title: Thyroid hormone influences muscle mechanics in carp (Cyprinus carpio) independently from SERCA activity.
abstract: 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.
authors.affiliation: Research Centre for Applied Biological and Exercise Sciences, Coventry University, Coventry CV1 5FB, UK r.james@coventry.ac.uk.
authors.forename: Rob S
authors.identifier: http://orcid.org/0000-0002-3969-8261
authors.initials: RS
authors.lastname: James
authors.affiliation: School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Little
authors.affiliation: Research Centre for Applied Biological and Exercise Sciences, Coventry University, Coventry CV1 5FB, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Tallis
authors.affiliation: School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Frank
authors.initials: F
authors.lastname: Seebacher
keywords: Calcium; Fatigue; Force; Hypothyroidism; Stress