Neural recordings from the lateral line in free-swimming toadfish, Opsanus tau.

changes in fluorescence with NP-EGTA-loaded cells persisted for many seconds after the UV stimulus was turned off. Additionally, the size of the fluorescent signal did not decay with subsequent UV stimuli. Our work demonstrates that local stimulation of caged calcium trapped within horizontal cells by ultraviolet light delivered by small optic fibers can be used to increase intracellular levels of calcium in isolated horizontal cells. For future studies, this approach must be modified to achieve the proper spatial resolution of calcium uncaging. Currently, we are examining various methods to decrease the UV light output of the pulled optical fiber by adding neutral density filters and optimal alignment of the laser source. We hope to use this technique, in conjunction with self-referencing recordings of H flux from horizontal cells, to examine the spatial dependence of proton flux from these cells. This work was supported by grants from the National Center for Research Resources (P41 RR01395), the National Science Foundation (009-1240), and a Grass Foundation Summer Fellowship.