| Author/Editor | Meznarič, Marija; Čarni, Andrej | |
| Title | Characterisation of flexor digitorum profundus, flexor digitorum superficialis and extensor digitorum communis by electrophoresis and immunohistochemical analysis of myosin heavy chain isoforms in older men | |
| Type | članek | |
| Vol. and No. | , št. Vol. | |
| Publication year | 2019 | |
| Volume | str. str. | |
| ISSN | 0940-9602 - Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft | |
| Language | eng | |
| Abstract | Introduction Few data exist on the fiber type composition of the extrinsic finger muscles. The aim of the present study was to describe myosin heavy chain (MyHC) composition of flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC). MyHC composition is relevant for whole muscle contractile performance and several studies on single muscle fibers demonstrated that fibers expressing only slow MyHC-1 develop less specific force than fibers expressing fast MyHCs. Since contraction force of finger extensors is smaller than of finger flexors a hypothesis was posited that the content of MyHC-1 is higher in EDC than in extrinsic finger flexors. Methods Autopsy samples of FDP, FDS, and EDC in 27 healthy older men were analyzed and compared with each other and with biceps brachii (BB). MyHC isoforms were quantified on silver-stained 6% SDS-PAGE. Muscle fibers were classified immunohistochemically according to the expression of adult MyHC isoforms and their morphometric parameters were determined. Results EDC stood out for its higher proportion of slow MyHC-1 (50%) compared to FDP (37%), FDS (38%) and BB (35%) (p < 0.001 in all), and its lower proportion of fast MyHC-2x (13%) compared to FDP (26%, p = 0.001), FDS (22%, p = 0.028) and BB (29%, p < 0.001) detected on SDS-PAGE. Immunohistochemically, EDC had a higher area proportion of pure slow type-1 fibers (63%) than FDP (47%, p = 0.002), FDS (49%, p = 0.007) and BB (47%, p = 0.002), and lower area proportion of pure fast type-2x fibers (2%) than FDP (12%, p = 0.014), FDS (8%, p = 0.256) and BB (14%, p = 0.002). All muscles contained a similar area proportion of pure type-2a fibers and hybrid type-2a/2x fibers. Conclusions The study results support the hypothesis that the content of MyHC-1 is higher in EDC than in extrinsic finger flexors, which is in agreement with the lower contraction force of finger extensors compared to finger flexors. | |
| Keywords | immunohistochemistry fiber types muscles imunohistokemija vrste vlaken mišice |