Synthesis and characterization of cell-permeant 6-nitrodibenzofuranyl-caged IP3.

We have synthesized in a 6-nitrodibenzofuranyl (NDBF) derivative of inositol-1,4,5-trisphosphate (IP(3)) for efficient two-photon uncaging in living cells. As its hexakis acetoxymethyl ester, this caged compound may be applied at low concentration to the extracellular milieu to load the intact astrocytes in acutely isolated brain slices from the mouse cortex. Two-photon irradiation of single astrocytes evoked intracellular calcium signals that required 10% of the energy dosage compared to nitroveratyl (NV)-IP(3). Since NDBF-IP(3) has a 5-fold higher quantum yield than NV-IP(3), these data imply that photolysis of the new NDBF caged compound mobilized intracellular calcium about twice as efficiently as the NV cage.