Figure 8. CaMKII acts on the ‘on’ bipolar cell cGMP-activated channels.

Upper trace: whole-cell recording from an ‘on’ bipolar cell with 1 mm IBMX, 1 mm cGMP and 50 μm Ca²⁺ in the patch pipette solution. The upward deflections are current responses to 2 mV voltage command pulses applied to monitor changes in input conductance, whilst the downward deflections are inward current responses to 1 Rh** test flashes. At intervals, the intensity-response relation was determined, marked by the horizontal arrows below the trace. The dark holding potential was −29 mV. The input conductance decreased from 29 to 19 nS, with an outward shift in dark current of 21 pA. Lower trace: ‘on’ bipolar cell recording with 10 μm AIP added to the patch pipette solution containing 50 μm Ca²⁺, 1 mm IBMX and 1 mm cGMP. The dark holding potential was −39 mV. Current responses to 1 mV voltage commands and responses to 0.5 Rh** test flashes are shown below on expanded time scales at the same gain. The input conductance increased from 11 to 16 nS, with an inward shift in the dark current of −54 pA.