title: Lipoprotein lipase activity in rat cardiomyocytes is stimulated by insulin and dexamethasone.
abstract: Lipoprotein lipase (LPL) activity was studied in rat cardiomyocytes after overnight culture (16 h) in the presence of insulin (100 nM) and/or dexamethasone (100 nM). Insulin in combination with dexamethasone (INS/DEX) increased heparin-releasable LPL activity by 71% over the control level (566+/-85 versus 331+/-48 nmol/h.mg cell protein). This was accompanied by a 61% increase in total cellular LPL activity (914+/-89 versus 567+/-64 nmol/h.mg cell protein). The increase in LPL activity occurred at sub-nanomolar concentrations of the hormones, but neither hormone was effective alone. LPL protein mass, quantified by ELISA, was the same in both control and INS/DEX-treated cells (27.7 versus 28.6 ng/mg cell protein, respectively), thus LPL specific activity in cardiomyocytes was increased by INS/DEX treatment (0.113 versus 0.069 mU/ng LPL protein). These findings emphasize the importance of hormonal interactions in the regulation of LPL in heart tissue.
authors.affiliation: The University of Calgary, Department of Pharmacology and Therapeutics, 3330 Hospital Drive N.W., Calgary, AB, T2N 4N1, Canada.
authors.forename: H S
authors.initials: HS
authors.lastname: Ewart
authors.forename: R
authors.initials: R
authors.lastname: Carroll
authors.forename: D L
authors.initials: DL
authors.lastname: Severson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006352:Heart Ventricles; D006493:Heparin / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000096:biosynthesis / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007328:Insulin; D003907:Dexamethasone; D006493:Heparin; D008071:Lipoprotein Lipase