Effects of amiodarone and thyroid dysfunction on myocardial calcium, serum calcium and thyroid hormones in the rat

1 Myocardial calcium content was found to be elevated and serum calcium reduced in hypothyroid rats. 2 Treatment of rats with amiodarone at either 30 mg kg−1 or 150 mg kg−1 daily did not result in any significant changes in myocardial or serum calcium. 3 The administration of amiodarone to hypothyro...

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Bibliographic Details
Published in:British journal of pharmacology 1987-10, Vol.92 (2), p.363-370
Main Authors: Gammage, M.D., Franklyn, J.A., Logan, S.D.
Format: Article
Language:English
Subjects:
Amiodarone - analogs & derivatives
Amiodarone - metabolism
Amiodarone - pharmacology
Animals
Antiarythmic agents
Biological and medical sciences
Calcium - blood
Calcium - metabolism
Cardiovascular system
Hypothyroidism - metabolism
In Vitro Techniques
Male
Medical sciences
Muscle Proteins - metabolism
Myocardium - metabolism
Pharmacology. Drug treatments
Rats
Rats, Inbred Strains
Thyroid Diseases - metabolism
Thyroid Hormones - blood
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Summary:1 Myocardial calcium content was found to be elevated and serum calcium reduced in hypothyroid rats. 2 Treatment of rats with amiodarone at either 30 mg kg−1 or 150 mg kg−1 daily did not result in any significant changes in myocardial or serum calcium. 3 The administration of amiodarone to hypothyroid rats attenuated the changes in serum but not myocardial calcium, suggesting that amiodarone may exert a thyroid hormone‐like effect in the hypothyroid state. 4 The administration of amiodarone to thyroid hormone‐treated rats resulted in attenuation of the effects on serum calcium and calculated intracellular calcium; this was consistent with an antagonistic interaction between amiodarone and thyroid hormones. 5 Administration of amiodarone resulted in significant changes in circulating thyroid hormone levels in the rat; triiodothyronine was reduced and basal thyrotrophin elevated compared to euthyroid controls. Serum thyroxine was not changed; this is in contrast to the effects in man. 6 Amiodarone does not exert its anti‐arrhythmic action via changes in total myocardial calcium content in the euthyroid rat; nonetheless the described interactions between the drug and thyroid hormones may be involved in its mechanism of action.
ISSN:0007-1188
1476-5381
DOI:10.1111/j.1476-5381.1987.tb11332.x