title: sGC{alpha}1 mediates the negative inotropic effects of NO in cardiac myocytes independent of changes in calcium handling.
abstract: In the heart, nitric oxide (NO) modulates contractile function; however, the mechanisms responsible for this effect are incompletely understood. NO can elicit effects via a variety of mechanisms including S-nitrosylation and stimulation of cGMP synthesis by soluble guanylate cyclase (sGC). sGC is a heterodimer comprised of a β(1)- and an α(1)- or α(2)-subunit. sGCα(1)β(1) is the predominant isoform in the heart. To characterize the role of sGC in the regulation of cardiac contractile function by NO, we compared left ventricular cardiac myocytes (CM) isolated from adult mice deficient in the sGC α(1)-subunit (sGCα(1)(-/-)) and from wild-type (WT) mice. Sarcomere shortening under basal conditions was less in sGCα(1)(-/-) CM than in WT CM. To activate endogenous NO synthesis from NO synthase 3, CM were incubated with the β(3)-adrenergic receptor (β(3)-AR) agonist BRL 37344. BRL 37344 decreased cardiac contractility in WT CM but not in sGCα(1)(-/-) myocytes. Administration of spermine NONOate, an NO donor compound, did not affect sarcomeric shortening in CM of either genotype; however, in the presence of isoproterenol, addition of spermine NONOate reduced sarcomere shortening in WT but not in sGCα(1)(-/-) CM. Neither BRL 37344 nor spermine NONOate altered calcium handling in CM of either genotype. These findings suggest that sGCα(1) exerts a positive inotropic effect under basal conditions, as well as mediates the negative inotropic effect of β(3)-AR signaling. Additionally, our work demonstrates that sGCα(1)β(1) is required for NO to depress β(1)/β(2)-AR-stimulated cardiac contractility and that this modulation is independent of changes in calcium handling.
authors.affiliation: Massachusetts General Hospital, 505 Thier Bldg, Boston, MA 02114, USA. Scawley@partners.org
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Cawley
authors.forename: Starsha
authors.initials: S
authors.lastname: Kolodziej
authors.forename: Fumito
authors.initials: F
authors.lastname: Ichinose
authors.forename: Peter
authors.initials: P
authors.lastname: Brouckaert
authors.forename: Emmanuel S
authors.initials: ES
authors.lastname: Buys
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Bloch
mesh_terms: D058667:Adrenergic beta-3 Receptor Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004983:Ethanolamines / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D043585:Receptor, Muscarinic M2 / Q000502:physiology; D018342:Receptors, Adrenergic, beta-1 / Q000502:physiology; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology; D022702:Receptors, Adrenergic, beta-3 / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000502:physiology*; D012518:Sarcomeres / Q000502:physiology / Q000648:ultrastructure; D000071756:Soluble Guanylyl Cyclase; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D058667:Adrenergic beta-3 Receptor Agonists; D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D004983:Ethanolamines; C000605665:Gucy1a2 protein, mouse; C000605670:Gucy1b2 protein, mouse; C000605673:Gucy1b3 protein, mouse; D043585:Receptor, Muscarinic M2; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D022702:Receptors, Adrenergic, beta-3; D018160:Receptors, Cytoplasmic and Nuclear; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide; C057368:BRL 37344; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D002118:Calcium