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 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 Lipoprotein Lipase Activity and mRNA Are Up-Regulated by Refeeding in Adipose Tissue and Cardiac Muscle of Sheep

2000 ◽  
Vol 130 (4) ◽  
pp. 749-756 ◽  
Author(s):  
Muriel Bonnet ◽  
Christine Leroux ◽  
Yannick Faulconnier ◽  
Jean-François Hocquette ◽  
François Bocquier ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Cardiac Muscle ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity

scholarly journals The inhibition in vivo of lipoprotein lipase (clearing-factor lipase) activity by triton WR-1339

1976 ◽  
Vol 156 (3) ◽  
pp. 539-543 ◽  
Author(s):  
J Borensztajn ◽  
M S Rone ◽  
T J Kotlar
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity ◽  
Rat Hearts ◽  
Maximum Inhibition ◽  
Triton Wr 1339 ◽  
Perfused Rat Hearts ◽  
Hydrolysis Of ◽  
Isolated Perfused Rat Hearts

1. Lipoprotein lipase activity was measured in heart homogenates and in heparin-releasable and non-releasable fractions of isolated perfused rat hearts, after the intravenous injection of Triton WR-1339. 2. In homogenates of hearts from starved, rats, lipoprotein lipase activity was significantly inhibited (P less than 0.001) 2h after the injection of Triton. This inhibition was restricted exclusively to the heparin-releasable fraction. Maximum inhibition occurred 30 min after the injection and corresponded to about 60% of the lipoprotein lipase activity that could be released from the heart during 30 s perfusion with heparin. 3. Hearts of Triton-treated starved rats were unable to take up and utilize 14C-labelled chylomicron triacylglycerol fatty acids, even though about 40% of heparin-releasable activity remained in the hearts. 4. It is concluded that Triton selectively inhibits the functional lipoprotein lipase, i.e. the enzyme directly involved in the hydrolysis of circulating plasma triacylglycerols. 5. Lipoprotein lipase activities measured in homogenates of soleus muscle of starved rats and adipose tissue of fed rats were decreased by 25 and 39% respectively after Triton injection. It is concluded that, by analogy with the heart, these Triton-inhibitable activities correspond to the functional lipoprotein lipase.

scholarly journals Rapid effects of isoprenaline, glucagon, pacing and potassium arrest on post-heparin lipoprotein lipase activity in the perfused rat heart

1979 ◽  
Vol 182 (1) ◽  
pp. 253-255 ◽  
Author(s):  
J Simpson
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Rat Heart ◽  
Lipoprotein Lipase Activity ◽  
Perfusion Medium ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Isolated Rat

The amount of lipoprotein lipase activity released by heparin into the perfusion medium of isolated rat hearts could be increased within 60s by isoprenaline, glucagon or pacing. Potassium arrest and propranolol inhibited the effects of isoprenaline and pacing respectively.

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.

Lipoprotein lipase activity of adult rat cardiocytes

1980 ◽  
Vol 620 (1) ◽  
pp. 63-69 ◽  
Author(s):  
George V. Vahouny ◽  
Ashlesha Tamboli ◽  
Mary Vander Maten ◽  
Hans Jansen ◽  
Twu Jer-Shung ◽  
...  
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity ◽  
Adult Rat

scholarly journals Lipoprotein lipase activity of rat cardiac muscle. The intracellular distribution of the enzyme between fractions prepared from cardiac muscle and cells isolated from the hearts of fed and starved animals

1979 ◽  
Vol 181 (1) ◽  
pp. 83-93 ◽  
Author(s):  
P Chohan ◽  
A Cryer
Keyword(s):  
Cardiac Muscle ◽  
Lipoprotein Lipase ◽  
Diethyl Ether ◽  
Lipase Activity ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Lipoprotein Lipase Activity ◽  
Powder Preparation ◽  
Isolated Cells ◽  
Relative Specific Activity

1. Subcellular fractions, characterized by using morphological, compositional and enzymic markers, were prepared from rat heart tissue and cells isolated from the hearts of fed and 24 h-starved rats. 2. The lipoprotein lipase activity of fractions from whole tissue and isolated cells was determined in either fresh fractions or in acetone/diethyl ether powders of the fractions. 3. Lipoprotein lipase activity was present in all the fractions from tissue and cells, but was found to be of highest relative specific activity in the microsomal () fractions. 4. In fractions prepared from the isolated cells of hearts from starved rats the proportion of the total lipoprotein lipase present and its relative specific activity in the microsomal fraction were greater than in the equivalent fractions from fed animals. 5. The enhancement of lipoprotein lipase activity as a result of the acetone/diethyl ether powder preparation of fractions was most extensive in the microsomal fractions. 6. Investigation of the microsomal fraction showed that the lipoprotein lipase activity present was in two pools, one of which was within endoplasmic-reticulum vesicles. 7. The observations were consistent with the possibility that the cardiac-muscle cell could be the origin of the lipoprotein lipase activity functional in triacylglycerol uptake by the heart.

Instability of endothelium-bound lipoprotein lipase activity in perfused rat hearts

1984 ◽  
Vol 62 (2-3) ◽  
pp. 89-93 ◽  
Author(s):  
Simon-Pierre Noël
Keyword(s):  
Enzymatic Activity ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Aortic Pressure ◽  
Lipoprotein Lipase Activity ◽  
Perfused Heart ◽  
Experimental Conditions ◽  
Rat Serum ◽  
Rat Hearts ◽  
Heart Perfusion

The enzymatic activity of endothelium-bound lipoprotein lipase was measured in rat hearts perfused for 1 h at 37 °C. Viability parameters such as beating rate, flow rate, aortic pressure, and oxygen consumption were all kept strictly constant during the entire perfusion time. The lipase activity was determined by input–output difference of the triacylglycerol content in the nonrecirculating heart perfusate which contained either an artificial triolein emulsion or rat lymph chylomicrons. With either substrate, the lipase activity decreased with time: approximately 2% of initial lipase activity was lost per minute. The presence of rat serum (10%) in heart perfusate enhanced the rate at which the lipase activity disappeared. Only a small portion of the lipoprotein lipase activity, which was lost from the perfused heart, was recovered in the outflow perfusate. Our data demonstrate that, under our experimental conditions, the enzymatic activity of rat heart lipoprotein lipase does not remain constant during heart perfusion. Caution should therefore be taken by users of heart perfusion technique, especially for those who need constant lipoprotein lipase activity. The results suggest that the first step in the catabolic fate of endothelium-bound cardiac lipoprotein lipase is the loss of its catalytic activity. Whether the inactivated enzyme is released from the endothelium or remains in situ is not yet known.

Sign in / Sign up

Export Citation Format

Share Document