Role of creatine phosphate in the discharge of the electric organ of Torpedo marmorata.

The role of creatine phosphate and adenosine triphosphate, as high energy phosphate sources, has been investigated during the discharge and recovery of the electric organ of Torpedo. ATP serves as the immediate source of energy for the biochemical process supporting the electrical activity of the electric organ. Under repetitive stimulation, when the energy demands exceed production, ATP levels are maintained constant at the expense of creatine phosphate. Only when the reservoir of creatine phosphate is depleted do the levels of ATP decrease, and this point corresponds to the state of maximal fatigue of the electric organ. Recovery studies show that the electric organ rapidly recovers the capacity to respond to single pulse stimuli. This recovery is statistically related to the recovery of the levels of ATP and acetylcholine. However, in this phase, the fatiguability of the electric organ is very high since its energy reservoir is still depleted. The complete recovery of the electric organ requires several hours and is closely related to the restoration of the levels of creatine phosphate.