Effect of Digoxin on Chick Embryos with Hypothyroidism Induced by Thiamazole

Takashi Sugiyama1, Kazuru Saito2, Hideyo Shimada1,2, Kanji Tsuchimoto1,2 and Yuji Yoshiyama3

1Division of Pathophysiology, Center for Clinical Pharmacy and Clinical Sciences, School of Pharmaceutical Sciences, Kitasato University,
2Kitasato Institute Hospital,@9-1, Shirokane 5-chome, Minato-ku, Tokyo 108-8641, Japan
3Division of Clinical Pharmacy, Kyoritsu College of Pharmacy, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan

Correspondence: Takashi.Sugiyama,Ph.D.
Division of Pathophysiology, Center for Clinical Pharmacy and Clinical Sciences, School of Pharmaceutical Sciences, Kitasato University, 9-1, Shirokane 5-chome, Minato-ku, Tokyo 108-8641, Japan
Tel: +81-3-3444-6161 ext 3231 Fax: +81-3-3446-9036
E-mail: sugiyamat@platinum.pharm.kitasato-u.ac.jp.

Running title: Effect of Digoxin on chick Embryos with hypothyroidism

Original paper :AATEX 6(2,3):89-96,2000

Abstract
Heart failure patients with hypothyroidism show unexpected reactions to cardiovascular drugs. In the present study, we proposed a chick embryonic model of hypothyroidism by injection of thiamazole (TMZ) and investigated whether this model can be used to examine the pharmacological and toxicological effects of cardiovascular drugs. When 1.2 mg/egg or more of TMZ was injected into the albumen of fertile eggs on the 9th day of incubation, the thyroid gland in the 16th day-chick embryos showed the same pathological characteristics as those in mammals. Although the effect of TMZ on the chick embryonic heart was morphologically mild, the heart rates decreased with the increase of dose of TMZ. An injection of digoxin into the TMZ-treated eggs increased the sensitivity of the heart to TMZ compared with that in the embryos treated with digoxin alone at the same dose. These results suggest that the TMZ-treated chick embryonic models can be used to investigate the effects of cardiovascular drugs.

Key words: Chick embryo, hypothyroidism, thiamazole, digoxin, electro-cardiogram



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