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Myosin heavy chain‐based fibre types in red cell hyper‐ and normovolaemic Standardbred trotters
Author(s) -
KARLSTRÖM K.,
ESSÉNGUSTAVSSON B.
Publication year - 2002
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.2002.tb05433.x
Subject(s) - myosin , myofibril , immunohistochemistry , medius , muscle fibre , staining , gene isoform , fibre type , atpase , horse , chemistry , fast twitch muscle , fiber type , anatomy , pathology , medicine , biology , biochemistry , skeletal muscle , enzyme , gene , paleontology
Summary An assumed link between red cell hypervolaemia, an excessive amount of training and impaired performance of hypervolaemic horses has led to a theory that the muscle fibres could be affected. Myosin heavy chain (MHC)‐based fibre type composition in gluteus medius muscle of red blood cell normo‐ (NV) and hypervolaemic (HV) Standardbred trotters was evaluated using immunohistochemistry. Muscle biopsies were obtained from 13 NV and 16 HV horses. Serial transverse sections were cut and reacted with antibodies against different isoforms of the myosin heavy chains MHC I , MHC IIA and MHC IIX . Sections were also stained for myofibrillar ATPase pH 4,6 to identify types I, IIA and IIB , and NADH tetrazolium reductase to evaluate the oxidative capacity. The results show that types I and IIA fibres corresponded between staining methods, whereas IIB fibres in the ATPase stains were more numerous than pure MHC IIX fibres from immunohistochemistry. Many fibres identified histochemically as type IIB fibres contained both MHC isoforms IIA and IIX (MHC IIAX ). Most fibres had a high oxidative capacity, but among the fibres within a section, the lowest was seen subjectively in pure MHC IIX fibres. Immunohistochemical stains make it possible to detect differences in fibre type composition that are not observed with myosin ATPase stainings, as it was found that HV horses had a lower percentage of MHC IIX fibres than NV horses. Immunohistochemical methods are, therefore, valuable for use in further research and clinical studies concerning muscle adaptations.