Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation



We show that focused laser irradiation can generate Ca2+ waves in differentiated PC12 cells, using highly penetrating and locally acting near-infrared femtosecond pulsed laser light. Similar to photolytic uncaging experiments, intracellular Ca2+ concentrations could be elevated to produce a whole cell Ca2+ rise, but without the requirement for caged Ca2+. Irradiation of subcellular volumes in the soma or in PC12 neurites generated a relatively slow calcium rise (speed ∼20 µm/s). Less frequently, a fast calcium rise (speed >1200 µm/s) was observed, consistent with laser-induced membrane depolarization. The probability of Ca2+ generation increased with laser power and was found to be the same in excitable (PC12) and nonexcitable (HeLa) cells. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)