title: Prazosin-stimulated release of hepatic triacylglyceride lipase from primary cultured rat hepatocytes is involved in the regulation of cAMP-dependent protein kinase through activation of the Ca(2+)/calmodulin-dependent protein kinase-II.
abstract: BACKGROUND
  Prazosin is an α1 adrenoceptor antagonist used in pharmacotherapy for the treatment of hypertension. Prazosin alters lipid metabolism in vivo, but the involved mechanism is not fully understood. In this study, we investigated the mechanism underlying the alteration of lipid metabolism. We show that the prazosin-stimulated release of hepatic triacylglyceride lipase (HTGL) from primary cultured rat hepatocytes involved Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) activation.
  
  
  METHODS
  Primary cultured rat hepatocytes were incubated with prazosin and other agents. The hepatocytes were used in the CaMK-II and protein kinase A (PKA) activity assay. The supernatant was used in the HTGL activity assay and western blotting.
  
  
  RESULTS
  Prazosin-stimulated HTGL release was suppressed by the inositol triphosphate receptor inhibitor xestospongin C and by the calmodulin inhibitor trifluoperazine but not by the protein kinase C inhibitor chelerythrine chloride or a diacylglycerol kinase inhibitor (R59949). Furthermore, the calmodulin-dependent protein kinase II (CaMK-II) activity in prazosin-treated hepatocytes increased in a time- and dose-dependent manner. The cAMP-dependent PKA activity of prazosin-stimulated hepatocytes was suppressed by a phospholipase C (PLC) inhibitor (U-73122), trifluoperazine, and a CaMK-II inhibitor (KN-93).
  
  
  CONCLUSIONS
  These results suggested that prazosin-stimulated HTGL release from hepatocytes was caused by activation of PKA associated with stimulation of CaMK-II activity through a signal cascade from PLC.
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Japan. Electronic address: tnaka@fupharm.fukuyama-u.ac.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kamishikiryo
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Morita
mesh_terms: D000818:Animals; D053119:Benzophenanthridines / Q000494:pharmacology; D001596:Benzylamines / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004963:Estrenes / Q000494:pharmacology; D022781:Hepatocytes / Q000378:metabolism*; D008071:Lipoprotein Lipase / Q000378:metabolism*; D047028:Macrocyclic Compounds / Q000494:pharmacology; D008297:Male; D010080:Oxazoles / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011224:Prazosin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D061251:Primary Cell Culture; D011760:Pyrrolidinones / Q000494:pharmacology; D052999:Quinazolinones / Q000494:pharmacology; D051381:Rats; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D014268:Trifluoperazine / Q000494:pharmacology; D000096926:Benzenesulfonamides
chemical_list: D053119:Benzophenanthridines; D001596:Benzylamines; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017868:Cyclic AMP-Dependent Protein Kinases; D004963:Estrenes; D008071:Lipoprotein Lipase; D047028:Macrocyclic Compounds; D010080:Oxazoles; D010880:Piperidines; D011224:Prazosin; D011760:Pyrrolidinones; D052999:Quinazolinones; D013449:Sulfonamides; D014268:Trifluoperazine; C511704:xestospongin C; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C058544:R 59949; C072105:KN 93; D000096926:Benzenesulfonamides; C016299:chelerythrine
keywords: Calcium/calmodulin-dependent protein kinase II; Hepatic lipase; Prazosin; Primary cultured rat hepatocytes