Figure 2. 25 μM fluoxetine hydrochloride in the bath inhibits depolarization-induced IK(Ca) outward currents of isolated salamander rod photoreceptors to a similar extent as CdCl₂, a generic inhibitor of voltage-gated calcium channels

A: Representative outward current responses from different cells resulting from a series of 20 ms depolarizing steps from -60 to +40 mV in the presence of control bath solution, bath solution containing 25 μM fluoxetine hydrochloride, or in the presence of a test puff of 150 μM CdCl₂. Note that currents are significantly reduced to similar degrees in the presence of 25 μM fluoxetine and the generic calcium channel blocker CdCl₂. Since E_Cl is about 0 mV under our experimental conditions, the reduction of outward currents at 0 mV by fluoxetine represents an inhibition of predominantly IK(Ca), while the reduction at +40 mV represents an inhibition of both IK(Ca) and ICl(Ca). B: Statistical comparison of mean outward current amplitudes of cells preincubated in bath solution containing 25 μM fluoxetine (n=5) with currents measured from cells in control bath solution (n=7) or bath solution containing 150 μM CdCl₂, a generic blocker of voltage-gated calcium channels. Steady-state currents were measured at 18 ms after the onset of the depolarizing voltage step were used for comparisons. Note a virtual elimination of currents by both fluoxetine and CdCl₂. Statistical tests were done using Student's t-test.