scholarly journals The effect of noradrenaline on glyceride synthesis and oxidative metabolism in vitro in the brown fat of newborn rabbits

1971 ◽  
Vol 125 (1) ◽  
pp. 1-8 ◽  
Author(s):  
B. L. Knight ◽  
N. B. Myant
Keyword(s):  
Gas Exchange ◽  
Specific Radioactivity ◽  
Substrate Oxidation ◽  
Brown Fat ◽  
Fat Cells ◽  
Glyceride Synthesis ◽  
Pyruvate Oxidation ◽  
Fully Coupled ◽  
Stimulation Of

1. The effect of noradrenaline on the synthesis of glyceride from [U-14C]glucose and on gas exchange in the brown fat of newborn rabbits in vitro was investigated. 2. The specific radioactivity of l-glycerol 3-phosphate was lower than that of lactate, presumably because glycerol derived from glyceride was rephosphorylated by glycerokinase. 3. In the basal state more than 25% of the total respiration was due to pyruvate oxidation. Noradrenaline stimulated glyceride synthesis and total respiration without changing the proportion of the total respiration due to pyruvate oxidation. 4. The extra ADP released by noradrenaline stimulation of glyceride synthesis could not have supported more than 2% of the observed increase in substrate oxidation if mitochondria from brown-fat-cells remain fully coupled in the stimulated state, but could have supported about one-third of the observed increase if they become uncoupled in the presence of noradrenaline.

scholarly journals The regulation of glyceride synthesis in isolated white-fat cells. The effects of palmitate and lipolytic agents

1972 ◽  
Vol 128 (5) ◽  
pp. 1057-1067 ◽  
Author(s):  
E. D Saggerson
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Fat Cells ◽  
Glyceride Synthesis ◽  
Glucose Incorporation ◽  
High Concentrations ◽  
Stimulation Of

1. 0.5mm-Palmitate stimulated incorporation of [U-14C]glucose into glyceride glycerol and fatty acids in normal fat cells in a manner dependent upon the glucose concentration. 2. In the presence of insulin the incorporation of 5mm-glucose into glyceride fatty acids was increased by concentrations of palmitate, adrenaline and 6-N-2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate up to 0.5mm, 0.5μm and 0.5mm respectively. Higher concentrations of these agents produced progressive decreases in the rate of glucose incorporation into fatty acids. 3. The effects of palmitate and lipolytic agents upon the measured parameters of glucose utilization were similar, suggesting that the effects of lipolytic agents are mediated through increased concentrations of free fatty acids. 4. In fat cells from 24h-starved rats, maximal stimulation of glucose incorporation into fatty acids was achieved with 0.25mm-palmitate. Higher concentrations of palmitate were inhibitory. In fat cells from 72h-starved rats, palmitate only stimulated glucose incorporation into fatty acids at high concentrations of palmitate (1mm and above). 5. The ability of fat cells to incorporate glucose into glyceride glycerol in the presence of palmitate decreased with increasing periods of starvation. 6. It is suggested that low concentrations of free fatty acids stimulate fatty acid synthesis from glucose by increasing the utilization of ATP and cytoplasmic NADH for esterification of these free fatty acids. When esterification of free fatty acids does not keep pace with their provision, inhibition of fatty acid synthesis occurs. Provision of free fatty acids far in excess of the esterification capacity of the cells leads to uncoupling of oxidative phosphorylation and a secondary stimulation of fatty acid synthesis from glucose.

Effect of norepinephrine and uncoupling agents on brown adipose tissue

1968 ◽  
Vol 46 (6) ◽  
pp. 897-902 ◽  
Author(s):  
Barbara A. Horwitz ◽  
Paul A. Herd ◽  
Robert Emrie Smith
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Brown Fat ◽  
Brown Adipose ◽  
In Vitro Response ◽  
Stimulation Of ◽  
Thermogenic Response

Examination of the in vivo effect of 2,4-dinitrophenol (DNP) on the brown adipose tissue of cold-exposed rats, as well as the in vitro response of this tissue to DNP and dicumarol, indicates that brown fat does possess a functional electron transport coupled phosphorylating system. Moreover, the fact that a norepinephrine-induced thermogenic response (in vivo) can be elicited from the brown fat after DNP administration implies that the effect of norepinephrine (NE) is not primarily due either to a physiological uncoupling by fatty acids, the level of which is increased by NE, or to stimulation of an ATP-ase system. Alternatively, our data suggest that under basal conditions (i.e. when the animal is not stimulated by cold stress or NE), the heat production (oxygen consumption) of the brown fat is limited by the availability of substrate rather than ADP. It is thus proposed that the thermogenic effect of NE results from the stimulation of lipolysis and an attendant increase of substrate available for oxidation.

Expression of developmental genes in brown fat cells grown in vitro is linked with lipid accumulation

2015 ◽  
Vol 51 (10) ◽  
pp. 1003-1011 ◽  
Author(s):  
S. Singh ◽  
Y. S. Rajput ◽  
A. K. Barui ◽  
R. Sharma ◽  
S. Grover
Keyword(s):  
Lipid Accumulation ◽  
Brown Fat ◽  
Fat Cells ◽  
Developmental Genes

scholarly journals Adrenergic control of induction of type II iodothyronine 5′-deiodinase activity in cultured mouse brown adipocytes

1993 ◽  
Vol 292 (1) ◽  
pp. 303-308 ◽  
Author(s):  
S Pavelka ◽  
J Hermanská ◽  
M Baudysová ◽  
J Houstĕk
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Brown Fat ◽  
Fat Cells ◽  
Type Ii ◽  
Brown Adipocytes ◽  
Adrenergic Agents ◽  
Adrenergic Control ◽  
Stimulation Of

Iodothyronine 5′-deiodinase (5′D) of mouse brown adipocytes differentiated in cell culture was characterized in detail with respect to the adrenergic control of its biosynthesis. The stimulation of 5′D required mRNA and protein synthesis and was dependent on the stage of differentiation of the cells. The maximum induction was observed around confluence (7-day-old cells), in pre- and post-confluent cells the 5′D activity was significantly less induced. The transient responsiveness of brown fat-cells to the stimulatory effect of adrenergic agents was reflected also in the time course of the induction of 5′D by different concentrations of agonists. The maximum response occurred regularly after an 8 h incubation and implicated a rather fast turnover of the induced enzyme. On the basis of the inhibitory effects of cycloheximide and actinomycin D, the half-life of the induced 5′D and its mRNA were estimated to be 1.5 and 3.3 h respectively. The noradrenaline-induced 5′D activity was shown to be that of the type II enzyme, insensitive to propylthiouracil (PTU). The estimated values of its apparent Km for thyroxine, Km for the co-substrate dithiothreitol, and Vmax. in the presence of 1 mM PTU were 2 nM, 2.6 mM, and 0.1 pmol of I-/h per mg of protein respectively. The 5′D activity was effectively induced by forskolin and dibutyryl cyclic AMP, as well as by isoprenaline, noradrenaline and CGP-12177, but not by phenylephrine, cirazoline or oxymetazoline. This indicates that, contrary to previous observations in vivo, stimulation of 5′D in cultured brown fat-cells involves elevated cyclic AMP levels and is mediated predominantly via beta-receptors, particularly via the so-called beta 3-adrenoceptors.

scholarly journals Effect of adrenaline on 32P incorporation into rat fat-cell phospholipids

1972 ◽  
Vol 128 (3) ◽  
pp. 531-541 ◽  
Author(s):  
Janet M. Stein ◽  
C. N. Hales
Keyword(s):  
Phosphatidic Acid ◽  
Specific Radioactivity ◽  
Phospholipid Composition ◽  
Fat Cells ◽  
Fat Pad ◽  
Fat Cell ◽  
32P Incorporation ◽  
The Individual ◽  
Adrenergic Blocking ◽  
Stimulation Of

1. The phospholipid composition of fat-cells prepared from rat epididymal fat-pad was determined. 2. The incorporation of [32P]Pi into the phospholipids of fat-cells incubated in glucose-free medium and the effect of adrenaline and of α- and β-adrenergic blocking agents, were studied. 3. Incorporation of [32P]Pi into fat-cell phospholipid increased with time; incubation with adrenaline resulted in increased incorporation that was related to the concentration of adrenaline. 4. The pattern of incorporation of [32P]Pi into the individual phospholipids of fat-cells after incubation for 1h was determined; adrenaline (5.4μm) resulted in increased incorporation into phosphatidylcholine. 5. Incubation of fat-cells with propranolol (34μm) and adrenaline (5.4μm) resulted in abolition of adrenaline-stimulated lipolysis; there was a decrease in the specific radioactivity of phosphatidylcholine and an increase in the specific radioactivity of phosphatidylethanolamine, phosphatidic acid, phosphatidylinositol and cardiolipin compared with cells incubated with adrenaline alone. 6. Incubation of fat-cells with phenoxybenzamine (0.1mm) and adrenaline (5.4μm) resulted in stimulation of lipolysis, and in diminished specific radioactivities of phosphatidylcholine, phosphatidic acid, phosphatidylinositol, phosphatidylglycerol and choline plasmalogen compared with cells stimulated with adrenaline alone.

Effects of pertussis toxin treatment on metabolism in hamster brown adipocytes

1985 ◽  
Vol 249 (5) ◽  
pp. C456-C463 ◽  
Author(s):  
R. J. Schimmel ◽  
L. McCarthy ◽  
D. Dzierzanowski
Keyword(s):  
Adenylate Cyclase ◽  
Adenosine Deaminase ◽  
Pertussis Toxin ◽  
Insulin Action ◽  
Brown Fat ◽  
Fat Cells ◽  
Inhibitory Effects ◽  
Brown Adipocytes ◽  
Stimulation Of ◽  
Adrenergic Agent

This communication reports the effects of the exotoxin of Bordetella pertussis (pertussis toxin) on hamster brown fat cells. Pertussis toxin significantly increased the lipolytic and respiratory responses to isoproterenol but did not increase the basal rates of either of these processes. In contrast, the stimulation of respiration by the alpha-adrenergic agent phenylephrine was not altered by pertussis toxin. The inhibitory effects of adenosine on stimulated lipolysis, respiration, and adenylate cyclase activity were completely abolished by pertussis toxin, as was the ability of methylxanthines or adenosine deaminase to potentiate isoproterenol stimulation of respiration or lipolysis. These effects of pertussis toxin were associated with an ADP ribosylation of a single membrane protein having a molecular weight of approximately 41. These data demonstrate that pertussis toxin can prevent the inhibitory action of adenosine on brown fat cells and suggest that the effects of the nucleoside on these cells results from inhibition of adenylate cyclase. We further suggest that the enhanced responses to isoproterenol in pertussis-treated adipocytes results from a blockade of the action of endogenous adenosine. In addition to blocking adenosine action, pertussis toxin also abolished the antilipolytic effect of insulin. However, because the antilipolytic effect of insulin was prevented by adenosine deaminase and 3-isobutyl-1-methylxanthine and restored by 2-chloroadenosine, we conclude that insulin action on these cells is dependent on adenosine. Thus pertussis toxin blockade of insulin action appears to be secondary to blockade of adenosine action.

scholarly journals Modifications of major aspects of myocardial ribonucleic acid metabolism as a response to noradrenaline. Behaviour of polyadenylate polymerase and ribonucleic acid polymerase, acetylation of histones and rate of synthesis of polyamines

1977 ◽  
Vol 168 (3) ◽  
pp. 333-340 ◽  
Author(s):  
A Casti ◽  
A Corti ◽  
N Reali ◽  
G Mezzetti ◽  
G Orlandini ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Ribonucleic Acid ◽  
Acid Metabolism ◽  
Specific Radioactivity ◽  
Rabbit Heart ◽  
Polymerase Activity ◽  
Dibutyryl Cyclic Amp ◽  
General Increase ◽  
Stimulation Of

Noradrenaline added to perfused rabbit heart previously perfused with labelled precursors causes, after 2.5 and 5.0 min, a general increase of specific radioactivity or RNA in subcellular fractions, but no augmentation of acetylation of F2a2 and F2a1 histone fractions and no stimulation of DNA-dependent RNA polymerase activities. Synthesis of spermidine and spermine is enhanced at 10.0 min of treatment, when there is also a fall in specific radioactivity of RNA. The cytoplasmic Mn2+-stimulated polyadenylate polymerase activity is strongly enhanced 30s to 2.5 min after injection of noradrenaline or of dibutyryl cyclic AMP. Both the cyclic nucleotide and noradrenaline have no influence in vitro on the polyadenylate polymerase reaction.

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