A proton spin-echo study of the state of water in frog nerves.

A proton spin-echo study of the water in the sciatic nerve trunk of the bullfrog reveals two distinct types of water as distinguished by their spin-spin relaxation times. The relative concentrations of these two types were determined for nerves which had been treated with normal Ringer's solution and also for nerves which had been treated with potassium-doped (0.15 M) Ringer's solution. In both cases the relative concentrations are the same as those previously determined through signal integration of high resolution proton magnetic resonance spectra obtained for the same systems, although the high resolution studies were performed on nerves doped with paramagnetic ions and the spin-echo studies were performed on undoped nerves. The doping procedure would appear to be a valid and very useful way of studying water in this neural system.