Our laboratory has studied in detail the functional aspects of electrical coupling between AII amacrine cells in the inner retina of rat, and we are one of the few laboratories in the world to routinely use the challenging technique of simultaneous dual p atch-clamp recording. We recently observed an interesting phenomenon: a spontaneous, time-dependent increase in the junctional conductance of the recorded cells. The increase in coupling, evidence of a modulatory process, is thought to depend on the pertu rbation of the intracellular milieu induced by the patch pipette. Our laboratory has recently received funding for the project Biophysics of visual adaptation: tuning retinal microcircuits and networks for vision in starlight, twilight, and daylight to fu rther investigate the mechanisms that underlie the modulation of this electrical coupling.
The laboratory of Lorenzo Cangiano, Physiological Sciences, University of Pisa, Italy has recently begun to study the properties of electrical coupling between rod and cone photoreceptors in the outer retina of mouse, by recording responses from single cone photoreceptors using patch pipettes. Intriguingly, cones display a behavior similar to that described above for AII amacrine cells in rat in that there appears t o be a time-dependent increase in gap junction conductance in the recorded cells. This is evidenced by an increasingly larger rod signal that is coupled into the cone photoreceptor (see preliminary data).
This proposal will enable Sabrina Asteriti, a Ph D student in the laboratory of Cangiano, to join our laboratory for 6 months to develop technical skills including dual patch clamp recording and intracellular perfusion via patch pipettes with the goal of investigating this spontaneous increase in gap ju nction conductance. Both laboratories have the goal to investigate the biochemical mechanisms leading to the modulation of the gap junctions and the implications for adaptation in the inner and outer retina.