Ionic mechanism of mechano-perception in characeae

Abstract

Characean internodal cells generate receptor potential in response to mechanical stimuli. We studied responses of internodal cells to a long-lasting stimulus and the results were as follows. (i) The cell generated receptor potential at the moment of both compression and decompression, (ii) The receptor potential (ΔEm) was significantly larger at the moment of decompression than at compression. (iii) The longer the duration of the stimulus, the larger was the magnitude of ΔEm at the moment of decompression, (iv) Aequorin studies revealed that the increase in [Ca 2+]c (Δ|Ca2+]c) took place at the moment of both compression and decompression. (v) The amplitude of Δ[Ca2+]c was larger at the moment of decompression than at compression, as was the case for ΔEm. It was suggested that the amplitude of the receptor potential had a tight correlation with the degree of membrane deformation. We discussed the ionic mechanism of mechano-perception under a long-lasting stimulus in relation to mechanosensitive activation of Ca2+ channels at the plasma membrane. JSPP © 2005.