Figure 5. Effect of external Na⁺ concentration on receptor current recovery.

A, suction pipette recordings from an isolated olfactory receptor cell in response to 1 s stimulation with Ringer solution containing 100 μm IBMX. Following IBMX stimulation the cilia were returned either to Ringer solution, or to partially guanidinium-substituted solutions of reduced Na⁺ concentration as indicated beside each trace. B, final decay of receptor currents in low-Na⁺ solution from A, normalized to the value just following the solution change. Individual traces have been zeroed as in Fig. 5A to the initial baseline before the IBMX stimulus; note slight baseline drift. In each case the decay of receptor current has been fitted with a single exponential of time constant 99 mm: 0.067 s; 66 mm: 0.125 s; 33 mm: 0.285 s; 11 mm: 1.46 s. Time constant in normal Ringer solution 0.084 s. Each trace is the average of 2–3 trials and has been junction corrected.