Figure 3.

Characteristics of the I_heat current. (A) I_heat was reduced by 67% in this DRG neuron when extracellular Na⁺ was substituted by choline. (B) I_heat was reduced by 37% in another DRG neuron when Ca²⁺ was removed from the extracellular solution. (C) At 10 mM, extracellular Cs⁺ reduced I_heat in this neuron by 85%. I_heat recovered nearly to control levels within 2 min after removal of Cs⁺. (D) La³⁺ (100 μM) does not reduce I_heat. (E) A plot of leak-subtracted I_heat during a voltage ramp shows outward rectification at membrane potentials more negative than approximately −40 mV. (Inset) Protocol in which a voltage ramp is applied at the peak of the response to a 38°C stimulus (ramp 1), and leak current is measured by the same ramp applied after recovery from the stimulus (ramp 2).