Fig. 2. Observations on the OH^•-induced K_out and Ca_in in protoplasts from Arabidopsis root mature epidermis. (A) Mean (±s.e.m.) time-courses of OH^•-induced K_out and Ca_in measured at +80 and -160 mV, respectively; 1 mM Cu/a added at 0 minutes. (B) The effect of omitting K⁺ from the pipette solution (-K) or reducing bathing solution Ca²⁺ to 0.2 mM (-Ca) on currents measured 15 minutes after addition of 1 mM Cu/a (representative current-voltage curves). (C) Pharmacology of OH^•-induced K_out and Ca_in (20 mM TEA⁺, 50 µM La³⁺, 50 µM Gd³⁺, 20 µM verapamil, 20 mM Ca²⁺, 20 mM Ba²⁺).