Studies on Mechanoperception in Characean Cells: Pharmacological Analysis

The mechanisms for generating receptor potentials and action potentials upon mechanical stimulation were studied in internodal cells of Chara. Receptor potentials and the subsequent action potentials could be generated even when the electrogenic proton pump was inhibited, indicating that the proton pump does not play a central role in generating receptor potentials and action potentials. The involvement of Ca2+ and/or Cl− channels in both receptor and action potentials was suggested, based on the equilibrium potentials of these ions across the plasma membrane. Inhibitors of the Ca2+ channel, Cl− channel and stretch-activated channel could not inhibit generation of the receptor potential. These findings suggested that the channels involved in generating the receptor potential are insensitive to these channel inhibitors, although all inhibitors significantly inhibited the action potential.