Table 1.

Composition of IM

	CsCl	CsF	KCl	KF	CaCl2	EGTA	MgCl2	NaCl	HEPES
IM 1	140	0	0	0	1	2	2	4	10
IM 2	110	30	0	0	1	2	2	4	10
IM 3	0	0	110	30	1	2	2	4	10

Concentrations are expressed in mm. pH was adjusted to 7.4 with CsOH or KOH; ∼300 mOsm/L.