Figure 1. Photocurrent responses from porcine rods

Each trace is the averaged response of from 5 to 100 stimuli, DC-50 Hz, 36-37 °C. A: A family of responses recorded with suction pipette from an individual wild type rod. Stimulus strength varied from 1 to 209 photons/μm². B: A response family recorded from a rod containing the P347L transgene. Stimulus strength varied from 12 to 1460 photons/μm². C: A response family recorded from a rod containing the P347S transgene. Stimulus strength varied from 19 to 1960 photons/μm². D: Intensity response functions for three individual cells whose responses are shown in Panels A-C. Normalized response amplitude is plotted versus the log of the stimulus strength. Right shift of the transgenic rods indicates a loss of sensitivity; for mean values see Table 1 and Table 2. E: Mid-range responses from a wild type and P347L rod whose amplitudes (2.4 pA and 3.4 pA, respectively) have been normalized to 1.0 to permit comparison of peak time and recovery kinetics. Stimuli for the wild type cell was 15 photons/μm², and for the P347L rod 102 photons/μm². F: Mid-range responses from a wild type and two P347S rods whose amplitudes (2.4, 2.7, and 2.8 pA, respectively) have been normalized to 1.0 to permit comparison of peak time and recovery kinetics. Stimuli for the wild type cell was 15 photons/μm² and for the P347S rods 69 and 104 photons/μm². The two rods from transgenic animals have different rising phases but similar recovery kinetics.