Figure 4. BaCl₂ inhibition of both Kir and TASK-like currents.

A, a low concentration (30 μm) of BaCl₂ inhibits primarily an inward K⁺ current in DVN. Increasing BaCl₂ to 1 mm inhibited mainly an outward current. B, mean current amplitude at a command potential of −20 and −120 mV in the absence and presence of 30 μm or 1 mm BaCl₂, respectively (all bars n = 5). *P < 0.05 versus 30 μm BaCl₂ at holding potential (V_H) −20 mV; *P < 0.05 versus control at V_H−120 mV (paired t test). C, lower panel, I–V relation of current inhibited by 30 μm BaCl₂, indicative of a strongly rectifying Kir channel; upper panel, I–V relation of current inhibited by the increase of BaCl₂ from 30 μm to 1 mm. This current is described well by the GHK current equation (continuous line).