Table 1.

Time constants of LFD, LFD_AR, and PTP_LFD were obtained by fitting mean amplitude values of IPSC (I) at any stimulus from n experiments (see Materials and Methods)

	Stim.	n	ωfast (%)	τfast (s)	ωI (%)	τI (s)	ωII (%)	τII (min)
LFD low P	S	9			54.6 ± 4.9	54.5 ± 6.9	45.4 ± 2.3	8.9 ± 1.0
LFD high P	S	7			51.9 ± 3.3	39.1 ± 9.7	48.1 ± 5.5	8.1 ± 0.9
Stat. with LFD low P					*	*	NS	NS
LFD low P + ApSynAla	S	4			64.3 ± 2.1	39.1 ± 7.1	35.7 ± 3.9	10.2 ± 2.8
Stat. versus LFD low P					*	NS	NS	NS
LFD low P + PKAi6-22	S	4			57.2 ± 3.8	18.7 ± 2.9	42.8 ± 3.9	6.8 ± 1.7
Stat. with LFD low P					NS	**	NS	NS
LFD high P	PP	10			43.3 ± 4.1	26.8 ± 4.5	56.7 ± 5.8	10.4 ± 1.1
LFDAR rest 10 s	PP	4	100	1.2 ± 0.2
LFDAR rest 15 s	PP	4	100	1.6 ± 0.4
LFDAR rest 20 s	PP	6	85.8 ± 5.8	1.0 ± 0.1	14.2 ± 2.0	19.8 ± 6.1
Stat. with LFD high P			—	—	—	NS
LFDAR rest 40 s	PP	5	86.3 ± 13.5	1.5 ± 0.2	13.7 ± 1.7	70.8 ± 12.0
Stat. with LFD high P			—	—	—	**
LFDAR rest 60 s	PP	4	76.7 ± 9.7	1.4 ± 0.4	23.3 ± 10.3	34.3 ± 10.2
Stat. with LFD high P			—	—	—	NS
LFDAR rest 90 s	PP	6	69.0 ± 12.0	1.0 ± 0.2	18.4 ± 7.8	13.2 ± 3.9	12.6 ± 0.6	2.3 ± 0.6
Stat. with LFD high P			—	—	—	NS	—	***
LFDAR rest 120 s	PP	5	65.0 ± 12.2	1.4 ± 0.2	22.1 ± 6.0	24.3 ± 8.3	12.1 ± 0.5	2.2 ± 0.1
Stat. with LFD high P			—	—	—	NS	—	**
LFDAR rest 240 s	PP	4	63.1 ± 3.6	1.6 ± 0.4	23.3 ± 6.1	22.8 ± 5.5	13.6 ± 1.4	3.4 ± 0.3
Stat. with LFD high P			—	—	—	NS	—	**
LFDAR rest 900 s	PP	7	49.0 ± 8.9	1.3 ± 0.2	29.2 ± 6.1	17.8 ± 2.7	21.8 ± 3.0	4.3 ± 0.3
Stat. with LFD high P			—	—	—	NS	—	***
PTPLFD rest 20 s	PP	5	60.3 ± 12.7	1.0 ± 0.1	27.7 ± 5.3	6.6 ± 0.1	12.0 ± 2.7	5.5 ± 0.8
Stat. with LFD high P			—	—	—	**	—	**
PTPLFD rest 120 s	PP	3	59.1 ± 6.9	1.6 ± 0.4	26.1 ± 4.1	9.4 ± 3.8	14.8 ± 2.7	3.4 ± 1.2
Stat. with LFD high P			—	—	—	**	—	**
Stat. with PTPLFD rest 20 s			NS	NS	—	NS	—	NS

Low P and high P correspond to [Ca²⁺]/[Mg²⁺]_e = 0.42 and [Ca²⁺]/[Mg²⁺]_e = 2.1, respectively. LFD_AR and PTP_LFD were probed at [Ca²⁺]/[Mg²⁺]_e = 2.1. LFD, LFD_AR, and PTP_LFD were probed using either a single stimulus (denoted as S) or a paired-pulse stimulation (interval, 40 ms; denoted as “PP”). The statistical differences (mentioned as “Stat.”) in the weights (ω_I and ω_II) and in the time constants (τ_I and τ_II) of the exponential decays were tested for two different conditions using either the t test or the Mann–Whitney rank sum test. The statistical difference in τ_fast calculated during LFD_AR and PTP_LFD at any rest period was probed using a one-way ANOVA. This test did not detect any statistical difference in τ_fast (p = 0.64).

*p < 0.05,

**p < 0.01, and

***p < 0.001. NS denotes no significant difference (i.e., p > 0.05).