title: Absence of developmental and unconventional myosin heavy chain in human suprahyoid muscles.
abstract: BACKGROUND
  Contradictory reports of the myosin heavy chain (MHC) composition of adult human suprahyoid muscles leave unresolved the extent to which these muscles express developmental and unconventional MHC.
  
  
  METHODS
  By immunohistochemistry, separation sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-Coomassie, separation SDS-PAGE-Western blot, and mRNA PCR, we tested for conventional MHCI, MHCIIA, MHCIIX, developmental MHC embryonic and MHC neonatal, and unconventional MHC alpha-cardiac, MHC extraocular, and MHC slow tonic in adult human anterior digastric (AD), geniohyoid (GH), and mylohyoid (MH) muscles.
  
  
  RESULTS
  By separation SDS-PAGE-Coomassie and Western blot, only conventional MHC are present. By immunohistochemistry all muscle fibers are positive for MHCI, MHCIIA, or MHCIIX, and fewer than 4 fibers/mm(2) are positive for developmental or unconventional MHC. By PCR, mRNA of MHCI and MHCIIA dominate, with sporadically detectable MHC alpha-cardiac and without detectable mRNA of other developmental and unconventional MHC.
  
  
  CONCLUSIONS
  We conclude that human suprahyoid muscles AD, GH, and MH are composed almost exclusively of conventional MHC isoforms.
authors.affiliation: Department of Physiology, Emory University, 615 Michael Street, Atlanta, Georgia, 30322, USA.
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Luo
authors.forename: Megan
authors.initials: M
authors.lastname: Douglas
authors.forename: Thomas
authors.initials: T
authors.lastname: Burkholder
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Sokoloff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D005333:Fetus; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000737:chemistry; D018482:Muscle, Skeletal / Q000737:chemistry / Q000254:growth & development; D018995:Myosin Heavy Chains / Q000032:analysis*; D009334:Neck Muscles / Q000737:chemistry* / Q000254:growth & development*
chemical_list: D018995:Myosin Heavy Chains
keywords: human; muscle; myosin heavy chain; suprahyoid; swallowing