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Cross-Bridge and Calcium Behavior in Ferret Papillary Muscle in Different Thyroid States
- Source :
- The Japanese Journal of Physiology. 51:319-326
- Publication Year :
- 2001
- Publisher :
- Physiological Society of Japan, 2001.
-
Abstract
- X-ray diffraction studies were made using synchrotron radiation on ferret right ventricular papillary muscle under three different thyroid states: euthyroidism, hyperthyroidism, and hypothyroidism. The latter two states were induced by treatment with L-thyroxine and methimazole, respectively. The X-ray equatorial reflections were recorded at a time resolution of 10 ms to study the mass movement of myosin cross-bridges from thick to thin filaments. The myosin isomer content was measured by gel electrophoresis which showed that V3 isomer was predominant in euthyroid muscle and 27% of myosin was V1 isomer in hyperthyroid muscle. The intracellular free Ca concentration was measured by using the aequorin method. The peak Ca concentration was similar in all three states, but in the hypothyroid state the time-to-peak was longer and the decay was slower. The time-to-peak of twitch tension was shorter in hyperthyroidism and longer in hypothyroidism than in euthyroidism. The different time courses of twitch tension in different thyroid states accompanied a cross-bridge movement which closely followed the tension development. In hyperthyroidism, the cross-bridge movement significantly preceded tension development, suggesting that hyperthyroid myosin (V1) has a longer latency period between the shift to the vicinity of the thin filament and force development.
- Subjects :
- Male
endocrine system
medicine.medical_specialty
endocrine system diseases
Physiology
Aequorin
chemistry.chemical_element
Myosins
Calcium
Hyperthyroidism
Hypothyroidism
X-Ray Diffraction
Internal medicine
Myosin
medicine
Animals
Euthyroid
Papillary muscle
Actin
biology
Myocardium
Thyroid
Ferrets
Cardiac muscle
Heart
General Medicine
Endocrinology
medicine.anatomical_structure
chemistry
biology.protein
hormones, hormone substitutes, and hormone antagonists
Subjects
Details
- ISSN :
- 0021521X
- Volume :
- 51
- Database :
- OpenAIRE
- Journal :
- The Japanese Journal of Physiology
- Accession number :
- edsair.doi.dedup.....5fef95eced0bab351ea3d38433cea732