Local photolysis using tapered quartz fibres.

We describe a versatile, low-cost photolysis system in which sub-millisecond flashes generated by a xenon flash lamp are conveyed through a silica fibre directly onto a cell. The fibre, which is tapered to a sub-micrometre diameter and sputtered with chromium and aluminium, illuminates an area of about 1 microm2. Site and timing of photolysis can be chosen independently from other experimental parameters. As an application example we show the spatially heterogeneous distribution of Ca2+-dependent Cl- channels in olfactory receptor neurons.