Gravity Shock in Rabbits. I. Lack of Correlation Between Plasma Protein and Specific Gravity.

Abstract

The calculation of protein concentration from the specific gravity of human and dog serum or plasma 1 , 2 has been widely used in clinical and experimental laboratories especially since the development of the falling drop method for measuring specific gravity, 3 , 4 because it is quicker than analyses by the Kjeldahl method. It is important to know how the serum or plasma protein concentration changes in traumatic, hemorrhagic, and other kinds of shock, as well as in other pathological conditions, and much reliance has been placed on specific gravity determinations on the blood of such subjects.5

In order to determine whether the same relationship between specific gravity and portein concetration exists in rabbit plasma as in human and dog plasma, blood from 20 normal rabbits fed on Purina chow and later from the same animals suspended by their ears until the became unconsious from peripheral circulatory deficiency (“gravity shock”) 6 has been studied. The plasma of arterial heart blood was analyzed for protein by the micro-Kjeldahl method, for glucose by the Folin-Wu method as modified by Andes and Northup, 7 and the specific gravity was determined by the falling drop method.

In Fig. 1 plasma protein before and during gravity shock is plotted against plasma specific gravity. The data for normal animals are well described by the line drawn through the open circles having the equation: P = 375 (G_p −1.0064), which is of the same order of magnitude as the equation reported for human 1 and dog 2 plasma. For rabbits in gravity shock, however, the constant relation between specific gravity and protein concentration did not hold, as indicated by the solid circles, showing even greater divergencies than those found by Moore and Van Slyke 1 in human nephritic patients.