Figure 2.

Determination of Q₁₀ and the thermal threshold in a typical cold-activated TRP channel. (A) Simulation of a patch clamp recording of a membrane where a cold activated TRP channel is expressed. Parameters: Maximal conductance = 10 µS (at 0°C), Temperature ramp: from 0°C to 50°C. Q_10,K = 1/30, Q_{10, gi} = 1.5 Q_{10, bg} = 2, conductance of background = 0.5 nS (at 50°C). (B) The same data as in A represented as the logarithm of the current vs. the reciprocal of the temperature (red line: TRP current; gray line: background current; pink line: total current changing because the temperature dependency of the unitary current if the open probability was ever the same as that at 0°C; black line: the total current). (C) The reciprocal of apparent Q₁₀ calculated from the slope of the data in B versus the temperature reciprocal is represented by the black line (red line: reciprocal of Q₁₀ obtained from the product between reciprocals of Q_{10, K} and Q_{10, gi}). (D) Results of a simulation as in A except that the maximal conductance of the TRP channels is 100 µS (at 0°C). (E) The same data as in D represented as the logarithm of the current vs. the reciprocal of the temperature (red line: TRP current; gray line: background current; pink line: total current changing because the temperature dependency of the unitary current if the open probability was the same as that at 0°C; black line: the total current). (F) The reciprocal of apparent Q₁₀ calculated from the slope of the data in E versus the temperature reciprocal is represented by the black line (red line: reciprocal of Q₁₀ obtained from the product of reciprocals of Q_{10, K} and Q_{10, gi}).