Figure 6.

K_IR current in cerebral arterial endothelial cells and its virtual impact on conducted depolarization. Whole-cell K⁺ current was measured in isolated endothelial cells in a high K⁺ solution (60 mM) using a voltage ramp protocol (−100 to +20 mV) in presence and absence of BaCl₂ (1 µM–1 mM). Representative whole-cell current recording (a) and Ba²⁺-subtracted currents (b). Summary plots (n = 7) illustrating the effect of Ba²⁺ (1 µM–1 mM) on whole-cell current (c) and on peak inward current at −100 mV (d). Ba²⁺ induces a concentration-dependent inhibition of K_IR current (E, n = 7) at −100 mV (IC₅₀ = 0.68 ± 0.02 µM) and −60 mV (IC₅₀ = 0.67 ± 0.02 µM). Data are means ± SE. **Significant difference from control. Simulation in (f): a defined number of endothelial and smooth muscle cells in the initial 62 µm segment of the virtual vessel (see Figure 4 for details) were voltage clamped (200 ms) 20 mV positive to the resting V_M (−40 mV), while voltage responses were monitored at rest (smooth muscle and endothelial K_IR) and following the subtraction of K_IR current in one or both cell types. Dotted lines represent resting V_M (V_rest) under control conditions (black, V_M: −38.7 mV), and following the subtraction of K_IR conductance in the endothelium (green, V_M: −39.1 mV) or both cell layers (red, V_M: −36.7 mV). Conduction decay (g) along the virtual vessel under control conditions and in the absence of one or both K_IR currents.