ACTIN CYTOSKELETON REGULATES ION-CHANNEL ACTIVITY IN RETINAL NEURONS

THE actin cytoskeleton is an important contributor to the integrity of cellular shape and responses in neurons. However, the molecular mecha nisms associated with functional interactions between the actin cytosk eleton and neuronal ion channels are largely unknown. Whole-cell and s ingle channel recording techniques were thus applied to identified ret inal bipolar neurons of the tiger salamander (Ambystoma tigrinum) to a ssess the role of acute changes in actin-based cytoskeleton dynamics i n the regulation of voltage-gated ion channels. Disruption of endogeno us actin filaments after brief treatment (20-30 min) with cytochalasin D (CD) activated voltage-gated K+ currents in bipolar cells, which we re largely prevented by intracellular perfusion with the actin filamen t-stabilizer agent, phalloidin. Either CD treatment under cell-attache d conditions or direct addition of actin to excised, inside-out patche s of bipolar cells activated and/or increased single K+ channels. Thus , acute changes in actin-based cytoskeleton dynamics regulate voltage- gated ion channel activity in bipolar cells.