Fibre composition and enzyme activities in five different muscles from the Svalbard reindeer.
beta R fibres (type I) constitute less than 10% of the semimembranosus and longissimus dorsi muscles and about twice as much of the gluteobiceps and flexor hallucis. Except for longissimus dorsi, 50% or more consist of alpha W (type IIB) fibres--in semimembranous, as much as 70%. Despite the comparatively large content of alpha W fibres, both the oxidative capacity and the capacity to metabolize fatty acids is high. Furthermore, unexpectedly small differences in oxidative capacity between the three fibre types beta R, alpha R and alpha W (I, IIA and IIB) are revealed by histochemical staining. These results indicate a tendency to bring the three fibre types closer together as regards metabolic activities, as an adaptation to the relatively tranquil life of this animal. However, the large content of alpha W fibres does not accord well with this way of life, as they guarantee quick movements. The comparatively high oxidative capacity of the alpha W fibres in the Svalbard reindeer and the fact that during starvation it is primarily alpha W fibres that contribute to the energy supply by protein degradation may nevertheless account for their abundant occurrence.
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000033:anatomy & histology* / Q000201:enzymology; D012053:Reindeer / Q000033:anatomy & histology* / Q000378:metabolism
D015094:3-Hydroxyacyl CoA Dehydrogenases; D007770:L-Lactate Dehydrogenase; D003576:Electron Transport Complex IV