Abstract
Procaine hydrochloride decreases potential and effective resistance of the membrane and does not produce prolonged spikes. Tetraethylammonium (TEA) and barium ions prolong the spikes of internodal cells of Nitella evidently by delaying K+ activation as is the case in many other excitable cells. The last two agents do not increase the amplitude of the spikes in contrast to their effect on some arthropod muscle fibers. The other effects of Ba2+ and TEA on the spikes of Nitella and animal cells are almost identical. We conclude that the same molecular mechanism is involved in K+ activation in animals and plants.