Figure 3. Receptor current recovery is retarded when Na⁺–Ca²⁺ exchange is inhibited by ${\text{Ni}}_0^{\text{2+}}$.

Suction pipette recordings from an isolated olfactory receptor cell in response to 1 s stimulation with Ringer solution containing 500 μm IBMX. Following IBMX stimulation the cilia were returned to Ringer either immediately (A) or following exposure for 2 s (B) or 3 s (C) to a solution which included 5 mm ${\text{Ni}}_0^{\text{2+}}$. In each case the rapid decay of receptor current upon the return to Ringer solution has been fitted with a single exponential of time constant A: 0.434 s; B: 0.335 s; C: 0.454 s. Interrupted curves in B and C reproduce the exponential fit to A for comparison. Each trace is the average of 2–3 trials and has been junction corrected.