Research ArticleBIOELECTRONICS

Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations

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Science Advances  23 Dec 2016:
Vol. 2, no. 12, e1600516
DOI: 10.1126/sciadv.1600516

Figures

  • Fig. 1 Sensitive detection of C6 glioma cells.

    (A) Equivalent circuit model. (B) Photograph of glioma cells. The bright part denotes cells on top of the Au electrode; the darker region indicates the cells outside the Au electrode. Scale bar, 60 μm. (C) Cell number as a function of time after cell deposition. For all measurements, the average cell viability was 79% (±12%). Each data point was repeated five times. The straight diagonal line represents a guide to the eye.

  • Fig. 2 Evolution of the magnitude and frequency of current noise of C6 glioma cell populations with time.

    (A) Recording of current noise with time. The recordings are taken after an incubation period of about 10 hours. Three distinct periods of activities can be detected. (B) Zoom-in of the current trace of the bursting activity of region III showing quasi-periodic spikes. (C) Histogram of the interspike intervals recorded for the whole burst activity shown in (A). The interspike intervals were distributed into time slots with a resolution of 0.36 s. (D and E) Quantitative electrical data from 10 experiments. In acidified cells, spike amplitudes ranged from 1 to 125 pA, with a mean amplitude value of 46.8 pA. In nonacidified cells, spike amplitudes varied between 1 and 20 pA, with a mean spike amplitude of 4.7 pA.

  • Fig. 3 pH and cell growth with time.

    Cell metabolism–related pH changes in culture medium. Initially, 2.3 × 105 cells were seeded in a volume of 200 μl. Each data point was repeated five times. Straight lines represent a guide to the eye.

  • Fig. 4 Time evolution of current noise of C6 glioma cells upon adding TTX.

    The black trace on the left depicts the noise of acidified cells. The red trace on the right depicts the noise measured immediately after adding TTX to the acidified cell culture medium with a concentration of 1 μM.

  • Fig. 5 Current noise of ASICs demonstrated by applying the inhibitor PcTX-1.

    (A) Time evolution of current noise of C6 glioma cells upon adding PcTX-1, up to a concentration of 100 nM in acidified cell culture medium. The black line represents the original state. The red line is recorded after adding PcTX-1 to a concentration of only 100 nM. The blue curve represents the recovery plot after thrice washing. (B) The corresponding current noise spectra of Fig. 4A. (C) The mean of 300 spike amplitudes of acidified cells as depicted in Fig. 1D. PcTX-1 data quantification recorded over two inhibitory experiments.

  • Fig. 6 External acidification of C6 glioma cells.

    After deposition, the cells were allowed to adhere to the electrodes for 10 hours. (A) The evolution of the current noise upon acidification of the medium. The current noise changes from weak and sporadic current fluctuations to a bursting activity of quasi-periodic spikes. (B) Histogram of the interspike intervals recorded for the entire burst activity shown in (A). The interspike intervals were distributed into time slots with a resolution of 0.36 s. Inset: Data quantification of 600 spikes comprising two distinct experiments. After the addition of HCl, the spike magnitude mean value becomes 24.7 pA. The interval recorded varies between 1 and 159.4 pA.

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