Quantitative Nature of the Red Cell Response to a Single Bleeding,

Abstract

In the course of experiments designed to test for the presence of an erythrocytogenic hormone in the serum of rabbits subjected to bleedings, 1 a close correspondence between the number of red cells and reticulocytes of several control animals during the recovery period was observed. These control rabbits were bled a certain percentage of their body weight by cardiac puncture, and red cell and reticulocyte counts made daily for approximately 2 weeks following the bleeding. Because considerable discrepancy was found between counts made on successive samples taken from the ear veins, the red cells and reticulocytes were counted in samples drawn from the heart. Care must be taken that the heart punctures are made cleanly and that the needle is held steadily while the blood is being withdrawn. When these precautions are observed, autopsies performed on animals subjected to daily heart punctures for as long as a period of a month showed no damage to the heart or hemorrhage around it. The red cell counts which were required to agree to within 2.5%, were made in duplicate, a total of 800 squares on a Levy-Hausser chamber being counted for each sample of blood. Reticulocytes were counted in wet mounts according to the method described by Ramsey and Warren.²

In Table I are presented the red cell counts (X 10^-3), and reticulocyte counts (%) for 5 animals bled 1/64 of their body weight on the first day. The reticulocyte peak, ranging from 7.2% to 8.1%, is reached in all the animals on the 4th or 5th day of anemia. There is a fairly close similarity in the behavior of the red cell counts. Some of the animals, however, showed a greater post-hemorrhagic drop (i. e., that occurring after the first day of anemia) than others.