Table 1.

Parameters under conditions with three different calcium concentrations

Parameter	Normal Ca2+ condition (2 mM)	Half‐Ca2+ condition (1 mM)	Low Ca2+ condition (0.2 mM)
Cell diameter D cell	15.8 μm	16.8 μm	17.8 μm
Cell spacing d cc	2.84 μm	1.84 μm	0.84 μm
Volume ratio r V *	0.63	0.36	0.15

^*Volume ratio r _V can be described as:

$r_{\mathrm{V}}=[\frac{4\pi R_{\mathrm{out}}^3}{3}-\frac{4\pi R_{\mathrm{cell}}^3}{3}]/\frac{4\pi R_{\mathrm{cell}}^3}{3}$.