Table 2.

General parameters that were not derived from least‐square fits

Description	Symbol	Units	Value	Comment
General
Intracellular free [Mg2+]	[Mg2+]i	m	5×10−4
Resting intracellular free [Ca2+]	[Ca2+]rest	m	5×10−8	for low [EGTA]i
			2×10−8	for high [EGTA]i
Calcium current (P13–15)
Initial current	I Ca,0	A	−1.07 ± 0.07×10−9	mean
Duration of current flow	∂	s	1×10−3	depolarizing steps
			3.22×10−4	mature APW
			4.83×10−4	immature APW
Facilitation parameter y
Time constant	τy	s	0.023
Maximum value	y max		1.56
Increment	y incr		0.47
Inactivation parameter z
Time constant	τz	s	0.11
Minimum value	z min		0.75	for low [EGTA]i
			0.67	for high [EGTA]i
Decrement	z decr		0.032
Fast buffers
Total concentration of fixed endogenous		m	8.44×10−3	calculated to yield κs = 21.1 at low [Ca2+]i
Dissociation constant of fixed endogenous	K D	m	4×10−4
Total concentration of Ca2+ indicator dye		m	10−4
Dissociation constant of Ca2+ indicator dye	K D	m	1.78×10−5	Fura‐6F (Woehler et al. 2014)