Distribution of alpha-aminoisobutyric-C14 acid in rats deficient in thiamine, pantothenate, fatty acids, or potassium.
Explore the source record for details and available documents.
Adrenalectomy↗
SEARCH · PubMed Health
Results for “AMINOISOBUTYRIC ACID”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Insulin stimulates amino acid and lipid metabolism in isolated fetal rat hepatocytes.
Although fetal hyperinsulinemia is associated with excessive deposition of glycogen in liver, both in vivo and in vitro studies show little effect of insulin on glycogen synthesis from glucose or the activity of the enzyme glycogen synthase in the fetus. To investigate whether lack of insulin effect extends to other fetal metabolic processes, we compared the influence of insulin on amino acid uptake (14C-alpha-aminoisobutyric acid) and lipid synthesis [14C-acetate) in freshly isolated hepatocytes from 21-day fetal (F) and adult (A) rats. Viability of F and A hepatocytes was documented by trypan blue exclusion (greater than 90%). In A, insulin stimulated 14C-alpha-aminoisobutyric acid uptake in a dose dependent manner with an apparent Km at 2 ng/ml and a Vmax at 10 ng/ml. When corrected for cell surface area, F cells responded to insulin in a similar dose response manner, although absolute values per 1 X 10(6) cells always remained lower. In contrast, whereas A cells demonstrated a typical dose dependent response of 14C-acetate incorporation into lipid with a Km at 5 ng/ml and Vmax at 10 ng/ml of insulin, F cells remained totally unresponsive when the concentration of acetate was 5 mM or less. However, at higher medium acetate concentrations (15-30 mM) fetal responses were equal to or greater than that of adult, both basally and with insulin. These findings suggest differences in the maturation of insulin-mediated processes in fetal rat hepatocytes; effects on amino acid uptake appear earlier than those on lipid or glycogen synthesis.
Amino Acids↗
Insensitivity of bacteria to proposed antimetabolites of D-alanyl-D-alanine.
alpha-Aminoisobutyryl-d-alanine, d-alanyl-alpha-aminoisobutyric acid, and alpha-amino-isobutyryl-alpha-aminoisobutyric acid, proposed as antimetabolites of d-alanyl-d-alanine in bacterial cell wall synthesis, failed to inhibit bacterial growth.
Alanine↗
Studies on the role of protein synthesis and of sodium on the regulation of ornithine decarboxylase activity.
The minimum requirements for eliciting or enhancing ornithine decarboxylase activity (EC. 4.1.1.17); L-ornithine carboxylase) in neuroblastoma cells incubated in salts-glucose solutions have been investigated. These incubation conditions permit the study of changes in ornithine decarboxylase activity independently of the growth-associated reactions that occur in cell culture media (Chen, K.Y. and Canellakis, E.S. (1977) Proc. Natl, Acad. Sci. U.S.A. 74, 3791-3795). Ornithine decarboxylase activity can be elicited by a variety of asparagine and other amino acid analogs, including alpha-aminoisobutyric acid, that cannot participate in protein synthesis. Of the eleven asparagine analogs tested, alpha-N-CH3-DL-asparagine is the most potent in eliciting ornithine decarboxylase activity and is equivalent to asparagine in this regard. Inclusion of polar groups into the asparagine molecule results in the loss of its ability to elicit ornithine decarboxylase activity. With the use of these analogs and of analogs of other amino acids it is shown that the rapid fall in ornithine decarboxylase activity that is noted following cycloheximide treatment may not be a consequence of the inhibition of protein synthesis. The rapid fall in ornithine decarboxylase activity is primarily due to the removal of the agent that elicits and stabilizes its activity. These results, the finding that alpha-aminoisobutyric acid stimulates ornithine decarboxylase activity and that sodium is required for the stimulation of ornithine decarboxylase activity are discussed in relation to the "A" amino acid transport system.
Amino Acids↗
Characterization of neutral amino acid transport in a marine pseudomonad.
The transport of neutral amino acids in marine pseudomonad B-16 (ATCC 19855) has been investigated. From patterns of competitive inhibition, mutant analysis, and kinetic data, two active transport systems with overlapping substrate specificities were distinguished and characterized. One system (DAG) served glycine, D-alanine, D-serine, and alpha-aminoisobutyric acid (AIB) and, to a lesser extent, L-alanine and possibly other related neutral D- and L-amino acids. The other system (LIV) showed high stereospecificity for neutral amino acids with the L configuration and served primarily to transport L-leucine, L-isoleucine, L-valine, and L-alanine. This system exhibited low affinity for alpha-aminoisobutyric acid. Neither system was able to recognize structural analogues with modified alpha-amino or alpha-carboxyl groups. The kinetic parameters for L-alanine transport by the DAG and LIV systems were determined with appropriate mutants defective in either system. For L-alanine, Kt values of 4.6 X 10(-5) and 1.9 X 10(-4) M and Vmax values of 6.9 and 20.8 nmol/min per mg of cell dry weight were obtained for transport via the DAG and LIV systems respectively. alpha-Aminoisobutyric acid transport heterogeneity was also resolved with the mutants, and Kt values of 2.8 X 10(-5) and 1.4 X 10(-3) M AIB were obtained for transport via the DAG and LIV systems, respectively. Both systems required Na+ for activity (0.3 M Na+ optimal) and in this regard are distinguished from systems of similar substrate specificity reported in nonmarine bacteria.
Alanine↗
Superoxide dismutase in rats with sepsis. Effect on survival rate and amino acid transport.
In a recent study, administration of the free radical scavenger superoxide dismutase (SOD) improved survival in rats with sepsis when administered two hours before induction of sepsis. The present study was designed to determine whether free radical-induced membrane damage is involved in the pathogenesis of decreased muscle amino acid uptake, noted in sepsis. Additionally, the effect on survival rate of SOD given after the onset of sepsis was studied. Sepsis was induced by cecal ligation and puncture in rats. Amino acid transport in incubated soleus muscles was studied using tritiated alpha-aminoisobutyric acid. Amino acid uptake was significantly reduced in muscle from rats with sepsis. Administration of SOD before induction of sepsis or added in vitro to incubated muscles with sepsis had no effect on alpha-aminoisobutyric acid uptake. Survival rate was not increased when SOD was given two hours after cecal ligation and puncture. The results suggest that free radical-induced membrane damage is not the mechanism of inhibited muscle amino acid transport in sepsis. Since survival was not improved by SOD administered after induction of sepsis, the role of the enzyme in the treatment of sepsis may be questioned.
Amino Acids↗
Regulation of amino acid and glucose transport activity expressed in isolated membranes from untransformed and SV 40-transformed mouse fibroblasts.
Membrane vesicles isolated from untransformed Balb/c and Swiss mouse fibroblasts and their SV 40-transformed derivatives were shown to catalyze carrier-mediated, intravesicular uptake of alpha-aminoisobutyric acid and D-glucose. Concentrative uptake of alpha-aminoisobutyric acid required the presence of a Na+-gradient (external greater than internal) and could occur independently of endogenous (Na+ + K+)ATPase activity. A K+ diffusion gradient (internal greater than external) in the presence of valinomycin, or the addition of the Na+ salt of a highly permeant anion, conditions expected to create an interior-negative membrane potential stimulated Na+-gradient-dependent uptake, suggesting this process is electrogenic. D-Glucose uptake was nonconcentrative and did not require ion gradients or metabolic conversion. Na+ gradient-dependent transport of alpha-aminoisobutyric acid was reduced both in initial rate and extent of uptake in vesicles from confluent untransformed cells and increased in those from SV 40-transformed cells, compared with activities observed in vesicles from proliferating untransformed cells. No changes in D-glucose carrier activity were observed when assayed at low glucose concentrations.
Aminoisobutyric Acids↗
Insulin stimulatory action on amino acid uptake in bovine adrenal cortex or glomerulosa zone.
1. Insulin stimulated the [1-14C] methylaminoisobutyric acid and [1-14C] aminoisobutyric acid uptake in the bovine adrenal cortex or in the glomerulosa zone through the A system. 2. Verapamil nullified the insulin stimulatory action indicating that this hormonal action is probably related to the voltage-dependent Ca2+ channels.
Adrenal Cortex↗
Inhibition of cellular transport processes by 5-thio-D-glucopyranose.
5-Thio-d-glucopyranose, the nearest analogue of normal d-glucose, which is proving a useful tool in examinations of d-glucose biochemistry, affects active and facilitated-diffusion transport processes. 5-Thio-d-glucose is readily transported in rabbit kidney-cortex slices and reaches a tissue/medium ratio of 6.5 within 40min. The sulphur analogue shows typical saturation kinetics with a K(m) value of 2.4mm and V(max.) value of 70mumol/h per g of cell water. Uptake of 5-thio-d-glucose is phlorrhizin-sensitive, Na(+)-dependent and energy-dependent. d-Galactose and methyl alpha-d-glucopyranoside transport is competitively inhibited by 5-thio-d-glucose with K(i) values of 4.8 and 9.7mm respectively. 5-Thio-d-glucose thus shows all of the characteristics of active transport in kidney cortex. Transport of neutral amino acids in rat kidney cortex is inhibited by 5-thio-d-glucose. Thus 5.6mm-5-thio-d-glucose causes a 25-30% inhibition of the transport of glycine and the non-metabolized amino acids cycloleucine and alpha-aminoisobutyric acid. 5-Thio-d-glucose is freely taken up by the facilitated-diffusion transport system in rat diaphragm muscle. The sulphur analogue inhibits the transport of d-xylose in this tissue but has no effect on the uptake of d-arabinose. It is concluded that the ring heteroatom is not an effector of binding in the transport processes examined and causes no important alteration in the conformation of the sugar. The diabetogenic action produced by 5-thio-d-glucose is due, in part, to the ability of the analogue to interfere with cellular transport processes that use d-glucose.
Amino Acids↗
Pulmonary absorption of amino acids in the rat: evidence of carrier transport.
To investigate the absorption of nonmetabolized amino acids from the rat lung, 0.1 ml of Krebs-Ringer phosphate solution containing either 14C-labeled 1-aminocyclopentanecarboxylic acid (cycloleucine) or alpha-aminoisobutyric acid (AIB) was administered to anesthetized animals by way of a catheter introduced through a tight-fitting tracheal cannula. After various times, lungs were removed and assayed for the amount of amino acid that remained. Cycloleucine appeared to be absorbed by a combination of at least two processes: saturable carrier-type transport and a nonsaturable process. The saturable process was inhibited to varying degrees by a number of L- and D-amino acids but not by D-ornithine, betaine, 3-O-methyl-D-glucose, phenol red, disodium cromoglycate, or tetraethylammonium. The nonsaturable process appeared to be too rapid to be accounted for by diffusion alone, thus suggesting interaction with a second carrier system of high capacity. Although AIB was a weak inhibitor of cycloleucine transport, it appeared to be absorbed solely by a nonsaturable process at a rate consistent with diffusion through aqueous membrane channels.
Absorption↗
Mechanisms of amino acid-induced insulin secretion from the glucose-responsive BRIN-BD11 pancreatic B-cell line.
The effects of different classes of amino acids known to be transported and utilized by pancreatic B-cells were examined using the novel glucose-responsive pancreatic B-cell line, BRIN-BD11. Amino acids tested included alpha-aminoisobutyric acid, L-alanine, L-arginine, L-glutamine, glycine, L-leucine, L-lysine, L-proline and L-serine. At non-stimulatory (1.1 mmol/l) glucose, acute incubations with either 1 or 10 mmol/l amino acid evoked 1.3- to 4.7-fold increases of insulin release. Raising glucose to 16.7 mmol/l enhanced the effects of all amino acids except L-glutamine, and increased insulin output at 10 mmol/l compared with 1 mmol/l amino acid. Glyceraldehyde (10 mmol/l) also served to promote 10 mmol/l amino acid-induced insulin secretion with the exceptions of L-arginine, glycine, L-lysine and L-proline. At 16.7 mmol/l glucose, diazoxide (300 mumol/l) significantly decreased the secretory response to all amino acids except L-glutamine. Likewise, verapamil (20 mumol/l) or depletion of extracellular Ca2+ reduced insulin output indicating the importance of Ca2+ influx in the actions of amino acids. These data indicate that BRIN-BD11 cells transport and utilize amino acids, acting in association with glycolysis, K(+)-ATP channels and/or voltage-dependent Ca2+ channels to promote Ca2+ influx and insulin secretion. The response of BRIN-BD11 cells to glucose and amino acids indicates that this is a useful cell line for future research on the mechanisms of nutrient regulation of insulin secretion.
Alanine↗
Neurotrophic regulation of insulin-sensitive amino acid uptake in rat fast muscle.
Our object was to determine how innervation regulates muscle insulin sensitivity. Insulin-stimulated uptake of the nonmetabolized amino acid, 2-amino-isobutyric acid, was used as a measure of insulin sensitivity in denervated rat extensor digitorum longus muscles retaining either a similar 2.5-cm (""proximal denervation'') or a similar to 0.5-cm (""distal denervation'') length of distal nerve stump. Because both muscles were inactive in the first 24 h, any difference in insulin sensitivity could be due only to some trophic influence of the distal nerve stump. Fifteen hours after either type of denervation, 2-aminoisobutyric acid uptake was refractory to insulin. However, at 24 h, insulin sensitivity of distally denervated muscles (with or without a second ipsilateral proximal denervation) was normal, whereas that of proximally denervated muscles was still relatively insensitive. In the absence of insulin, the two types of denervated muscles at 24 h showed no difference in 2-aminoisobutyric acid uptake. Finally, organ culture of paired muscles with or without long nerve stumps showed corresponding differences in insulin-stimulated 2-aminoisobutyric acid uptake after 48 h in vitro. Thus, a neurotrophic factor, independent of impulse activity, stretch, or changes in blood flow, regulates one type of muscle insulin sensitivity.
Amino Acids↗
Stimulation of amino acid transport in isolated diaphragm by growth hormone added in vitro.
The influence of the pituitary on the transport of alpha-aminoisobutyric acid-1-C(14) into the cells of isolated rat diaphragm was investigated. Hypophysectomy results in a lower-than-normal rate of alpha-aminoisobutyric acid-1-C(14) penetration into muscle. Adding either simian or bovine growth hormone preparations to the incubation medium in concentrations of 2.5 to 25 microg/ml of medium resulted in a doubling of the alpha-aminoisobutyric acid-l-C(14) penetration rate. The stimulatory effect was minimized when the hormone concentration was reduced to 0.25 microg/ml of medium.
Abdominal Muscles↗
Hexose and amino acid transport by chicken embryo fibroblasts infected with temperature-sensitive mutant of Rous sarcoma virus. Comparison of transport properties of whole cells and membrane vesicles.
The effect of transformation on hexose and amino acid transport has been studied using whole cells and membrane vesicles of chicken embryo fibroblasts infected with the temperature-sensitive mutant of the Rous sarcoma virus, TS-68. In whole cells, TS-68-infected chicken embryo fibroblasts cultured at the permissive temperature (37 degrees C) had a 2-fold higher rate of 2-deoxy-D-glucose uptake than the same cells cultured at the non-permissive temperature (41 degrees C). However, both the non-transformed and transformed cells had comparable rates of alpha-aminoisobutyric acid transport. Membrane vesicles, isolated from TS-68-infected chicken embryo fibroblasts cultured at 41 degrees C or 37 degrees C, displayed carrier-mediated, intravesicular uptake of D-glucose and alpha-aminoisobutyric acid. Membrane vesicles from TS-68-infected chicken embryo fibroblasts cultured at 37 degrees C had an approx. 50% greater initial rate of stereospecific hexose uptake than the membrane vesicles from fibroblasts cultured at 41 degrees C. The two types of membrane vesicle had similar uptake rates of alpha-aminoisobutyric acid. The results of hexose and amino acid uptake by the membrane vesicles correlated well with those observed with the whole cells. Km values for stereospecific D-glucose uptake by the membrane vesicles from TS-68-infected chicken embryo fibroblasts cultured at 41 and 37 degrees C were similar, but the V value was greater for the membrane vesicles from TS-68-infected cells cultured at 37 degrees C. Cytochalasin B competitively inhibited stereospecific hexose uptake in both types of membrane vesicle. These findings suggest that the membrane vesicles retained many of the features of hexose and amino acid transport observed in whole cells, and that the increased rate of hexose transport seen in the virally-transformed chicken embryo fibroblasts was due to an increase in the number or availability of hexose carriers.
Amino Acids↗
Alamethicin biosynthesis: acetylation of the amino terminus and attachment of phenylalaninol.
Alamethicin synthetase was extracted from the fungus Trichoderma viride at the end of its exponential growth phase. It is multienzyme complex with a molecular weight of approx. 480 000. The biosynthesis of alamethicin is initiated on the synthetase by acetylation of thiolester-bound aminoisobutyric acid, which remains enzyme bound. Acetyl-CoA serves as the acetate donor. Of the alamethicin constituents, glycine, alanine and valine are also acetylated when incubated alone. This acetylation is prevented by added aminoisobutyric acid, which indicates that the site on alamethicin synthetase catalyzing the acetylation has a preference for aminoisobutyric acid. Alamethicin formation on the synthetase is terminated by linkage of phenylalaninol to the carboxyl terminus of the peptide. It is unlikely that the amino alcohol is a degradation product of alamethicin or that it had been split off from the synthetase complex. Thus it is probably the reaction product of a separate enzyme system.
Acetylation↗
Adenosine induces System A amino acid transport in cultured rat hepatocytes.
Adenosine caused a 2.5-fold increase in the sodium-dependent uptake of 2-aminoisobutyric acid in rat hepatocytes in primary culture following incubation for 3 h. The range of stimulating concentrations of adenosine corresponded to that of cAMP formation. Adenosine increased the Vmax of the transport without altering the Km for 2-aminoisobutyric acid. These effects of adenosine were abolished by actinomycin D. N6-L-Phenylisopropyladenosine also caused twofold increase in the amino acid transport. These findings suggest that adenosine induces System A amino acid transport in a transcription-dependent manner, and the P1-purinergic receptors are mainly involved in this action of the nucleoside.
Adenosine↗
Gas chromatographic analysis of free amino acids in the hyaloplasm of the hypophysis, pineal gland, thyroid gland, spinal cord, thymus and lymph nodes of the cow.
Studies of the qualitative and quantitative composition of free amino acids in the hyaloplasm of the hypophysis, pineal gland, thyroid gland, spinal cord, thymus and lymph nodes of the cow are described. The following findings are reported: the highest levels of alanine, valine, glycine, isoleucine, histidine, leucine, threonine, serine, phenylalanine, tyrosine and lysine are found in the thyroid gland, methionine and aspartic acid in the spinal cord, tryptophan and hydroxyproline in the pineal gland, and proline and glutamic acid in the thymus gland. The highest level by weight is that of glutamic acid in all tissues. The presence of alpha-aminobutyric acid combined with sarcosine and 4-aminoisobutyric acid with 2-AOA and citrulline with cystine was demonstrated. alpha-Aminoisobutyric acid and isovaline were found in the spinal cord.
Amino Acids↗
Colchicine effects on lysosomal enzyme induction and intracellular degradation in the cultivated macrophage.
The effects of colchicine on lysosomal fusion and lysosomal enzyme induction in the cultivated mouse peritoneal macrophage have been examined. Colchicine (10- minus 6 M), but not lumicolchicine, inhibited lysosomal enzyme induction by both phagocytic and pinocytic stimuli. In addition, the drug significantly retarded pinocytic uptake of [3-H] sucrose and transport of the amino acids [3-H] alpha aminoisobutyric acid and L-[3-H] leucine. In contrast, lumicolchicine had no effect on pinocytosis or amino acid transport. Thus, a role for intact microtubules in lysosomal enzyme induction, pinocytosis, and amino acid uptake in these cells is suggested. That colchicine inhibited lysosomal enzyme induction by phagocytic stimuli under conditions in which pinocytosis contributed little to the enzyme rise indicated that inhibition of pinocytosis was unlikely to account for colchicine effects on lysosomal enzyme induction. Effects of colchicine on degradation of phagocytized and pinocytized substrates were examined to determine if intact microtubules are required for fusion among lysosomes, pinosomes, and phagosomes. Colchicine did not alter the rate of intracellular digestion of radiolabeled bacteria by the cultivated macrophage. Similarly, it had no effect on enzymatic hydrolysis of intracellular [3-H] sucrose resulting from uptake of exogenous invertase. The finding that colchicine had no effect on the functional consequences of fusion of lysosomes with endosomes suggests that intact microtubules are not required for fusion among these constituents of the vacuolar apparatus.
Acid Phosphatase↗