The role of ATP-sensitive potassium channels in a hippocampal neuron (Huang et al. 2007)

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"Hyperglycemia-related neuronal excitability and epileptic seizures are not uncommon in clinical practice. However, their underlying mechanism remains elusive. ATP-sensitive K(+) (K(ATP)) channels are found in many excitable cells, including cardiac myocytes, pancreatic beta cells, and neurons. These channels provide a link between the electrical activity of cell membranes and cellular metabolism. We investigated the effects of higher extracellular glucose on hippocampal K(ATP) channel activities and neuronal excitability. The cell-attached patch-clamp configuration on cultured hippocampal cells and a novel multielectrode recording system on hippocampal slices were employed. In addition, a simulation modeling hippocampal CA3 pyramidal neurons (Pinsky-Rinzel model) was analyzed to investigate the role of K(ATP) channels in the firing of simulated action potentials. ..."
1 . Huang CW, Huang CC, Cheng JT, Tsai JJ, Wu SN (2007) Glucose and hippocampal neuronal excitability: role of ATP-sensitive potassium channels. J Neurosci Res 85:1468-77 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Hippocampus CA3 pyramidal GLU cell;
Channel(s): I K; I Potassium; ATP-senstive potassium current;
Gap Junctions:
Simulation Environment: XPP;
Model Concept(s): Activity Patterns; Bursting; Oscillations; Action Potentials; Epilepsy;
Implementer(s): Wu, Sheng-Nan [snwu at]; Huang, Chin-Wei;
Search NeuronDB for information about:  Hippocampus CA3 pyramidal GLU cell; I K; I Potassium; ATP-senstive potassium current;
# Adoped from Pinsky-Rinzel CA3 pyramidal cell model
# Pinsky and Rinzel, J Comput Neurosci 1994;1:39-60.
# K(ATP) channel was inserted into the model.
# Parameters for K(ATP) channels were from Koyto model
# Matsuoka et al. Prog Biophys Mol Biol 2004;85:279-299.
# stochastic simulation of flunctuations in intracellular ATP

# initial conditions
init Vs=-60, Vd=-60, s=0.185
wiener w

# Parameter values
par ip0=0.75
par gLs=0.1  gLd=0.1  gNa=30  gKdr=15  gCa=9  gKahp=0.8  gKC=15
par VNa=60  VCa=80  VK=-75  VL=-60  Vsyn=0
par gc=2.1 pp=0.5  Cm=3
par alphac=2 betac=0.1
par tstim=4.0e3 n=500
par gkatp=0.0236*(4^0.24)
par init_atp=0.1 final_atp=0.5
par natp=10

# Pyramidal cell functions
ICad =  gCa*sd*sd*(Vd-VCa)
alphams(v) =  0.32*(-46.9-v)/(exp((-46.9-v)/4.0)-1.0)
betams(v) =  0.28*(v+19.9)/(exp((v+19.9)/5.0)-1.0)
Minfs(v) =  alphams(v)/(alphams(v)+betams(v))
alphans(v) =  0.016*(-24.9-v)/(exp((-24.9-v)/5.0)-1.0)
betans(v) =  0.25*exp(-1.0-0.025*v)
alphahs(v) =  0.128*exp((-43.0-v)/18.0)
betahs(v) =  4.0/(1.0+exp((-20.0-v)/5.0))
alphasd(v) = 1.6/(1.0+exp(-0.072*(v-5.0)))
betasd(v) =  0.02*(v+8.9)/(exp((v+8.9)/5.0)-1.0)
alphacd(v) = (1.0-heav(v+10.0))*exp((v+50.0)/11-(v+53.5)/27)/18.975+heav(v+10.0)*2.0*exp((-53.5-v)/27.0) 
betacd(v) =  (1.0-heav(v+10.0))*(2.0*exp((-53.5-v)/27.0)-alphacd(v))
alphaqd = min(0.00002*Cad,0.01)
betaqd = 0.001
chid = min(Cad/250.0,1.0)

# Level of intracellular ATP concentration
poatp = 0.8/(1+(iatp*s/0.023)^2)

# Stochastics
par alphas=1, taus=100, noise=1, s0=0.2
betas = alphas*(1/s0 - 1)
varnoise=sqrt((alphas*(1 - s)+betas*s)/(taus*natp))

# Output cols are t, ODEs, AUXs in order, here:
# t versus vd cad hs ns sd cd qd gqk gkc 
Cad'=  -0.13*ICad-0.075*Cad
hs'=  alphahs(Vs)-(alphahs(Vs)+betahs(Vs))*hs
ns'=  alphans(Vs)-(alphans(Vs)+betans(Vs))*ns
sd'=  alphasd(Vd)-(alphasd(Vd)+betasd(Vd))*sd
cd'=  alphacd(Vd)-(alphacd(Vd)+betacd(Vd))*cd
qd'=  alphaqd-(alphaqd+betaqd)*qd
s' = (alphas*(1-s)-betas*s)/taus + noise*w*varnoise

# auxiliary equationns
aux Ica=ICad
aux gkq = gKahp*qd
aux gkc = gKC*cd*chid
aux ikatp = gkatp*natp*poatp*(Vs-VK)
aux iatp=iatp*s

# For stochastics, CVODE can not be used.
@ maxstor=1000000, total=1.0e4, bounds=10000, xlo=0, xhi=1.0e4, ylo=-90, yhi=60
@ meth=Euler, atol=1e-10, toler=1e-10, dt=0.05