The Release of Phosphate from the Electric Organ of Torpedo

The electroplates of the electric organ of Torpedo are embryonically derived from striated muscle fibres which lose their ability to contract and develop greatly expanded end-plate surfaces (cf. Rosenberg, 1928). From consideration of the thermodynamics of the Torpedo organ discharge, Bernstein (1912) concluded that the electric energy of the discharge was derived from a difference between the concentration of ions on the inside and outside of the electroplate, and was released by a breakdown in the selective ion permeability of the innervated surface of the electroplate. One ion species whose movement would be expected to play a part in generating the electric discharge is the sodium outside the electroplate. If, however, the activation of the electric organ is at all analogous to that of the motor end-plate, it is necessary to invoke the movement of additional ions (Fatt, 1950; Fart & Katz, 1951). Among the ions in the electric organs which could contribute to the discharge there is the internal phosphate of the electroplate (Kisch, 1930; Baldwin, 1933). In the present experiments analyses have been made on the fluid issuing from a perfused electric organ during stimulation to find out if an outward movement of phosphate takes place during activity. The movement of other anions has also been studied.