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Release of lipoprotein lipase from cardiac myocytes by low-molecular weight heparin
1MRC Signal Transduction Group, University of Calgary, Faculty of Medicine, Alberta, Canada.
Abstract:
Incubation of cardiac myocytes from rat heart with low-molecular weight heparin (LMWH; Mr approx. 3 kDa) for 30 min resulted in a concentration-dependent release of lipoprotein lipase (LPL) activity into the incubation medium. The release of lipoprotein lipase from cardiac myocytes isolated from both control and diabetic rat hearts induced by LMWH (10 micrograms/mL) following incubation times of 10 or 30 min was significantly greater than that produced by unfractionated heparin (10 and 30 micrograms/mL) or decavanadate (1 mM). Since LMWH released more LPL activity into the incubation medium than unfractionated heparin following a short (10 min) incubation time. LMWH is probably more effective in displacing LPL bound to heparan sulfate proteoglycan binding sites on the cell surface of cardiac myocytes.
Insights
Low-molecular weight heparin (LMWH) effectively releases lipoprotein lipase (LPL) from cardiac myocytes. This suggests LMWH is more efficient than unfractionated heparin in displacing cell-surface bound LPL.
Area of Science:
- Biochemistry
- Cardiology
- Pharmacology
Background:
- Cardiac myocytes possess cell-surface heparan sulfate proteoglycans that bind lipoprotein lipase (LPL).
- Understanding LPL release mechanisms is crucial for cardiac metabolism and lipid regulation.
Purpose of the Study:
- To investigate the effect of low-molecular weight heparin (LMWH) on LPL release from cardiac myocytes.
- To compare the efficacy of LMWH with unfractionated heparin (UFH) and decavanadate in LPL displacement.
Main Methods:
- Incubation of rat cardiac myocytes (control and diabetic) with varying concentrations of LMWH, UFH, and decavanadate.
- Measurement of released lipoprotein lipase (LPL) activity in the incubation medium.
- Time-course analysis of LPL release.
Main Results:
- LMWH induced a concentration-dependent release of LPL activity from cardiac myocytes.
- LMWH (10 µg/mL) significantly increased LPL release compared to UFH (10 and 30 µg/mL) and decavanadate (1 mM) at both 10 and 30 min.
- LMWH demonstrated greater LPL releasing capacity than UFH even after a short incubation period (10 min).
Conclusions:
- LMWH is a potent agent for releasing LPL from cardiac myocytes.
- LMWH appears more effective than UFH in displacing LPL from heparan sulfate proteoglycan binding sites on cardiac myocytes.
- These findings highlight LMWH's potential in modulating cardiac LPL activity.