Modulation by phenobarbital of the differentiation of 3T3 preadipocytes

1986 ◽  
Vol 64 (11) ◽  
pp. 1141-1146 ◽  
Author(s):  
Joel G. Parkes ◽  
Roshan A. Hussain ◽  
David M. Goldberg
Keyword(s):  
Lipoprotein Lipase ◽  
Cell Lines ◽  
Lipase Activity ◽  
Extracellular Enzyme ◽  
Lipoprotein Lipase Activity ◽  
Intact Cells ◽  
Intracellular Enzyme ◽  
Triglyceride Content ◽  
Increased Activity ◽  
Total Lipoprotein

The effect of phenobarbital upon the differentiation of two preadipocyte cell lines, 3T3 F442A and 3T3 L-1, was examined by measuring the synthesis and secretion of lipoprotein lipase. Extracellular enzyme was measured by treating intact cells with heparin, and the intracellular enzyme was subsequently assayed in cell homogenates. When confluent cultures of 3T3 F442A cells were treated with insulin, the cells underwent differentiation as indicated by increased activity of lipoprotein lipase within 6 days, followed in turn by increased levels of protein and triglyceride. Addition of phenobarbital with insulin enhanced total lipoprotein lipase, protein, and triglyceride content. The activity of lipoprotein lipase accumulated in the heparin-releasable fraction during differentiation was increased 2- to 3-fold and the intracellular enzyme was enhanced 15- to 20-fold by the addition of phenobarbital. The ability of phenobarbital to modulate differentiation was dependent upon the time of addition. When added early in the postconfluent period, there was a greater increase in lipoprotein lipase activity than when the drug was added at later times. Phenobarbital also stimulated lipoprotein lipase in differentiating 3T3 L-1 cells in the presence of insulin, although lipoprotein lipase activity was moderately enhanced by phenobarbital alone in these cells. These results suggest that phenobarbital may affect the conversion of adipoblasts into preadipocytes and thereby increase the proportion of cells susceptible to the differentiating stimulus.

Serum Activation of Lipoprotein Lipase from Sheep Adipose Tissue

1985 ◽  
Vol 38 (1) ◽  
pp. 131
Author(s):  
RK Tume ◽  
RF Thornton
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity ◽  
Nutritional Restriction ◽  
Adipose Tissue Lipoprotein Lipase ◽  
Increased Activity ◽  
Substrate Concentrations

The effects of species and plane of nutrition on serum activation of sheep adipose tissue lipoprotein lipase were studied over a range of substrate (triolein) concentrations. Serum, either from two species or from the same species on a different plane of nutrition, had differing effects on adipose tissue lipoprotein lipase activity. Serum from fed sheep was more effective than serum from fed rats in activating sheep adipose tissue lipoprotein lipase at low substrate concentrations. Serum taken from sheep on a restricted plane of nutrition, stimulated adipose tissue lipoprotein lipase activity at physiological substrate concentrations. The increased activity promoted by the factor(s) present in serum would ensure that those tissues (e.g. cardiac and skeletal muscle) which continue to synthesize lipoprotein lipase during fasting or nutritional restriction, are able to assimilate the relatively low amounts of circulating triacylglycerol.

scholarly journals The lipoprotein lipase (clearing-factor lipase) activity of cells isolated from rat cardiac muscle

1978 ◽  
Vol 174 (2) ◽  
pp. 663-666 ◽  
Author(s):  
P Chohan ◽  
A Cryer
Keyword(s):  
Cardiac Muscle ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity ◽  
Cell Type ◽  
Cardiac Muscle Cells ◽  
Adult Rat ◽  
Rat Hearts ◽  
Major Cell Type ◽  
Total Lipoprotein

The total lipoprotein lipase activity recovered in suspension of cells prepared from adult rat hearts was unaffected by the nutritional state of the animals used. The enzyme activity present in the cell suspensions was almost exclusively associated with the cardiac muscle cells present as the major cell type.

scholarly journals Changes with starvation in the rat of the lipoprotein lipase activity and hydrolysis of triacylglycerols from triacylglycerol-rich lipoproteins in adipose tissue preparations

1983 ◽  
Vol 210 (3) ◽  
pp. 639-643 ◽  
Author(s):  
M A Lasunción ◽  
E Herrera
Keyword(s):  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Extracellular Enzyme ◽  
Tissue Preparation ◽  
Lipoprotein Lipase Activity ◽  
Fat Pad ◽  
Isolated Adipocytes ◽  
Hydrolysis Of

Lipoprotein lipase activity was higher in fat-pad pieces than in isolated adipocytes from the same fed rats, whereas hydrolysis of triacylglycerols from triacylglycerol-rich lipoproteins was similar in the two preparations when incubated either in basal conditions or in the presence of heparin. In both preparations there was a similar release of lipoprotein lipase activity into the medium during basal incubation, enhanced by the presence of heparin. In fat-pad pieces, but not in isolated adipocytes, incubation with heparin produced a decrease in the lipoprotein lipase activity measured in the tissue preparation. In fat-pad pieces from 24 h-starved rats, lipoprotein lipase activity was the same as in isolated adipocytes from the same animals and incubation with heparin did not affect the appearance of lipoprotein lipase in the medium or the utilization of triacylglycerols from triacylglycerol-rich lipoproteins. These results support the following conclusions. (1) The effectiveness of lipoprotein lipase in adipose tissue preparations in vitro depends more on its availability to the substrate than on its total activity. (2) Heparin acts on adipose tissue preparations from fed animals both by enhancing the release of pre-existing extracellular enzyme (which is absent in isolated adipocytes) and by enhancing the transfer outside the cells of the intracellular (and mainly undetectable) enzyme that is activated in the secretion process. (3) In adipose tissue from starved animals there is not only a decrease in the active extracellular form of lipoprotein lipase activity but also a reduction in the intracellular (and mainly undetectable) pool of the enzyme.

Indirect Measurement of the Production of Plasma Triacylglycerols by Horses Given a High-Fat Diet

2002 ◽  
Vol 72 (3) ◽  
pp. 142-146 ◽  
Author(s):  
Suzanne Geelen ◽  
Marianne Sloet van Oldruitenborgh-Oosterbaan ◽  
Anton Beynen
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
High Fat Diet ◽  
Control Diet ◽  
Indirect Measurement ◽  
Lipoprotein Lipase Activity ◽  
High Fat ◽  
Low Fat ◽  
Rate Of Increase ◽  
Total Lipoprotein

The hypothesis tested was that the feeding of extra fat to horses would raise the production of plasma triacylglycerols (TAG). To measure TAG secretion, the indirect Triton method was used. Six adult horses were given a low-fat control or a high-fat diet according to a crossover design. In keeping with our earlier work, the high-fat diet lowered fasting plasma TAG concentrations by an average of 42% and raised post-heparin total lipoprotein lipase activity by 79%. The rate of increase in plasma TAG concentration after Triton administration was 49% lower when the horses were fed the high-fat diet instead of the low-fat control diet. Thus, the hypothesis is rejected. It is suggested that the dose of Triton used in the study might have been too low to fully depress lipoprotein lipase activity, leading to an outcome of the study that was opposite to that expected.

scholarly journals Lipoprotein lipase activity of rat cardiac muscle. Changes in the enzyme activity during incubations of isolated cardiac-muscle cells in vitro

1980 ◽  
Vol 186 (3) ◽  
pp. 873-879 ◽  
Author(s):  
P Chohan ◽  
A Cryer
Keyword(s):  
Enzyme Activity ◽  
Cardiac Muscle ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Muscle Cells ◽  
Total Activity ◽  
Lipoprotein Lipase Activity ◽  
Cardiac Muscle Cells ◽  
Intracellular Enzyme

1. Isolated cardiac-muscle cells from the hearts of adult rats were shown to retain a high amount of viability during 4 h of incubation when viability was assessed by Trypan Bue stain exclusion and intracellular enzyme leakage. 2. The cells also retained their ability to take up O2 and utilize added substrates over the period of incubation at both 25 and 30 degrees C. 3. When cells from the hearts of fed rats were incubated in a buffered-salts solution at pH 7.4 in the presence of amino acids and heparin, lipoprotein lipase activity in the medium increased progressively. 4. During these incubations the intracellular activity of the enzyme remained constant and the total activity of lipoprotein lipase in the system (cells plus medium) increased by 80% over the 4 h of incubation at 25 degrees C. 5. In the absence of heparin only low amounts of enzyme activity were detectable in the medium and the total lipoprotein lipase activity in the system remained constant. 6. The measurement of lipoprotein lipase activity in either fresh homogenates of the cells or in homogenates of acetone/diethyl ether-dried powders of the cells had no effect on the overall pattern of activity change during the incubations, although as reported previously the total activity detected with acetone/diethyl either-dried preparations was approx. 3-fold higher than with fresh cell homogenates. 7. The observations were compared with published data on lipoprotein lipase activity changes in neonatal heart cell cultures maintained in vitro.

scholarly journals Retention of glucose by N-linked oligosaccharide chains impedes expression of lipoprotein lipase activity: effect of castanospermine.

1992 ◽  
Vol 33 (9) ◽  
pp. 1343-1349
Author(s):  
H Masuno ◽  
EJ Blanchette-Mackie ◽  
CJ Schultz ◽  
AE Spaeth ◽  
RO Scow ◽  
...  
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity ◽  
Activity Effect
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