Dids 4 4 diisothiocyanatostilbene 2 2 disulfonic acid

Standard HEPES-buffered Tyrode solution (air equilibrated) was composed of (in mM): 140 NaCl, 4.5 KCl, 1 MgCl₂, 2.5 CaCl₂, 11 glucose, 20 HEPES. In Na⁺ free HEPES solution, 140 NaCl were replaced with 140 NMDG (N-methyl-D-glucamine).
Nigericin Calibration Solution containing (mM): KCl 140, MgCl2 1, and Nigericin 0.01, was buffered with one of the following organic buffers: 20mM MES (pH 5.5 and 6.5), 20 mM HEPES (pH 7.0, 7.5, and 8.5), or 20 mM CAPSO (pH 9.5), and was adjusted to the correct pH with 1 M NaOH at 37 °C (Sigma, Dorset, UK).
In the NH₄Cl prepulse solution, NH₄Cl was added directly to the solution without osmotic compensation. All different solutions were adjusted to 7.4 with 4N NaOH, 4N HCl, and KOH, respectively, at 37 °C.
HOE 694 (3-methylsulphonyl-4-piperidinobenzoyl, guanidine hydrochloride, Sanofi-Aventis, Paris, France), Bafilomycin A1 (LC Laboratories, Woburn, MA, USA), DIDS (4,4′-Diisothiocyanatostilbene-2,2′-disulfonic acid, Sigma-Aldrich, St. Louis, MO, USA), were added to the solutions at the indicated concentrations shortly prior to use. All other chemicals were purchased from Sigma (Dorset, UK) and Merck (Dorset, UK).

KCl 140, MgCl₂ 1, and nigericin 0.01, buffered with one of the following organic buffers: 20 mM MES (pH 5.5 and 6.5), 20 mM HEPES (pH 7.0, 7.5, and 8.5) or 20 mM CAPSO (pH 9.5), and were adjusted to the correct pH with 1 M NaOH at 37 °C.
HOE694 (3-methylsulphonyl-4-piperidinobenzoyl, guanidine hydrochloride, Sanofi-Aventis, Paris, France), Bafilomycin A1 (LC Laboratories, Woburn, MA), CHC (2-Cyano-3-(4-hydroxyphenyl)-2-propenoic acid, Tocris Bioscience, Minneapolis, MN), DIDS (4,4′-Diisothiocyanatostilbene-2,2′-disulfonic acid, Sigma-Aldrich, St. Louis, MO), Lactate (Sigma) were added to the solutions at the indicated concentrations shortly prior to use.