Regensburg 2004 – scientific programme

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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.83: Poster

Friday, March 12, 2004, 10:30–13:00, B

Transistor Array probes Release of Vesicles of Chromaffin Cells — •Janosch Lichtenberger and Peter Fromherz — Membran and Neurophysics,MPI for Biohemistry

We monitored the release of large dense core vesicles from bovine chromaffin cells using a linear array of open field effect transistors with a pitch of 3.6 µm. When secretion was induced by barium, brief spikes in the transistor current were observed. The events were well localized on the transistor array with an amplitude of effective gate voltage up to 17 mV. We assign the events to the local drop of pH in the narrow cleft between cell and chip that is caused by the release of ATP by individual vesicles. The pH change affects the threshold of the transistor by proton binding to the exposed gate oxide. We found good agreement for amplitude, duration and localization of the signals with the change of the electrical surface potential that is computed with a model that takes into account (i) local release of ATP from a vesicle at pH 5.5 into the cleft with an extracellular buffer at pH 7.2, (ii) diffusion of protons, buffer and ions along the cleft and (iii) binding of protons to the negatively charged oxide. The investigation establishes the first chemical neuron-silicon synapse.