A tissue stimulating device that provides biological stimulation of tissue has a release surface adapted for arrangement adjacent to a tissue to be stimulated. An agent reservoir of the device includes an ionic agent capable of causing a stimulation if present at sufficient high extracellular concentration close to the tissue. An agent releaser is provided in the device for releasing a selected amount of the ionic agent from the agent reservoir to an outside of the release surface at a stimulation occasion for stimulating the tissue. The ionic agent will cause a temporary change in ion permeability of the tissue cell membranes and a depolarization of the tissue cells.