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In the present work the authors studied the conductance changes associated with …


Biology Articles » Biophysics » Molecular Biophysics » Voltage-Induced Nonconductive Pre-Pores and Metastable Single Pores in Unmodified Planar Lipid Bilayer » Figures

Figures
- Voltage-Induced Nonconductive Pre-Pores and Metastable Single Pores in Unmodified Planar Lipid Bilayer

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FIGURE 1   Dependence of lag-time before the onset of fluctuations on voltage applied. Experiments were on membrane patches. Bars represent SEM (n >= 5).

Figure 1

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FIGURE 2   Conductance fluctuations induced by electric field. (a and b) Experiments on BLM; U = 400 mV (a), U = 180 mV (b). (c-e) Experiments on membrane patches; U = 300 mV (c), U = 250 mV (d), U = 350 mV (e). Each recording represents a characteristic fragment of the recording obtained in an independent experiment.

Figure 2

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FIGURE 3   Histogram of the distribution of the pore conductance. Gaussian fit is shown as a solid curve. Histogram is based on the records obtained on the membrane patches clamped at 450 mV. Total number of analyzed pores was 1475.

Figure 3

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FIGURE 4   Dependence of the mean pore conductance on voltage for membrane patches. Points and error bars present mean conductance and its dispersion, respectively.

Figure 4

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FIGURE 5   All-points amplitude histogram of the conductance fluctuations. Gaussian fit is shown as a solid curve. Histogram is based on the records obtained on the BLMs clamped at 180 mV.

Figure 5

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FIGURE 6   Bursts of electrical activity are separated by long intervals with background conductance. This recording represents a characteristic fragment of the conductance recording obtained for BLM clamped at 180 mV. Inset shows baseline conductance of membrane before onset of the first fluctuation. Temporal and amplitude resolution on the inset is the same as on the figure.

Figure 6

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FIGURE 7   Histogram of the distribution of the number of short-lived closed states (conductance staying within 1.5 times of background variance for less than 20 ms) within the same burst. Histogram is based on the 12-min record obtained for BLM clamped at 180 mV. Total number of closed states in the record was 9032; the number of short closed states was 7023. Solid line represents the distribution expected, based on computer simulation assuming that short closed states were independent events.

Figure 7

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FIGURE 8   Membrane response to the second step of voltage depends on the time interval after the end of the first step. BLM was treated with two successive voltage steps of 400 mV each. Between the steps BLM was clamped at 50 mV for 50 ms (a) or 1 s (b).

 

Figure 8

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Source: Biophys J, April 2001, p. 1829-1836, Vol. 80, No. 4

 

 

 

 

 

 


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