Electron probe X-ray microanalysis of K, Rb, Cs, and T1 in cryosections of striated muscle.

Muscles containing the normal amount of K+ or loaded with Rb+, Cs+, or T1+ were cryofixed, cryosectioned and analysed by electron probe X-ray microanalysis. Previously reported results obtained with independent methods were confirmed: The alkali-metals and T1 are mainly localized in the A bands and at Z lines of the striated muscle. The results are in accordance with the association-induction hypothesis and the concept that K+ is physically adsorbed onto beta- and gamma-carboxyl side chains of myosin and other proteins.