BIOELECTRIC EFFECTS OF IONS MICROINJECTED INTO THE GIANT AXON OF LOLIGO* BY HARRY GRUNDFEST, C. Y. KAO~ A~ro

The bioelectric phenomena of excitable tissues involve a complex series of events associated with ionic movements across the labile relative barrier of the cell which is termed the excitable membrane. Present day theories postulate that the resting potential is essentially determined by asymmetry in the distribution of different ions between the interior of the cell and its exterior, that asymmetry being produced at least partly by Donnan effect (17), and partly by specific, metabolically energized secretory activity (34, 45). The magnitude of the resting potential is believed to be complexly determined by the ratios of the distribution of K +, Na +, and C1and by their effective mobiLities (25). The sign of the potential is in the direction that would be determined by the tendency of the ion of greatest effective mobility (K +) to diffuse from the more to the less concentrated phase (17). Activity superimposes upon this electrochemical system an alteration of electromotive force which is determined by a characteristic response of the membrane. According to the theory of Hodgkin and Huxley (22) this response