Table 1.
Parameters describing the rod dim flash response in vivo
ParameterDescriptionValue
Ex vivoaIn vivo
kRRate of R* deactivation (s−125 — 
kE Rate of G*-E* deactivation (s−15 (WT) or 12.5 (RGS9-ox) 8 (WT) or 21.7 (RGS9-ox) 
νRE Max rate of G*-E* activation per R* (s−1300 350 
βidvb Rate of cGMP hydrolysis per G*-E* (s−143 — 
βdark Rate of spontaneous cGMP hydrolysis (s−14.1 — 
DcGb Longitudinal diffusion coefficient of cGMP (µm2 s−140 — 
fCab Fraction of current carried by calcium 0.12 — 
αdarkc Dark cGMP synthesis rate (µM s−116.7 19.1 
darkb Dark adapted Ca2+ concentration (nM) 320 Set by αdark 
cGdarkb Dark adapted cGMP concentration (µM) 4.1 Set by αdark and βdark 
BCab Calcium buffer capacity 50 — 
ncycb Hill coefficient for Ca2+ dependence of cGMP synthesis 1.5 — 
Kcycb K1/2 for Ca2+ dependence of cGMP synthesis (nM) 80 — 
αmax Max rate of cGMP synthesis (µM s−1150 172 
Kex K1/2 for NCKX activation (µM) 1.1 — 
Jexsat Maximum NCKX current (pA µm−10.21 — 
ParameterDescriptionValue
Ex vivoaIn vivo
kRRate of R* deactivation (s−125 — 
kE Rate of G*-E* deactivation (s−15 (WT) or 12.5 (RGS9-ox) 8 (WT) or 21.7 (RGS9-ox) 
νRE Max rate of G*-E* activation per R* (s−1300 350 
βidvb Rate of cGMP hydrolysis per G*-E* (s−143 — 
βdark Rate of spontaneous cGMP hydrolysis (s−14.1 — 
DcGb Longitudinal diffusion coefficient of cGMP (µm2 s−140 — 
fCab Fraction of current carried by calcium 0.12 — 
αdarkc Dark cGMP synthesis rate (µM s−116.7 19.1 
darkb Dark adapted Ca2+ concentration (nM) 320 Set by αdark 
cGdarkb Dark adapted cGMP concentration (µM) 4.1 Set by αdark and βdark 
BCab Calcium buffer capacity 50 — 
ncycb Hill coefficient for Ca2+ dependence of cGMP synthesis 1.5 — 
Kcycb K1/2 for Ca2+ dependence of cGMP synthesis (nM) 80 — 
αmax Max rate of cGMP synthesis (µM s−1150 172 
Kex K1/2 for NCKX activation (µM) 1.1 — 
Jexsat Maximum NCKX current (pA µm−10.21 — 
a

Gross et al. (2012a).

b

Value was held fixed for all simulations.

c

Value was adjusted so that for both ex vivo and in vivo, αdarkmax = 9.

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