Effects of thyroid hormones on the biochemical specialization of human muscle fibers.

TitleEffects of thyroid hormones on the biochemical specialization of human muscle fibers.
Publication TypeJournal Article
Year of Publication1985
AuthorsSalviati, G, Zeviani, M, Betto, R, Nacamulli, D, Busnardo, B
JournalMuscle Nerve
Volume8
Issue5
Pagination363-71
Date Published1985 Jun
ISSN0148-639X
KeywordsAdult, Calcium, Cyclic AMP, Dose-Response Relationship, Drug, Electrophoresis, Polyacrylamide Gel, Female, Humans, Hyperthyroidism, Hypothyroidism, Middle Aged, Muscle Fibers, Skeletal, Myosins, Sarcoplasmic Reticulum, Thyroid Diseases, Thyroid Hormones
Abstract

The effects of thyrotoxicosis and of hypothyroidism on human muscle have been studied on single fiber preparations. In thyrotoxic muscle, the ratio between fibers showing the fast type of myofibrillar protein isoforms (fast fibers) and fibers showing the slow type (slow fibers) is increased, as is the percentage of fibers with incomplete segregation of fast and slow myosin (intermediate fibers). Furthermore, in fast fibers, the volume and, to a greater extent, the rate of Ca transport of sarcoplasmic reticulum (SR) are increased, without changes in the affinity for Ca2+ of the Ca-pump or in its sensitivity to the cyclic adenosine monophosphate (cAMP) dependent protein kinase system. These effects are completely reversed by the removal of thyroid hormones, as demonstrated by hypothyroid muscles. It is suggested that in human muscle cells thyroid hormones are critical for the expression of fast genes and for SR Ca transport.

DOI10.1002/mus.880080504
Alternate JournalMuscle Nerve
Citation Key10.1002/mus.880080504
PubMed ID16758581