Table 1.

Composition of external solutions (in mm)

External solutions0 Ba2+–MA+0 Ba2+–Cs+0 Ba2+–Na+3 μmBa2+–MA+3 mmBa2+–MA+3 mmBa2+–NMG+
MA·Cl909090
Cs·Cl90
Na·Cl90
NMG·HEPES1010101010 10
NMG·HEDTA10101010
NMG·Cl30115
Ba·Cl20.09 3  3
  • The concentration of Ba2+ added to make the buffered 3 μm Ba2+ external solution was calculated from the stability constant of HEDTA (Martell and Smith, 1974) using a computer program based on Fabiato and Fabiato (1979). This program, written by H. Liang, determined the concentration of the divalent cation to be added to a solution given the desired final concentration and the chelator to be used.