QUANTITATIVE STUDIES IN ION ANTAGONISM

I. EXPERIMENTS ON THE STRIATED MUSCLE OF THE FROG

¹ From the Department of Animal Biology, University of Oregon, Eugene, Oregon

The irritability of the sartorius muscle of Rana esculenta has been studied in different mixtures of NaCl, KCl, and CaCl₂. The method permits the detection of very small differences in the KCl effect. Usually the minimal effective KCl and CaCl₂ concentration is determined which leads to a rapid loss in irritability. The dependence of the KCl effect upon the NaCl and the CaCl₂ concentration is represented by a straight line. Concerning the antagonism between Na and K the result is that the ratio Na : K is constant. That does not hold for the antagonism between K and Ca although this also corresponds to a straight line. But in the latter case the relation is represented by the equation y = ax + b and b has a definite value, while in the first case b = 0 and therefore a = y/x. The quantitative results show that within certain limits 0.014 M NaCl has the same antagonistic value against KCl as 0.00081 M CaCl₂. Therefore, it is possible to predict the behavior of the muscle in any other solution if the antagonism has been investigated for one single mixture of these three salts. The results agree rather exactly with this assumption. here is, however, a very characteristic limit of the validity of these equations. It is found that the NaCl concentration determines the highest KCl concentration, the effect of which can still be offset by the addition of CaCl₂. It is higher the greater the NaCl concentration. Therefore the antagonistic action of Na against K is not only quantitatively but also qualitatively different from the antagonistic effectof Ca against K.

An antagonism between Na and Ca was also found. The complete analysis leads to the qualitative formula: [See formula in the PDF file] in which the arrow indicates the cation which is able to balance the toxic effect of another cation.