an apparent pK alpha of 7.9. The coupling ratio was unaltered between 6 and 30 degrees C, but decreased to 0.4 at 42 degrees C. Uncoupling by alkaline pH and high temperatures was reversible. The coupling process was Ca2+-dependent, with a K0.5 value for Ca2+ of 0.12 microM and a Hill coefficient of 2.0. Ca2+ ions, which were transported into vesicles under conditions resulting in low coupling ratios, were retained as the calcium oxalate precipitate, following complete hydrolysis of substrate. Passive Ca2+ efflux and Ca2+ exchange, were independent of pH. The observed variations in Ca2+/ATP ratio cannot readily be explained on the basis of a pump-leak model. Rather, the Ca2+-ATPase appears to be capable of pumping Ca2+ ions, under physiological conditions, with variable stoichiometry that is dependent upon its thermodynamic loading.

Energy levels at systole vs. diastole in normal hamster hearts vs. myopathic hamster hearts.

The following studies were carried out to examine energy metabolites and cardiac performance of the failing heart (hereditary cardiomyopathy) of the Syrian hamster (strain UM-X7.1) perfused either by normal or stress conditions, and to determine whether cyclical changes in energy-related metabolites occurred in the glucose-perfused hearts of both normal and heart failure animals. Hamster hearts from 250-day-old animals with moderate heart failure were removed and perfused either as nonworking hearts (Langendorff method, an afterload pressure of 90 mm Hg and 2.5 mM calcium in the perfusate) or as working hearts with stress conditions [an afterload of 110 mm Hg, high calcium concentrations in the perfusate (3.5 mM), and 10(-8) M isoproterenol]. Mechanical parameters (developed pressure and max dP/dt) and measurements of oxygen consumption indicated that both contractility and oxygen consumption had fallen 50% in myopathic hearts, compared with those of normal hamsters perfused with either of the two conditions. By means of a specially designed stimulator-triggered freeze clamp, hearts were terminated at systole and diastole, and tissue content of ATP, ADP, AMP, adenosine, phosphocreatine, creatine, pyruvate, lactate, and inorganic phosphate were analyzed. A 50% reduction in cardiac performance of the cardiomyopathic hamster hearts was associated with a corresponding reduction in systolic ATP, adenosine, and phosphocreatine values, while inorganic phosphate and lactate increased. With glucose as the sole substrate, the high energy phosphates, ATP and phosphocreatine, reached maximum values during diastole and minimum values during systole.(ABSTRACT TRUNCATED AT 250 WORDS)

VARIABILITY IN RATIOS OF PHYTOPLANKTON CARBON AND RNA TO ATP AND CHLOROPHYLL A IN BATCH AND CONTINUOUS CULTURES1,2

ABSTRACTThe feasibility of estimating phytoplankton carbon and RNA concentrations from measurements of ATP and chlorophyll a (chl a) concentrations was studied using chemostat populations of the marine diatom Thalassiosira weissflogii (Grunow) Fryxell & Hasle (= T. fluviatilis Hustedt). C:ATP and RNA:ATP ratios were studied for six additional marine species in batch culture representing five classes of phytoplankton. Statistical analyses revealed that both the growth rate and the factor limiting growth (NO3‐, NH4+, PO43‐ or light) could alter C:ATP, RNA: ATP, C:chl a and RNA:chl a ratios by amounts which were large compared to measurement error. An analysis of variance of the batch culture results indicated that both species and the source of inorganic nitrogen (NO3‐, or NH4+) had a significant effect on C:ATP and RNA:ATP ratios. Light had less of an influence on C:ATP and RNA:ATP ratios than on C:chl a and RNA:chl a ratios, and for this reason we feel that phytoplankton C and RNA concentrations can be estimated with greater reliability from ATP than from chl a measurements. The range of C:ATP and RNA:ATP values found for T. weissflogii under a variety of growth conditions was similar to that for the six additional species grown in batch culture, suggesting that this range of values is indicative of the extremes likely to occur in living cells. Our results and additional data in the literature indicate that phytoplankton C and RNA concentrations can be estimated to within a factor of two by multiplying ATP concentrations by 311 and 35, respectively, in N limited systems, and by 341 and 36, respectively in PO43‐ limited systems.

ATP content of soils estimated by two contrasting extraction methods

The ATP content of a series of soils was investigated in relation to various soil properties. Special attention was paid to the discrepancy in ATP, as estimated after extracting with TEA/NRB and TCA. It appears that the first procedure particularly relates to active microbial cells but extracts rather poorly certain types of older microbial biomass. Nevertheless, the TEA/NRB ATP values correlate very significantly with total soil microbial biomass as determined by the CHCl 3 fumigation method. In soils with active growing microbial biomass, the TEA/NRB and the TCA ATP values are about equal. In normal equilibrated soils the TEA/NRB ATP levels average about 40% of the total soil ATP levels. Finally, in densely rooted soils, the TCA ATP levels surpass largely the TEA/NRB levels, but they appear to a major extent to be due to plant cells.

Cardiac synthesis and degradation of pyridine nucleotides and the level of energy-rich phosphates influenced by various precursors.

This chapter is concerned with the question of whether under normoxic and anoxic conditions the myocardial concentrations of pyridine nucleotides (NAD, NADP), adenine nucleotides (AN), and creatine phosphate (CP) can be influenced by addition of various precursors of these compounds to the perfusion solution in order to improve anoxic survival of cardiac cells. After i.p. injection of 10 mmol nicotinamide/kg guinea pig, a NAD level increased by 40–58% can be observed for a period of 12–24 hr, but there is no change in the AN and CP concentrations. In isolated atria of guinea pigs under normoxic conditions, the atrial concentration of NAD increases threefold over a 24-hr period if 10–20 mM nicotinamide is added to the Krebs-Henseleit solution with 15 mM glucose. Analysis of metabolites after incubation with 20 mM [14C]nicotinamide showed that this increase resulted from new synthesis of NAD by activation of the nicotinamidase that deamidates nicotinamide to nicotinic acid via the Preiss-Handler pathway. Simultaneously, the high concentration of nicotinamide inhibits the degradation of NAD by the glycohydrolase. However, a high concentration of nicotinamide also impairs the new synthesis of AN from adenine and ribose in the salvage pathway. The anoxic degradation of NAD could be protected, compared with controls, by this high nicotinamide concentration. After aerobic incubation with 10 μM [14C]nicotinamide, no deamidation to nicotinic acid could be observed, and a small but significant incorporation into NAD by the Dietrich pathway could be measured. This pathway is obviously located in the mitochondria. No increased NAD concentration could be observed, and in anoxia there was no protective effect. With 10 μM [14C]nicotinic acid, a twofold higher synthesis of [14C]-NAD could be observed than is seen with 10 μM [14C]nicotinamide. Here, the Preis s-Handler pathway was operating for NAD synthesis. The glycohydrolase was not inhibited as observed with 20 mM nicotinamide. The total NAD level increased by 42%. The degradation of [14C]-NAD to [14C]-nicotinamide (Nam) could be observed in atria as well after its penetration in the nutritive solution. [14C]Nicotinamide was also used for new synthesis of mitochondrial NAD via the Dietrich pathway. Therefore, we assume that the physiological precursor for cardiac NAD synthesis is nicotinic acid. Higher concentrations of nicotinic acid (50 μM) together with adenine and ribose significantly enhanced the total NAD level under aerobic conditions by 77%, ATP by 37%, and AN by 24% during a 24-hr period. Adenine (100 μM) and ribose (500 μM) increased the ATP and AN level in the same range under these conditions. Low concentrations of nicotinamide and nicotinic acid have little effect on the change of anoxic NAD concentration which is shifted to NADH or degraded. The anoxic loss of AN can be protected effectively only if the PRPP pool and the ATP pool have not been decreased to a great degree in the myocardial cell. Standstill before anoxic conditions are started or strongly reduced cardiac work (30 beats/min) in the anoxia test reported can save ATP by 70% through unrestricted anaerobic glycolysis during a 2-hr anoxic period, as compared with the aerobic values. In contrast, in spontaneously beating atria with a high frequency of 200 beats/min when anoxia was started, after 2 hr of anoxia the ATP level decreased strongly to 23%. The addition of adenine (100 μM) and ribose (500 μM) during anoxia produced only a weak but significant protective effect, whereas with higher anoxic ATP values in the anoxia test, the ATP and AN concentrations could be protected with concentrations of ribose (15 mM) and adenine (0.1 mM) comparable to the aerobic values. No protection of CP could be obtained by addition of CP(5–10 mM) or precursors during the 2-hr anoxic period. Therefore, strongly reduced contractile work or cardiac arrest before anoxic conditions are started, as most energy protective effect, may be beneficial for anoxic myocardial survival combined with addition of AN and NAD precursors to myocardial perfusion solutions during cardioplegia.KeywordsNicotinic AcidAdenine NucleoNicotinamide Adenine DinucleotidePyridine NucleotideAnoxic PeriodThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

On the relationship between rate of ATP synthesis and H+ electrochemical gradient in rat-liver mitochondria.

The relationship between rate of ATP synthesis, JATP, and value of the proton electrochemical gradient, delta mu H, has been analyzed in intact mitochondria. Onset of phosphorylation causes a depression of delta mu H of 1.5 kJ/mol. There is a close parallelism between inhibition of JATP and restoration of delta mu H to its state-4 value during titrations with oligomycin or atractyloside. Titrations with ionophores display the following features: (a) delta mu H can be depressed by 3-4 kJ/mol by valinomycin + K+ without affecting the rate of ATP synthesis; (b) uncouplers abolish JATP completely while depressing delta mu H by 3 kJ/mol; (c) complete abolition of ATP synthesis by inhibitors of electron transport is accompanied by a depression of delta mu H of only 1 kJ/mol. The results indicate that: (a) there is a close functional relationship between redox and ATPase H+ pumps, whereby inhibition of electron transfer is accompanied by simultaneous inhibition of the ATPase H+ pumps; and (b) uncoupling of oxidative phosphorylation is not due to depression of delta mu H per se. The consistence of the present data with either a chemiosmotic model where delta mu H is the sole and obligatory intermediate for energy coupling, or models where there is a direct transfer of energy between the two pumps is discussed.

Factors limiting regeneration of ATP following temporary ischemia in cat brain.

Cerebral ischemia was induced in cats using bilateral carotid artery occlusion coupled with hemorrhagic hypotension. Thirty minutes of ischemia, which depleted levels of ATP and phosphocreatine throughout the cerebral cortex, was followed by 2-4 hours of recirculation. During the recovery period, cortical perfusion and NADH fluorescence were monitored through a cranial window. Postischemic perfusion, as indicated by transit time, was initially higher than control, but declined to subnormal levels by 60 minutes. NADH fluorescence transients, induced by brief anoxia, also decreased steadily during recirculation, indicating a failure of oxidation-reduction capability. The disappearance of anoxic-NADH transients usually preceded the decline of flow, suggesting that O2 delivery was not the factor limiting redox reactions. Furthermore, tissue levels of NADH, which were nearly normal after 2-4 hours of recirculation, did not indicate tissue hypoxia. In spite of normalization of NADH, resynthesis of high energy phosphates were severely impaired. The degree of ATP recovery varied widely in different cortical regions; however, there were two general groups of ATP values--one at 5% and the other at 70% of control levels. In the energy-depleted areas, NADH levels were normal, but the total pool of NAD (NADH + NAD+) and the tissue content of K+ were 43% lower than control. In contrast, the NAD pool and K+ content were only slightly diminished in the regions with greater ATP restitution. The results suggest that postischemic resynthesis of ATP may be limited not by inadequate delivery of O2, but rather by defective production of NADH.

Primary oscillator of contractional rhythm in the plasmodium of Physarum polycephalum: Role of mitochondria.

Various inhibitors were microinjected into the cytoplasm of the plasmodium of Physarum polycephalum, and their effects were monitored by measurements of contractile activity, and the intracellular ATP and cytoplasm-ic Ca2+ concentrations. Fluoride and monoiodoacetate (glycolytic inhibitors) reduced the ATP by 50 %, but the contractional rhythm was unaffected. In contrast, azide and arsenate (respiratory inhibitors) and 2, 4-dinitrophenol (uncoupler) induced a transient decrease of 50 % in the ATP value and a 2-3-fold transient prolongation of the rhythm. A combined injection of glycolytic and respiratory inhibitors reduced the ATP to 10 % and led to complete ces-sation of the rhythm. P-chloromercuribenzoate (SH-blocking reagent) had similar effects as those of a respiratory inhibitor, but N-ethylmaleimide had no affect. Ruthenium red (inhibitor of mitochondrial Ca2+-uptake) did not affect the ATP value, but did bring about gradual prolongation of the rhythm accompanying an increase in the Ca2+ efflux into the cytoplasm.These results are evidence that the time-keeping of contractional rhythm inPhysarum plasmodium is related primarily to mitochondrial activity.

Blood flow and high-energy phosphates in microregions of left ventricular subendocardium.

Blood flow and high-energy phosphate (HEP) content were determined simultaneously in multiple microregions of left ventricular subendocardium in 29 normal anesthetized open-chest rabbits by use of a new micromethod to determine whether a direct linear relationship existed between these parameters. Tissue samples weighed 1-2 mg. ATP and creatine phosphate (CP) content were quantitated in quick-frozen hearts by fluorometry at sites where tissue perfusion was measured by H2 clearance by use of bare-tipped platinum electrodes. A series of validation studies were conducted to ensure that 1) no significant damage to the tissue surrounding the electrode occurred during the period of experimentation and 2) no significant loss of biochemical constituents had occurred due to labile processes during freezing or storage of the tissue. Blood flow, ATP, and CP values averaged 79.1 +/- 24.1 (SD) ml.min-1.100 g-1, 4.9 +/- 1.3 mumol/g tissue, and 8.0 +/- 3.0 mumol/g tissue, respectively, and are similar to those reported in studies using larger tissue samples. Correlation between the heterogeneous distribution of tissue perfusion and HEP revealed no direct linear relationship between these parameters in the normal unstressed rabbit subendocardium.

Brain energy metabolism in mice exposed to oxygen at 1 atmosphere absolute.

Breathing of 100% oxygen at ambient pressure causes disorders in mouse brain organic phosphate phosphocreatine (PC), ATP, ADP, and AMP. The fast increase in PC level attains a maximum augmentation of about 50% after 16-18 h of exposure with subsequent slight alterations between 18 and 50 h. The initial losses (a) in ATP amount to approximately 20% after 4 h; (b) in ADP, 32% after 6-8 h; and (c) in AMP, about 40% after 30 min and 50% after 50 h. contrary to the continual decrease in AMP, the ATP and ADP values exhibit a later increase to a constant level during the full time of exposure up to 50 h. The initial loss in adenosine nucleotides points to an intense effect of hyperoxia in nerve cell metabolism with subsequent attainment of a new adenylate equilibrium at lower concentrations. The increased but constant level of PC may be due to an inhibition of the oxygen sensitive SH-groups, which are an essential center in the creatine kinase. Although the absolute concentration of AMP is by far the lowest of the three nucleotides, the continual decrease in AMP is of considerable importance because of its direct response to ATP via adenylate kinase reaction.

The Metabolism of Purine and Pyrimidine Nucleotides in Rat Cortex During Insulin‐Induced Hypoglycemia and Recovery

Brains of paralysed rats with insulin-induced hypoglycemia were frozen in situ after spontaneous EEG activity had been absent for 5 or 15 min ("coma"). Recovery (30 min) was achieved in a different group of rats by administering glucose after a 30-min coma period. Purine and pyrimidine nucleotides, nucleosides and free bases were determined in the cortical extracts by high pressure liquid chromatography (HPLC). The ATP values obtained with the HPLC method were in excellent agreement with those obtained using standard enzymatic/fluorometric techniques, while values for ADP and AMP obtained with the HPLC method were significantly lower. Comatose animals showed a severe (40-80%) reduction in the concentrations of all nucleoside triphosphates (ATP, GTP, UTP and CTP) and a simultaneous increase in the concentrations of all nucleoside di- and monophosphates, including that of IMP. The adenine nucleotide pool size decreased to 50% of control level. The concentrations of the nucleosides adenosine, inosine, and uridine increased 50- to 250-fold, while the concentrations of the purine bases, xanthine and hypoxanthine, rose 2- and 30-fold, respectively. There were no increases in the concentrations of adenine, guanine, or xanthosine. Following glucose administration there was a partial (ATP, UTP and CTP) or almost complete (GTP) recovery of the nucleoside triphosphate levels. During recovery, the levels of nucleoside di- and monophosphates and of adenosine decreased to values close to control; the rise in the inosine level was only partially reversed, and the concentrations of hypoxanthine and xanthine rose further. The adenine nucleotide pool size was only partially restored (to 67% of control value). The adenine nucleotide pool size was not increased by i.p. injection of adenosine or adenine under control condition, or during the posthypoglycemic recovery period.

Metabolism of Oat Leaves during Senescence

The ATP content of 7-day-old Avena sativa leaves during senescence in dark and in light, and after treatment with cytokinins and other reagents, has been determined by the luciferin-luciferase method. Special care was taken to avoid decomposition of the ATP, and a detailed procedure is presented for ATP analysis at the picomole level. Preliminary experiments with several inhibitors of photophosphorylation suggest, though not conclusively, that the delaying effect of light on senescence is mediated by photophosphorylation. The ATP values of the leaves senescing in darkness are found to increase in parallel with the large increase in respiratory rate, and kinetin prevents this increase just as completely as it prevents the respiratory rise. It is concluded that the respiratory increase in senescence cannot be simply due to uncoupling. In light the ATP level also rises, though more slowly, and again kinetin prevents this rise. l-Serine, which promotes dark senescence, does not significantly modify the dark ATP level, but both arginine and kinetin, which antagonize the action of serine on senescence, greatly lower the ATP level below that on serine alone. Cycloheximide has a similar effect, and the combination of cycloheximide and kinetin lowers the ATP level drastically. Fusicoccin, which opens stomata in the dark, correspondingly maintains the ATP at a low level. Thus, in general, a low level of ATP is associated with the prevention of dark senescence, i.e. probably with ATP utilization, and the ATP level at any time may thus be determined more by the rate of utilization than by the efficiency of respiratory coupling.

Regulation of Cellular Metabolism During Synthesis and Expression of the Luminous System in Beneckea and Photobacterium

Parameters of cellular energetics (ATP pools, adenylate energy charge, GTP pools and oxygen consumption) as well as bioluminescence and growth have been examined in batch cultures of four different species of luminous bacteria. The findings indicate that all of these energetic parameters remain constant throughout the growth cycle while bioluminescence is induced and increases many fold. These observations hold true for very bright strains during their dim and bright phases of growth, as well as for a luminescence-conditional strain under bright or dark conditions. The percentage of the total oxygen consumption that was due to bioluminescence was shown to vary by as much as a factor of 103 during growth. For very bright cells, the oxygen consumption experiments suggest both that the energetic requirements of the bioluminescent system are significant, and that the quantum efficiency (Q o2 ) of the luciferase in vivo is quite high, possibly approaching 10. Similar considerations based on ATP pool size and energetic estimates of luminescence indicate that the luminous system in bright cells represents a small but possibly significant energy drain. Finally, two methodological features are discussed. First, it was shown that extracts of cells that have been grown in media devoid of inorganic phosphate contain a heat-stable ATPase activity, which can lead to falsely low ATP values. Second, it was shown that the interfering effect of GTP on the assay of ATP could be completely overcome by the addition of GDP to the assay mixture.

Blood preservation. XXIX. Pyruvate maintains normal red cell 2,3-DPG for six weeks of storage in CPD-adenine.

Pyruvate was placed in experimental CPD-adenine (0.25 mM) blood preservative mixtures in four concentrations ranging from 40 to 320 mM. In the 320 mM pyruvate preservative, 2,3-DPG levels were elevated above normal for six weeks of whole blood storage at 4 C. The lower pyruvate concentrations maintained elevated or normal 2,3-DPG levels for less time: four weeks with 160 mM, two weeks with 80 mM, and one week or less with 40 mM or the control. ATP values were best maintained in the control. The higher pyruvate concentrations resulted in the most rapid decreases at ATP. However, even the 320 mM pyruvate did not cause ATP to fall below 2 microM/gm of Hb. The higher pyruvate concentrations produced and maintained a higher pH during storage. On the other hand, 2,3-DPG levels increased with pyruvate during the first week of storage when the pH was decreasing rapidly. This could be the result of its oxidation of NADH to NAD. The high pyruvate concentration which maintained elevated 2,3-DPG levels throughout the six weeks might be simulating the effect reported in pyruvate kinase-deficient red blood cells, in which blockage of glycolysis at that step is preventing 2,3-DPG catabolism.

Brain energy metabolism in dogs following artificial embolization in the cerebral arteries (author's transl)

Regional cerebral ischemia was induced in dogs by injecting a silicone rubber cylinder through the cervical internal carotid artery. The embolus was found to be lodged in the proximal portion of the middle cerebral artery in 33 dogs, distal portion of the middle cerebral artery in seven dogs, anterior cerebral artery in 11 dogs, posterior communicating artery in three dogs and osseous portion of the internal carotid artery in five dogs. Cerebral ATP and lactate and protein concentrations were quantitatively analysed in the parietal lobe, temporal lobe and basal ganglia of both the embolized and non-embolized hemispheres of each group. Relationships between the neurological signs and the changes in regional brain energy metabolism of each group were studied. In the group in which the embolus was lodged in the proximal portion of the middle cerebral artery, ATP depletion and lactate accumulation were most predominant in the basal ganglia of the embolized hemisphere. Disturbed consciousness and hemiparesis were observed. In the group in which the embolus was lodged in the distal portion of the middle cerebral artery, ATP depletion was evident only in the temporal lobe of the embolized hemisphere. Hemianopsia was observed in two of the three animals. In the group in which the embolus was lodged in the anterior cerebral artery, no neurological defect could be observed except in one animal showing disturbed consciousness and hemiparesis. This animal showed ATP depletion in the basal ganglia of the embolized hemisphere probably caused by obstruction of the perforating arterial branches from the anterior cerebral artery. In the group in which the embolus was lodged in the posterior communicating artery, protein concentration was decreased remarkably at all sites in the embolized hemisphere. It was considered to be acute brain swelling. Animals were comatose, and one of them died 3 hours after embolization. It was suggested that hypothalamus or posterior thalamus, the territory of the posterior communicating artery, might play an important role in causing acute brain swelling. In the group in which embolus was lodged in the osseous portion of the internal carotid artery, no neurological defect nor any change in energy metabolism could be seen. Regional energy metabolism was analysed 1, 3, 5, 12, 24 hours after embolization of the proximal middle cerebral artery. ATP levels in the basal ganglia of the embolized hemisphere which is the ischemic focus of this group decreased linearly up to 5 hours after embolization but were restored to the resting level 12 hours after embolization and were depleted again 24 hours after embolization. The transient restoration of the ATP values probably occurred because ischemic cell damage first took place at the site of ATP consumption such as a synapse rather than at the mitochondria where ATP was synthesized.

Adenosine 5′-Triphosphate Flux Through the North Inlet Marsh System

The distribution, fluctuation, and short-term transport of total microbial biomass (measured as adenosine 5'-triphosphate [ATP]) was investigated in a large salt marsh creek. Hourly samples were collected synoptically for 25 h from 10 boats positioned across the 320-m width of the creek. Samples were collected from three depths ranging from 0.2 to 8.0 m. Hourly data obtained from each station were graphed, plotting depth against ATP. Subsequently, interpolated ATP values were generated for every one-tenth depth from the surface to the bottom with the use of an 11-point proportional divider. A total of 2,750 values were generated, and a mean value of 0.865 mg of ATP per m was determined. Maximum levels of ATP were found at high tide and minimal values were found at low tide. The distribution of ATP concentrations was found to be complex, with no suggestion of vertical stratification; however, horizontal divisions were apparent. ATP values corrected for direction of flow or velocity indicated two ebb-directed channels; however, when considered in total, there was a net import of ATP through the interface. The total import of ATP for this 25-h sampling period was calculated to be 3.58 kg, corresponding to a net transport of 39.8 mg of ATP per s through the cross section. Results suggest that detailed characterization of a creek transect in terms of ATP or any similar parameter requires the simultaneous measurements of both the concentration of the parameter in question and the velocity at the time and point from which the sample was taken.

Chemical composition of cholinergic synaptic vesicles from Torpedo marmorata based on improved purification.

Cholinergic synaptic vesicles from the electric organ of Torpedo marmorata have been purified to a constant composition and a higher transmitter content than previously reported. By optimising the extraction conditions and using a two-step purification on discontinuous and continuous sucrose density gradients, 10-fold higher acetylcholine and ATP values per weight of protein were obtained. The purity of the vesicle preparation was confirmed by electronmicroscopy, absence of marker enzymes, behaviour in density gradient centrifugation, as well as by a specific and reproducible protein composition. Vesicles contain 6.9 mumol acetylcholine and 1.0 mumol ATP per mg protein. The lipid/protein ratio of 3.5 (w/w) indicates a lipid-rich membrane. The value suggests the absence of a proteinaceous core. Upon dodecylsulphate gel electrophoresis a distinct protein pattern is obtained with components ranging from 20000 to 160000 in molecular weight. Vesiculin, reported earlier to be a low-molecular-weight vesicle protein, is not detected. One of the major bands comigrates with muscle actin from the same animal. Further characterisation of this protein by two-dimensional gel electrophoresis suggested that it is an actin-like polypeptide. Evidence for a specific association of this actin-like protein with vesicles and its possible involvement in the neurosecretory process is discussed.

Occurrence and Ecological Significance of GTP in the Ocean and in Microbial Cells

A comparison between the ATP concentrations based on peak height light emission values (0 to 3 s) and integrated light flux determinations (15 to 75 s) for a variety of seawater samples revealed that the integrated method of light detection consistently yielded higher ATP concentrations, ranging from 1.38 to 2.35 times larger than the corresponding peak ATP values. A significant correlation (r = 0.923) was observed for a plot of DeltaADP (i.e., integrated ATP - peak ATP) versus GTP + UTP, suggesting that the analytical interference on the ATP assay was the result of the presence of non-adenine nucleotide triphosphates. Size-fractionation studies revealed an enrichment of the non-adenine nucleotide triphosphates, relative to ATP, in the smallest size fraction analyzed (<10 mum). Investigations were conducted with 20 species of unicellular marine algae to determine their intracellular nucleotide concentrations, and these determinations were compared to the levels measured in lab cultures of the marine bacterium Serratia marinorubra. These results indicated that the intracellular GTP/ATP ratios in S. marinorubra increase in direct proportion to the rate of cell growth, and that the GTP/ATP ratios in bacteria are much greater than in growing algae, presumably due to the differences in rates of cellular biosynthesis. It is concluded that quantitative determinations of GTP/ATP ratios in environmental sample extracts may be useful for measuring microbial growth.

Blood preservation XXVI, CPD-adenine packed cells: benefits of increasing the glucose.

In searching for the optimal glucose concentration, this lab has monitored ATP, 2,3-DPG, pH, and glucose levels of samples taken from full blood units stored for 6 weeks at 4 C. The blood was collected into CPD-adenine containing 100, 125, 150, 175, and 200 per cent of the glucose present in CPD. The units were stored as whole blood, soft packed (50 to 70% Hct), or hard packed units (80 to 95% Hct). ATP values in general did not decrease very greatly in whole blood units and only moderately in soft packed units. However, in hard packed units a steady progressive decrease in the ATP values was seen to begin at day 14. In these hard-packed units the only improvement with extra glucose was seen beginning at day 14 when ATP maintenance was better with 200 per cent glucose, but the improvement was not significant until day 42. However, at 35 days the ATP values for 200 and 175 per cent glucose were noticeably better than for the other preservatives. Therefore, it appears from this study that the glucose concentration in CPD-adenine for hard-packed cells should be at least 175 per cent of that in regularly formulated CPD. Also, there would appear to be an advantage of having 200 per cent glucose in those units of blood that may be stored beyond 35 days for emergency blood shortage times.

The adenosine triphosphate content of some marine bivalve molluscs

The total ATP-content of representatives of 23 bivalve families was found to vary from 1.26–0.26 % of the dry tissue weight, with the dry tissue containing about 40 % carbon. Representatives from certain families consistently had more than average and others less than average ATP values, and there were greater differences between species from different families than between closely related species. Variations in the oxygen uptake of whole animals accounted for little of the observed variation in ATP-content. The ATP-content of individual tissues from the same individual showed wide variation, as did that of the same tissue from different species. The highest values of ATP were found in muscle tissues. High maintained levels of ATP were associated with the ability of the species to use energy rapidly for short periods, for example, in escape responses.