Summary
Muscle contents of ATP, ADP, AMP, creatine phosphate and creatine as well as glycogen,
some glycolytic intermediates, pyruvate and lactate were compared in the intact, thyroidectomized
and triiodothyronine (T3) treated dogs under resting conditions. After thyroidectomy
muscle glycogen, glucose 1 -phosphate and glucose 6-phosphate contents were significantly
elevated while in T3-treated animals these variables were decreased in comparison
with control dogs. Muscle free glucose was not altered by thyroidectomy but T3 treatment
significantly increased its content. Muscle lactate content was elevated both in hypo-
and hyperthyroid animals. Muscle ATP and total adenine nucleotide contents were significantly
increased in hyperthyroid dogs while no differences were found between the three groups
in the muscle creatine phosphate content.
It is assumed that in T3-treated animals carbohydrate catabolism is enhanced in the
resting skeletal muscle in spite of high tissue ATP content. Muscle metabolite alterations
in hypothyroid dogs seem to reflect the hypometabolism accompanied by a diminished
rate of glycogenolysis with inhibited rate of pyruvate oxidation or decreased rate
of lactate removal from the cells.
Key-Words
Triiodothyronine
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Thyroidectomy
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Muscle Glycogen
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Glycogenolysis
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Muscle Adenine Nucleotides
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Creatine Phosphate
