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1.
Abstract: Hypoxia impairs brain function by incompletely defined mechanisms. Mild hypoxia, which impairs memory and judgment, decreases acetylcholine (ACh) synthesis, but not the levels of ATP or the adenylate energy charge. However, the effects of mild hypoxia on the synthesis of the glucosederived amino acids [alanine, aspartate, γ-amino butyric acid (GABA), glutamate, glutamine, and serine] have not been characterized. Thus, we examined the incorporation of [U-14C]glucose into these amino acids and ACh during anemic hypoxia (injection of NaNO2), hypoxic hypoxia (15 or 10% O2), and hypoxic hypoxia plus hypercarbia (15 or 10% O2 with 5% CO2). In general, the synthesis of the amino acids and of ACh declined in parallel with each type of hypoxia we studied. For example, anemic hypoxia (75 mg/kg of NaNO2) decreased the incorporation of [U-14C]glucose into the amino acids and into ACh similarly. [Percent inhibition: ACh (57.4), alanine (34.4), aspartate (49.2), GABA (61.9). glutamine (59.2), glutamate (51.0), and serine (36.7)]. A comparison of several levels (37.5, 75, 150, 225 mg/kg of NaNO2) of anemic hypoxia showed a parallel decrease in the flux of glucose into ACh and into the amino acids whose synthesis depends on mitochondrial oxidation: GABA (r= 0.98), glutamate (r= 0.99), aspartate (r= 0.96), and glutamine (r= 0.97). The synthesis of the amino acids not dependent on mitochondrial oxidation did not correlate as well with changes in ACh metabolism: serine (r= 0.68) and alanine (r= 0.76). The decreases in glucose incorporation into ACh and into the amino acids with hypoxic hypoxia (15% or 10% O2) or hypoxic hypoxia with 5% CO2 were very similar to those with the two lowest levels of anemic hypoxia. Thus, any explanation of the brain's sensitivity to a decrease in oxygen availability must include the alterations in the metabolism of the amino acid neurotransmitters as well as ACh. 相似文献
2.
In order to elucidate changes accompanying mild cerebral hypoxia, the synthesis of the neurotransmitter acetylcholine and the concentrations of cyclic AMP and cyclic GMP have been compared to changes in brain lactate in the forebrain of mice made mildly hypoxic. Both histotoxic hypoxia (injection of KCN) and anemic hypoxia (injection of NaNO2) were studied. Acetylcholine synthesis was followed by a double-label technique using [U-14C] glucose and [2H4] choline. A 43%, decrease in the synthesis of acetylcholine from [U-14C]glucose and an 80% increase of the level of cyclic GMP accompanied hypoxia so mild that there were no significant changes in cerebral lactate, or in cyclic AMP (or in AMP: Gibson & Blass , 1976b). Changes in glucose utilization do not account for the decrease in glucose incorporation into acetylcholine. Glucose utilization decreases and then increases with increasing hypoxia, whereas incorporation into acetylcholine decreased with increased hypoxia. 相似文献
3.
Joanna Strosznajder 《Neurochemical research》1980,5(12):1265-1277
In the presence of ATP, Mg, and CoA-SH[1-14C]linoleic acid was incorporated into membrane phospholipids (P2 fraction and synaptosomes) prepared from rat brain cortex. The relative order for linoleate incorporation was: phosphatidylcholine >phosphatidylethanolamine>phosphatidylinositol>ethanolamine plasmalogen >phosphatidylserine. The incorporation of labeled linoleate into P2 fraction phospholipids was investigated in rats, aged 4, 16, and 90 days, after being subjected to ischemic and hypoxic conditions. With the exception of a small increase in the incorporation of the radioactivity into diacyl-GPC, little change in incorporation profile was observed with 4-day-old rats submitted to ischemic and hypoxic conditions. However, the incorporation of labeled linoleate into membrane phospholipids was decreased in 16-and 90-day-old rats after being subjected to ischemic and hypoxic conditions. Among the phospholipids, the decrease in incorporation of radioactivity was most prominent with ethanolamine plasmalogens and phosphatidylinositol although the radioactivity of phosphatidylcholine seemed to remain relatively constant. The decreased incorporation activity in these two age groups was noted along with concomitant increase in the FFA content, whereas an increase in FFA was not observed in the 4-day-old brain samples. Thus, the specific decrease in labeling of ethanolamine plasmalogens and phosphatidylinositol may be the result of increased enzymic degradation of these compounds after ischemic and hypoxic treatment. Furthermore, the decrease in incorporation of linoleate into membrane phospholipids may be due to an increase in the membrane, FFA pool which subsequently, gave a dilution of the labeled precursor. 相似文献
4.
The effect of mild hypoxic hypoxia on brain metabolism and acetylcholine synthesis was studied in awake, restrained rats. Since many studies of hypoxia are done with animals anesthetized with nitrous oxide (N2O), the effects of N2O were evaluated. N2O (70%) increased the cerebral cortical blood flow by 33% and the cortical metabolic rate of oxygen by 26%. In addition, the synthesis of acetylcholine in N2O-anesthetized animals, measured with [U-14C]glucose and [1-2H2,2-2H2]choline, decreased by 45 and 53%, respectively. Consequently, mild hypoxia was studied in unanesthetized rats. Control rats breathing 30% O2 (partial pressure of oxygen, Pao2= 120 mm Hg) were compared with rats exposed to 15% O2 (Pao2= 57 mm Hg) or 10% O2 (Pao2= 42 mm Hg). The synthesis of acetylcholine, measured with [U-14C]glucose, was decreased by 35 and 54% with 15% O2 and 10% O2 respectively; acetylcholine synthesis, measured with [1-2H2,2-2H2]choline, was decreased by 50 and 68% with 15% O2 and 10% O2 respectively. Animals breathing either 15% or 10% O2 had normal cerebral metabolic rates of oxygen but had increased brain lactates and increased cortical blood flows compared with animals breathing 30% O2. These results show that even mild hypoxic hypoxia impairs acetylcholine synthesis, which in turn may account for the early symptoms of brain dysfunction associated with hypoxia. 相似文献
5.
Effects of acute hypoxia on incorporation of [1-14C]arachidonic acid into glycerolipids of rat brain
The effects of 1 min of acute hypoxic treatment (1% O2 in N2) on incorporation of [1-14C]arachidonic acid into brain lipids of 16-day-old rats were investigated at 3, 6, and 12 min after intracerebral injection of the labeled fatty acid. The hypoxic-hypoxia condition associated with convulsive seizures caused a decrease in the conversion of labeled arachidonate to its acyl-CoA as well as incorporation of the label into the brain phospholipids. Among the phospholipids, there was a specific decrease in the labeling of diacylglycerophosphoinositol (GPI), and this change was accompanied by an increase in labeling of the diacylglycerols. These results indicate that metabolism of the long-chain fatty acids and some glycero-lipids in brain are vulnerable to acute hypoxic treatment. 相似文献
6.
Konstantin Yu Kulichikhin Tamara V Chirkova Kurt V Fagerstedt 《Plant signaling & behavior》2008,3(4):240-242
The influence of anoxia and hypoxia on dynamic of intracellurar pH and ATP content in rice and wheat root tips was investigated with 31P-NMR spectroscopy. Both cereals responded to hypoxia similarly, by rapid cytoplasmic acidification (from pH 7.6–7.7 to 7.1), which was followed by slow partial recovery (0.3 units). Anoxia led to a dramatic pHcyt drop in tissues of both species (from pH 7.6–7.7 to less than 7.0) and partial recovery took place in rice only. In wheat, the acidification continued to pH 6.8 after 6 h of exposure. Anoxic wheat root tips were deficient in ADH induction, whereas increased activity of alcoholic fermentation enzymes took place in anoxic rice root tips, as well as in both species after hypoxic treatment. In both plants, NTP content followed the dynamics of pHcyt. There was a strong correlation between NTP content and cytoplasmic H+ activity ([H+]cyt = 10−pHcyt) for both hypoxic and anoxic conditions. In this addendum we want to focus the reader''s attention on the importance of adequate experimental design when hypoxia is under investigation and on some further perspectives of intracellular pH regulation in plants under anaerobic conditions.Key words: anoxia, hypoxia, rice, wheat, cytoplasmic pH regulation 相似文献
7.
Supply and partitioning of assimilates to roots of Medicago sativa L. and Lotus corniculatus L. under anoxia 总被引:3,自引:0,他引:3
A. L. BARTA 《Plant, cell & environment》1987,10(2):151-156
Abstract A current explanation of the mechanism of flooding injury to roots suggests that oxygen deficiency depresses the supply of respirable carbohydrates sufficiently to inhibit fermentation. However, even though it has been shown that phloem transport of assimilate is sharply reduced to anaerobic roots, inhibition of assimilate metabolism has also been suggested to be an important factor. This study examines these hypotheses by relating assimilate supply and metabolic activity in anoxic roots of alfalfa (Medicago sativa L.), a flood-intolerant species, and birdsfoot trefoil (Lotus corniculatus L.), a flood-tolerant plant. Roots were made anoxic (severe O2 deficiency) for 2, 4 or 6 d and shoots were labelled with 14CO2. Assimilate transport to the roots and metabolism to structural components were significantly decreased in both species in response to anoxia. Trefoil exhibited significantly greater 14C incorporation into the residue fraction at 4 d anoxia than did alfalfa, and this was consistent with the greater flooding tolerance of trefoil. When assimilate supply to O2-deficient roots was decreased by shoot shading, shoot fresh weight was reduced by both anoxia and light treatments. Root-soluble sugars were significantly decreased by shading but were greatly increased in response to anoxia. Root starch concentration also increased under anoxia. Root K+ concentration was reduced by anoxia only. The energy status (ATP/ADP) of roots was significantly decreased by shading; however, anoxia reduced the energy status only in unshaded plants. The data indicate that carbohydrate supply to anaerobic roots does not appear to be a limiting factor in the metabolic response of alfalfa roots. Alternatively, metabolism of assimilate in anoxic roots may be an important determinant of survival. 相似文献
8.
Hypoxia in neonates can lead to biochemical and molecular alterations mediated through changes in neurotransmitters resulting
in permanent damage to brain. In this study, we evaluated the changes in the receptor status of GABAA in the cerebral cortex and brainstem of hypoxic neonatal rats and hypoxic rats supplemented with glucose and oxygen using
binding assays and gene expression of GABAAα1 and GABAAγ5. In the cerebral cortex and brainstem of hypoxic neonatal rats, a significant decrease in GABAA receptors was observed, which accounts for the respiratory inhibition. Hypoxic rats supplemented with glucose alone and with
glucose and oxygen showed a reversal of the GABAA receptors, andGABAAα1 and GABAAγ5 gene expression to control. Glucose acts as an immediate energy source thereby reducing the ATP-depletion-induced increase
in GABA and oxygenation, which helps in encountering anoxia. Resuscitation with oxygen alone was less effective in reversing
the receptor alterations. Thus, the results of this study suggest that reduction in the GABAA receptors functional regulation during hypoxia plays an important role in mediating the brain damage. Glucose alone and glucose
and oxygen supplementation to hypoxic neonatal rats helps in protecting the brain from severe hypoxic damage. 相似文献
9.
10.
Isabelle Lardon Marleen Eyckmans Trung Nghia Vu Kris Laukens Gudrun De Boeck Roger Dommisse 《Metabolomics : Official journal of the Metabolomic Society》2013,9(6):1216-1227
All 20.000 different fish species vary greatly in their ability to tolerate and survive fluctuating oxygen concentrations in the water. Especially fish of the genus Carassius, e.g. the crucian carp and the goldfish, exhibit a remarkable tolerance to limited/absent oxygen concentrations. The metabolic changes of anoxia-tolerant crucian carp were recently studied and published. Contrary to crucian carp, the hypoxia-tolerant common carp cannot survive a complete lack of oxygen (anoxia). Therefore, we studied the 1H-NMR-based metabolomics of brain, heart, liver and white muscle extracts of common carp, subjected to anoxia (0 mg O2 l?1) and hypoxia (0.9 mg O2 l?1) at 5 °C. Specifically, fish were exposed to normoxia (i.e. 9 mg O2 l?1; controls 24 h, 1 week and 2 weeks), acute hypoxia (24 h), chronic hypoxia (1 week) and chronic hypoxia (1 week) with normoxic reoxygenation (1 week). Additionally, we also investigated the metabolic responses of fish to anoxia for 2 h. Both anoxia and hypoxia significantly changed the tissue levels of standard energy metabolites as lactate, glycogen, ATP/ADP and phosphocreatine. Remarkably, anoxia induced increased lactate levels in all tissues except for the heart whereas hypoxia resulted in decreased lactate concentrations in all tissues except for brains. Furthermore, hypoxia and anoxia influenced amino acids (alanine, valine/(iso)leucine) and neurotransmitters levels (GABA, glutamate). Lastly, we also detected ‘other’ i.e. previously not reported compounds to play a role in the present context. Scyllo-inositol levels changed significantly in heart, liver and muscle, providing novel insights into the anoxia/hypoxic responses of the common carp. 相似文献
11.
12.
Lupine seedlings were exposed to 4 kPa partial pressure oxygen (hypoxically pretreated) for 18 hours before treatment with
strictly anaerobic conditions (anoxia). Seedlings previously exposed to hypoxia were more tolerant than the controls (not
hypoxically pretreated) to anoxic stress in both roots and shoots. Hypoxic pretreatment induced roots and shoots survival
in anoxia. Improved viability of roots, following hypoxic pretreatment, was associated with increased activity of ADH. In
nonacclimated roots and shots significant increase in LDH activity occurd during the first hours under anoxia but the in vitro activity of LDH was two orders of magnitude lower than that of ADH. The results are discussed in relation to the ability
of lupine seedlings to survive anoxia. 相似文献
13.
J. van Waversveld A. D. F. Addink G. van den Thillart 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(3):263-268
Summary The energy flow of the anaerobic metabolism of glodfish at 20°C during hypoxia and anoxia was studied by simultaneous direct and indirect calorimetry. During anoxia the heat production as determined by direct calorimetry (180 J · h–1 · kg–0.85) is reduced to 30% of the normoxic level (570 J · h–1 · kg–0.85), which is the same reduction as found previously. The patterns of substrate utilization are compared with previous results, where the anoxic pattern was established by simultaneous calorimetry without carbon dioxide measurements. The present results, which do include carbon dioxide measurements, show the same pattern: carbohydrate and protein as substrates and carbon dioxide, ethanol and fat as end products. The pattern of substrate utilization at low oxygen levels is a combination of the anoxic pattern with an aerobic component. During anoxia only 5% of the metabolizable energy is used for energy metabolism. Of the remaining part (metabolizable energy for production) 60% is converted into ethanol and 40% into fat. At two hypoxia levels the distribution of the metabolizable energy for production into ethanol and fat is the same. 相似文献
14.
The physiological role of the mitochondrial ATP synthase complex is to generate ATP through oxidative phosphorylation. Indeed, the enzyme can reverse its activity and hydrolyze ATP under ischemic conditions, as shown in isolated mitochondria and in mammalian heart and liver. However, what occurs when cancer cells experience hypoxia or anoxia has not been well explored. In the present study, we investigated the bioenergetics of cancer cells under hypoxic/anoxic conditions with particular emphasis on ATP synthase, and the conditions driving it to work in reverse. In this context, we further examined the role exerted by its endogenous inhibitor factor, IF1, that it is overexpressed in cancer cells. Metabolic and bioenergetic analysis of cancer cells exposed to severe hypoxia (down to 0.1% O2) unexpectedly showed that Δψm is preserved independently of the presence of IF1 and that ATP synthase still phosphorylates ADP though at a much lower rate than in normoxia. However, when we induced an anoxia-mimicking condition by collapsing ΔμΗ+ with the FCCP uncoupler, the IF1-silenced clones only reversed the ATP synthase activity hydrolyzing ATP in order to reconstitute the electrochemical proton gradient. Notably, in cancer cells IF1 overexpression fully prevents ATP synthase hydrolytic activity activation under uncoupling conditions. Therefore, our results suggest that IF1 overexpression promotes cancer cells survival under temporary anoxic conditions by preserving cellular ATP despite mitochondria dysfunction. 相似文献
15.
Aquatic plants frequently encounter multiple stresses under natural conditions. Nuttall's water weed, Elodea nuttallii (Planch.) is a submerged aquatic macrophyte which has flexible ability to use different nutrient sources from various environments. However, recently the growth of E. nuttallii has been declining in waters of Japan and in the Chesapeake Bay, a large estuary in the United States. In the present experiment, we studied growth and survival capabilities of the plant under a gradient of redox conditions; from highly oxic (+400 to +440 mV) to extremely reduced (−180 to −120 mV) conditions. Reduced environment was prepared by adding glucose to growth medium and nitrogen gas bubbling, while the oxic environment was brought about by atmospheric air bubbling. In comparison to the oxic environment, growth rate and carbon–nitrogen content of the plants were significantly affected negatively at hypoxic and anoxic conditions. In hypoxic and anoxic environments, indole acetic acid (IAA), tissue nitrogen and chlorophyll levels were down-regulated, whereas hydrogen peroxide (H2O2), indole acetic acid oxidase (IAAO) and peroxidase (POD) levels were up-regulated. It was also found that high NH4–N concentrations (10–40 ppm) affect the growth rate and biochemical parameters of the plant; however, in hypoxic and anoxic treatments the effects were more severe. We conclude that E. nuttallii is poorly tolerant to hypoxia/anoxia. Moreover, oxygen stress combined with high ammonium concentration act as important factors influencing distribution and abundance of this species. 相似文献
16.
Thoppil R Anju Sadanandan Jayanarayanan Cheramadatikudiyil S Paulose 《Journal of biomedical science》2011,18(1):31
Background-
Hypoxia during the first week of life can induce neuronal death in vulnerable brain regions usually associated with an impairment of cognitive function that can be detected later in life. The neurobiological changes mediated through neurotransmitters and other signaling molecules associated with neonatal hypoxia are an important aspect in establishing a proper neonatal care.Methods-
The present study evaluated total GABA, GABAB receptor alterations, gene expression changes in GABAB receptor and glutamate decarboxylase in the cerebellum and brain stem of hypoxic neonatal rats and the resuscitation groups with glucose, oxygen and epinephrine. Radiolabelled GABA and baclofen were used for receptor studies of GABA and GABAB receptors respectively and Real Time PCR analysis using specific probes for GABAB receptor and GAD mRNA was done for gene expression studies.Results-
The adaptive response of the body to hypoxic stress resulted in a reduction in total GABA and GABAB receptors along with decreased GABAB receptor and GAD gene expression in the cerebellum and brain stem. Hypoxic rats supplemented with glucose alone and with oxygen showed a reversal of the receptor alterations and changes in GAD. Resuscitation with oxygen alone and epinephrine was less effective in reversing the receptor alterations.Conclusions-
Being a source of immediate energy, glucose can reduce the ATP-depletion-induced changes in GABA and oxygenation, which helps in encountering hypoxia. The present study suggests that reduction in the GABAB receptors functional regulation during hypoxia plays an important role in central nervous system damage. Resuscitation with glucose alone and glucose and oxygen to hypoxic neonatal rats helps in protecting the brain from severe hypoxic damage. 相似文献17.
It is now well documented that apoptosis represents the prevalent mode of cell death in hybridoma cultures. Apoptotic or programmed cell death occurs spontaneously in late exponential phase of batch cultures. Until lately, no specific triggering factors had been identified. Recently, we observed that glutamine, cystine or glucose deprivation induced apoptosis in both hybridoma and myeloma cell lines whereas accumulation of toxic metabolites induced necrotic cell death in these cells. Other triggering factors such as oxygen deprivation might also be responsible for induction of apoptosis. In the present study, induction of cell death by exposure to anoxia was examined in batch culture of the SP2/0-derived hybridoma D5 clone. The mode of cell death was studied by morphological examination of acridine orange-ethidium bromide stained cells in a 1.5 L bioreactor culture grown under anoxic conditions for 75 hours. Under such conditions, viable cell density levelled off rapidly and remained constant for 25 hours. After 45 hours of anoxia, cell viability had decreased to 30% and the dead cell population was found to be 90% apoptotic. In terms of cellular metabolism, anoxia resulted in an increase in the utilization rates of glucose and arginine, and in a decrease in the utilization rate of glutamine. The lactate production rate and the yield of lactate on glucose increased significantly while the MAb production rate decreased. These results demonstrate that glycolysis becomes the main source of energy under anoxic conditions.Cells incubated for 10 hours or less under anoxic conditions were able to recuperate almost immediately and displayed normal growth rates when reincubated in oxic conditions whereas cells incubated for 22 hours or more displayed reduced growth rates. Nonetheless, even after 22 h or 29 h of anoxia, cells reincubated in oxic conditions showed no further progression into apoptosis. Therefore, upon removal of the triggering signal, induction of apoptosis ceased.Abbreviations VNA
Viable non-apoptotic cells
- VA
Viable apoptotic cells
- NVNA
Nonviable non-apoptotic or necrotic cells
- NVA
Nonviable apoptotic cells
- CF
Chromatin-free cells (late nonviable apoptotic cells)
- AO
Acridine orange
- EB
Ethidium Bromide
- MAb
Monoclocnal antibody
- D.O.
Dissolved oxygen
- qMAb
Specific MAb production rate (mg. (109 cells)–1.day–1)
-
Specific growth rate (h–1)
- Xv
Viable cell number (105 cells.mL–1)
- Xt
Total cell number (105 cells.mL–1)
- Ylac/glc
Yield coefficient of lactate on glucose (mM lactate produced/mM glucose consumed) 相似文献
18.
Kazuyoshi Morimoto. Joan Brengman Takehiko Yanagihara 《Journal of neurochemistry》1978,31(5):1277-1282
The alteration of polypeptide synthesis was evaluated with microsomes isolated from anoxic rabbit, hypoxic rat and ischemic gerbil brains to estimate the extent of functional or structural changes in polyribosomes in situ and the extent of artifact during tissue preparation. By using two-stage experimentation with combination of control and pathological microsomes and supernatant, it was found that the previously observed effects on microsomal or polyribosomal polypeptide synthesis in the above pathophysiological conditions were mainly the reflection of the alteration of polyribosomes in situ rather than the artifact during tissue preparation by degradative processes. In support of this finding. the use of inhibitors of degradative enzymes did not significantly protect microsomes either in normal or in pathological conditions. It was noted that the decline of tissue pH, to a certain extent, could be correlated with dysfunction of polyribosomes both in situ and during tissue preparation in cerebral hypoxia and anoxia. Since there is little change in ATP level, it was postulated that the alteration of pH in situ is responsible for the observed suppression of polypeptide synthesis in vitro at least in cerebral hypoxia. This hypothesis was supported by the subsequent experiments with incubation of brain slices and homogenization of brain tissue under various pH. It was emphasized that the environmental biochemical elements surrounding polyribosomes in cytoplasm should be evaluated as possible contributing factors for polyribosomal dysfunction in such pathological conditions as cerebral anoxia, hypoxia or ischemia if the alteration of energy state does not explain the phenomenon entirely. 相似文献
19.
While α1-adrenergic receptors (ARs) have been previously shown to limit ischemic cardiac damage, the mechanisms remain unclear. Most previous studies utilized low oxygen conditions in addition to ischemic buffers with glucose deficiencies, but we discovered profound differences if the two conditions are separated. We assessed both mouse neonatal and adult myocytes and HL-1 cells in a series of assays assessing ischemic damage under hypoxic or low glucose conditions. We found that α1-AR stimulation protected against increased lactate dehydrogenase release or Annexin V+ apoptosis under conditions that were due to low glucose concentration not to hypoxia. The α1-AR antagonist prazosin or nonselective protein kinase C (PKC) inhibitors blocked the protective effect. α1-AR stimulation increased 3H-deoxyglucose uptake that was blocked with either an inhibitor to glucose transporter 1 or 4 (GLUT1 or GLUT4) or small interfering RNA (siRNA) against PKCδ. GLUT1/4 inhibition also blocked α1-AR-mediated protection from apoptosis. The PKC inhibitor rottlerin or siRNA against PKCδ blocked α1-AR stimulated GLUT1 or GLUT4 plasma membrane translocation. α1-AR stimulation increased plasma membrane concentration of either GLUT1 or GLUT4 in a time-dependent fashion. Transgenic mice overexpressing the α1A-AR but not α1B-AR mice displayed increased glucose uptake and increased GLUT1 and GLUT4 plasma membrane translocation in the adult heart while α1A-AR but not α1B-AR knockout mice displayed lowered glucose uptake and GLUT translocation. Our results suggest that α1-AR activation is anti-apoptotic and protective during cardiac ischemia due to glucose deprivation and not hypoxia by enhancing glucose uptake into the heart via PKCδ-mediated GLUT translocation that may be specific to the α1A-AR subtype. 相似文献
20.
Incubation of 3-d-old seedlings of Oryza sativa L. cv Arborio under anaerobic conditions, leads to a large increase in the titer of free putrescine while aerobic incubation causes a slight decrease. After 2 days, the putrescine level is about 2.5 times greater without oxygen than in air. The rice coleoptile also accumulates a large amount of bound putrescine and, to a lesser extent, spermidine and spermine (mainly as acid-soluble conjugates). Accumulation of conjugates in the roots is severely inhibited by the anaerobic treatment. Feeding experiments with labeled amino acids showed that anoxia stimulates the release of 14CO2 from tissues fed with [14C]arginine and that arginine is the precursor in putrescine biosynthesis. After 2 d of anoxia, the activity of arginine decarboxylase was 42% and 89% greater in coleoptile and root, respectively, than in the aerobic condition. The causes of the differences in polyamine metabolism in anoxic coleoptiles and roots are discussed. 相似文献