scholarly journals Effect of diabetes on acid and neutral triacylglycerol lipase and on lipoprotein lipase activities in isolated myocardial cells from rat heart

1986 ◽  
Vol 238 (1) ◽  
pp. 233-238 ◽  
Author(s):  
I Ramírez ◽  
D L Severson
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Specific Activity ◽  
Subcellular Fractions ◽  
Capillary Endothelium ◽  
Myocardial Cells ◽  
Protamine Sulphate ◽  
Triacylglycerol Lipase ◽  
Neutral Lipase ◽  
High Concentrations

A neutral triacylglycerol lipase activity that is separate and distinct from lipoprotein lipase (LPL) could be measured in homogenates of myocardial cells if protamine sulphate and high concentrations of albumin were included in the assay. This neutral lipase was predominantly particulate, with the highest relative specific activity in microsomal subcellular fractions. The induction of diabetes by the administration of streptozotocin to rats resulted in a decrease in LPL activity in myocyte homogenates and in particulate subcellular fractions, but the percentage of cellular LPL activity that was released during incubation of myocytes with heparin was normal. In contrast, neutral lipase activity was increased in diabetic myocyte homogenates and microsomal fractions. Acid triacylglycerol lipase activity was not changed in diabetic myocytes. The decrease in LPL in myocytes owing to diabetes may result in the decreased functional LPL activity at the capillary endothelium of the diabetic heart.

Modulation by phenobarbital of lipolytic activity in postheparin plasma and tissues of the rat

1982 ◽  
Vol 60 (11) ◽  
pp. 1077-1083 ◽  
Author(s):  
David M. Goldberg ◽  
M. Waheed Roomi ◽  
Alex Yu
Keyword(s):  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipolytic Activity ◽  
Sodium Dodecyl ◽  
Male Rats ◽  
Lipoprotein Lipase Activity ◽  
Protamine Sulphate ◽  
Triacylglycerol Lipase ◽  
Postheparin Lipolytic Activity

Male rats injected with phenobarbital at a dose of 100 mg/kg for 5 days manifested increased postheparin lipolytic activity of fasting plasma. Inhibition studies with protamine sulphate, 1 M NaCl, and sodium dodecyl sulphate revealed that the activities of both lipoprotein lipase and hepatic triacylglycerol lipase were increased in the postheparin plasma of the drug-treated rats. Adipose tissue lipoprotein lipase activity was also increased in the phenobarbital-treated rats. The triacylglycerol lipase activity elutable by heparin from liver slices and the residual activity of liver microsomes increased significantly in the drug-treated rats. Lipoprotein lipase of cardiac muscle and red skeletal muscle was unaltered by phenobarbital treatment. The increased postheparin lipolytic activity of fasting phenobarbital-treated rats seems to be accountable through increased lipoprotein lipase activity of adipose tissue and increased triacylglycerol lipase activity of liver, both of which may contribute to the lowered fasting concentrations of serum triacylglycerol mediated by the drug, as previously reported.

Methylamine does not inhibit rates of endogenous lipolysis in isolated myocardial cells from rat heart

1987 ◽  
Vol 65 (2) ◽  
pp. 226-229 ◽  
Author(s):  
Albert Kryski Jr. ◽  
Terje S. Larsen ◽  
Ignasi Ramírez ◽  
David L. Severson
Keyword(s):  
Fatty Acids ◽  
Lipase Activity ◽  
Rat Heart ◽  
Diabetic Rat ◽  
Myocardial Cells ◽  
Acid Lipase ◽  
Ph Optimum ◽  
Triacylglycerol Lipase ◽  
Rat Hearts ◽  
Lysosomotropic Agent

Triacylglycerol lipase activity with a pH optimum of 5 was present in homogenates of myocardial cells from rat heart. Acid lipase activity was inhibited by serum, heparin, and increased ionic strength. Methylamine, a lysosomotropic agent, did not inhibit the basal or isoproterenol-stimulated rate of endogenous lipolysis as measured by glycerol output from control myocytes. Similarly, accelerated rates of glycerol output that are a consequence of an elevation in the intracellular stores of triacylglycerols in myocytes from diabetic rat hearts and from myocytes prepared with free fatty acids in the isolation solutions were not reduced by methylamine. Therefore, the acid lysosomal triacylglycerol lipase must not be involved in the mobilization of endogenous triacylglycerols in myocardial cells from rat heart.

scholarly journals Intralipid administration induces a lipoprotein lipase-like activity in the livers of starved adult rats

1986 ◽  
Vol 236 (1) ◽  
pp. 273-278 ◽  
Author(s):  
S Vilaró ◽  
M Reina ◽  
I Ramírez ◽  
M Llobera
Keyword(s):  
Lipoprotein Lipase ◽  
Adult Rats ◽  
Protamine Sulphate ◽  
Triacylglycerol Lipase ◽  
Apolipoprotein C ◽  
Hepatic Triacylglycerol

The administration of Intralipid to starved adult rats induces the appearance of lipoprotein lipase (LPL)-like activity in the liver, whereas the so-called hepatic triacylglycerol lipase is unaffected. This LPL-like activity is eluted by 1.5 M-NaCl from heparin-Sepharose columns. This partially purified fraction is inhibited by 1.0 M-NaCl (91%) and by 1.0 mg of protamine sulphate/ml (79%), whereas it is stimulated 69-fold by the presence of 8.0 micrograms of apolipoprotein C-II/ml and inhibited by anti-LPL antibodies. We conclude that Intralipid administration induces the appearance of LPL activity in livers of starved adult rats. Its possible origin is discussed.

Characterization of the triacylglycerol lipase activity in three types of rat skeletal muscle

1987 ◽  
Vol 65 (3) ◽  
pp. 317-322 ◽  
Author(s):  
Wayne C. Miller ◽  
Warren K. Palmer ◽  
David A. Arnall ◽  
Lawrence B. Oscai
Keyword(s):  
Skeletal Muscle ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipolytic Activity ◽  
Vastus Lateralis ◽  
High Energy ◽  
Glycolytic Flux ◽  
Ph Optimum ◽  
Triacylglycerol Lipase ◽  
Triglyceride Lipase

The purpose of this study was to characterize the lipolytic activity of the alkaline triglyceride lipase in homogenates of three types of skeletal muscle obtained from heparin-perfused rat hindlimb. Specifically, the red portion of the vastus lateralis, the white portion of the vastus lateralis, and the soleus muscles were examined. To remove capillary-bound lipoprotein lipase from the capillary beds, muscle was perfused with an erythrocyte-free buffer containing 4% albumin, 5 units of heparin/mL, and 7.5 μM adenosine. Adenosine reduced perfusion pressure from 117 ± 5 to 86 ± 6 mmHg (1 mmHg = 133.32 Pa), providing evidence for an effective vasodilation. This vasodilation increased the amount of lipoprotein lipase removed from the capillary beds. By the end of the experiment, perfusates were lipoprotein lipase-free. Oxygen supply to the perfused hindlimb appeared adequate as evidenced by similar high energy phosphate values for perfused and contralateral control tissues. For example, in soleus muscle, ATP content was 4.5 ± 0.6 vs. 4.2 ± 0.3 μmol/g, ADP concentration was 1.0 ± 0.2 vs. 1.4 ± 0.2 μmol/g, and creatine phosphate level was 12.9 ± 0.7 vs. 11.0 ± 0.6 μmol/g for perfused and contralateral control soleus, respectively. In addition, K+ output by the hindlimb was negligible, while glycolytic flux of perfused muscle was similar to that measured in control tissue. The findings that triglyceride levels of soleus and red vastus lateralis were decreased suggest that endogenous triglyceride was providing energy for the hindlimb during perfusion. Skeletal muscle triglyceride lipase activity was stimulated by serum and heparin, inhibited by NaCl and protamine, and had a pH optimum of 8.1. These results are consistent with the hypothesis that the major lipolytic activity present in the intracellular compartment of skeletal muscle is the alkaline triglyceride lipase with characteristics similar to those of lipoprotein lipase.

scholarly journals The storage and synthetic pools of heparin-releasable lipoprotein lipase and hepatic triacylglycerol lipase in the growing puppy

1982 ◽  
Vol 206 (3) ◽  
pp. 663-666 ◽  
Author(s):  
J B Das ◽  
I D Joshi ◽  
A I Philippart
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Marked Rise ◽  
Triacylglycerol Lipase ◽  
Endogenous Insulin ◽  
Age Related ◽  
Constant Rate ◽  
Hepatic Triacylglycerol ◽  
Insulin Secretory Response ◽  
Insulin Secretory Capacity

Age-related changes in the activities of extrahepatic lipoprotein lipase and hepatic triacylglycerol lipase were determined during a primed/constant-rate infusion of heparin for 2 h in puppies between birth and 18 weeks of age. The early (storage) and late (synthetic) phases were measured. Both phases of hepatic triacylglycerol lipase activity were well developed in the first week, reflecting the metabolic maturity of the liver at birth. During the 18 weeks of study, the activity remained relatively unchanged except for a sharp peak at 12 weeks. Extrahepatic lipoprotein lipase activity was low in the first 4 weeks of suckling. Its storage pool increased 6-fold in the next 14 weeks, with a less marked rise in its late (synthetic) pool. Sustained increases in the activity of this enzyme were first noticed during weaning, when the insulin-secretory response matured. Endogenous insulin-secretory capacity rather than the fat content of the feed appeared significant in the postnatal development of lipoprotein lipase (Clearing-factor lipase) activity.

scholarly journals Triacylglycerol Lipase Activities of Cultured Rat L6 Myoblasts

1985 ◽  
Vol 38 (1) ◽  
pp. 41
Author(s):  
RK Tume ◽  
F D Shaw
Keyword(s):  
Lipoprotein Lipase ◽  
Cell Lines ◽  
Lipase Activity ◽  
Maximum Velocity ◽  
Acid Lipase ◽  
Ph Optimum ◽  
Triacylglycerol Lipase ◽  
Inhibitory Component ◽  
Cell Homogenate ◽  
Hydrolysis Of

The utilization of exogenous triacylglycerol by fusing and non-fusing rat L6 myoblasts grown in culture was investigated. Although small quantities of triacylglycerol were accumulated by both cell lines during an incubation of 2 h, no evidence could be found for the presence of lipoprotein lipase, either in the cells or released into the medium. Cell homogenate studies confirmed the absence of lipoprotein lipase but revealed the presence of an acid lipase having a pH optimum at 4�6. Acid lipase activity was mainly associated with a 15 000 g pellet and was capable of hydrolysing triolein at maximum velocity in the millimolar range. Unlike lipoprotein lipase, acid lipase was strongly inhibited by serum and preliminary investigations suggest that the inhibitory component of serum is located amongst the higher density lipoproteins. It is likely that the acid lipase is of lysosomal origin and is responsible for the hydrolysis of internalized triacylglycerol for subsequent utilization by the cell.

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.

scholarly journals SITES OF LIPOPROTEIN LIPASE ACTIVITY IN ADIPOSE TISSUE PERFUSED WITH CHYLOMICRONS

1971 ◽  
Vol 51 (1) ◽  
pp. 1-25 ◽  
Author(s):  
E. Joan Blanchette-Mackie ◽  
Robert O. Scow
Keyword(s):  
Endothelial Cells ◽  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Capillary Endothelium ◽  
Lipoprotein Lipase Activity ◽  
Subendothelial Space ◽  
Capillary Endothelial Cells ◽  
E 600 ◽  
Cytochemical Reaction

Lipoprotein lipase activity was studied in rat parametrial adipose tissue perfused with chylomicrons and in gelatin blocks containing postheparin plasma and chylomicrons. The tissues and blocks were fixed in glutaraldehyde and incubated in 0.035 M CaCl2-0.1 M Tris medium (pH 8.3) at 38°C. The doubly labeled chylomicron triglycerides (glycerol-3H and palmitate-14C) in the tissues and blocks were hydrolyzed during incubation to free fatty acids (FFA) and the FFA remained in the specimens; hydrolysis was inhibited by 0.004 M diethyl paranitrophenyl phosphate (E-600). Incubated blocks and tissue were treated with 0.05 M Pb(NO3)2, postfixed in OsO4, dehydrated with acetone, embedded in Epon, and examined by electron microscopy. The incubated blocks contained electronlucent areas and granular and laminar precipitates at sites of hydrolysis. Similar precipitates were found in incubated tissue, within vacuoles and microvesicles of capillary endothelium, and in the subendothelial space (between the endothelium and pericytes), but not in the capillary lumen or in or near fat cells. The cytochemical reaction was greatly reduced, in blocks and tissues incubated with E-600. It is concluded that plasma glycerides are hydrolyzed by lipoprotein lipase in capillary endothelial cells and in the subendothelial space of adipose tissue and that glycerides across the endothelial cells within a membrane-bounded system.

scholarly journals The characterization of lipoprotein lipase isolated from the post-heparin plasma of the rainbow trout, Salmo gairdneri Richardson

1982 ◽  
Vol 203 (3) ◽  
pp. 727-734 ◽  
Author(s):  
E R Skinner ◽  
A M Youssef
Keyword(s):  
Lipoprotein Lipase ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Salmo Gairdneri ◽  
High Density Lipoproteins ◽  
Very Low Density Lipoproteins ◽  
Protamine Sulphate ◽  
Heparin Plasma

1. Intravenous injection of heparin into the trout resulted in the appearance in the plasma of a lipase with the properties of lipoprotein lipase. 2. The enzyme was purified to apparent electrophoretic homogeneity by means of heparin-Sepharose affinity chromatography. The enzyme was eluted with 1.5 M-NaCl and had a specific activity approx. 450-fold that of the post-heparin plasma. 3. The activity of the purified enzyme was inhibited by 1.0 M-NaCl and protamine sulphate and was stimulated between 3- and 8.8-fold by the addition of trout plasma. 4. The activity was strongly stimulated by trout very low density lipoproteins and to a lesser extent by high density lipoproteins. 5. The isolated enzyme fraction gave a single band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and had an apparent subunit M4 of 63 000. 6. These results suggest that the uptake of lipid by the tissues in the trout can occur by a process similar to that in mammals.

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