The effect of hypothyroidism on myocardial contractility and sarcoplasmic reticulum function in rats.
Changes in contractility and ATPase activity of SR from hearts of hypothyroid rats were investigated. Rats were made hypothyroid by daily injection of 100 mg/kg methimazole for 14 days. In methimazole-treated rats, the contractile force, the maximum velocity of tension development and relaxation were significantly decreased, however, the time to peak tension remained unchanged. Function of SR was studied by determining of Ca2+-activated ATPase activity, which was significantly decreased after methimazole treatment. This diminution may be partially responsible for a slower reduction of the free Ca2+ in the surroundings of contractile proteins and thus decrease the rate of relaxation.
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate; D007037:Hypothyroidism / Q000503:physiopathology*; D008297:Male; D008713:Methimazole; D009200:Myocardial Contraction; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D013385:Succinate Dehydrogenase / Q000378:metabolism
D008713:Methimazole; D013385:Succinate Dehydrogenase; D000252:Calcium-Transporting ATPases