Contractile properties and myosin heavy chain isoform composition in single fibre of human laryngeal muscles.

摘要: In the present study we aimed to determine functional properties and myosin heavy chain (MHC) isoform composition of single chemically skinned fibres from vocal muscle four adult men (age: 55–67 years). Single fibres, dissected bioptic samples, were isometric tension (P0) maximal shortening velocity (V0) measured at pCa 4.6. MHC light (MLC) fibre segments distribution biopsy samples analysed by SDS–poly-acrylamide gel electrophoresis (SDS—PAGE) densitometry. Four isoforms (1, 2A, 2X a fourth isoform, provisionally called L) five MLC (MLC1s, MLC1f, MLC3f, MLC2f, MLC2s) identified. The major findings this were: (1) fast (in particular MHC-2A) predominant, (2) one-third mixed or hybrid, i.e. expressed more than one (3) V0 P0 values determined showed which intermediate between pure fibres; MHC-L was associated with similar those MHC-2A, (4) compared limb muscles, laryngeal containing same whereas lower for slow expressing MHC-2A.