| Abstract: | Frog sartorius muscles were pretreated in 11.6 M (87%) ion-free glycerol. Then half of them were put in 5.8 M glycerol solutions containing 55 mM LiCl, NaCl, RbCl or CsCl and their pairs in ion-free 5.8 M glycerol solutions at 1:40 Vol. muscle:Vol. solution ratio. The release of potassium during exposure to the 5.8 M glycerol solution was significantly faster in the presence of Li or Na, but significantly slower in the presence of Rb than in the ion-free circumstance. The effect of Rb can be related to a cooperative phenomenon that implies existence of a structured phase of K-protein complexes. Some postulates of Ling's association-induction hypothesis are used for interpretation of two phases and their phase transitions in this type of bound-K structure in muscle. The phase transitions in this system could have an important role in the fast processes of excitation in muscle. |
