BACKGROUND: Studies have shown that canine laryngeal muscle contains a large number of muscle fibers that coexpress varying combinations of myosin heavy-chain (MyHC) isoforms. Currently, it is not clear whether this phenomenon is unique to canine laryngeal muscle or occurs in all mammals. OBJECTIVES: To examine the single-fiber MyHC isoform composition of rodent laryngeal muscle and to examine the plasticity of single-fiber MyHC isoform composition via manipulation of thyroid state. RESULTS: (1) Findings of single-fiber electrophoretic analyses clearly demonstrate that most fibers in both the posterior cricoarytenoid and thyroarytenoid muscles exhibit MyHC polymorphism. However, the proportions and patterns of polymorphism appear to be muscle specific. (2) Although the fast type IIL isoform was observed in fibers from both muscles, it was always coexpressed in combination with other MyHC isoforms (ie, no pure type IIL fibers were found), and always represented a minor proportion of the total MyHC pool. (3) Altering the thyroid state proved a useful tool for exploring the scope of MyHC isoform expression in these muscles. While the posterior cricoarytenoid muscle seemed more sensitive to the thyroid state, transitions in both muscles were primarily confined to the fast type IIX and IIB MyHC isoforms. CONCLUSION: The findings of this study support the concept that single-fiber MyHC polymorphism occurs commonly in mammalian laryngeal muscle.
BACKGROUND: Studies have shown that canine laryngeal muscle contains a large number of muscle fibers that coexpress varying combinations of myosin heavy-chain (MyHC) isoforms. Currently, it is not clear whether this phenomenon is unique to canine laryngeal muscle or occurs in all mammals. OBJECTIVES: To examine the single-fiber MyHC isoform composition of rodent laryngeal muscle and to examine the plasticity of single-fiber MyHC isoform composition via manipulation of thyroid state. RESULTS: (1) Findings of single-fiber electrophoretic analyses clearly demonstrate that most fibers in both the posterior cricoarytenoid and thyroarytenoid muscles exhibit MyHC polymorphism. However, the proportions and patterns of polymorphism appear to be muscle specific. (2) Although the fast type IIL isoform was observed in fibers from both muscles, it was always coexpressed in combination with other MyHC isoforms (ie, no pure type IIL fibers were found), and always represented a minor proportion of the total MyHC pool. (3) Altering the thyroid state proved a useful tool for exploring the scope of MyHC isoform expression in these muscles. While the posterior cricoarytenoid muscle seemed more sensitive to the thyroid state, transitions in both muscles were primarily confined to the fast type IIX and IIB MyHC isoforms. CONCLUSION: The findings of this study support the concept that single-fiber MyHC polymorphism occurs commonly in mammalian laryngeal muscle.
Authors: Carlos M Castorena; Edward B Arias; Naveen Sharma; Jonathan S Bogan; Gregory D Cartee Journal: Am J Physiol Endocrinol Metab Date: 2014-12-09 Impact factor: 4.310
Authors: Hannah S Rhee; Catherine M Steel; Frederik J Derksen; N Edward Robinson; Joseph F Y Hoh Journal: J Histochem Cytochem Date: 2009-04-27 Impact factor: 2.479
Authors: Giuseppe D'Antona; Aram Megighian; Susan Bortolotto; Maria Antonietta Pellegrino; Rosario Marchese-Ragona; Alberto Staffieri; Roberto Bottinelli; Carlo Reggiani Journal: J Muscle Res Cell Motil Date: 2002 Impact factor: 2.698