Figure 4. Enhancement of ACh release from myocytes by extracellular alkalinization.

Single channel recordings were made by cell-attached patch clamp in 1-day-old Xenopus cultured myocytes. The patch was hyperpolarized +60 mV from rest. Compared with control in normal Ringer solution (pH 7.6, A), a patch pipette filled with pH 8.6 Ringer solution enhanced the opening of ACh channels (B and C). Application of vesamicol or quinacrine in the patch pipette or bath application of NH₄Cl to cause intracellular alkalinization inhibited the potentiating effect (C). Data are presented as means ± s.e.m (n). *P < 0.05 compared with pH 7.6 normal Ringer solution. †P < 0.05 compared with pH 8.6 Ringer solution.