Figure 1. Simultaneous measurement of intraciliary Ca²⁺ concentration and receptor current using laser spot fluorescence microscopy and suction pipette recording.

Schematic diagram of the experimental arrangement. The beam of an argon ion laser illuminated a pinhole and entered the inverted microscope through the epi-fluorescence port. A dichroic mirror reflected the recollimated beam through a ×40 oil-immersion objective, which formed an image of the pinhole with a diameter of 10 μm on the cilia protruding from the dendritic knob of an isolated salamander olfactory receptor cell loaded with the fluorescent Ca²⁺ indicator fluo-3 AM. The cell body was drawn into the orifice of a suction pipette, which not only recorded the receptor current but also held the cell in a fixed position relative to the laser spot. Movement of the cilia was constrained by a constant streamline flow of solution emerging from a manifold built into the back of the recording chamber, which delivered solution from one of seven inlet tubes. The solution superfusing the olfactory cilia was exchanged by activating one of the seven inlet tubes via computer-controlled solenoid valves, allowing odour stimulation or ionic exchanges. Ca²⁺-dependent fluo-3 fluorescence evoked by laser illumination passed through an emission filter and was relayed via a multimode optical fibre to the photomultiplier.