Effect of stretching on the water-binding of muscle.

Frog muscles stretched to a length about 1.2 times greater than the original one lost 19 per cent of their water content on the average when kept in normal Ringer solution at a temperature of 2 degrees C for 24 hours. In NaHCO3-free Ringer solution containing 1.5 x 10(-4) per cent lactic acid (pH 6.8) the water content increased by 6 per cent. The change in the weight of non-stretched control muscles taken from the opposite side was insignificant in normal Ringer solution. The increase of water content in Ringer solution containing lactic acid was 22 per cent on the average. The conclusion is drawn that muscle is not an osmotic sack of water-medium and muscle water is bound, a least in part, through swelling.