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.

Kinetics Of Anticoagulant And Lipolytic Activity And Radiolabel After Intravenous Administration Of 35S-Heparin Fractions Of Different Molecular Weight

1981 ◽  
Author(s):  
C A M de Swart ◽  
J J Sixma ◽  
A Nijmeijer ◽  
E Holmer ◽  
L O Andersson ◽  
...  
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Antithrombin Iii ◽  
Lipolytic Activity ◽  
Convex Curve ◽  
Lipoprotein Lipase Activity ◽  
Hepatic Triglyceride ◽  
Triglyceride Lipase ◽  
Heparin Fractions ◽  
Hepatic Triglyceride Lipase

Heparin fractions were prepared from commercial pig mucosal by affinity chromatography on antithrombin III, 35S- radiolabelling and gelchromatography. Three fractions were obtained with moLwt.of < 6.000, 6 - 35.000 and > 35.000 daltons. They were administered intravenous as a bolus into human volunteers. The anticoagulant activity was measured with the APTT and Xa inactivation, using standard curves. The lipolytic activity was as^ed as hepatic triglyceride lipase activity, and as extra-hepatic lipoprotein lipase activity by hydrolysis of tritiated triolein. Radioactivity data were corrected for degraded heparin fragments uncomplexed to protein by subtracting radiolabel with a mol.wt. < 10.000 passing through a filter.Low mol.wt. fractions induced neither of both lipase activity and had no effect on the APTT. Anti Xa activity and radioactivity disappeared in parallel with slightly concave curves in semilogarthmic plots. Heparin of intermediate and high mol.wt. induced both lipolytic and both anticoagulant activities. The elimination of radioactivity, hepatic triglyceride lipase activity and anti-Xa activity occurred parallel according to a convex curve in semilogarthmic plots. The extra-hepatic lipoprotein lipase activity disappeared following a slightly concave curve.These data indicate that relatively large heparin molecules are required for lipolytic and APTT activity. Hepatic triglyceride lipase activity might be present complexed to heparin, comparable to the antithrombin III-heparin complex. The elimination of anti Xa activity and hepatic triglyceride lipase activity might be determined by the heparin part of the complexes.

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.

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 Lysosomal triacylglycerol lipase activity in L6 myoblasts and its changes on differentiation

1985 ◽  
Vol 227 (2) ◽  
pp. 583-589 ◽  
Author(s):  
V S Sauro ◽  
H J Klamut ◽  
C H Lin ◽  
K P Strickland
Keyword(s):  
Neutral Lipid ◽  
Lipase Activity ◽  
Lipolytic Activity ◽  
Thiol Group ◽  
Cell Fractionation ◽  
Marker Enzyme ◽  
Ph Optimum ◽  
Triacylglycerol Lipase ◽  
Lipid Stores ◽  
Triton X

L6 myoblasts, before fusion, accumulate large stores of neutral lipid when cultured in medium supplemented with fatty acid. Upon fusion to terminally differentiated myotubes, a noticeable decrease in these neutral-lipid stores was observed. Triacylglycerol lipase activity was examined in L6 myoblasts at various stages of cell differentiation to assess a possible role for this enzyme in the above phenomenon. In this first study to demonstrate lipolytic activity in cultured muscle cells, the activity was found to be totally dependent on the presence of a detergent, either Cutscum or Triton X-100, during homogenization. The inhibition by many thiol-specific reagents [N-ethylmaleimide, p-chloromercuribenzoate, iodoacetate, 5,5′-dithiobis-(2-nitrobenzoic acid)] suggest that a thiol group is at or near the active site. The observed acidic pH optimum (5.5-6.0), the acute inhibition by chlorpromazine (a lysosomal lipase inhibitor) and the distribution of lipolytic activity upon cell fractionation (which co-sediments with acid phosphatase, a lysosomal marker enzyme) suggest that the lipase may be of lysosomal origin. Under the optimal conditions described, the triacylglycerol lipase activity of L6 myoblasts was determined to be 2.9 +/- 0.4 nmol of oleic acid released/min per mg of DNA. This activity increased 3-fold, to 9.0 +/- 1.6 nmol/min per mg, in the myotube phase. This increase in lipolytic activity may be responsible for the observed decrease in neutral-lipid stores of differentiating myoblasts.

Dibutyryl cAMP-induced Increases in triacylglycerol lipase activity in developing L8 myotube cultures

1990 ◽  
Vol 68 (6) ◽  
pp. 689-693 ◽  
Author(s):  
Warren K. Palmer ◽  
Lawrence B. Oscai ◽  
Peter J. Bechtel ◽  
Glenn A. Fisher
Keyword(s):  
Enzyme Activity ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Culture Medium ◽  
Cultured Cells ◽  
Muscle Cells ◽  
Cell Types ◽  
Dibutyryl Camp ◽  
Ph Optimum ◽  
Triacylglycerol Lipase

Triacylglycerol (TG) lipase activity, with an alkaline pH optimum, has been identified in the cellular fraction of L8 myotube cultures. This TG lipase activity was stimulated by serum and inhibited by NaCl and protamine sulfate. These characteristics have been classically described for lipoprotein lipase. It was possible to increase the activity of this TG lipase three- to fivefold by incubating the cells with dibutyryl cAMP Maximal enzyme activity was observed 16 h following the addition of 10–100 μM dibutyryl cAMP to the cultured cells. Enzyme activity returned to control levels 24 h after removal of the nucleotide from the culture medium. Serum-sensitive alkaline TG lipase activity was also identified in five other myotube preparations of cultured muscle cells. The highest levels of activity were found in rat skeletal muscle primary, H9, and L6 cell types. The finding that dibutyryl cAMP is an effective inducer of alkaline TG lipase activity provides us with a valuable model to investigate mechanisms regulating synthesis, compartmentalization, and transport of lipoprotein lipase in muscle.Key words: lipoprotein lipase, cultured muscle cells, enzyme induction.

Increased lipoprotein lipase activity of skeletal muscle in cold-acclimated rats

1977 ◽  
Vol 55 (12) ◽  
pp. 1241-1243 ◽  
Author(s):  
N. Bégin-Heick ◽  
H. M. C. Heick
Keyword(s):  
Skeletal Muscle ◽  
Cold Acclimation ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Skeletal Muscles ◽  
Lipoprotein Lipase Activity ◽  
Slow Twitch ◽  
Respiratory Movements ◽  
Parallel Fashion

The activity of lipoprotein lipase (LPL) in the heart, diaphragm, and soleus muscles was markedly increased in cold-acclimated rats and it was even greater in rats treated with oxytetracycline (OTC) while exposed to cold. Other skeletal muscles studied had low and variable activities which were not significantly increased by cold acclimation or by cold plus OTC treatment. It appears therefore that, apart from the heart and the muscles involved in respiratory movements, LPL activity is primarily associated with those muscles which contain a predominance of slow-twitch oxidative fibers, and that the enzyme in muscle, heart, and diaphragm responds to cold acclimation and cold plus OTC treatment in a parallel fashion in these tissues.

scholarly journals G0/G1 Switch Gene 2 controls adipose triglyceride lipase activity and lipid metabolism in skeletal muscle

2016 ◽  
Vol 5 (7) ◽  
pp. 527-537 ◽  
Author(s):  
Claire Laurens ◽  
Pierre-Marie Badin ◽  
Katie Louche ◽  
Aline Mairal ◽  
Geneviève Tavernier ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Lipid Metabolism ◽  
Lipase Activity ◽  
Adipose Triglyceride Lipase ◽  
Triglyceride Lipase

Skeletal muscle pyruvate dehydrogenase activity during maximal exercise in humans

1995 ◽  
Vol 269 (3) ◽  
pp. E458-E468 ◽  
Author(s):  
C. T. Putman ◽  
N. L. Jones ◽  
L. C. Lands ◽  
T. M. Bragg ◽  
M. G. Hollidge-Horvat ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Dehydrogenase ◽  
Maximal Exercise ◽  
Vastus Lateralis ◽  
Active Form ◽  
Lactate Production ◽  
Glycolytic Flux ◽  
Muscle Lactate ◽  
Mitochondrial Oxidation ◽  
Exercise In Humans

The regulation of the active form of pyruvate dehydrogenase (PDHa) and related metabolic events were examined in human skeletal muscle during repeated bouts of maximum exercise. Seven subjects completed three consecutive 30-s bouts of maximum isokinetic cycling, separated by 4 min of recovery. Biopsies of the vastus lateralis were taken before and immediately after each bout. PDHa increased from 0.45 +/- 0.15 to 2.96 +/- 0.38, 1.10 +/- 0.11 to 2.91 +/- 0.11, and 1.28 +/- 0.18 to 2.82 +/- 0.32 mmol.min-1.kg wet wt-1 during bouts 1, 2, and 3, respectively. Glycolytic flux was 13-fold greater than PDHa in bouts 1 and 2 and 4-fold greater during bout 3. This discrepancy between the rate of pyruvate production and oxidation resulted in substantial lactate accumulation to 89.5 +/- 11.6 in bout 1, 130.8 +/- 13.8 in bout 2, and 106.6 +/- 10.1 mmol/kg dry wt in bout 3. These events coincided with an increase in the mitochondrial oxidation state, as reflected by a fall in mitochondrial NADH/NAD, indicating that muscle lactate production during exercise was not an O2-dependent process in our subjects. During exercise the primary factor regulating PDHa transformation was probably intracellular Ca2+. In contrast, the primary regulatory factors causing greater PDHa during recovery were lower ATP/ADP and NADH/NAD and increased concentrations of pyruvate and H+. Greater PDHa during recovery facilitated continued oxidation of the lactate load between exercise bouts.

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.

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