title: {beta}1-Adrenergic receptor activation induces mouse cardiac myocyte death through both L-type calcium channel-dependent and -independent pathways.
abstract: Cardiac diseases persistently increase the contractility demands of cardiac myocytes, which require activation of the sympathetic nervous system and subsequent increases in myocyte Ca(2+) transients. Persistent exposure to sympathetic and/or Ca(2+) stress is associated with myocyte death. This study examined the respective roles of persistent beta-adrenergic receptor (beta-AR) agonist exposure and high Ca(2+) concentration in myocyte death. Ventricular myocytes (VMs) were isolated from transgenic (TG) mice with cardiac-specific and inducible expression of the beta(2a)-subunit of the L-type Ca(2+) channel (LTCC). VMs were cultured, and the rate of myocyte death was measured in the presence of isoproterenol (ISO), other modulators of Ca(2+) handling and the beta-adrenergic system, and inhibitors of caspases and reactive oxygen species generation. The rate of myocyte death was greater in TG vs. wild-type myocytes and accelerated by ISO in both groups, although ISO did not increase LTCC current (I(Ca-L)) in TG-VMs. Nifedipine, an LTCC antagonist, only partially prevented myocyte death. These results suggest both LTCC-dependent and -independent mechanisms in ISO induced myocyte death. ISO increased the contractility of wild type and TG-VMs by enhancing sarcoplasmic reticulum function and inhibiting sarco(endo)plasmic reticulum Ca(2+)-ATPase, Na(+)/Ca(2+) exchanger, and CaMKII partially protected myocyte from death induced by both Ca(2+) and ISO. Caspase and reactive oxygen species inhibitors did not, but beta(2)-AR activation did, reduce myocyte death induced by enhanced I(Ca-L) and ISO stimulation. Our results suggest that catecholamines induce myocyte necrosis primarily through beta(1)-AR-mediated increases in I(Ca-L), but other mechanisms are also involved in rodents.
authors.affiliation: Institute of Burn Research, Southwest Hospital, State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Gao
authors.forename: Hajime
authors.initials: H
authors.lastname: Kubo
authors.forename: Remus M
authors.initials: RM
authors.lastname: Berretta
authors.forename: Xiongwen
authors.initials: X
authors.lastname: Chen
authors.forename: Steven R
authors.initials: SR
authors.lastname: Houser
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists; D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology*; D008564:Membrane Potentials; D051379:Mice; D008822:Mice, Transgenic; D009200:Myocardial Contraction / Q000187:drug effects*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009336:Necrosis; D021122:Protein Subunits; D017382:Reactive Oxygen Species / Q000378:metabolism; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013997:Time Factors
chemical_list: C547788:Adrb1 protein, mouse; D058665:Adrenergic beta-1 Receptor Agonists; D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists; D000975:Antioxidants; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D021122:Protein Subunits; D017382:Reactive Oxygen Species; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D019831:Sodium-Calcium Exchanger; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D020169:Caspases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D007545:Isoproterenol