title: Restoration of contractility in hyperhomocysteinemia by cardiac-specific deletion of NMDA-R1.
abstract: Homocysteine (HCY) activated mitochondrial matrix metalloproteinase-9 and led to cardiomyocyte dysfunction, in part, by inducing mitochondrial permeability (MPT). Treatment with MK-801 [N-methyl-d-aspartate (NMDA) receptor antagonist] ameliorated the HCY-induced decrease in myocyte contractility. However, the role of cardiomyocyte NMDA-receptor 1 (R1) activation in hyperhomocysteinemia (HHCY) leading to myocyte dysfunction was not well understood. We tested the hypothesis that the cardiac-specific deletion of NMDA-R1 mitigated the HCY-induced decrease in myocyte contraction, in part, by decreasing nitric oxide (NO). Cardiomyocyte-specific knockout of NMDA-R1 was generated using cre/lox technology. NMDA-R1 expression was detected by Western blot and confocal microscopy. MPT was determined using a spectrophotometer. Myocyte contractility and calcium transients were studied using the IonOptix video-edge detection system and fura 2-AM loading. We observed that HHCY induced NO production by agonizing NMDA-R1. HHCY induced the MPT by agonizing NMDA-R1. HHCY caused a decrease in myocyte contractile performance, maximal rate of contraction and relaxation, and prolonged the time to 90% peak shortening and 90% relaxation by agonizing NMDA-R1. HHCY decreased contraction amplitude with the increase in calcium concentration. The recovery of calcium transient was prolonged in HHCY mouse myocyte by agonizing NMDA-R1. It was suggested that HHCY increased mitochondrial NO levels and induced MPT, leading to the decline in myocyte mechanical function by agonizing NMDA-R1.
authors.affiliation: Dept. of Physiology and Biophysics, 500 S. Preston St., HSC Bldg. A-1115, Univ. of Louisville, Louisville, KY 40202, USA.
authors.forename: Karni S
authors.initials: KS
authors.lastname: Moshal
authors.forename: Munish
authors.initials: M
authors.lastname: Kumar
authors.forename: Neetu
authors.initials: N
authors.lastname: Tyagi
authors.forename: Paras K
authors.initials: PK
authors.lastname: Mishra
authors.forename: Naira
authors.initials: N
authors.lastname: Metreveli
authors.forename: Walter E
authors.initials: WE
authors.lastname: Rodriguez
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Tyagi
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D004195:Disease Models, Animal; D020138:Hyperhomocysteinemia / Q000378:metabolism / Q000503:physiopathology*; D051379:Mice; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000172:deficiency* / Q000235:genetics
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C409466:NR1 NMDA receptor; D017382:Reactive Oxygen Species; D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide