SKELETAL-MUSCLE CHARACTERISTICS OF RACING REINDEER (RANGIFER TARANDUS)

Samples from the middle gluteal muscle of 3-7-year-old racing reindeer were taken before (7 reindeer) and at the end of the racing season (1 2 reindeer) for determination of fibre type composition, activities of citrate synthase (CS), 3-hydroxyacyl-CoA-dehydrogenase (HAD) and the glycogen content. Muscle samples were also taken from 7 female and 18 male reindeer of same age for histochemical determination of muscle fi bre composition. During the racing season the fibre type composition r emained unchanged as did the activities of CS and HAD. The high activi ties of CS and HAD together with the high intensity in the NADH-dehydr ogenase stain indicate that the reindeer muscle has a high oxidative c apacity. The glycogen content increased during the winter which can ex plain the increasing tendency in the transverse fibre area. The racing reindeer had a lower percentage of type I fibres and a higher percent age of type IIA fibres than the ordinary male reindeer. The difference s in the fibre type composition suggest that the racing reindeer repre sent a selected reindeer population.