Lipoprotein lipase activity in human heart

1963 ◽  
Vol 205 (2) ◽  
pp. 401-404 ◽  
Author(s):  
J. David Schnatz ◽  
John W. Ormsby ◽  
Robert H. Williams
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Human Heart ◽  
Ammonium Hydroxide ◽  
Cottonseed Oil ◽  
Heart Tissue ◽  
Lipoprotein Lipase Activity ◽  
Oil Emulsion ◽  
Ventricular Tissue ◽  
Hydrolysis Of

Human ventricular tissue was obtained 11–28 hr post mortem, homogenized in ammonium hydroxide, and tested for its ability to catalyze the hydrolysis of an "activated" cottonseed oil emulsion. Lipolysis, as indicated by a rise in fatty acids, occurred in the presence of a freshly prepared homogenate, but not in the presence of a boiled homogenate. Sodium chloride, 1 m, inhibited the reaction, but sodium fluoride, 0.2 m, did not. An activated cottonseed oil emulsion was more readily hydrolyzed than a "nonactivated" cottonseed oil emulsion. Approximately 50% of the activity of the homogenate sedimented at a gravitational force produced by centrifugation at 800 g for 10 min. The conclusion is that human heart tissue, like animal heart, contains lipoprotein lipase activity and that this activity is associated, in part, with the heavier cellular particles.

scholarly journals The functional status of lipoprotein lipase in rat liver

1968 ◽  
Vol 108 (3) ◽  
pp. 483-487 ◽  
Author(s):  
P A Mayes ◽  
J M Felts
Keyword(s):  
Functional Status ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Heart Tissue ◽  
Lipoprotein Lipase Activity ◽  
Plasma Triglycerides ◽  
Hydrolysis Of ◽  
Marked Suppression ◽  
Fat Meal ◽  
Direct Hydrolysis

1. Acetone-dried powders of liver and heart tissues from rats given a high-carbohydrate diet or a fat meal were assayed for lipoprotein lipase activity. Heart tissue showed typical lipoprotein lipase activity, whereas none was detected in liver by the usual assay procedures. 2. When mixed acetone-dried powders were prepared from heart plus liver, there was a marked suppression of the expected activity, indicating that an inhibitor was present in the liver. This inhibition was partially overcome in the presence of relatively large amounts of heparin. 3. Lipoprotein lipase was also detected in liver alone when large quantities of heparin were added to the assay system. 4. No increase in lipoprotein lipase activity in either liver or heart was detected when rats were given a fat meal. 5. It is concluded that the liver of the rat contains lipoprotein lipase that is normally present in an inactive state. The results imply that a heparinase is the agent responsible for the inactivation. 6. The significance of the non-functional status of lipoprotein lipase in the liver is discussed. The results support the view that direct hydrolysis of plasma triglycerides by the liver is not a significant physiological process.

Heparin-released lipolytic and esterolytic activities of human and rabbit plasmas

1961 ◽  
Vol 201 (5) ◽  
pp. 915-922 ◽  
Author(s):  
B. Shore ◽  
V. Shore
Keyword(s):  
Fatty Acids ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Ethyl Esters ◽  
Lipoprotein Lipase Activity ◽  
Hydrolysis Of

The enzymes released into both human and rabbit plasmas by heparin injection hydrolyzed, in addition to triglyceride moieties of lipoproteins, a number of mono- and diglycerides of C16 and C18 fatty acids after in vitro addition of the unemulsified glycerides to the plasma. In human postheparin plasma, these enzymes also hydrolyzed glycerides of butyric and caproic acids. The pure triglycerides and methyl or ethyl esters of C16 and C18 fatty acids were not substrates. The heparin-released activities for the hydrolysis of glycerides added in vitro persisted after all activity for the lipolysis of lipoproteins had been destroyed by heat. These activities also differed from lipoprotein lipase activity with respect to the effects of 1 m NaCl, dialysis, and aging the plasma at 4 C. It appears that heparin releases into the blood more than one enzyme or more than one form of an enzyme which may be involved in a stepwise degradation to fatty acids and glycerol of the triglyceride moieties of lipoproteins of density less than 1.007 g/ml.

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.

Effect of Triton on Lipoprotein Lipase of Rat Plasma

1957 ◽  
Vol 188 (2) ◽  
pp. 399-402 ◽  
Author(s):  
Michael C. Schotz ◽  
A. Scanu ◽  
Irvine H. Page
Keyword(s):  
Fatty Acids ◽  
Lipoprotein Lipase ◽  
Intravenous Injection ◽  
Optical Density ◽  
Lipase Activity ◽  
Coconut Oil ◽  
Rat Plasma ◽  
Plasma Lipoproteins ◽  
Lipoprotein Lipase Activity ◽  
Oil Emulsion

When postheparin plasma was incubated with a coconut oil substrate, a decrease in optical density and an increase in unesterified fatty acids occurred. The increase in unesterified acids was prevented by previous intravenous injection of Triton to rats. Addition of post-Triton plasma to a system containing postheparin plasma and coconut oil emulsion inhibited the lipoprotein lipase activity. Incubation of Triton with coconut oil substrate before addition of postheparin plasma caused inhibition of lipoprotein lipase activity. It is concluded that inhibition of lipoprotein lipase activity by Triton is due to modification of the substrate such that the enzyme can no longer act. Further, it is suggested that the chief cause of Triton hyperlipemia is coating of the plasma lipoproteins by Triton resulting in their faulty catabolism.

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.

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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