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Hyperthyroidism and cation pumps in human skeletal muscle.
Anne Lene Dalkjaer Riis1, Jens Otto Lunde Jørgensen, Niels Møller
1Medical Dept. M (Endocrinology and Diabetes), Aarhus Univ. Hospital, 8000 Aarhus C, Denmark. anne.lene.riis@ki.au.dk
American Journal of Physiology. Endocrinology and Metabolism
|December 16, 2004
Summary
Thyroid hormone impacts skeletal muscle energy expenditure by altering calcium (Ca2+-ATPase) and sodium-potassium (Na+-K+-ATPase) pump levels. Hyperthyroidism increases these pumps, which correlate with higher energy expenditure and thyroid hormone levels.
Area of Science:
- Endocrinology
- Skeletal Muscle Physiology
- Metabolism
Background:
- Skeletal muscle is a primary site for thyroid hormone's thermogenic effects.
- Thyroid hormones influence cellular energy dynamics and ion transport.
- Understanding the link between thyroid status, muscle function, and energy expenditure is crucial.
Purpose of the Study:
- To investigate the relationship between thyroid status, energy expenditure (EE), and the levels of Ca2+-ATPase and Na+-K+-ATPase in human skeletal muscle.
- To compare these levels in hyperthyroid patients, euthyroid state post-treatment, and healthy controls.
Main Methods:
- Studied 11 hyperthyroid patients (Graves' disease) before and after methimazole treatment, compared with 8 healthy controls.
- Measured energy expenditure (EE) using indirect calorimetry.
- Analyzed Ca2+-ATPase and Na+-K+-ATPase content in vastus lateralis muscle biopsies.
Main Results:
- Hyperthyroid patients exhibited significantly elevated Ca2+-ATPase and Na+-K+-ATPase content compared to euthyroid and healthy states.
- Ca2+-ATPase content correlated positively with plasma T3 levels and resting EE.
- In the euthyroid state, muscle cation pump content was comparable to healthy controls.
Conclusions:
- Human skeletal muscle's capacity for Ca2+ handling and Na+-K+ transport is linked to EE and thyroid status.
- Increased Ca2+-ATPase and Na+-K+-ATPase content in hyperthyroidism may contribute to elevated EE.
- These findings provide evidence for thyroid hormone's direct impact on key muscle ion transport mechanisms affecting metabolism.