A noninvasive detection scheme based on glutamate dehydrogenase (GDH) enzymatic assay combined with microscopy was developed to measure the glutamate release in cultured cells from the central nervous system (CNS). The enzyme reaction is very specific and sensitive. The detection limit with charge-coupled device (CCD) imaging is down to mu M levels of glutamate with reasonable response time (~ 30 s). The standard glutamate test shows a linear response over 3 orders of magnitude, from mu M to 0.1 mM range. The in vitro monitoring of glutamate release from cultured neuron cells demonstrated excellent spatial and temporal resolution.
Ziqiang Wang and Edward S. Yeung, "Fluorescence Imaging of Glutamate Release in Neurons," Appl. Spectrosc. 53, 1502-1506 (1999)