Table 2.

The effects of [Ca²⁺]_o and FK506 on the amplitude and decay of Ca²⁺ sparks and associated Ca²⁺ release fluxes

	[Ca2+]o (mm)	1	3	5	10	5
	FK506 (μm)	0	0	0	0	50
[Ca2+] signal	Amplitude (nm)	102 ± 5	126 ± 8	174 ± 12 *	154 ± 13 *	167 ± 12
	Decay time constant (ms)	16.6 ± 3.6	14.7 ± 1.4	10.8 ± 1.0 *	13.6 ± 1.2	29.5 ± 2.9 †
Release flux	Amplitude (nm ms−1)	2632 ± 163	3029 ± 150	3887 ± 202	3406 ± 236 *	3519 ± 260
	Decay time constant (ms)	9.5 ± 0.9	7.9 ± 0.7	6.5 ± 0.5 *	6.9 ± 0.7	11.2 ± 1.0 †

Data represented as means ± s.e.m. of measurements from 14–29 individual sparks. The amplitudes of the local [Ca²⁺]_i and relase flux signals were determined as differences between the background and peak values. Decay time constants were determined by fitting single exponential functions to the initial descending face of linear profiles through the peaks of the signals.

^*P < 0.05 vs. values at 1 mm [Ca²⁺]_o

^†P < 0.05 vs. values at 5 mm [Ca²⁺]_o and no FK506.