Fig. 6. Hydroxyl radical effects on epidermal root fluxes of different species. (A) Representative traces of OH^•-induced net K⁺ efflux measured by MIFE^TM from mature epidermal cells of different species. Initial flux values are shown as dotted lines. The 1 mM Cu/a was added as indicated by arrows. (B) Hydroxyl radical-induced net Ca²⁺ influx measured by MIFE^TM simultaneously with K⁺ efflux. Control Ca²⁺ fluxes before Cu/a addition were negligible (up to 100 times smaller) in comparison with OH^•-induced influxes. Mean values (±s.e.m.) are maximal Ca²⁺ influx between 2 to 40 minutes exposure to 1 mM Cu/a.