scholarly journals Effect of substrates on the cyclic AMP-dependent lipolytic reaction of hormone-sensitive lipase.

1994 ◽  
Vol 35 (7) ◽  
pp. 1267-1273
Author(s):  
H Okuda ◽  
C Morimoto ◽  
T Tsujita
Keyword(s):  
Cyclic Amp ◽  
Hormone Sensitive Lipase ◽  
Hormone Sensitive

scholarly journals Hormonal activation of type-L hormone-sensitive lipase measured in defatted heart powders

1983 ◽  
Vol 212 (2) ◽  
pp. 379-383 ◽  
Author(s):  
W K Palmer ◽  
T A Kane
Keyword(s):  
Cyclic Amp ◽  
Diethyl Ether ◽  
Rat Heart ◽  
Hormone Sensitive Lipase ◽  
Dependent Manner ◽  
Ph Optimum ◽  
Protamine Sulphate ◽  
Hormone Sensitive ◽  
The Stability ◽  
Ether Treatment

Adrenaline, 3-isobutyl-1-methylxanthine (MIX) and dibutyryl cyclic AMP (Bt2 cyclic AMP) stimulated type-L hormone-sensitive lipase (HSL) activity when measurements were made on defatted rat heart powders. These lipolytic agents stimulated the activity of this enzyme in a time- and dose-dependent manner. This activation was reversible, because removal of adrenaline from the perfusate was accompanied by the return of type-L HSL activity to control levels. We have reported [Palmer, Caruso & Oscai (1981) Biochem. J. 198, 159-166] that perfusion with low levels of adrenaline, MIX or Bt2 cyclic AMP reduced type-L HSL activity below control levels when measurements were made in aqueous homogenates. However, in the present study, when activities were measured in acetone/diethyl ether heart powders, all concentrations of these agents studied stimulated enzyme activity, and at no concentration was there enzyme inhibition. These data suggest that acetone/diethyl ether treatment may remove a factor that plays a role in type-L HSL regulation. Type-L HSL activity measured in acetone/diethyl ether powders of control and stimulated rat heart exhibited properties that include alkaline pH optimum, serum requirement, activation by heparin and inhibition by high salt and protamine sulphate. These characteristics, in addition to the stability of the enzyme to treatment with organic solvents, fulfil the requirements for the type-L HSL classification.

scholarly journals Hormone-stimulated lipolysis in cardiac myocytes

1983 ◽  
Vol 216 (1) ◽  
pp. 241-243 ◽  
Author(s):  
W K Palmer ◽  
T A Kane
Keyword(s):  
Fatty Acid ◽  
Cyclic Amp ◽  
Cardiac Myocytes ◽  
Diethyl Ether ◽  
Lipase Activity ◽  
Intracellular Concentration ◽  
Hormone Sensitive Lipase ◽  
Extracellular Compartment ◽  
Triacylglycerol Content ◽  
Hormone Sensitive

Type L hormone-sensitive lipase (HSL) activity was increased approx. 35% above control in cardiac myocytes incubated for 15 min with 5 nM-adrenaline. Concomitantly. adrenaline-stimulated myocytes had a lower triacylglycerol content, released more non-esterified fatty acid and had a higher intracellular concentration of cyclic AMP than did myocytes incubated without hormone. The lipase activity measured in adrenaline-stimulated and non-stimulated myocytes was stable in acetone/diethyl ether, stimulated by serum and inhibited by NaCl. These properties are consistent with the type L designation of this HSL. The finding that type L HSL is stimulated by adrenaline indicates that the enzyme that is being activated is found in the cell and not associated with an extracellular compartment of the myocardium.

scholarly journals Lipolysis

2003 ◽  
Vol 161 (6) ◽  
pp. 1011-1012 ◽  
Author(s):  
Morris J. Birnbaum
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adipocyte Differentiation ◽  
Hormone Sensitive Lipase ◽  
Related Protein ◽  
Hormone Sensitive ◽  
Subcellular Compartmentalization ◽  
Kinase A

Successful adaptation to starvation in mammals depends heavily on the regulated mobilization of fatty acids from triacylglycerols stored in adipose tissue. Although it has long been recognized that cyclic AMP represents the critical second messenger and hormone-sensitive lipase (HSL)**Abbreviations used in this paper: ADRP, adipocyte differentiation-related protein; HSL, hormone-sensitive lipase; PKA, protein kinase A; TAG, triacylglycerol. the rate-determining enzyme for lipolysis, simple activation of the enzyme has failed to account for the robust augmentation of fatty release in response to physiological agonists. In this issue, Sztalryd et al. (2003) provide convincing support to the notion that the subcellular compartmentalization of lipase also regulates lipolysis, and, more importantly, that proteins other than HSL are localized to the lipid droplet and are indispensable for its optimal hydrolysis.

scholarly journals Hormone-sensitive lipase in differentiated 3T3-L1 cells and its activation by cyclic AMP-dependent protein kinase.

1981 ◽  
Vol 78 (2) ◽  
pp. 732-736 ◽  
Author(s):  
M. Kawamura ◽  
D. F. Jensen ◽  
E. V. Wancewicz ◽  
L. L. Joy ◽  
J. C. Khoo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Hormone Sensitive Lipase ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Hormone Sensitive

scholarly journals Relationship between type L hormone-sensitive lipase activity and endogenous triacylglycerol in the hearts of colchicine-treated rats

1984 ◽  
Vol 224 (3) ◽  
pp. 793-798 ◽  
Author(s):  
W C Miller ◽  
W K Palmer ◽  
L B Oscai
Keyword(s):  
Enzyme Activity ◽  
Cyclic Amp ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Negative Relationship ◽  
Indirect Evidence ◽  
Colchicine Treatment ◽  
Hormone Sensitive Lipase ◽  
Control Value ◽  
Hormone Sensitive

Colchicine injection was used as a tool to potentiate the increase in intracellular lipoprotein lipase (type L hormone-sensitive lipase) activity normally seen with fasting to determine if elevation of enzyme activity by this method produced a reduction in endogenous triacylglycerol (TG) in rat heart. Both fasting and fasting+colchicine treatment increased total lipoprotein lipase (LPL) activity from a control value of 80 units/g to approx. 144 units/g. The initial control value was obtained at 08:00 h after overnight feeding and the final values were obtained at 17:00 h, after 9 h of fasting. Fasting alone increased activity in both the capillary-bound LPL and type L hormone-sensitive lipase (HSL) fractions of cardiac muscle. In contrast, colchicine treatment, by blocking the export of enzyme from the cell as a result of microtubular disruption, restricted the increase in enzyme activity to the intracellular fraction of the heart. There was a highly significant (P less than 0.001) negative relationship (r = −0.73) between type L HSL activity and TG content in hearts of fasting and fasting+colchicine-treated rats. At a time when type L HSL activity was increased and TG content decreased, the cyclic AMP concentration of heart remained unchanged, ruling out the possibility that cyclic AMP might be activating any one of the identified cardiac TG lipases. These data provided indirect evidence that type L HSL is ‘seeing the intracellular TG droplet’ and that this enzyme may play a role in the regulation of myocardial lipolysis.

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