Fig. 7.

Stepwise model of redox and bioelectric integration during regeneration. NADPH oxidase-mediated electron flow and H₂O₂ production independently regulate different bioelectric activities. This dual property – electrogenic and catalytic – of NADPH oxidases explicitly represents the proposed two-way regulation hypothesis. The focus is on the early timing of 6 hpa, when the hallmark H₂O₂-switched current reversal occurs in regenerative tadpoles. A redox-bioelectric feedback module may be present, where bioelectric signals (instant primary EF) might activate redox signals (NADPH oxidases and generated H₂O₂), which in turn regulate bioelectricity (V_m, TEP, secondary EF and J_I) to modulate regeneration. Bioelectrically controlled cell migration and subsequent permissive wound epithelium is suggested as a mechanism by which, ultimately, H₂O₂ may control regeneration. e⁻, electrons; ∇, gradient.