A Clearer Picture Of Cell Secretion

Combining electrochemical and optical measurements will give scientists a better window into exocytosis, a process by which cells secrete chemicals such as neurotransmitters, French researchers report (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201101148). Electrochemical measurements have good time resolution, but they can’t detect early stages of exocytosis before vesicles fuse with the cell membrane and secrete their chemical cargo. In contrast, optical measurements can track individual vesicles before fusion begins but have poorer time resolution. Christian Amatore and coworkers at the École Normale Supérieure, in Paris, used transparent indium tin oxide electrodes to monitor the release of the neurotransmitter serotonin from cultured endocrine cells with amperometry; they used total internal reflection fluorescence (TIRF) microscopy of fluorescently labeled neuro­peptide Y to visualize the vesicles. The 150-nm-thick band-shaped electrodes allowed sufficient resolution for TIRF without compromising the quality of the electrochemical measurements. The electrochemical and TIRF signals are obtained simultaneously, which allows information from the two methods to be correlated.