Hemoglobin (presumably its essential protein globin), given intraperitoneally to a protein-fasting dog, will be used effectively to supply the protein requirements of the body. Nitrogen balance may thus be maintained for 20 days under favorable conditions. New hemoglobin and plasma protein will be formed related to hemoglobin injections in depleted dogs where there is urgent need for these proteins (anemia and hypoproteinemia). Obviously this calls for supplementary amino acids which in globin are low and we assume these amino acids must be contributed from body protein stores.
Plasma proteins (in plasma) tested in the same manner are completely utilized with no loss of nitrogen, positive nitrogen balance, weight balance, and no change in the albumin-globulin ratios.
Hemoglobin (globin) is less effectively utilized as compared with plasma protein given parenterally and there is some increase in urinary nitrogen above control periods. The albumin-globulin ratio may be somewhat modified by hemoglobin injections intraperitoneally. Hemoglobin (globin) digests contribute effectively to body maintenance of nitrogen equilibrium. These digests are about as effective as whole hemoglobin in maintaining nitrogen balance but cause a rise in undetermined nitrogen not seen when hemoglobin alone is given intraperitoneally.
Pigment radicles derived from hemoglobin given intraperitoneally are thrown away and appear as surplus bile pigment even when there is urgent need for all available nitrogenous material—given protein fasting, anemia, and hypoproteinemia in a bile fistula dog. The body evidently prefers to make rather than conserve the pyrrol aggregate (pigment radicle).
We assume that the injected hemoglobin (globin) or hemoglobin digests contribute to the body protein pool and from this pool various proteins emerge to supply protein requirements of tissue or organ cells or to produce new hemoglobin or plasma protein if needed. We have no explanation as to what determines the pattern of this protein flow but new hemoglobin is very high on the priority list.