Controlling KCa channels with different Ca2+ buffering models in Purkinje cell (Anwar et al. 2012)

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Accession:138382
In this work, we compare the dynamics of different buffering models during generation of a dendritic Ca2+ spike in a single compartment model of a Purkinje cell dendrite. The Ca2+ buffering models used are 1) a single Ca2+ pool, 2) two Ca2+ pools respectively for the fast and slow transients, 3) a detailed calcium model with buffers, pump (Schmidt et al., 2003), and diffusion and 4) a calcium model with buffers, pump and diffusion compensation. The parameters of single pool and double pool are tuned, using Neurofitter (Van Geit et al., 2007), to approximate the behavior of detailed calcium dynamics over range of 0.5 µM to 8 µM of intracellular calcium. The diffusion compensation is modeled using a buffer-like mechanism called DCM. To use DCM robustly for different diameter compartments, its parameters are estimated, using Neurofitter (Van Geit et al., 2007), as a function of compartment diameter (0.8 µm-20 µm).
Reference:
1 . Anwar H, Hong S, De Schutter E (2012) Controlling Ca2+-activated K+ channels with models of Ca2+ buffering in Purkinje cells. Cerebellum 11:681-93 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Dendrite;
Brain Region(s)/Organism:
Cell Type(s): Cerebellum Purkinje GABA cell;
Channel(s): I K,Ca; I Calcium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Calcium dynamics;
Implementer(s):
Search NeuronDB for information about:  Cerebellum Purkinje GABA cell; I K,Ca; I Calcium;
create dend[4]

dend[1] {
  nseg = 1
  L = 20
  diam = 4
}

dend[1] {
  insert leak
  
  insert CALC_DP
  insert CALC2
  
  insert newCaP_DP

  gbar_leak = 1e-6
  e_leak = -61
  cm = 1.5
  Ra = 250	
 	
  pcabar_newCaP_DP = 0.000260

  beta_CALC_DP = 3.77
  beta_CALC2 = 0.00306

  d_CALC_DP = 0.351 
  d_CALC2 = 0.928	

  vshift_newCaP_DP = 4.7

  frac1_newCaP_DP = 0.994
  frac2_newCaP_DP = 0.006

  frac1 = 0.994
  frac2 = 0.006


}


dend[0] {
  nseg = 1
  L = 20
  diam = 4
}

dend[0] {
        insert leak
        insert CALC
        insert newCaP

        gbar_leak = 1e-6
        e_leak = -61
        cm = 1.5
        Ra = 250

        pcabar_newCaP = 0.000260

        beta_CALC = 1.35
        d_CALC = 0.891

        vshift_newCaP = 4.7

}

dend[2] {
  nseg = 1
  L = 20
  diam = 4
}

dend[2] {
  insert leak

  insert cdp3

  insert newCaP

 gbar_leak = 1e-6
  e_leak = -61
  cm = 1.5
  Ra = 250

  pcabar_newCaP = 0.000260

  vshift_newCaP = 4.7

}

dend[3] {
  nseg = 1
  L = 20
  diam = 4
}

dend[3] {
  insert leak

for(x,0) {
	insert cdp5
	Nannuli_cdp5(x) = 0.326 + (1.94 * diam(x)) + (0.289*diam(x)*diam(x)) - ((3.33e-2)*diam(x)*diam(x)*diam(x)) + ((1.55e-3)*diam(x)*diam(x)*diam(x)*diam(x)) - (2.55e-5*diam(x)*diam(x)*diam(x)*diam(x)*diam(x))
	Buffnull2_cdp5(x) = 64.2 - 57.3*exp(-diam(x)/1.4)
	rf3_cdp5(x) = 0.162 - 0.106*exp(-diam(x)/2.29)
	if (diam(x)>=2) {
		rf4_cdp5(x) = 0.000267 + 0.0167*exp(-diam(x)/0.722) + 0.0028*exp(-diam(x)/4)
	} else {
		rf4_cdp5(x) = 0.003
	}
}

  insert newCaP

 gbar_leak = 1e-6
  e_leak = -61
  cm = 1.5
  Ra = 250

  pcabar_newCaP = 0.000260

  vshift_newCaP = 4.7

}


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