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.

Lipoprotein lipase-suppressing mediator in serum of endotoxin-treated rats

1986 ◽  
Vol 251 (4) ◽  
pp. E470-E476 ◽  
Author(s):  
G. J. Bagby ◽  
C. B. Corll ◽  
J. J. Thompson ◽  
L. A. Wilson
Keyword(s):  
Lipoprotein Lipase ◽  
Exposure Time ◽  
Lipase Activity ◽  
Significant Suppression ◽  
Lipoprotein Lipase Activity ◽  
Activity Maximum ◽  
A Cell

The conditions under which lipoprotein lipase-suppressing mediator is present in serum of endotoxin-treated rats was determined in this study. The suppression of lipoprotein lipase activity in 3T3-L1 cells was used as a bioassay for mediator in serum. Endotoxin (0.1-10 micrograms/ml) and serum from control rats did not suppress lipoprotein lipase activity. Maximum suppression of cell lipoprotein lipase activity (70%) by serum from endotoxic rats required a cell exposure time of 5 h. At the highest dose of endotoxin used (1 mg/100 g), significant suppression was achieved when cells were incubated with 0.5% serum from endotoxic rats (P less than 0.05). Serum obtained 2-3 h after endotoxin injection possessed the maximal ability to suppress lipase activity, but suppressing activity was not present in serum collected 8 h after endotoxin. Rats rendered tolerant to endotoxin by 5 daily injections (0.1 mg/100 g) did not contain detectable levels of mediator in serum after endotoxin injection. The results demonstrate that the presence of lipoprotein lipase activity-suppressing mediator is transitory after in vivo exposure of naive rats to endotoxin, but does not appear in serum of endotoxin tolerant rats.

Regulation of lipoprotein lipase activity in cardiac myocytes from control and diabetic rat hearts by plasma lipids

1992 ◽  
Vol 70 (9) ◽  
pp. 1271-1279 ◽  
Author(s):  
Brian Rodrigues ◽  
Janice E. A. Braun ◽  
Michael Spooner ◽  
David L. Severson
Keyword(s):  
Lipoprotein Lipase ◽  
Cardiac Myocytes ◽  
Lipase Activity ◽  
Plasma Lipids ◽  
Inhibitory Effect ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Lipoprotein Lipase Activity ◽  
Triton Wr 1339 ◽  
Plasma Triacylglycerol

The objective of this investigation was to test the hypothesis that the diabetes-induced reduction in lipoprotein lipase activity in cardiac myocytes may be due to hypertriglyceridemia. Administration of 4-aminopyrazolopyrimidine (50 mg/kg) to control rats for 24 h reduced plasma triacylglycerol levels and increased the heparin-induced release of lipoprotein lipase into the incubation medium of cardiac myocytes. The acute (3–5 days) induction of diabetes by streptozotocin (100 mg/kg) produced hypertriglyceridemia and reduced heparin-releasable lipoprotein lipase activity in cardiac myocytes. Treatment of diabetic rats with 4-aminopyrazolopyrimidine resulted in a fall in plasma triacylglycerol content and increased heparin-releasable lipoprotein lipase activity. Administration of Triton WR-1339 also resulted in hypertriglyceridemia, but the heparin-induced release of lipoprotein lipase from control cardiac myocytes was not reduced in the absence of lipolysis of triacylglycerol-rich lipoproteins. Treatment with Triton WR-1339 did, however, increase the heparin-induced release of lipoprotein lipase from diabetic cardiac myocytes. Preparation of cardiac myocytes with 0.9 mM oleic acid resulted in a decrease in both total cellular and heparin-releasable lipoprotein lipase activities. These results suggest that the diabetes-induced reduction in heart lipoprotein lipase activity may, at least in part, be due to an inhibitory effect of free fatty acids, derived either from lipoprotein degradation or from adipose tissue lipolysis, on lipoprotein lipase activity in (and (or) release from) cardiac myocytes.Key words: diabetes, plasma triacylglycerols, cardiac myocytes, lipoprotein lipase.

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.

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 release of 3′:5′-cyclic monophosphate from the isolated perfused rat heart

1975 ◽  
Vol 152 (2) ◽  
pp. 429-432 ◽  
Author(s):  
John A. O'Brien ◽  
Richard C. Strange
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
Perfused Rat Heart ◽  
Cyclic Monophosphate ◽  
Isolated Perfused Rat Heart ◽  
Rat Hearts ◽  
Basal Release ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Although basal release of cyclic AMP from isolated perfused rat hearts was not measurable, isoprenaline induced substantial release of the nucleotide, suggesting that in vivo the myocardium can contribute to plasma cyclic AMP. Anoxia also increased the amount of cyclic AMP released, but insulin and nicotinate alone or in combination had no effect.

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 Effect of protamine on lipoprotein lipase and hepatic lipase in rats

1994 ◽  
Vol 304 (3) ◽  
pp. 959-966 ◽  
Author(s):  
M Hultin ◽  
G Olivecrona ◽  
T Olivecrona
Keyword(s):  
Endothelial Cell ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Binding Sites ◽  
Hepatic Lipase ◽  
Lipoprotein Lipase Activity ◽  
Cell Surfaces ◽  
Intravenous Injections

The polycation protamine impedes the catabolism of triglyceride-rich lipoproteins and this has been suggested to be due to intravascular inactivation of lipoprotein lipase. We have made intravenous injections of protamine to rats and found that both lipoprotein lipase and hepatic lipase activities were released to plasma. The effect of protamine was more short-lived than that obtained by injection of heparin. The release of hepatic lipase by protamine was as effective as the release by heparin, while the amount of lipoprotein lipase released by protamine was only about one-tenth of that released by heparin. This was not due to inactivation of lipoprotein lipase, since injection of an excess of heparin 10 min after injection of protamine released as much lipoprotein lipase activity to plasma as in controls. The results in vivo differed from those obtained in model experiments in vitro. Protamine was able to almost quantitatively release both lipoprotein lipase and hepatic lipase from columns of heparin-agarose. The displacement was dependent on the total amount of protamine that had passed over the column, indicating that it was due to occupation by protamine of all available binding sites. Our results in vivo showed that the binding sites for lipoprotein lipase were not blocked as efficiently as those for hepatic lipase, indicating that the binding structures were not identical. It was concluded that the impaired turnover of lipoproteins by protamine probably was due to prevention of binding of the lipoproteins to endothelial cell surfaces rather than to impaired lipase function.

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