Aza and DNR effects on zebrafish heart rate. The zebrafish larvae heart rate in the cardiotoxicity assays was found by filming the zebrafish for 12 s and using a self-written ImageJ macro to calculate the heart rate from the obtained video as described in the Materials and Methods section. (A) Still image from a film analysing zebrafish larvae heart rate. The red rectangle marking the region of interest (ROI) for pixel intensity measurement. (B) Average pixel intensity in the ROI. (C) Fourier transform of pixel intensity from the ROI to calculate beats per minute (BPM). (D) Heart rate of zebrafish larvae injected with 4 nL PBS (n=11) or Aza (1 mM, n=11). (E) Heart rate of zebrafish larvae injected with 4 nL PBS (n=10) or DNR (1 mM, n=13). For the Aza-test, the zebrafish larvae were injected daily after Pre-injection, 1 dpi and 2 dpi measurements. For the DNR-test, the zebrafish larvae were injected once, after the Pre-injection observation. The heart rate was related to the average heart rate of the control group pre-injection. Significance found using two-tailed Welch's t-test. Not annotated: P>0.05, *P≤0.05, **P≤0.01.
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