Mechanosensitive Ca²⁺ Channels of Characeae may be Triggered by the Membrane Stretching.

Abstract

Plants generates receptor potential which is explained as an activation of mechanosensitive Ca²⁺ channels, followed by an activation of Cl^-.
What triggers the activation of Ca²⁺ channels may be a change of membrane tension or membrane stretching as follows. Membrane potential, E_m, significantly changed during hypertonic treatment (plasmolysis) and the following hypotonic treatment (deplasmolysis). By contrast, the deplasmolyzed cell did not show any change in E_m upon the second hypertonic treatment. This may suggest that membrane streching triggers changes of E_m, because membrane stretching should occur during plasmomolysis and deplasmolysis but not during the second hypotonic treatment. Effect of membrane stretching upon activation of Ca²⁺ channel was also studied. Significant increase in cytoplasmic level of Ca²⁺ occurred during the plasmolysis and during the deplasmolysis, but did not during the second hypotonic treatment. We discussed the mechanism of receptor potential in relation with the membrane stretching.