New data concerning the role of water in biosystems.

Data concerning the state and role of water (H2O) in the nerve, muscle and retina, obtained by the deuteriation technique, nuclear magnetic resonance (NMR) spectrometry and freeze-drying are reported. The existence of at least three distinct tissue water compartments is disclosed, whose sizes depend on the nature and state of the tissue. Some of these water populations appear to be indispensable to keeping up both the (supra) molecular architecture and the function of the system, while others have only a role in securing normal functioning. The mechanisms of the anesthetic action are also discussed and water involvement in this process is pointed out. Heavy water (D2O) effects on the cellular energy mechanisms are critically analysed. A change in the hydration degree of various species and the stabilization of the native conformation of biopolymers, as possible causes of heavy water effects, are remarked.