الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
One of the primary consequences of hyperthyroidism is lower tolerance to physical exertion, because of its implications involving the muscle . This interferes directly in the patients ability to perform daily activities, thereby reducing quality of life. The mechanism of exercise intolerance in hyperthyroidism has not been fully elucidated. The aim of the present investigation is to study effect of experimental hyperthyroidism on maximum acute exercise tolerance, neuromuscular performance, some oxidative stress markers and total antioxidant capacity in rats. Thirty adult male albino rats ,of the local strain ,weighed 150-200 grams, each, were used in this investigation. Rats were divided into the following groups: Group I : Normal Euthyroid group. Group II : Hyperthyroid group. Group III : Hyperthyroid recovered group. At the end of experiment maximal swim time and body weight were estimated, then retro-orbital blood samples were collected for estimation o of FT3 (Tri-iodothyronin), FT4 (Tetra-iodothyronin), TSH (Throid stimulating hormone),BUN (Blood urea nitrogen) , CPK (Creatin phosphokinase) , malondialdehyde and total antioxidant capacity. Rats were then sacrificed by cervical decapitation, and phrenic-nerve diaphragm preparations were excised , put in organ bath and connected to 4 channel oscillograph as described below. The preparations were used for measuring of the following parameters: - The strength of muscle contraction: It was measured at the start of 130 Summary experiment and after 30 minutes activity by using both direct and indirect stimulation. - Glucose uptake by the muscle: It was measured during 30 minutes activity and 30 minutes recovery. In the present investigation , hyperthyroidism was associated with significant decrease in body weight, maximal swim time, total antioxidant capacity, strength of muscle contraction caused by direct and indirect repetitive electrical stimulation and its glucose uptake during 30 min. activity and 30 min. recovery ; but caused significant increase in serum CPK and oxidative stress markers compared to the corresponding value in Euthyroid group. Although recovery of hyperthyroid rats by withdrawal of thyroxin administration did not resume basal levels of measured parameters but, it caused significant increase in body weight, maximal swim time, total antioxidant capacity, strength of muscle contraction caused by direct and indirect repetitive electrical stimulation and its glucose uptake during 30 min. activity and 30 min. recovery , but caused significant decline in serum CPK and oxidative stress markers compared to the corresponding value in hyperthyroid group.