The temperature dependence of some kinetic and conductance properties of acetylcholine receptor channels.

We examined the temperature dependence of single-channel properties of the nicotinic acetylcholine receptor channel from clonal BC3H-1 cells over a range of 10-40 degrees C. We found temperature sensitivities (Q10 values) of 2-4 for the mean channel open time. The Q10 did not depend strongly on voltage and the voltage dependence of the mean open time was temperature-independent. The Q10 of closing rate of the long-lived open state was 3-4 but the Q10 of closing rate of the brief open state was independent of temperature. The duration of brief closures could be measured only between 10 and 25 degrees C. Since this approached the limit of the experimental time resolution, an accurate determination of the Q10 could not be made. The current decay due to desensitization after rapid application of high concentrations of agonist varied with a Q10 of about 2. The conductance of single channels (the inverse of the ion translocation rate) had a Q10 of 1.3-1.5. We found no obvious nonlinearities in the Arrhenius curves for any of the measured properties.