Standardization of Liver Extract.

Abstract

When rabbits are injected intranarrowly with B. welchii toxins according to the Torrey-Kahn 1 technique, they rapidly become anemic and exhibit many of the characteristic blood changes described in reports of pernicious anemia in man.

There is a rapid decrease in the number of red cells (for 5 rabbits: 31, 32, 38, 38, 41%) and in hemoglobin content (for 5 rabbits: 29, 30, 30, 31, 37%), the lowest values being reached between the fifth and tenth days. Following this, there is a compensatory period of 10 to 15 days during which time the experimental animals show definite increase in the number of red cells and hemoglobin. Beginning with about the thirtieth day after injection of the toxin, the experimental animals show a progressive decrease in the number of red cells and in the hemoglobin content.

If an aqueous solution of liver extract is given by stomach tube to these anemic rabbits while they are at the lowest point in red count and hemoglobin (about the fifteenth day), there is a definite increase in each. This is, however, the period in which the animals are making a strong effort to compensate for the injury to the hematopoietic system and one does not obtain such striking results as when liver extract is given in the stage of progressive decline (35 days, or later).

There can be no doubt as to the beneficial effects of liver extract in this type of experimental anemia. Our results with some 20 animals indicated a rough proportionality between the amount of liver extract given and the increase in the number of red cells and in the hemoglobin content. This at once suggests the use of such experiments as a means of standardizing commercial liver extracts. Further work is in progress.