Fig. 3.

Early termination of CNG current during olfactory response. Replacement of external Na⁺ by Li⁺ (permeant cation) or Chol⁺ (impermeant or near-impermeant cation) as a method to determine whether CNG current is still flowing at a given time instant during the olfactory response. A 30-ms, 3 mM (+)-limonene pulse. At the time instant of Na⁺ replacement (vertical dashed line), there is no instantaneous shift in the overall response regardless of Li⁺ or Chol⁺ as the substituent, indicating that CNG current has already terminated at that moment. See text for details. Junction currents caused by the cation substitutions have already been subtracted away. Timings of (+)-limonene application and cation substitutions based on junction currents are at Top.