Table S1.

List of model parameters

Parameter	Unit	Description	Value	Source
Li–Rinzel model
rrel	s−1	Maximal rate of Ca2+ release	1.11	(67)
rleak	s−1	Maximal rate of Ca2+ leak	0.02035	(67)
vserca	µM·s−1	Maximal rate of SERCA pumps	0.9	(67)
kserca	µM	Ca2+ affinity of SERCA pumps	0.11	Fitted, Fig. 2B
d1	µM	Li–Rinzel model parameter	0.13	(67)
d2	µM	Li–Rinzel model parameter	1.049	(67)
d3	µM	Li–Rinzel model parameter	0.9434	(67)
d5	µM	Li–Rinzel model parameter	0.08234	(67)
a2	µM−1·s−1	Li–Rinzel model parameter	0.2	(67)
α	—	Ratio between cytosol and ER volume	0.185	(67)
[Ca2+]TOT	µM	Total free Ca2+ concentration	2	(67)
IP3 subsystem
vPLC	µM·s−1	Initial value of the maximal rate of IP3 production by PLC	0.101	Fitted, Fig. 2B
kPLC	µM	ATP dissociation constant	0.038	Fitted, Fig. 2B
nPLC	—	Hill exponent for ATP-dependent IP3 production	0.28	Fitted, Fig. 2B
$r_{\text{deg}}^{{\text{IP}}_3}$	s−1	Rate of IP3 degradation	0.13	Fitted, Fig. 2B
pu	µm3·s−1	Unitary IP3 permeability of gap junction channels	72 × 10−3	(44)
V	µm3	Cell volume	3,900	Fitted, Fig. 2B
Nch	—	No. channels between two adjacent supporting cells	935	Fitted, Fig. S2 and ref. 47
A1	s	$v_{\text{PLC}}$ time constant parameter	1,313	Fitted
A2	µM−1	$v_{\text{PLC}}$ time constant parameter	0.97	Fitted
A3	s	$v_{\text{PLC}}$ time constant parameter	46.66	Fitted
ATP subsystem
$r_{\text{deg}}^{\text{ATP}}$	s−1	ATP degradation rate	0.001–100	Main text
vHC	µM·s−1	ATP maximal release rate	0–2000	Main text
D	µm2·s−1	ATP diffusion coefficient	363	(74)
k1	µM−1·s−1	Hemichannel model constant	10.619	Fitted, Fig. 1C
k2	µM−1·s−1	Hemichannel model constant	2.47	Fitted, Fig. 1C
k−1	s−1	Hemichannel model constant	3.4	Fitted, Fig. 1C
k−2	s−1	Hemichannel model constant	2.38	Fitted, Fig. 1C
γ	—	Hemichannel model constant	9	Fitted, Fig. 1C