Laser-scanning velocimetry measures the cardiac toxicity of tricaine. (a and b) Velocity and acceleration profiles acquired from the dorsal aorta of 48 hpf embryos untreated (a) or treated (b) with 500 μM tricaine. (c-g) Cardiac parameters of a single Danio rerio embryo treated with successively increasing doses of tricaine. Dose-response relationship of peak velocity (c), peak acceleration (d), stroke volume (e), heart rate (f) and cardiac output (g). Error bars represent the SEM of values obtained from four to six heartbeats in a single embryo. Lines are a non-linear least squares fit to a sigmoidal dose-response curve. Laser-Scanning Velocimetry Data Analyzer smoothing parameters used for trace, velocity, and acceleration smoothing were 5, 60, and 80, respectively.