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  • Histochemical and immunohistochemical profile of human and rat ocular medial rectus muscles
    Stirn-Kranjc, Branka ; Smerdu, Vika ; Eržen, Ida
    Purpose: To compare the organization of human and rat ocular medial recti muscles (MR). Methods: The cryosections of human and rat MR were processed formyofibrillar ATPase (mATPase), succinate ... dehydrogenase and glycerol-3-phosphate dehydrogenase. To reveal myosin heavy chain (MyHC) isoforms, specific monoclonal antibodies against MyHC-1/beta- slow, alpha-cardiac (-alpha), -2a, -2x, -2b, -extraocular (eom), -embryonic (-emb) and -neonatal (-neo) were applied. The MyHC gene expression was studied by in situ hybridization in human muscle. Results: The muscle fibers were arranged in two distinct layers in both species. In the orbital layer most fibers were highly oxidative and expressed fast MyHC isoforms, whereas slow and oxidative fibers expressed MyHC-1 and -alpha, some of them also MyHC-2a, -2x, -eom, very rarely -emb, and -neo. In the global layer, slow fibers with very low oxidative and glycolytic activity and three types of fast fibers, glycolytic, oxidative and oxidative-glycolytic, could be distinguished. The slow medium-sized fibers with mATPase activity stable at pH 4.4 expressed mostly MyHC-1 and -alpha in rat, while in humans they co-expressed MyHC-1 with -2b, -2x, -eom, and -neo. In both species, the fast fibers showed variable mATPase activity after preincubation at pH 9.4, and co-expressed various combinations of MyHC-2b, -2x, -2a and -eom but not -emb and -neo. MyHC-2b expressing fibers were larger and glycolytic, while MyHC-2a expressing fibers were smaller and highly oxidative in both species. To our knowledge, the present study is the first that demonstrated the expression of MyHC-2b in any of humanskeletal muscles. Though the expression of MyHC genes did not correlate with the immunohistochemical profile of fibers in human MR, the expression of MyHC-2b gene was undoubtedly confirmed. (Abstract truncated at 2000 characters)
    Source: Graefe's archive for clinical and experimental ophthalmology. - ISSN 0721-832X (Letn. 247, št. 11, 2009, str. 1505-1515)
    Type of material - article, component part
    Publish date - 2009
    Language - english
    COBISS.SI-ID - 26132953
    DOI