Figure 11.

Proposed model for the action of the sulfhydryl (SH) blockers and La³⁺ on membrane potential, electrolyte leakage, H⁺ influx, O₂ uptake, and H₂O₂ production burst in E. densa leaves. According to this scheme, Ca²⁺ influx would influence the effects on NADPH oxidase independently of its action on ion transport and transmembrane potential. However, the present evidence is compatible with the alternative interpretation, that the activation of NADPH oxidase is a consequence of the changes at the ion-transport level (see Jabs et al., 1997).