FREE CYCLIC-AMP INCREASES IN PC12 CELLS ON DEPOLARIZATION

The temporal dynamics of the intracellular second messenger cyclic AMP (cAMP) were monitored in living PC12 cells by digital fluorescence ra tio imaging using FICRhR, a single-excitation dual-emission cAMP indic ator, When the cells were depolarized by exposure to high K+, the free cAMP concentration was elevated, and then slowly decreased back to re sting levels when the depolarizing stimulus was removed, Furthermore, the cAMP elevation due to depolarization decreased with successive dep olarizations. (C) 1997 Wiley-Liss, Inc.