Table 2.

Actions of Iso on currents.

Increase of L-type Ca2+ current

$i_{\text{Ca,}L}=\left[\left(\mathrm{1}+f_{\text{Ca,max}}\frac{[\text{Iso}]}{K_{\mathrm{0.5},{\text{Ca}}^{\prime }}+[\text{Iso}]}\right)\times g_{\text{Ca,}L}\right]\left[f_L{d}_L+\frac{\mathrm{0.006}}{\mathrm{1}+e^{-(V+\mathrm{14.1})/\mathrm{6}}}\right](V-E_{\text{Ca,}L})$6

Shift of the activation curve of hyperpolarization-activated current

$y_{\mathrm{\infty }}=\frac{e^{-(V+\mathrm{78.91}-S_f)/\mathrm{26.2}}}{e^{-(V+\mathrm{78.91}-S_f)/\mathrm{26.2}}+e^{(V+\mathrm{75.131}-S_f)/\mathrm{21.25}}}$,  ${\mathrm{\tau }}_y=\frac{\mathrm{1000.0}}{e^{-(V+\mathrm{78.91}-S_f)/\mathrm{26.2}}+e^{(V+\mathrm{75.131}-S_f)/\mathrm{21.25}}}$

$\frac{dy}{dt}=\frac{y_{\mathrm{\infty }}-y}{{\mathrm{\tau }}_y}$,  $S_f=S_{f,\max }\frac{{[\text{Iso}]}^{n_f^{\prime }}}{K_{\mathrm{0.5},f^{\prime }}^{n_f^{\prime }}+{[\text{Iso}]}^{n_f^{\prime }}}$

Actions on rapid delayed rectifying K+ current

$i_{\text{K},r}=\left[\left(\mathrm{1}+f_{\text{K},\max }\frac{[\text{Iso}]}{K_{\mathrm{0.5},g_{\text{K}}}+[\text{Iso}]}\right)\times g_{\text{K},r}\right][(\mathrm{1}-F_{\text{K},r})p_{a,f}+F_{\text{K},r}{p}_{a,s}]p_i(V-E_{\text{K}})$

$\frac{d{p}_{a,f}}{dt}=\frac{\mathrm{1}/\left(\mathrm{1}+e^{-(V+\mathrm{14.2}-S_{\text{K}})/\mathrm{10.6}}\right)-p_{a,f}}{{\mathrm{\tau }}_{p_{a,f}}}$,  $\frac{d{p}_{a,s}}{dt}=\frac{\mathrm{1}/\left(\mathrm{1}+e^{-(V+\mathrm{14.2}-S_{\text{K}})/\mathrm{10.6}}\right)-p_{a,s}}{{\mathrm{\tau }}_{p_{a,s}}}$

$S_{\text{K}}=S_{\text{K},\max }\frac{[\text{Iso}]}{K_{\mathrm{0.5},\text{Kacti}}+[\text{Iso}]}$,  $\frac{d{p}_i}{dt}=\frac{\mathrm{1}/\left(\mathrm{1}+e^{(V+\mathrm{18.6})/\mathrm{10.1}}\right)-p_i}{\left(\mathrm{1}-d_{{\mathrm{\tau }}_{\text{K,}r,\max }}\left(\left[\text{Iso}\right]/K_{\mathrm{0.5},{\mathrm{\tau }}_{\text{K,}r}}+\left[\text{Iso}\right]\right)\right)\times {\mathrm{\tau }}_{p_i}}$

Increase of slow delayed rectifying K+ current

$i_{\text{K},s}=\left[\left(\mathrm{1}+f_{\text{K},\max }\frac{\left[\text{Iso}\right]}{K_{\mathrm{0.5},g_{\text{K}}}+\left[\text{Iso}\right]}\right)\times g_{\text{K},s}\right]x_s^{\mathrm{2}}\left(V-E_{\text{K},s}\right)$

Increase of sustained inward current

$i_{\text{st}}=\left[\left(\mathrm{1}+f_{\text{st,max}}\frac{\left[\text{Iso}\right]}{K_{\mathrm{0.5},\text{st}}+\left[\text{Iso}\right]}\right)\times g_{\text{st}}\right]q_n{q}_i\left(V-E_{\text{st}}\right)$

Actions on Ca2+ handling

$j_{\text{up}}=\left(\mathrm{1}-{\mathrm{\beta }}_{\text{Iso}}\right)\times P_{\text{up}}\frac{{\left({[\text{C}{\text{a}}^{\text{2+}}]}_i/K_{\text{mf}}\right)}^{n_{\text{up}}}-{\left({[\text{C}{\text{a}}^{\text{2+}}]}_{\text{up}}/K_{\text{mr}}\right)}^{n_{\text{up}}}}{\mathrm{1}+{\left({[\text{C}{\text{a}}^{\text{2+}}]}_i/K_{\text{mf}}\right)}^{n_{\text{up}}}-{\left({[\text{C}{\text{a}}^{\text{2+}}]}_{\text{up}}/K_{\text{mr}}\right)}^{n_{\text{up}}}}$

j rel⁡ = (1 + αIso) × k s O([Ca2+]rel⁡ − [Ca2+]sub)