Determination of Reaction Constants of Phosphorus Fractions in Liver of Rats

Abstract

Ali reaction constants for fractions of phosphorus combinations in the liver of rats have been computed in Part II of this study. Phosphorus concentrations in this fraction, determined by Chemical analysis, have been dealt with, along with quantities of phosphorus radioactivity at different periods after oral administration, already in Part I.

In the first place, the quantities of percentual increase of radioactivity concerning four fractions (adenilyic acid, coenzymes, nucleoproteids and phospholipoids) were computed from the gradual increase of their radioactivity in successive periods during the stage of the rise of radiophopshorus content. The data obtained are most valuable for several reasons. First of all because the percentages of increased radioactivity are identical, in principle, with those of the renewal of stable phosphorus in the fractions, and both quantities for their part are identical with the percentual quantity of phosphorus transport for individua! fractions. Indeed, the importance of all these quantities is to be seen from the fact that the absolute phosphorus transport rates are identical m the unit of time with the actual velocity rates of the syntheses as well as those on the splitting of fractions in the period when the balance of their radioactivity has been reached.

The time of phosphorus renewal in a fraction can be determined by computation from a known percentual quantity of maximum radioactivity of the fractions (during their saturation period) and a known quantity of the rise of radioactivity. The time of phosphorus renewal in a fraction can also be determined directly from the actual quantities of radioactivity increase by means of a graphical technique. The results of this technique (concerning the duration of the period of renewal) are approximately those obtained by arithmetical computation. The graphic method is only applicable provided several data, from successive periods, relative to the increase of radioactivity are available. If the data available are only those concerning one interval of the period of increase in radioactivity, then the only possible way of computing the percentage of the increase and the period of renewal is the application of the arithmetical method. The actual transport quantities relative to the four fractions have been given in the text.

For three fractions (inorganic phosphorus, the labile and tle stable phosphorus from. ATP) the periods of phosphorus renewal taken from reports in the literature (for our own analyses of radioactivity of the fractions were made too late, i. e. when the period of the rise in radioactivity had been over) have been used for the purpose of computing the quantity of transport. As regards the labile phosphorus, its reconstruction value has been taken from the data of Rappoport, and the computation concerning the inorganic and the stable phosphorus from ATP has been made from the proportions relative to the attainment of the maximum of the absolute quantity of radioactivity. These quantities fit well into a uniform system with the data concerning the four fractions, the radioactivity of which we were able to measure already

at the phase of increase.

For the group of sugar fractions (which, in our analyses, are always treated as a uniform system of radioactivity) the transport quantity and the time of renewal of fractions have been computed indirectly by the application of the equations No. 4/I-a and No. 4/I-b taken from one of our earlier papers. We have made use here of one of the distinctive characteristics of sugar (according to the findings of Havesy) whose quantities in food direct the whole synthesis of phosphorus organic combination in the liver of rats. It was for this reason that ive started from the hypothesis that the combination of phosphorus proceeds on the lines of a chain of reaction, probably headed by the phosphorus plus sugar reaction. In this case, according to our equation, the transport of phosphorus equals the square root of the product of multiplication of the concentrations of two substances that are being synthesized (i. e. the inorganic phosphorus and sugar). Because of our not having measured experimentally the concentrations of sugar in the liver of rats but only those of phosphorus, we have had to estimate the former approximately from the relevant data in the literature, since the authors themselves who analysed phosphorus in the liver of rats (e. g. Hevesy and J. Sachs) have omitted to do so. This was made easier for us by the above-mentioned finding of Hevesy’s to the effect that a large amount of sugar in food tends to diminish the quantity of phosphorus in the liver of rats, at the same time proportionately increasing the concentration of organically combined phosphorus in the liver fractions of rats. From a piece of Information provided by Magnus Levy (bearing on the downward gradient of glucose concentration in the blood of different organs) we have come to the conclusion that, allowing for the abundant quantity of sugar in the rats used by Hevesy, there may have been a maximum concentration of sugar in the liver (0,3 mg’/o) along with a minimum concentration of phosphorus, and vice-versa, a minimum concentration of sugar (0,1 mg°/o) after feeding pure protein stuffs to rats where the phosphorus concentration is the highest (31 mg%). Table 2 shows the results of the computation, concerning the two extreme concentrations in the rats used by Hevesy as -well as our own analyses. The transport quantity, as computed, of the sugar group fits well into the scale of transports so that, as regards the gradient of the decrease, it takes the place between the inorganic fraction and the labile phosphorus from ATP.

From the quantities of transport and those of concentrations of fractions determined in the foregoing exposition, computation has been made of specific velocities of the syntheses and those of the splitting by means of our formulas No. 24 and No. 25 (from the publication quoted under No. 6). The formulas and the actual quantities for each fraction are shown in Table 4, i. e. for the specific velocity of the syntheses and that of the splitting process in the columns No. 2 and No. 3 respectively.

The Table shows the inorganic fraction as having the lowest specific velocity of synthesis, closely followed by the group of sugar fractions and the labile fraction from ATP; next come the two fractions with approximately equal specific velocities of synthesis (the stable phosphorus from ATP and the phospholipoids) followed closely by nucleoproteids.

It is the conferment’s that show the highest specific velocity of synthesis, the adenyl acid coming next with its velocity slightly less. The specific velocities of the splitting-up reveal a different gradient of the increase.

The lowest specific velocity rate of the splitting-up is shown by the fractions of nucleoproteids and phospholipoids, the highest velocity rates bcing those of the inorganic phosphorus fraction and of the sugar group.

The column in 5 Table 4 shows that the stable phosphorus concentration expressed in mg°/o can be computed from the quantities of radioactivity of the fraction during the period of rise. This column confirms the correctness both of our formulas (entered at the top of each column in the Table) and the computed values concerning the transports of individual fractions in the liver of rats.