Abstract
The existence of superfast myosin heavy chain (MHC), found in jaw-closing muscle and extraocular muscle (EOM), was also found in rat laryngeal muscles. Immunostaining and western blot using anti-EOM superfast MHC antibody were performed to identify and localize superfast MHC in rat laryngeal muscles. Specific reactivity of laryngeal II L MHC was confirmed by western blot. By immunostaining, all fibers in the thyroarytenoid muscle reacted with EOM superfast MHC antibody. A scattered pattern of positive fibers was observed in the vocalis, the posterior cricoarytenoid and the lateral cricoarytenoid muscles. EOM superfast MHC was not detected in thecricothyroid muscle. Co-expression of EOM superfast MHC and type II B MHC was observed, and expression of EOM superfast MHC was seen in laryngeal muscle innervated only by recurrent laryngeal nerve, with the highest density of EOM superfast MHC in the thyroarytenoid muscle. The expression of EOM superfast MHC in rat laryngeal muscle is consistent with the functional demands for airway protection and glottic closure reflex. The MHC phenotype, or relative composition of myosin heavy chains, reflected the physiologic demands on each laryngeal muscle.
