Figure 6. Effects of halothane (H) on the intracellular potential of bradykinin (BK)-stimulated cells. (A) Whole cell experiment carried out in zero current conditions using a patch electrode filled with a 200 mM KCl + 0.2 micro Meter free Calcium²⁺solution. The bathing medium was an Earle's solution. Under control conditions, the cell potential was -21 mV. Superfusion with bradykinin caused a 47-mV hyperpolarization that could be reversed by the addition of 2 mM halothane. (B) Single channel activity recorded in the cell-attached configuration. Cells were superfused continuously with a normal Earle's medium. The pipette was filled with a 200 mM KCl + 1 micro Meter free Calcium²⁺solution, and a potential of 30 mV was applied throughout. Expanded portions of the original recording are illustrated in (i) and (ii). The initial portion of the recording shows a single channel activity typical of the inward rectifying I^K1channel. After bradykinin stimulation, the amplitude of I^K1increased, indicating a 63-mV hyperpolarization of the cell potential [see enlargement (i)]. This increase was correlated with the activation of a Potassium(Calcium²⁺) channel of 40 pS conductance. The addition of halothane led to a reduction of the I^K1current jump amplitude compatible with a depolarization of more than 47 mV of the cell potential, and to a marked inhibition of the Potassium(Calcium²⁺) channel activity [see enlargement (ii)]. The current/voltage relation of the inward rectifying I^K1channel is presented in (iii). The current/voltage curve was measured in cell-attached, patch-clamp experiments with KCl-containing pipettes on BAE cells bathed in a Potassium⁺-Earle's solution, to abolish the contribution of the cell resting potential.