Morphology alteration (a), mortality (b) and Hatching rate (c) of zebrafish embryos exposed to different concentrations of isoniazid at 48 and 72hpf. The red arrows represented some typical deformities in the embryo development like yolk sac edema and spinal curvature due to the abnormal development of somatic ganglia.^*P < 0.05, ^**P < 0.1, ^***P < 0.001

The alteration in the cardiac morphology at 48hpf by using transgenic strain zebrafish (Cmlc2-GFP) The red lines represented the outline of the heart (a). The results of in situ hybridization by using a cmlc2 probe (b). Isoniazid lead to yolk sac edema during the cardiac development (c). Measurement of Pericardial asc area and normalized to 0 mM groups (d). Expression level of cTNT (Cardiac Troponin T) at 48hpf in 0 mM, 0.04 mM, 0.16 mM and NAC groups (e). ^*P < 0.05, ^**P < 0.1, ^***P < 0.001

The heart rate of zebrafish embryos recorded at different times in control, 0.04 mM, 0.16 mM and NAC groups. ^*P < 0.05, ^**P < 0.1, ^***P < 0.001, ns means no significantly different

The expression of four cardiac-specific transcript factors in zebrafish embryos after 48 hpf of isoniazid exposure. ^*P < 0.05, ^**P < 0.1, ^***P < 0.001, ns means no significantly different

The ROS level in control, 0.04 mM, 0.16 mM and NAC groups (a). The activity of CAT (b) and SOD (c) induced by isoniazid. The concentration of MDA (d), ROS (e) and apoptosis level (f) in different treated groups. The unit of SOD and CAT were ul/mg protein while MDA nmol/mg protein. The concentration of ROS was normalized to 0 mM groups. The red arrows represented the pericardial areas. ^*P < 0.05, ^**P < 0.1, ^***P < 0.001, ns means no significance