Figure 4.

Effects of sodium azide on single channel currents. Continuous single channel currents recorded from inside-out membrane patches exposed to symmetrical 140 mM KCl at a membrane potential of +40 mV. Single channel openings are denoted by upward deflections. (a) Sodium azide (3 mM) inhibited K_ATP channels in the absence of Mg²⁺ in the bathing medium. This action of sodium azide was partially reversed on washout. The Nf.Po values obtained in control conditions, in the presence of sodium azide and following washout of azide were 1.06, 0.13 and 0.62, respectively. (b) In contrast, sodium azide (3 mM) activated K_ATP channels when 0.1 mM MgATP bathed the intracellular surface of inside out patches. Washout of azide partially reversed this action. The Nf.Po values were as follows: control 0.214; 0.1 mM MgATP 0.036; sodium azide and MgATP 0.600; wash 0.023.