Levels of high-energy phosphates in crayfish nerve during prolonged repetitive impulse activity

1. Levels of ATP and arginine phosphate (ArgP) in the mixed nerve bundle of the crayfish walking leg were assayed in fresh tissue and after prolonged repetitive stimulation. 2. In fresh tissue, ATP and ArgP levels were estimated to be about 34 n-mole/mg protein and 157 n-mole/mg protein, respectively, corresponding to concentrations of 3 . 0 and 13 . 9 mM. 3. Following 5 min of repetitive stimulation at 30 impulses/sec, the ATP concentration in the nerve increased by 0 . 52 mM; after 10 and 20 min of stimulation, the concentrations returned to values similar to those of fresh tissue. 4. The ArgP concentrations were similar to those of fresh tissue after 5 min of stimulation at 30 impulses/sec but dropped to about 85% of those values after 10 and 20 min of stimulation. 5. Increased K+ in the physiological saline reduced [ATP] following stimulation; decreased Na+ in the saline increased the content of ATP in unstimulated nerves. 6. It is concluded that repetitive action potential activity may be associated with relatively constant and perhaps increased production of ATP.