Skip to main content
. Author manuscript; available in PMC: 2014 May 1.
Published in final edited form as: Nat Neurosci. 2013 Oct 6;16(11):1692–1700. doi: 10.1038/nn.3534

Figure 3. High frequency noise arises from open/close transitions in the cGMP-gated channels.

Figure 3

a. Channel noise was separated from sources causing fluctuations in [cGMP] by suppressing cGMP synthesis by omitting ATP and GTP from the internal solutions in a two-electrode recording. Different concentrations of the cGMP-channel agonist 8′Bromo-cyclic-GMP (8′Br-cGMP) were added to the second electrode.

b. Changes in holding current before (black) and after (green) the introduction of a second electrode containing 27 μM 8′Br-cGMP. The filled black and green circles represent 500ms stretches of noise used to calculate the spectra in (c).

c. Average noise power spectra for the cone in (B) before (black) and after (green) the introduction of a second electrode containing 27 μM 8′Br-cGMP. Insets show example noise traces in each condition corresponding to (1) and (2) in (b).

d and e. Same as in (b) and (c) for an 8′Br-cGMP concentration of 100 μM.

f. Average (± SEM) ratio of power spectra before and after introduction of 8′Br-cGMP. The color scale corresponds to the concentration of 8′Br-cGMP (18 μM: n = 10; 27 μM: n = 4; 100 μM: n = 3; 200 μM: n = 2). Changes in noise below 10Hz are unreliable due to slow drift in the measured current and are displayed as open circles. The increase at high frequencies (100 Hz–600Hz) is significant across all concentrations.