Plasma substitutes; human and animal globin related to the production of hemoglobin and plasma protein; dog hemoglobin utilization improved by methionine but not by isoleucine.

Globin makes up 95 per cent of the hemoglobin molecule. Its construction is of fundamental importance. It is a protein and its production in the body relates to the building stones of protein and to other body proteins. In fact plasma protein introduced into a fasting anemic dog will bring about a large output of new hemoglobin (globin). Globin production and the related hemoglobin can be controlled by the protein intake, once the protein reserve stores have been exhausted (6). Globin utilization has been much studied in this laboratory. As red cells are constantly wearing out, the related globin must be a continuing factor in body protein metabolism. The body uses this globin waste material well. We have shown (10) that actually the globin (hemoglobin) nitrogen intake may balance the total urinary nitrogen output in protein fasting dogs receiving hemoglobin in considerable amounts intraperitoneally and carbohydrate, fat, and accessories by mouth. These observations suggest that globin might be useful as a plasma protein substitute and in fact in the dog it does have considerable usefulness in replacing protein wastage. Studies of globin utilization are very much in order together with similar studies of hemoglobin (globin + iron + pigment radicle). We can safely assume that the iron is well conserved and the pigment radicle is excreted (10). In fact the dog uses the whole hemoglobin more effectively than the pure globin, probably because the globin as prepared is slightly or moderately toxic and this reaction may impair or delay the hemoglobin production in anemia or the protein utilization and conservation in protein fasting dogs.