17 O nuclear magnetic resonance spectrum of H 2 17 O in frog striated muscle.

Whole striated muscles from the frog Rana esculenta were bathed in Ringer's solution enriched with H(2) (17)O; the muscle water was subsequently collected by vacuum distillation. The integrated intensity of the nuclear magnetic resonance (NMR) signal of (17)O in the muscle was measured to be approximately (3/4) of the signal observed in the distilled water. The phenomenon may arise either from immobilization of a population of the water molecules which may be a very small fraction or as much as (1/4) of the total, or may reflect tumbling of (1/3) of the water molecules in a compartment containing an anisotropic medium. Such an effect was demonstrated for H(2) (17)O using the model system of sodium linoleate in water.