Objectives: 

Energy deprivation during the winter time poses a challenge to skeletal muscle function. The objective of the present study was to determine the expression of specific Ca2+ regulating proteins in skeletal muscle of the reindeer during winter time adaptation and moderate weight loss.

Materials: 

In order to assess the possible changes in Cacna1, RyR1, SERCA1 and calsequestrin 1 (CASQ1) proteins, six mature female reindeer were held in experimental outdoor conditions with limited energy intake and muscle biopsies were taken from m. semitendinosus. In addition, muscle biopsies from m. semitendinosus and m. gluteus medius taken from freely ranging reindeer after slaughter (in October, N=7; in January, N=7) were included in the study. The muscle samples were analysed with Western blot.

Results: 

In general, the concentrations of nearly all calcium regulating components measured were maintained as a response to restricted feeding in experimental and freely ranging reindeer. Interestingly the expression of Cacna1 was 2.3-fold up-regulated after restricted feeding period in m. semitendinosus of the experimental reindeer. In freely ranging animals, on the contrary, the expression of RyR1 decreased 3.2-fold in the muscles of reindeer in January compared to October.

Conclusions: 

To conclude, the expression of Ca2+ regulating proteins is not altered during moderate weight loss and winter adaptation in order to maintain effective muscle contraction capacity. Up-regulation of Cacna1, however, indicates the ability to allocate Ca2+ cycling capacity to both oxidative and glycolytic metabolism pathways at times of energy deprivation.