BACKGROUND AND OBJECTIVES Dilated cardiomyopathy can be the end-stage of severe cardiac disorders and directly affects the cardiac muscle, inducing cardiomegaly and heart failure (HF). Although a wide variety of animal models are available to study dilated cardiomyopathy, there is no model to assess dilated cardiomyopathy with non-invasive, simple, and large screening methods.

METHODS We developed a dilated cardiomyopathy model in zebrafish larvae using short duration terfenadine, a known cardiotoxic drug that induces ventricular size dilation. Fractional shortening of zebrafish hearts was calculated.

RESULTS We treated zebrafish with 5 to 10 μM terfenadine for 24 hours. In terfenadine-treated zebrafish, blood frequently pooled and clotted in the chamber, and circulation was remarkably reduced. Atria and ventricles were swollen, and fluid was deposited around the heart, mimicking edema. Cardiac contractility was significantly reduced, and ventricular area was significantly enlarged. Heart rate was markedly reduced even after terfenadine withdrawal. Acridine orange staining also showed that terfenadine increased cardiomyocyte apoptosis. A significant increase of natriuretic peptide B (NPPB) mRNA was found in terfenadine-treated zebrafish. A low dose of terfenadine (5-10 μM) did not show mortality in short-term treatment (24 hours). However, moderate dose (35-45 μM) terfenadine treatment reduced zebrafish survival within 1 hour.

CONCLUSION With advantages of rapid sample preparation procedure and transparent observation of the live heart, this model can potentially be applied to large-scale drug screening and toxicity assays for non-ischemic HF.