Role of Ca2+ in the rapid cooling-induced Ca2+ release from sarcoplasmic reticulum in ferret cardiac muscles

Table 1 Composition of solutions

Solution	K₂ATP (mM)	AMP (mM)	EGTA (mM)	CaMs₂ (mM)	Mg²⁺ (mM)	MgMs₂ (mM)	KMs (mM)	NaMs (mM)	Caffeine (mM)	Fluo-3 (μM)
Load: 24°C
CaG1M1.5	4.1	0	1	0.4	1.5	5.5	117.5	10	0	0
Wash: 24°C
G1R	0	0	1	0	1.5	1.6	143.9	10	0	0
G10R	0	0	10	0	1.5	2.1	116.5	10	0	0
Pre-assay: 24°C
G0RM1.5F	0	0	0	0	1.5	1.5	147	10	0	20
G0RM0F	0	0	0	0	0	0	151.5	10	0	20
Assay: 3°C
G0M1.5F	4.6	0	0	0	1.5	5.5	120.7	10	0	20
G0RM0CafF	0	25	0	0	0	0	95.1	10	50	20

All solutions contained 10 mM PIPES, 5 μM CCCP and 10 μM DCB. Ionic strength was 0.2 M. Load and assay solutions contained 10–20 μg/ml leupeptin. pH was adjusted to 7.0 by KOH at 3 or 24°C. The meanings of the abbreviations are as follows: G0, 1, 10; 0, 1, 10 mM EGTA, M0, 1.5; 0, 1.5 mM free Mg²⁺, R; no ATP, Ca; pCa 6.5, Caf; 50 mM caffeine, F; 20 μM fluo-3

ISSN: 1880-6562