Muscle fibre type composition in young and racing Swedish cold-blooded trotters
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Abstract
Fibre type composition of skeletal muscle in horses varies due to factors like breed, age and training. Variations due to these factors in muscle fibre type composition of the Swedish cold-blooded trotter, a heavier and slower breed than the Standardbred trotter, have not previously been reported. The objective of this study was therefore to investigate muscle fibre type composition of young and racing cold-blooded trotters using both histochemical and immunohistochemical methods. Muscle biopsies (gluteus medius) were obtained from 2-year-old (n = 18) and 4–8-year-old horses (n = 6). Four of the 2-year-old horses were sampled again during their 4-yearold season. All of the horses were in professional training and the group included superior racehorses. Fibre types (I, IIA and IIB) were visualized with the myosin ATPase technique. Some samples were also stained immunohistochemically to identify MHCI, MHCIIA and MHCIIX fibres using myosin heavy chain (MHC) antibodies. The oxidative capacity of the fibres was subjectively evaluated from NADH-tetrazolium reductase stains. Type I and type IIA fibres were all identified as MHCI and MHCIIA fibres, respectively, whereas type IIB fibre population included both pure MHCIIX and hybrid MHCIIAX fibres. The older racehorses had a higher proportion of type MHCIIA and a lower proportion of type MHCIIX fibres than the 2-year-old horses. Areas of type I fibres were larger and those of type IIB fibres were smaller in racing horses compared with young horses. The proportion of type MHCIIX fibres that stained medium for oxidative capacity increased with age and training. In conclusion, training and racing induce muscular adaptations in cold-blooded trotters as in other breeds. Furthermore, immunohistochemical methods detect hybrid fibres indicating that transitions of fibre types may occur.
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| All Time | Past 365 days | Past 30 Days | |
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Muscle fibre type composition in young and racing Swedish cold-blooded trotters
In: Comparative Exercise PhysiologySearch for other papers by Kristina Karlström in
Current site
Google Scholar
PubMed
Search for other papers by Arne Lindholm in
Current site
Google Scholar
PubMed
Search for other papers by Eje Collinder in
Current site
Google Scholar
PubMed
Search for other papers by Birgitta Essén-Gustavsson in
Current site
Google Scholar
PubMed
Abstract
Fibre type composition of skeletal muscle in horses varies due to factors like breed, age and training. Variations due to these factors in muscle fibre type composition of the Swedish cold-blooded trotter, a heavier and slower breed than the Standardbred trotter, have not previously been reported. The objective of this study was therefore to investigate muscle fibre type composition of young and racing cold-blooded trotters using both histochemical and immunohistochemical methods. Muscle biopsies (gluteus medius) were obtained from 2-year-old (n = 18) and 4–8-year-old horses (n = 6). Four of the 2-year-old horses were sampled again during their 4-yearold season. All of the horses were in professional training and the group included superior racehorses. Fibre types (I, IIA and IIB) were visualized with the myosin ATPase technique. Some samples were also stained immunohistochemically to identify MHCI, MHCIIA and MHCIIX fibres using myosin heavy chain (MHC) antibodies. The oxidative capacity of the fibres was subjectively evaluated from NADH-tetrazolium reductase stains. Type I and type IIA fibres were all identified as MHCI and MHCIIA fibres, respectively, whereas type IIB fibre population included both pure MHCIIX and hybrid MHCIIAX fibres. The older racehorses had a higher proportion of type MHCIIA and a lower proportion of type MHCIIX fibres than the 2-year-old horses. Areas of type I fibres were larger and those of type IIB fibres were smaller in racing horses compared with young horses. The proportion of type MHCIIX fibres that stained medium for oxidative capacity increased with age and training. In conclusion, training and racing induce muscular adaptations in cold-blooded trotters as in other breeds. Furthermore, immunohistochemical methods detect hybrid fibres indicating that transitions of fibre types may occur.
| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 77 | 26 | 3 |
| Full Text Views | 7 | 0 | 0 |
| PDF Views & Downloads | 3 | 0 | 0 |
