Protein kinase activation of heparin-releasable lipoprotein lipase in rat heart.
An attempt was made to activate the capillary-bound fraction of lipoprotein lipase (LPL) with cAMP-dependent protein kinase catalytic subunit (PKC). Following a 30s washout period, hearts were perfused for 1 min with buffer containing heparin. Medium was collected during the second 30s of heparin perfusion. Addition of PKC+Mg-ATP to this capillary bed perfusate increased LPL activity from 6.84 +/- 0.72 nmol/ml/min to 13.76 +/- 1.12 nmol/ml/min (P less than 0.001). A similar 2-fold increase in activity was observed when results were expressed on a mg protein basis. Removal of serum from, or addition of 1.0M NaCl to, the assay system inhibited PKC-stimulated LPL activity approximately 85%. These results indicate that capillary alkaline LPL can be activated by PKC assayed under experimental conditions free of other TG lipases. Moreover, these findings suggest that the intracellular fraction of LPL can be activated by cAMP and that this activation is mediated through protein phosphorylation by cAMP-dependent protein kinase.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004727:Endothelium / Q000201:enzymology; D004789:Enzyme Activation; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats
D000255:Adenosine Triphosphate; D011494:Protein Kinases; D008071:Lipoprotein Lipase; D008274:Magnesium