Finite element model to study calcium distribution in oocytes involving voltage gated Ca²⁺ channel, ryanodine receptor and buffers

Peer review under responsibility of Alexandria University Faculty of Medicine.

Available online 20 March 2015

Figures & data

Table 1 Values of biophysical parameters.^16,23,24,31

Symbol	Parameter	Value
$D_{\text{Ca}}$	Diffusion coefficient	$250\mathrm{\mu }{\text{m}}^2/\text{s}$
$k_j^{+}$	On rate for EGTA	$3/\mathrm{\mu }\text{M}\text{s}$
$k_j^{-}$	Off rate for EGTA	$1/\text{s}$
$k_j^{+}$	On rate for BAPTA	$100/\mathrm{\mu }\text{M}\text{s}$
$k_j^{-}$	Off rate for BAPTA	$10/\text{s}$
${[B]}_{\infty }$	Total buffer concentration	$50\mathrm{\mu }\text{M}$
$\sigma$	Source amplitude	$1\text{pA}$
${[{\text{Ca}}^{2+}]}_o$	Extracellular Calcium Concentration	$3\text{mM}$
$P_{\text{Ca}}$	Calcium permeability	$4.3\times {10}^{-8}\text{m}/\text{s}$
$V_m$	Membrane potential	$-0.05\text{V}$
$z_{\text{Ca}}$	Valency of calcium	$2$
$V_{\text{Oocyte}}$	Volume of oocyte cytosol	$5.48\times {10}^{-11}\text{l}$
$F$	Faraday’s constant	$96487\text{C}/\text{mole}$
$R$	Gas constant	$8.314\text{J}/\text{K}\text{mole}$
$T$	Absolute temperature	$37°\text{C}$
$P_o$	Rate of calcium efflux	$0.5\text{M}/\text{s}$
$V_{\text{RyR}}$	RyR receptor rate	$0.5\mathrm{\mu }\text{M}/\text{s}$
${[{\text{Ca}}^{2+}]}_{\mathit{ER}}$	ER Ca^2+ concentration	$500\mathrm{\mu }\text{M}$

Figure 1 Spatial variation of calcium concentration for source amplitude $\sigma =1\text{pA}$ and for different concentration of buffer.

Figure 2 Calcium concentration in the absence and the presence of RyR and VGCC.

Figure 3 Spatial variation of calcium concentration for different time periods.

Figure 4 Spatial variation of calcium concentration for different concentrations of EGTA buffer.