TABLE I.

Permeation and Conductance Parameters of WT and Mutant CNGA2 Channels

Parameter	Vrev	ΔVrev (0.5)	ΔVrev (0.25)	PCl/PNa	n	γ	n
	mV	mV	mV			pS
WT CNGA2	−1.3 ± 0.6	11.8 ± 0.6	24.5 ± 0.7	0.07 ± 0.01	9	29 ± 6	3
E0′K mutant CNGA2	1.2 ± 0.4	−11.5 ± 0.8	−24.4 ± 1.3	14.4 ± 2.5	14	0.6 ± 0.2	3
E0′R mutant CNGA2	0.7 ± 0.2	−10.8 ± 0.9	−22.4 ± 1.7	9.8 ± 1.8	10	2 ± 1	3

A summary of the average reversal potentials, V_rev, in control (1 NaCl) solution and their shifts, ΔV_rev, in 0.5 NaCl and 0.25 NaCl solution dilutions (see Figs. 3–6 ), relative permeabilities, and single channel conductances, γ. The potentials were all corrected for liquid junction potentials and the relative permeabilities were calculated using the GHK equation (Eq. 2). The single channel conductances were measured from the relationship between mean current and variance at +40 mV, in response to four to five different cGMP concentrations in each patch, and the WT conductance value is in the range of the directly measured single channel γ of 46 ± 20 pS (Qu et al., 2000).