Positronium formation in muscle. An investigation of the structure of cell water.

Positronium formation in muscle at +4 degrees C and -4 degrees C was examined by the measurement of the angular correlation of positron annihilation radiation. Since the positronium formation rate in ice is considerably higher than it is in water, there should be a comparable increase in the positronium formation rate in muscle tissue if recent speculation that cellular water is ordered in a semicrystalline icelike state is correct. Comparison of the angular correlation from muscle at +4 degrees C with that from water at +4 degrees C shows no enhancement of the positronium formation rate. Frozen muscle at -4 degrees C shows an enhancement of the positronium formation rate of approximately half that found in ice at -4 degrees C, indicating that most cellular water undergoes a normal water-ice transition when frozen. It is concluded therefore that cell water in muscle is not ordered in a hexagonal icelike structure. While the results are consistent with the hypothesis that cell water is in the liquid state, the hypothesis that cell water is ordered in an undetermined close packed structure which transforms to the hexagonal ice structure at or near 0 degrees C cannot be ruled out.