Experiments on the Hofmeister series in heart muscle

Summary The distinct effects which anions have on the automaticity of the heart may be used as a demonstration of the validity of theHofmeister series in living cells.The following procedure is chosen: Heart strips ofRana esculenta are first immersed inRinger's and thereafter in isotonic non-electrolyte solutions until automaticity ceases. By replacing 30 parts of the nonelectrolyte solution by an isotonic Na-salt solution automaticity will be restored. The ions follow theHofmeister series: Citrate, SO⁴, C1, Br, I, SCN in their effectiveness, SCN being the most powerful anion. This is not only evident in that the last members of the series restore automaticity which has ceased in the presence of anions preceding them in theHofmeister series but also in, the duration of activity produced by different Na-salts and frequently in the height of contraction.The experiment also succeeds in heart strips without spontaneous activity.If the sequence in which the ions are applied is reversed (from SCN to Citrate) only the first ion is effective.The experiments show that the automaticity of the heart muscle depends on anions in the same way as the excitability of voluntary striated muscles.Non-electrolytes which bring about a standstill of the heart show frequently first a slowing of the heart rate and an increase in the time of relaxation. The effects are reversible if Na-salts are added to non-electrolyte solutions.Aided by the National Research Council and the Research Fund of the University of Oregon.