Effects of thyroid hormones on calcium contents and 45Ca exchange in rat skeletal muscle
In 4-wk-old rats, pretreatment with L-triiodothyronine (T3) increased calcium content by 100% and the 30-min /sup 45/Ca uptake by 64% in the soleus, whereas the extensor digitorum longus (EDL) muscle showed no significant change. The stimulation of /sup 45/Ca uptake was resistant to dantrolene and methoxyverapamil (D600) and could not be attributed to altered permeability of the plasma membrane to calcium, but appears to reflect increased net accumulation of calcium in intracellular pools. The stimulating effect of high K0 (20 mM) on /sup 45/Ca uptake was more pronounced in soleus than in EDL and could be suppressed by dantrolene and D600. The results indicate that the effects of T3 on calcium content and /sup 45/Ca exchange are primarily exerted on muscles containing a large proportion of slow-twitch, oxidative fibers. In soleus muscle from hyperthyroid rats the stimulating effects of high K0 on /sup 45/Ca uptake and lactate production were, respectively, 3.4 and 4.5 times larger than in those obtained from controls. These observations further support the earlier proposed idea (C. van Hardeveld and T. Clausen. Am. J. Physiol. 247 (Endocrinol. Metab. 10): E421-E430, 1984) that the metabolic effects of thyroid hormone depend on the availability of cellular as well as extracellular calcium.
- Research Organization:
- Aarhus Univ., Denmark
- OSTI ID:
- 5071538
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM 45
UPTAKE
MUSCLES
RADIONUCLIDE KINETICS
TRIIODOTHYRONINE
BIOLOGICAL EFFECTS
CALCIUM
HYPERTHYROIDISM
HYPOTHYROIDISM
LACTATES
MITOCHONDRIA
POTASSIUM
RATS
SARCOPLASMIC RETICULUM
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CARBOXYLIC ACID SALTS
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DISEASES
ELEMENTS
ENDOCRINE DISEASES
EVEN-ODD NUCLEI
HORMONES
INTERMEDIATE MASS NUCLEI
ISOTOPES
MAMMALS
METALS
NUCLEI
ORGANOIDS
PEPTIDE HORMONES
RADIOISOTOPES
RODENTS
THYROID HORMONES
VERTEBRATES
560172* - Radiation Effects- Nuclide Kinetics & Toxicology- Animals- (-1987)