Table 2.

Conductance and calcium pump regulation

[Ca]cyt-dependent activity sensor:
$S_A=\overline{S_A}{M_A}^4\hspace{1em}{M}_A=\frac{1}{1+e^{M_{\mathit{\text{thr}}\_A}-{[\mathit{\text{Ca}}]}_{\mathit{\text{cyt}}}}}$	S̅A = 8 Mthr_A = 0.9 µM
[Ca]cyt kinetics:
$d\frac{{[\mathit{\text{Ca}}]}_{\mathit{\text{cyt}}}}{dt}=-\gamma I_{\mathit{\text{Ca}}}-R_{\mathit{\text{pump}}}\frac{{[\mathit{\text{Ca}}]}_{\mathit{\text{cyt}}}^2}{{[\mathit{\text{Ca}}]}_{\mathit{\text{cyt}}}^2+{\alpha }_{\mathit{\text{pump}}}^2}$	γ = 0.00678 µM nA−1msec−1 αpump = 0.2 µM
ḠCa regulation:	ḠCa_min = 0.069 µS ḠS_Ca = 0.12 µS Sthr_A = 0.13, rS = 0.02, τA = 500 sec
${Ḡ}_{\mathit{\text{Ca}}}={Ḡ}_{\mathit{\text{Ca}}\_\mathit{\text{min}}}+G_{S\_\mathit{\text{Ca}}}\hspace{1em}{\tau }_A\frac{d{G}_{S\_\mathit{\text{Ca}}}}{dt}=\frac{{Ḡ}_{S\_\mathit{\text{Ca}}}}{1+e^{\frac{S_A-S_{\mathit{\text{thr}}\_A}}{r_S}}}-G_{S\_\mathit{\text{Ca}}}$
Calcium pump activity regulation:
Rpump = Rpump_min + F(M)	Rpump_min = 0.0026 µMmsec−1 Rpump_M = 0.006 µMmsec−1 Mthr = 0.1331, rM = 0.00001 Gthr = 0.01 µM, rG = 0.00001 τM = 2500 sec
$F(M)=\frac{R_{\mathit{\text{pump}}\_M}}{1+e^{-\frac{M_{\mathit{\text{thr}}}-M}{r_M}}}\hspace{1em}{\tau }_M\frac{dM}{dt}=\frac{1}{1+e^{\frac{G_{\mathit{\text{thr}}}-{Ḡ}_{MI}}{r_G}}}-M$