Photoelectrode with a very short time-constant for recording intracerebrally Ca2+ transients at a cellular level.

In order to study calcium transients in the central nervous system of vertebrates a microphotoelectrode was designed. It is composed of three channels, through the first aequorin is perfused into the extracellular space under constant pressure, the second is an optical glass light-conducting channel, and the third a classical NaCl-filled recording pipette. The light emitted by the interaction of the injected aequorin with the local extracellular calcium is transmitted through the optic fiber to a photomultiplier of high sensitivity.