Caffeine-induced effects on heart rate in zebrafish embryos and possible mechanisms of action: an effective system for experiments in chemical biology.

Zebrafish embryos are well suited as a model system to perform chemical biology experiments effectively in educational settings. We studied the effect of caffeine on heart rate (HR) and other phenotypes of zebrafish embryos using visual microscopy and simple imaging. Acute treatment with millimolar concentrations of caffeine in embryo medium caused a dose-dependent decrease in HR in 2-3-day-old zebrafish embryos, ultimately resulting in complete HR cessation.