Cardiotoxic Effects of Acute 4.5 mM Caffeine Exposure in 2-to-3-Day-Old Zebrafish are Attenuated by Tricaine.

A previous study reported that 4 mM caffeine halted cardiac activity in 2-to-3-day-old zebrafish embryos by 72 minutes of exposure, although it remains unclear whether this resulted from a combined effect of caffeine and anesthesia. We demonstrate that 4.5 mM Caffeine significantly alters heart rate and rhythm in 2-to-3-day-old zebrafish embryos with or without tricaine anesthesia but rarely abolishes cardiac activity, even after ~24.5 hours of exposure. Notably, tricaine anesthesia co-administration significantly attenuated caffeine-induced bradycardia at ~2.5 hours and reduced the incidence of arrhythmias at both ~2.5 and ~24.5 hours post-treatment.