This is the readme for the model associated with the paper
Liu XD, Kourennyi DE (2004) Effects of tetraethylammonium on Kx
channels and simulated light response in rod photoreceptors. Ann
Biomed Eng 32:1428-42
Rod photoreceptors express a unique type of noninactivating potassium
channels, Kx channels, which play an important role in setting the
dark potential and participate in shaping the light
response. Biophysical studies of Kx channels are limited. For example,
the effects of a conventional blocker of potassium channels,
tetraethylammonium (TEA), on Kx channels have not been extensively
studied. Here we demonstrate that TEA blocks Kx channels, one molecule
of TEA being sufficient to block the channel. Half of the Kx current
was inhibited at K0.5 = 5.6 mM. The TEA-induced block of Kx channels
depended on extracellular potassium: the higher the potassium
concentration, the stronger the block. Using TEA, we blocked potassium
channels to reveal their role in shaping the simulated light response
(SLR) of rods. We showed that TEA slowed down SLR and sometimes caused
generation of action potentials. We developed a complete computer
model of the rod, which accurately reproduced the main features of the
light response and allowed us to demonstrate that it was suppression
of Kx channels that was essential for slowing SLR and increasing
excitability of rods. The results reported in this work further
establish the importance of Kx channels in rod photoreceptor function.
How to use the model:
Simply auto-launch from ModelDB or 1)download archive and expand the
zip file, 2) compile the mod files with mknrndll (mswin) or nrnivmodl
(unix/linux), and 3) start the program by double clicking the
mosinit.hoc file (mswin), or by typing nrngui mosinit.hoc (unix).
Once the model is started press the button for the figure desired.
Figures 5, 8, and 9 from the paper are available.
20120125 upgrade from euler to derivimplicit in Cad.mod as per