scholarly journals Regulation of Na+ transport in brown adipose tissue

1986 ◽  
Vol 235 (2) ◽  
pp. 545-552 ◽  
Author(s):  
K F LaNoue ◽  
C Koch ◽  
D Strzelecka ◽  
T P Kobylski
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Fat Cell ◽  
Isolated Cells ◽  
Intact Cells ◽  
Dependent Atpase ◽  
Brown Adipose ◽  
Active Transport System

In order to test the hypothesis that Na+, K+-ATPase (Na+,K+-dependent ATPase) is involved in the noradrenaline-mediated stimulation of respiration in brown adipose tissue, the effects of noradrenaline on Na+,K+-ATPase in isolated brown-fat-cell membrane vesicles, and on 22Na+ and K+ (86Rb+) fluxes across the membranes of intact isolated cells, were measured. The ouabain-sensitive fraction of the K+-dependent ATPase activity in the isolated membrane-vesicle preparation was small and was not affected by the presence of noradrenaline in the incubation media. The uptake of 86Rb+ into intact hormone-sensitive cells was inhibited by 80% by ouabain, but it was insensitive to the presence of noradrenaline. 22Na+ uptake and efflux measured in the intact cells were 8 times more rapid than the 86Rb+ fluxes and were unaffected by ouabain. This indicated the presence of a separate, more active, transport system for Na+ than the Na+,K+-ATPase. This is likely to be a Na+/Na+ exchange activity under normal aerobic conditions. However, under anaerobic conditions, or conditions simulating anaerobiosis (2 mM-NaCN), the unidirectional uptake of Na+ increased dramatically, while efflux was unaltered.

scholarly journals The β-adrenergic radioligand [3H]CGP-12177, generally classified as an antagonist, is a thermogenic agonist in brown adipose tissue

1989 ◽  
Vol 261 (2) ◽  
pp. 401-405 ◽  
Author(s):  
N Mohell ◽  
A Dicker
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Maximal Effect ◽  
Binding Studies ◽  
Isolated Cells ◽  
High Affinity ◽  
Brown Adipose ◽  
High Affinity Binding Site ◽  
Cgp 12177 ◽  
The One

The effect of CGP-12177, originally developed as a radioligand with antagonist properties for binding studies of beta-adrenergic receptors, was investigated in brown adipose tissue. Contrary to expectations, CGP-12177 showed clear agonist properties in experiments with hamster brown-fat cells, with a maximal effect in stimulating oxygen consumption similar to that of the physiological stimulator noradrenaline, and also with a potency similar to that of noradrenaline [EC50 (50% effective concn.) approx. 70 nM]. This value could be contrasted with the very high affinity of CGP-12177 (KD about 1 nM) for ligand-binding sites on the cells. It is therefore suggested that the high-affinity binding site may not be the one that mediates the CGP-12177-stimulated thermogenesis in isolated cells. Also, when injected into cold-adapted rats, CGP-12177 stimulated non-shivering thermogenesis similarly to noradrenaline. This observation, in conjunction with the reported low general sympathomimetic effect of CGP-12177, may indicate that CGP-12177 could be of interest for the development of anti-obesity drugs.

Controlled cellular energy conversion in brown adipose tissue thermogenesis

1978 ◽  
Vol 235 (3) ◽  
pp. R121-R129
Author(s):  
J. M. Horowitz ◽  
R. E. Plant
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Thermodynamic Description ◽  
Atp Synthesis ◽  
Brown Fat ◽  
Parallel Mechanisms ◽  
Fat Cell ◽  
Membrane Pump ◽  
Cellular Models ◽  
Brown Adipose

Brown adipose tissue serves as a model system for nonshivering thermogenesis (NST) since a) it has as a primary physiological function the conversion of chemical energy to heat; and b) preliminary data from other tissues involved in NST (e.g., muscle) indicate that parallel mechanisms may be involved. Now that biochemical pathways have been proposed for brown fat thermogenesis, cellular models consistent with a thermodynamic representation can be formulated. Stated concisely, the thermogenic mechanism in a brown fat cell can be considered as an energy converter involving a sequence of cellular events controlled by signals over the autonomic nervous system. A thermodynamic description for NST is developed in terms of a nonisothermal system under steady-state conditions using network thermodynamics. Pathways simulated include mitochondrial ATP synthesis, a Na+/K+ membrane pump, and ionic diffusion through the adipocyte membrane.

Cold-induced developmental changes in fat cell size and number in brown adipose tissue of the rat

1981 ◽  
Vol 240 (4) ◽  
pp. E379-E383 ◽  
Author(s):  
C. Senault ◽  
G. Cherqui ◽  
M. Cadot ◽  
R. Portet
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Cold Acclimation ◽  
Cell Size ◽  
Brown Fat ◽  
Control Group ◽  
Fat Cells ◽  
Fat Cell ◽  
Brown Adipose ◽  
The Mean

Seven-week-old Long-Evans rats were acclimated to a constant temperature of either 28 degrees C (control group) or 5 degrees C (cold-acclimated group). Cold acclimation induced a 70% increase in the interscapular brown adipose tissue (IBAT) relative mass, a 35% increase in DNA content, and a 44% decrease in triglyceride (TG) content, which resulted in a 51% decrease of the TG/DNA ratio. A procedure is described by which brown fat cells were isolated, with a yield of 21% from the IBAT of the control group and of 38% in the cold-acclimated group. In both groups, the brown fat cells accounted for 35-37% of the total cells in the tissue. Cold acclimation induced decreases in the mean fat cell diameter (about 20%), the mean fat cell TG content (50%), and the fat cell TG/DNA ratio (50%). The total number of IBAT fat cells was significantly increased in cold-acclimated rats. It is concluded that cold acclimation involves a hyperplasia of the IBAT, associated with a decrease of fat cell size without any alteration of the fat cell-to-nonfat cell ratio.

scholarly journals Regulation of rat foetal lipogenesis in brown adipose tissue in vivo and in isolated brown adipocytes during the last day of, and after prolonged, gestation

1987 ◽  
Vol 243 (2) ◽  
pp. 617-620 ◽  
Author(s):  
C Roncero ◽  
M Lorenzo ◽  
M Benito
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Incubation Medium ◽  
Brown Adipocyte ◽  
Isolated Cells ◽  
Pregnant Rats ◽  
Brown Adipocytes ◽  
Brown Adipose

Rates of lipogenesis in foetal isolated brown adipocytes from 22-day-pregnant rats were significantly increased by lactate plus pyruvate as major substrates in the incubation medium, in comparison with the endogenous rates. Insulin stimulated foetal brown-adipocyte lipogenesis, and adrenaline or noradrenaline and isoprenaline decreased lipogenesis. Glucagon had no effect on the lipogenic rate in brown adipocytes. Progesterone administration to the mother significantly increased the rates of lipogenesis in brown adipose tissue and in isolated brown adipocytes from 22-day foetuses. Prolongation of gestation by progesterone to day 23 decreased the rates of brown-adipose-tissue lipogenesis in vivo and in isolated cells in the post-mature foetuses.

Deprivation of corticosterone does not prevent onset of obesity in Zucker fa/fa pups

1987 ◽  
Vol 252 (4) ◽  
pp. E461-E466
Author(s):  
R. Bazin ◽  
E. Planche ◽  
F. Dupuy ◽  
S. Krief ◽  
M. Lavau
Keyword(s):  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Cell Volume ◽  
Frequency Distribution ◽  
Fatty Acid Synthase ◽  
Metabolic Abnormalities ◽  
Fat Cell ◽  
Brown Adipose

Adrenalectomy has been shown to reduce the development of obesity in adult Zucker fatty rat. In this study, we examined whether adrenalectomy could prevent the emergence of obesity and correct any of the first abnormalities to develop in fa/fa pups. Four-day-old Zucker pups were adrenalectomized and fed by adrenalectomized wet nurses until 11 days of age. The frequency distribution curves of fat cell volume clustered in two groups as they do in control litters, providing evidence that two phenotypes were present. Oxygen consumption measured at 8 days of age was significantly lower in fa/fa than in Fa/fa. Adrenalectomy did not restore the decreased oxygen consumption of fa/fa. In control litters, the GDP binding to brown adipose tissue mitochondria was twofold lower, whereas fatty acid synthase activity of this tissue was significantly increased in fa/fa pups. In inguinal adipose tissue of fa/fa pups, fatty acid synthase, and lipoprotein lipase activities were twice as active as in the tissue of lean pups. In adrenalectomized fa/fa pups, none of these metabolic abnormalities was corrected. The results demonstrate that adrenalectomy early in life did not prevent the emergence of obesity in suckling fa/fa rats.

L-alanine transport in isolated cells of interscapular brown adipose tissue in rat

1991 ◽  
Vol 11 (2) ◽  
pp. 65-71 ◽  
Author(s):  
A. Rodríguez-Martín ◽  
X. Remesar
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Transport Systems ◽  
Isolated Cells ◽  
Interscapular Brown Adipose Tissue ◽  
Alanine Transport ◽  
Brown Adipose ◽  
Diffusion Component ◽  
Dependent Transport ◽  
Kinetic Pattern

The pattern of L-alanine uptake in isolated cells of interscapular brown adipose tissue has been determined. The uptake can be divided into the diffusion component (Kd=0.55 min−1) and a saturable Na+-dependent transport (KM=0.87 mM and Vmax=155 nmol/min/106 cells). The saturable component can be subdivided into MeAIB-sensitive (KM=1.63 mM and Vmax=162 nmol/min/106 cells) and MeAIB-insensitive (KM=3.2 mM and Vmax=39.5 nmol/min/106 cells). This kinetic pattern could indicate the presence of transport system (s) that resemble the commonly described transport systems for alanine uptake in several tissues.

Membrane vesicles from brown adipose tissue: A tool for the study of amino acid transport. The case of L-alanine

1992 ◽  
Vol 12 (2) ◽  
pp. 115-122
Author(s):  
A. Rodríguez-Martín ◽  
N. Bel ◽  
X. Remesar
Keyword(s):  
Adipose Tissue ◽  
Amino Acid ◽  
Brown Adipose Tissue ◽  
Density Gradient ◽  
Gradient Method ◽  
Amino Acid Transport ◽  
Membrane Vesicles ◽  
Acid Transport ◽  
Brown Adipose

A density gradient method is used to isolate membrane vesicles from brown adipose tissue. These respond to changes in osmolarity and show the classical overshoot pattern when L-alanine uptake is assayed. Transport is shown to be effected by two components: a linear (Kd=0.498 min−1) and Na+-dependent saturable component (Km=2.3 mM) and a Vmax=19.9 pmol/μg protein·min). This pattern is similar to that shown by cells isolated from brown adipose tissue.

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