Cardiac Hypertrophy in Rats and Mice Given 3, 3', 5-Triiodo-L-Thyronine Orally

Gemmill, Chalmers L.

doi:10.1152/ajplegacy.1958.195.2.385

Cited by 36 publications

(7 citation statements)

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“…Similar results have been well documented by many other investigators (19,23,25). Except for the increased diameter of the myocytes and mitochondriosis in the myocytes, however, there were no significant morphological differences from the hearts of control rats (details will be published elsewhere).…”

Section: Discussionsupporting

confidence: 93%

Biochemical and morphological study of cardiac hypertrophy. Effects of thyroxine on enzyme activities in the rat myocardium

et al. 1985

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Experimental hyperthyroidism induced in rats by daily injections of 3,3',5,5'-tetraiode-L-thyroxine (0.5 mg/kg i.p.) for 14 days resulted in a significant increase in heart weight and heart weight/body weight ratio. Hemodynamic and morphological studies were performed in one group. Thyroxine-treated rats showed a characteristic cardiovascular hyperdynamic state, such as tachycardia and augmented rate of contraction, but no evidence of heart failure such as elevated end-diastolic pressures. The cardiac cells in hyperthyroid rats had a significantly larger diameter and more mitochondria than did those of the control rats. In another group the activities of cardiac enzymes involved in energy utilization and liberation were measured biochemically and compared with those of normal controls. Hyperthyroidism resulted in increased specific activity of cytochrome C oxidase and actomyosin ATPase in the myocardium. The specific activity of long-chain acyl-CoA synthetase, carnitine palmityl-transferase, carnitine acetyltransferase, malate dehydrogenase and citrate synthase showed a moderate to marked increment, whereas the specific activity of lactate dehydrogenase and pyruvate kinase remained at the control values. These results suggest that in hyperthyroid rat hearts the functions of both energy liberation and utilization systems are enhanced to meet the added workload. Moreover, the increased activity of the enzymes participating in fatty acid metabolism suggest that in thyroxine-induced hypertrophic and hyperdynamic rat hearts, fatty acids contribute more to the energy supply than do carbohydrates.

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Section: Discussionsupporting

confidence: 93%

Biochemical and morphological study of cardiac hypertrophy. Effects of thyroxine on enzyme activities in the rat myocardium

et al. 1985

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“…Cardiac hypertrophy of similar degree has previously been noted in hyperthyroid animals (Gemmill 1958;Beznak 1962). On the other hand, creatine concentration was reduced 37% in hyperthyroid cardiac muscle.…”

Section: Resultssupporting

confidence: 80%

Mechanism of creatinuria in experimental hyperthyroidism

Carter

Benjamin

Faas

1981

Acta Endocrinologica

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Using rats pre-labelled by [14C]creatine injection, the mechanism of creatinuria induced by experimental hyperthyroidism during a 20 day treatment period has been examined. The excess creatine excretion is the result of increased release of creatine from muscle and increased excretion of creatine synthesized de novo. The increased excretion of newly synthesized creatine in hyperthyroidism appears to occur because of decreased creatine uptake by muscle, an increased rate of creatine synthesis, or a combination of both factors. The radioactive creatine content of hyperthyroid skeletal muscle was reduced at the time of death indicating an increased rated of creatine loss during the treatment period. In spite of the increased loss of labelled creatine, the specific activity of creatine obtained from hyperthyroid skeletal muscle was higher than control. This finding is probably due to decreased uptake of unlabelled creatine by hyperthyroid skeletal muscle during the treatment period. In contrast to skeletal muscle, the radioactive creatine content of hyperthyroid myocardium was higher than control at the time of death suggesting a decreased rate of creatine loss during the treatment period.

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“…This is true of thyroxine (Beznak, 1962;Edgren et al, 1976;Gemmill, 1958;Piatnek-Leunissen and Olson, 1967;Sandier and Wilson, 1959). There is considerable loss of body weight with administration of T 4 (Yazaki and Raben, 1975) which can lead to overestimation of the degree of cardiac hypertrophy through use of the heart weightto-body weight ratio.…”

Section: Discussionmentioning

confidence: 99%

“…HYPERTHYROIDISM increases whole body O 2 consumption (Beznak, 1962;Gemmill, 1956Gemmill, , 1958. This, together with direct cardiovascular effects, leads to important changes in the heart.…”

mentioning

confidence: 99%

“…This leads to increases in myocardial oxygen consumption and coronary blood flow in hyperthyroidism (Gunning et al, 1974;Leight et al, 1956;Piatnek-Leunissen and Olson, 1967;Skelton et al, 1970). Furthermore, the hyperthyroidism increases heart work, which leads to cardiac hypertrophy in many species, including man (Beznak, 1962;Edgren et al, 1976;Gemmill, 1958;Piatnek-Leunissen and Olson, 1967;Sandier and Wilson, 1959).…”

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confidence: 99%

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Thyroxine-induced hypertrophy of the rabbit heart. Effect on regional oxygen extraction, flow, and oxygen consumption.

Talafih¹,

Briden²,

Weiss³

1983

Circulation Research

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SUMMARY. The effects of the administration of 0.5 or 1 mg/kg of 1-thyroxine for 3 or 16 days were studied in 55 New Zealand white rabbits. Heart size was 29% above control after 16 days of 1-thyroxine, despite lower body weights. In an anesthetized open-chest animal, regional microspectrophotometric observations of small arteries and veins to determine oxygen extraction were combined with regional blood flow measurements using radioactive microspheres to determine regional oxygen consumption by the Fick principle. Vascular flow reserves were studied through measurement of blood flow after the administration of chromonar HC1, 10 mg/kg. Myocardial oxygen consumption was, respectively, 2.4 and 3.8 times control after 3 and 16 days of 1-thyroxine. This was accompanied by significant increases in both coronary blood flow and oxygen extraction. In control, oxygen extraction and consumption were higher in the subendocardial region compared to the subepicardial area. No significant regional differences were found in flow, oxygen extraction, or consumption after 1-thyroxine administration. Chromonar increased coronary blood flow 2.8 times in the control animals, but did not significantly increase flow or decrease vascular resistance in the rabbits given 1-thyroxine. Adenosine increased coronary blood flow 3.5 times in the control animals but only 2.2 times in animals given 1-thyroxine for 3 days. Animals given 1-thyroxine had hypertrophied hearts with increased oxygen consumption, markedly increased flow, and increased oxygen extraction but without regional left ventricular differences. (Circ Res 52: 272-279, 19S3)

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Cardiac Hypertrophy in Rats and Mice Given 3, 3', 5-Triiodo-L-Thyronine Orally

Cited by 36 publications

References 0 publications

Biochemical and morphological study of cardiac hypertrophy. Effects of thyroxine on enzyme activities in the rat myocardium

Biochemical and morphological study of cardiac hypertrophy. Effects of thyroxine on enzyme activities in the rat myocardium

Mechanism of creatinuria in experimental hyperthyroidism

Thyroxine-induced hypertrophy of the rabbit heart. Effect on regional oxygen extraction, flow, and oxygen consumption.

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