Thyroid hormone is a key regulator of metabolism, and in zebrafish, hypothyroidism decreases sustained and burst swimming performance. These effects are accompanied by decreases in both metabolic scope and the activity of sarco-endoplasmic reticulum ATPase (SERCA) in zebrafish. Our aim was to determine whether thyroid hormone affects skeletal muscle contractile function directly and whether these effects are mediated by influencing SERCA activity. We show that hypothyroidism reduces sustained locomotor performance but not sprint performance in carp (Cyprinus carpio). We accept our hypothesis that hypothyroidism reduces force production in isolated skeletal muscle, when compared with the thyroid hormone T2, but we reject the hypothesis that this effect is mediated by influencing SERCA activity. Blocking SERCA activity with thapsigargin reduced muscle fatigue resistance, but hypothyroidism had no effect on fatigue. Hence, thyroid hormone plays a role in determining isolated skeletal muscle mechanics, but its effects are more likely to be mediated by mechanisms other than affecting SERCA activity.
The authors declare no competing or financial interests.
R.S.J. conducted experiments, analysed data and wrote the manuscript; A.G.L. conceived and conducted experiments; J.T. conducted experiments; and F.S. conceived the experiments, analysed data and wrote the manuscript.
This research was supported by an Australian Research Council grant to F.S. J.T. was funded by a Society of Experimental Biology Company of Biologists Travel Grant and Coventry University International Experience Mobility funding. R.S.J. was funded by a Coventry University Applied Research Fellowship.
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.143529.supplemental
- Received May 20, 2016.
- Accepted June 29, 2016.
- © 2016. Published by The Company of Biologists Ltd