FIGURE 2.

Halothane potentiates the response of RyR1 to luminal Ca²⁺. Single channel activities of the R615C mutant were recorded as described in the legend to Fig. 1. The Ca²⁺ concentration on both the cytosolic and luminal sides of the channel was adjusted to ∼45 nm (A). The luminal Ca²⁺ concentration was then increased to 600 μm (B). C, single channel current traces after the addition of halothane to the cytosolic side of the channel. The luminal Ca²⁺ concentration was then reduced to ∼35 nm in the continued presence of halothane (D). The holding potential was –20 mV, and the openings are downward.