. 2022 Mar 21;154(9):e202112994. doi: 10.1085/jgp.202112994

Table A1.

Model equations

Buffering
SR	$\frac{d C a B}{d t} {= k}_{o n}^{B} \cdot {C a}_{S R} {(t)}^{n} \cdot (B_{T o t} - C a B) - k_{o f f}^{B} \cdot C a B$
Myoplasm	$\frac{{d C a E G T A}_{M}}{d t} = k_{o n}^{E G T A} \cdot {C a}_{M} (t) \cdot ({E G T A}_{T o t} {- C a E G T A}_{M}) - k_{o f f}^{E G T A} \cdot {C a E G T A}_{M}$
JS	$\frac{{d C a E G T A}_{J S}}{d t} = k_{o n}^{E G T A} \cdot {C a}_{J S} (t) \cdot ({E G T A}_{T o t} - {C a E G T A}_{J S}) - k_{o f f}^{E G T A} \cdot {C a E G T A}_{J S}$
Leaks
From t-system	$k_{L e a k}^{T} \cdot ({C a}_{T} (t) - {C a}_{M} (t))$
From SR, via RYR	$k_{L e a k}^{R y R} \cdot ({C a}_{S R} (t) - {C a}_{J S} (t))$
From SR, non-RYR	$k_{L e a k}^{S R} \cdot ({C a}_{S R} (t) - {C a}_{M} (t))$
Diffusion	$k_{D i f f} \cdot ({C a}_{J S} (t) - {C a}_{M} (t))$
Combined differential equations
$\frac{{d C a}_{T}}{d t} = \frac{V_{J S}}{V_{T}} \cdot M_{P M C A} ({C a}_{J} {, C a}_{T} {, K}_{D}^{P M C A} {, c}_{P M C A}) - k_{L e a k}^{T} \cdot ({C a}_{T} {(t) - C a}_{M} (t))$
$\frac{d C a_{S R}}{d t} = \frac{V_{M}}{V_{S R}} \cdot M_{S E R C A} (C a_{M}, C a_{S R}, K_{D}^{S E R C A}, c_{S E R C A}) - k_{L e a k}^{R y R} \cdot (C a_{S R} (t) - C a_{J S} (t)) - k_{L e a k}^{S R} \cdot (C a_{S R} (t) - C a_{M} (t)) - \frac{d C a B}{d t}$
$\frac{{d C a}_{J S}}{d t} = \frac{V_{S R}}{V_{J S}} \cdot k_{L e a k}^{R y R} \cdot ({C a}_{S R} (t) - {C a}_{J S} (t)) - \frac{{d C a}_{T}}{d t} - \frac{{d C a E G T A}_{J S}}{d t} - k_{d i f f} \cdot ({C a}_{J S} (t) - {C a}_{M} (t))$
$\begin{array}{l} \frac{{d C a}_{M}}{d t} = \frac{V_{S R}}{V_{M}} \cdot k_{L e a k}^{S R} \cdot ({C a}_{S R} (t) - {C a}_{M} (t)) + \frac{V_{T}}{V_{M}} \cdot k_{L e a k}^{T} \cdot ({C a}_{T} (t) - {C a}_{M} (t)) + \frac{V_{J S}}{V_{M}} \cdot k_{d i f f} \cdot ({C a}_{J S} (t) - {C a}_{M} (t)) - \\ M_{S E R C A} ({C a}_{M} {, C a}_{S R} {, K}_{D}^{S E R C A} {, c}_{S E R C A}) - \frac{{d C a E G T A}_{M}}{d t} \end{array}$