title: Diesterified nitrone rescues nitroso-redox levels and increases myocyte contraction via increased SR Ca(2+) handling.
abstract: Nitric oxide (NO) and superoxide (O(2) (-)) are important cardiac signaling molecules that regulate myocyte contraction. For appropriate regulation, NO and O(2) (.-) must exist at defined levels. Unfortunately, the NO and O(2) (.-) levels are altered in many cardiomyopathies (heart failure, ischemia, hypertrophy, etc.) leading to contractile dysfunction and adverse remodeling. Hence, rescuing the nitroso-redox levels is a potential therapeutic strategy. Nitrone spin traps have been shown to scavenge O(2) (.-) while releasing NO as a reaction byproduct; and we synthesized a novel, cell permeable nitrone, 2-2-3,4-dihydro-2H-pyrrole 1-oxide (EMEPO). We hypothesized that EMEPO would improve contractile function in myocytes with altered nitroso-redox levels. Ventricular myocytes were isolated from wildtype (C57Bl/6) and NOS1 knockout (NOS1(-/-)) mice, a known model of NO/O(2) (.-) imbalance, and incubated with EMEPO. EMEPO significantly reduced O(2) (.-) (lucigenin-enhanced chemiluminescence) and elevated NO (DAF-FM diacetate) levels in NOS1(-/-) myocytes. Furthermore, EMEPO increased NOS1(-/-) myocyte basal contraction (Ca(2+) transients, Fluo-4AM; shortening, video-edge detection), the force-frequency response and the contractile response to β-adrenergic stimulation. EMEPO had no effect in wildtype myocytes. EMEPO also increased ryanodine receptor activity (sarcoplasmic reticulum Ca(2+) leak/load relationship) and phospholamban Serine16 phosphorylation (Western blot). We also repeated our functional experiments in a canine post-myocardial infarction model and observed similar results to those seen in NOS1(-/-) myocytes. In conclusion, EMEPO improved contractile function in myocytes experiencing an imbalance of their nitroso-redox levels. The concurrent restoration of NO and O(2) (.-) levels may have therapeutic potential in the treatment of various cardiomyopathies.
authors.affiliation: Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Traynham
authors.forename: Steve R
authors.initials: SR
authors.lastname: Roof
authors.forename: Honglan
authors.initials: H
authors.lastname: Wang
authors.forename: Robert A
authors.initials: RA
authors.lastname: Prosak
authors.forename: Lifei
authors.initials: L
authors.lastname: Tang
authors.forename: Serge
authors.initials: S
authors.lastname: Viatchenko-Karpinski
authors.forename: Hsiang-Ting
authors.initials: HT
authors.lastname: Ho
authors.forename: Ira O
authors.initials: IO
authors.lastname: Racoma
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Catalano
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Han
authors.forename: Shang-U
authors.initials: SU
authors.lastname: Kim
authors.forename: Sandor
authors.initials: S
authors.lastname: Gyorke
authors.forename: George E
authors.initials: GE
authors.lastname: Billman
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Villamena
authors.forename: Mark T
authors.initials: MT
authors.lastname: Ziolo
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004951:Esterification; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009200:Myocardial Contraction / Q000187:drug effects*; D009203:Myocardial Infarction / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000502:physiology*; D009589:Nitrogen Oxides / Q000494:pharmacology*; D010084:Oxidation-Reduction; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D013113:Spin Labels; D013481:Superoxides / Q000378:metabolism
chemical_list: D009589:Nitrogen Oxides; D013113:Spin Labels; C015388:nitrones; D013481:Superoxides; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D002118:Calcium