We have synthesized a biologically inert, photosensitive derivative of the major excitatory amino acid, L-glutamate (which we call MDNI-glu) that makes more efficient use of incident light than all other caged glutamates. Laser flash photolysis of MDNI-glu in acutely isolated hippocampal brain slices evoked a rapid increase in intracellular Ca2+ concentration in astrocytes.
