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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The myofibrillar ATPase activity of the epaxial white muscle was measured in carp Cyprinus carpio L. acclimated to 10 degrees C or 28 degrees C. As previously reported, cold acclimation was associated with an increase in the ATPase specific activity and a decrease in the thermostability. The water content of the white muscle was significantly higher in cold-acclimated fish than in warm-acclimated fish (P less than 0.002). Starvation for 10 weeks resulted in a significant increase in the white muscle water content of both warm- and cold-acclimated fish (P less than 0.002). When carp were starved, the ability of the myofibrillar ATPase to show thermal compensation disappeared. Previously acclimated fish, when starved, showed steady alterations of the myofibrillar ATPase activity to a level mid-way between the acclimated extremes. Refeeding resulted in a gradual return to the normal acclimated level.
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PMID:Myofibrillar ATPase activity in the carp Cyprinus carpio: interactions between starvation and environmental temperature. 294 51

Oxygen consumption and Na+,K+-ATPase(EC 3.6.1.3)-dependent (ouabain-sensitive) and -independent respiration were measured for duodenal mucosa biopsies from 10-month-old sheep given two levels of digestible energy (DE) intake (7.6-7.7 and 14.8 MJ lucerne (Medicago sativa) pellets/d) and following 48 h of starvation. The mucosal biopsies were determined to be structurally intact and free of adherent bacteria on histological and scanning-electron-microscope examinations. The use of D-glucose as a substrate during incubations did not elevate (P greater than 0.05) the respiration indices of the biopsies over those measured during acetate incubations. Glucose uptake did not (P greater than 0.05) influence the Na+,K+-ATPase-dependent respiration of the mucosal biopsies. Na+,K+-ATPase-dependent respiration accounted for 50% of the total O2 consumption of the mucosal biopsies of sheep given the lower level of DE. Total O2 consumption of the duodenal mucosa was not (P greater than 0.05) increased when sheep were given the higher level of DE but Na+,K+-ATPase-dependent respiration of the mucosa was elevated (P less than 0.01) by 37% during this period. When sheep were starved for 48 h, total O2 consumption of the mucosal biopsies was not (P greater than 0.05) affected, however, Na+,K+-ATPase-dependent respiration of the biopsies dropped (P less than 0.01) by 45%. Na+,K+-ATPase-dependent respiration accounted for 61.3% of the O2 uptakes of mucosa from the sheep given the higher level of DE and 28.3% of the O2 uptake of mucosa from fasted sheep.
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PMID:Influence of feed intake and starvation on the magnitude of Na+,K+-ATPase(EC 3.6.1.3)-dependent respiration in duodenal mucosa of sheep. 299 48

Amino acid transport was studied in C1 cells which contain amplified levels of sodium- and potassium-activated adenosine triphosphatase (Na,K-ATPase), in C4 cells which are ouabain-sensitive revertants, and in parental HeLa S3. Sodium-dependent uptake of aminoisobutyric acid and alanine was increased 2-fold in the amplified C1 cells. After a 6 h amino acid starvation period, the rate of sodium-dependent uptake of methylaminoisobutyric acid was 70-90% greater for C1 than for C4 and HeLa. This uptake was inhibitable by ouabain and the apparent Km values for high affinity uptake were similar in all three lines. Overall, neutral amino acid uptake through Systems A, ASC, and L was 2-fold higher in the Na,K-ATPase amplified C1 cells relative to C4 or HeLa. The induction of System A uptake of methylaminoisobutyric acid after starvation was more rapid in both the amplified C1 cells and the revertant C4 when compared to HeLa, which suggests that the selection for amplification of the Na,K-ATPase produced membrane alterations affecting the adaptive regulation of System A.
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PMID:Alterations in amino acid transport in Na,K-ATPase amplified HeLa cells. 300 Oct 56

The effect of Ep on different ATPases and acetylcholinesterase of rat RBC membrane was studied. Starvation caused a slight decrease in Mg2+-, Ca2+-, and Na+ + K+-ATPases. However, these enzyme activities were markedly increased on Ep treatment of starved rats. Specific activities of all three ATPases increased linearly with increasing concentration of Ep. Under identical conditions the hormone failed to stimulate the ATPase activity of liver plasma membrane. Desensitization by fluoride of allosteric inhibition of erythrocyte membrane-bound Na+ + K+-ATPase was observed under starvation which showed a return to normal n values on Ep administration. The enzyme from normal animals was inhibited almost completely at 0.1 mM fluoride whereas enzyme from starved and Ep-treated animals showed only about 50% inhibition at that fluoride concentration. Ep increased the acetylcholinesterase activity of normal RBC membrane to a small extent whereas the stimulation was much higher under starvation. The fluoride inhibition curve of this enzyme changed from sigmoidal to hyperbolic under starvation which again changed to allosteric on administration of Ep. These changes were closely correlated to n values. Red blood cells of Ep-treated animals became more susceptible to osmotic shock under the experimental conditions.
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PMID:Effect of erythropoietin on the different ATPases and acetylcholinesterase of rat RBC membrane. 302 76

Sindbis virus infection of baby hamster kidney cells or chick embryo cells resulted in a significant increase in the rate of uptake of [2-3H]deoxy-D-glucose ([3H]dGlu). Stimulation of hexose transport in Sindbis virus-infected cells occurred only if the cells were rendered quiescent by culturing at high density or by serum starvation. In contrast, Sindbis virus-induced inhibition of potassium transport, measured as a decrease in the uptake of 86Rb+, was independent of cell growth state. Stimulation of [3H]dGlu uptake in Sindbis virus-infected cells was the result of an increase in the Vmax of the hexose transporter, but not a change in the Km. The stimulation of [3H]dGlu uptake induced by Sindbis virus was insensitive to the drug actinomycin D, but was blocked by cordycepin. The stimulation was also insensitive to treatment with tunicamycin, which prevented the virally induced inhibition of the plasma membrane-associated Na+/K+ ATPase and termination of host protein synthesis.
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PMID:Sindbis virus infection increases hexose transport in quiescent cells. 302 95

The ATP-binding component (Component II, hereafter referred to as ClpA) of a two-component, ATP-dependent protease from Escherichia coli has been purified to homogeneity. ClpA is a protein with subunit Mr 81,000. It has an intrinsic ATPase activity and activates degradation of protein substrates only in the presence of a second component (Component I, hereafter referred to as ClpP), Mg2+, and ATP. The amount of ClpA varies by less than a factor of 2 in cells grown in different media and at temperatures from 30 to 42 degrees C. ClpA does not appear to be a heat-shock protein since its synthesis is not dependent on htpR. Antibodies against purified ClpA were used to identify lambda transducing phage bearing the clpA gene. The cloned gene contains a DNA sequence expected to code for the first 28 amino acids of ClpA, which were determined by protein sequencing of purified ClpA. The clpA gene in the phage was mutated by insertion of delta kan defective transposons and the mutations were transferred to E. coli by homologous recombination. The clpA gene was mapped to 19 min on the E. coli chromosome. Mutant cells with insertions early in the gene produce no ClpA protein detectable in Western blots, and extracts of such mutant cells have no detectable ClpA activity. clpA- mutants grow well under all conditions tested and are not defective in turnover of proteins during nitrogen starvation nor in the turnover of such highly unstable proteins as the lambda proteins O, N, and cII, or the E. coli proteins SulA, RcsA, and glutamate dehydrogenase. The degradation of abnormal canavanine-containing proteins is defective in clpA mutants especially in cells that also have a lon- mutation. Extracts of clpA- lon- cells have ATP-dependent casein degrading activity.
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PMID:The two-component, ATP-dependent Clp protease of Escherichia coli. Purification, cloning, and mutational analysis of the ATP-binding component. 304 6

The transport of radioactive sodium in high sodium cat red blood cells has been studied under various experimental conditions. It was found that iodoacetate (IAA) and iodoacetamide (IAM) inhibit Na influx by 50% whereas NaF has no effect. Reversible dyes, such as methylene blue (Mb), also inhibit this influx by 60%. Both IAA and Mb effects show a lag period of about 40 min. Cell starvation abolishes the volume-dependent Na influx which is generally observed in these cells. IAA reduces significantly the volume-dependent Na influx but does not inhibit it completely. 5 mM magnesium chloride produces a twofold increase in Na influx. On the other hand, MgCl(2) has no effect on Na transport in human red cells or on potassium or sulfate transport in cat red cells. The effect of MgCl(2) is quite rapid and does not interfere with the volume-dependent Na influx. This effect is abolished in starved cells. Reincubation of previously stored cells in buffered solutions containing glucose and MgCl(2) causes more than one order of magnitude increase in Na influx. These several observations are discussed in terms of the possibility of a link between Na transport and Na-Mg-activated ATPase.
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PMID:Further studies of sodium transport in feline red cells. 473 97

The exchange of labelled calcium between the external medium and the whole body was investigated in the larva of Aedes aegypti (L.) using a closed, two-compartmental model. The transport system for the uptake of Ca2+ was found to be saturable and obeyed Michaelis-Menten kinetics. The efficiency of the inward transport of calcium from dilute solutions was markedly reduced by starvation or by ruthenium-red, a selective inhibitor of Ca2+ activated ATPase, indicating that this transport system is energy dependent. Unlike transport systems for the major monovalent ions, the Ca2+ transport system is not located in the anal papillae, since removal of these organs resulted in enhanced Ca2+ fluxes. While over 95% of the calcium in the larva appeared to be distributed in the extracellular haemolymph, only 16% of the total calcium was readily exchangeable with the external medium; thus the majority of the calcium is apparently bound to haemolymph constituents. The results suggest that calcium pumps consisting of Ca2+ activated ATPases play an important role in the absorption of Ca2+ from dilute solutions in the gut and its reabsorption from the urine in the rectum.
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PMID:The exchange of calcium in larvae of the mosquito Aedes aegypti. 619 97

The question of whether Thiobacillus acidophilus maintains its cytoplasmic pH at values close to neutrality by active or passive means was explored by subjecting the organism to long-term starvation (up to 22 days). Starving cells maintained a delta pH of 2 to 3 U throughout starvation, although cellular poly-beta-hydroxybutyric acid and ATP, the proton motive force, and culture viability were low or not detectable after 200 h. Cells exposed to azide or azide plus N,N'-dicyclohexylcarbodiimide immediately exhibited characteristics of cells starved for more than 200 h. Thus, a large delta pH in T. acidophilus was maintained in the absence of ATP, ATPase activity, respiration, significant levels of proton motive force, and cell viability and was therefore not dependent on chemiosmotic ionic pumping. The transition from a metabolically active to an inactive state was accompanied by a large increase in the positive membrane potential, which nearly completely compensated for the delta pH in the inactive cells. The longevity of the acidophile during starvation was comparable to that reported previously for neutrophiles, and the loss of viability occurred not because of the acidification of the cytoplasm but apparently because of energy depletion.
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PMID:Effect of starvation on cytoplasmic pH, proton motive force, and viability of an acidophilic bacterium, Thiobacillus acidophilus. 629 53

The mechanism of host shut-off following virus T1 infection was studied using Escherichia coli wild type and ATPase deficient (unc-) cells. Host protein synthesis measured either as amino acid incorporation into proteins or as enzyme synthesis is immediately inhibited in T1-infected wild type cells. In contrast, host repression in the ATPase-deficient cells is almost unaffected after T1 infection. The continuation of host macromolecule synthesis in the unc- cells is due to constant ATP concentrations after infection, whereas an immediate drop in intracellular ATP levels in T1-infected wild type cells causes repression of host protein synthesis. This result is confirmed when host protein synthesis is determined at decreasing ATP concentrations following the starvation of cells.
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PMID:Development of escherichia coli virus T1. ATP-mediated discrimination of gene expression. 644 98


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