Diffusible calcium in normal,rachitic,and experimental tetany blood

Abstract

In 1911, Rona and Takahashi 1 reported their work on the diffusible Ca of horse, ox, and pig serum, finding an average of 65 per cent. of the total serum Ca to be diffusible. No work was done with human blood. MacCallum, Lambert and Vogel 2 in 1914 made the following statement: “If tetany blood be dialyzed under exactly the same conditions as normal blood, it still loses a proportionate amount of its Ca, which would perhaps show that it is not especially the loss of a diffusible Ca as contrasted with a non-diffusible form—which is important in producing tetany.” Brinkman 3 in 1919 advanced the hypothesis that the calcium-ion concentration is dependent on the CO₂ tension of the blood. In view of the altered blood CO₂ combining power found in tetany by some workers, we have endeavored to correlate Brinkman's hypothesis with the low Ca content of the blood in tetany. During the past year, we have worked with human blood and experimental tetany dog blood.

The method of dialysis is an important factor in the results obtained. In the first place, collodion sacs are unsatisfactory, because they do not hold back protein for a sufficient length of time and because there is a progressive passage of fluid into the sac. We have used parchment paper thimbles, which obviate these objections. It was found that when serum was dialyzed against a Ca-free Ringer solution, there appeared to be a progressive dissociation of Ca, so that, at the end of 5-7 days' dialysis, 90 per cent. of the total Ca had diffused out. Where, however, compensation dialysis is employed, i.e., known amounts of Ca are added to the dialyzing fluid outside the sac, equilibrium is obtained in 24 hours, at ice box temperature, and the diffusible Ca is found to be between 60-70 per cent.