Ion Channel Compartments in Photoreceptors
Dr. MacLeish's work is directed toward understanding the functional organization of vertebrate rods and cones using single, isolated cells from the adult to study functional components such as phototransduction and signal processing. One current project examines ion channel compartments by examining the electrophysiological properties of cells before and after selective ablation of cellular compartments. Current interest is in the function of a calcium-activated anion channel that is selectively targeted to the synaptic terminal of rod and cone cells. The biophysical properties of the channel are being determined to gain insight into the calcium levels that required for channel activation. Recent work in the field has provided information on the molecular identity of the calcium-activated anion channel. The photoreceptor terminal provides an excellent system for understanding how membrane potential is controlled in a compartment that does not have action potentials but signals via graded potentials. The techniques used are whole-cell patch clamping and optical recording using calcium-sensitive indicators. Currently, both an amphibian and a primate system are available for short and long term experiments.
Research Key Words: Retina, photoreceptors, ion channels, cellular compartments, electrophysiology, optical imaging