title: Quantitative analysis of myosin heavy chain expression change in laryngeal muscle after irradiation in rats.
abstract: OBJECTIVE
  Radiotherapy for head and neck cancer does not impair the voice quality as much as laser treatment or surgery, but it can induce muscle wasting and fibrosis and symptoms of dry mouth. We investigated the effect of irradiation on the myosin heavy chain (MyHC) expression in laryngeal muscles.
  
  
  METHODS
  Rats were irradiated with one dose of 10, 15, 20, 25, 30, or 35 Gy and other rats were irradiated with 20 Gy. The thyroarytenoid (TA), posterior cricoarytenoid (PCA), and cricothyroid (CT) muscles were subjected to reverse transcription-polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  Two weeks after irradiation with 10, 15, or 20 Gy, all the MyHC type expressions had decreased in a dose-dependent manner in the TA, PCA, and CT muscles, and especially the expression of MyHC IIa decreased much more than the expressions of the other MyHC isoforms in all muscles. In the 20 Gy-irradiated rats, almost all the MyHC isoform expressions declined over 12 weeks in the TA, PCA, and CT muscles, except for the MyHC I expression in the PCA and CT muscle. The MyHC IIa expression was markedly decreased in all the muscles.
  
  
  CONCLUSIONS
  The laryngeal muscles responded differently to radiation, but they showed a time-dependent and long-lasting decrease in the expressions of all the MyHC isoforms in the TA, PCA, and CT muscles. In particular, the expression of the MyHC IIa isoform in all the muscles may be more sensitive to irradiation than the expressions of the other MyHC isoforms.
authors.affiliation: Department of Otorhinolaryngology, Institute of Health Science, College of Medicine, Gyeongsang National University, 90 Chilam-dong, Jinju 660-702, Korea. jinpyeong@gnu.ac.kr
authors.forename: Jin Pyeong
authors.initials: JP
authors.lastname: Kim
authors.forename: Roza
authors.initials: R
authors.lastname: Khalmuratova
authors.forename: Sea Yuong
authors.initials: SY
authors.lastname: Jeon
authors.forename: Jung Je
authors.initials: JJ
authors.lastname: Park
authors.forename: Dong Gu
authors.initials: DG
authors.lastname: Hur
authors.forename: Seong Ki
authors.initials: SK
authors.lastname: Ahn
authors.forename: Seung Hoon
authors.initials: SH
authors.lastname: Woo
authors.forename: Ki Mun
authors.initials: KM
authors.lastname: Kang
authors.forename: Gyu Young
authors.initials: GY
authors.lastname: Chai
mesh_terms: D000818:Animals; D001835:Body Weight / Q000528:radiation effects; D015870:Gene Expression / Q000528:radiation effects; D007821:Laryngeal Muscles / Q000378:metabolism* / Q000528:radiation effects*; D018995:Myosin Heavy Chains / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020033:Protein Isoforms; D018995:Myosin Heavy Chains