The toxic effect of Amiodarone on valve formation in the developing heart of zebrafish embryos

BACKGROUND: Amiodarone is a class D drug given to treat arrhythmia, including pregnant women, but its effects on the developing heart have not been studied. Although some studies have suggested that this drug is safe for fetuses, they have been conducted on mothers with fetuses at or beyond six months of gestational age. RESULTS: The occurrence of valve defect was positively proportional to Amiodarone concentrations over 9μM, but not lower than 6μM. Ectopic overexpression of versican was observed at the atrioventricular canal of the Amiodarone-treated embryos at 15μM (EC(50)). VE-cadherin (cdh5), normally downregulated at the endocardial cushion, was also ectopically overexpressed in the Amiodarone-treated embryos. Knockdown of either versican or cdh5 in the Amiodarone-treated embryos could rescue the valve defect caused by Amiodarone. CONCLUSIONS: By inducing versican ectopical overexpression, leading, in turn, to cdh5 ectopical overexpression, Amiodarone treatment causes failure of cardiac valve formation in zebrafish embryos.