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. 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 4. An additional noise source with power in the low to mid frequency range causes fluctuations in cGMP.

Figure 4

a. The membrane-permeable and fast acting PDE inhibitor IBMX increases the cGMP concentration and therefore the number of open channels and inhibits any noise source upstream of (and including) PDE.

b. Changes in holding current in the absence (black) and presence (gray) of IBMX. The filled black and gray circles represent 500 ms stretches of noise used to calculate the spectra in (c). Recordings were performed in complete darkness to avoid extrinsic noise.

c. Corresponding power spectra in the absence (black circles) and presence (gray circles) of IBMX. Insets show example noise traces in each condition corresponding to (1) and (2) in (b). Changes in noise below 10Hz (open circles) are unreliable due to slow drift in the measured current.

d. Average (± SEM) ratio of power spectra in the presence and in the absence of IBMX (n = 10) showing a decrease in noise in the 10 to 50 Hz range and an increase in noise at high frequencies (100 to 600Hz)

e. Average (± SEM) ratio of power spectra before and after puffing a vehicle solution lacking IBMX (n=4). The increase in noise at the high frequencies (100–600Hz) and the decrease at low frequencies (10–30 Hz) seen with IBMX were significantly different than the changes with vehicle.