Propagation of action potential over the trap-lobes of aldrovanda vesiculosa

In the trap-lobes of Aldrovanda vesiculosa, an action potential was generated in a cell located at the base of a sensory hair standing on the margin of central portion of the paired lobes, which spread over this portion within about 40 msec. The electrical coupling ratio for two adjacent cells in the middle layer of the lobes was 0.8. This showed that an action potential generated in a cell of the trap-lobes must spread electrotonically to adjacent cells. An analysis of an equivalent circuit for the cell injected with current and its neighboring cells in the middle layer of the lobes showed that the resistances of the plasmalemma, tonoplast and junction between two cells were 11.1, 4.7 and 0.56 Mω, respectively. Numerous plasmodesmata in the junctional walls of the cells were found by electron microscopy. The low resistance of the junction between cells must be due to the presence of the plasmodesmata which allows an electrotonic transmission of action potential from cell to cell.