Nitrogen Balance and Blood Volume Studies in Man During and Following Repeated Plasma Transfusions*

Chemical, Clinical, and Immunological Studies on the Products of Human Plasma Fractionation. Xxxiv. Comparative Studies on the Nutritive Value of Orally and Intravenously Administered Human Serum Albumin in Man 123

“…Parenterally injected albumin and plasma proteins disappear rapidly from the blood stream (1,21), but repeated injections are followed by an appreciable and readily detectable increase in the total circulating plasma proteins, as reported here and by others (5,10,12). It is clear that roughly 24 to 46 per cent of the protein retained in our subjects could be accounted for by the albumin increase in the blood plasma (Table II, hydrolysate).…”

“…The parenteral administration of large amounts of plasma as the sole source of nitrogen is analogous to small or moderate amounts of plasma plus a quantity of dietary protein which in itself could fulfill the body protein needs. The most plausible explanation for the observed increase in urine nitrogen (shown by Meyer [12] to be non-protein-non-peptide nitrogen by nitrogen partition) that follows intravenous plasma administration is that the retained plasma protein is' subsequently broken down to amino acids which, if present in excess of the body protein requirements, are then deaminated and the released nitrogen excreted. The critical observations of Albright (11) that "conversion" and "burning" of injected plasma protein do not start to an appreciable degree until several days after the plasma protein injections is readily explained by this hypothesis, for several days must elapse before the degradation of the injected plasma has released sufficient amino acids for resynthesis into tissue protein, and for those released in excess of these requirements to be deaminated and excreted in the urine.…”

“…Whole blood and plasma albumin behaved in a manner similar to blood plasma. During plasma transfusions in man, Meyer et al (12) noted a decrease in the urinary nitrogen excretion which resulted in a marked positive nitrogen. balance, but 13 per cent, 87 per cent, and 50 per cent of the "retained" nitrogen were subsequently excreted in the urine.…”

Metabolic Studies on Protein-Depleted Patients Receiving a Large Part of Their Nitrogen Intake From Human Serum Albumin Administered Intravenously 12

“…It is generally conceded that positive nitrogen balances can be established in both animals and man by the intravenous administration of homologous plasma, provided that the dose is in excess of the minimum protein requirements. It is felt by some investigators (7,8) that the positive balance obtained is an illusory affair and that the actual utilization is poor in some instances. On the other hand, Whipple and coworkers (9) believe that parenteral plasma protein can supply all the requirements for maintenance over a considerable period of time.…”

Alterations in Albumin Metabolism after Serum and Albumin Infusions*

“…The intravenous administration of whole serum or of serum albumin results in a temporary increase in the concentration of circulating protein; the rate of return toward preinfusion levels depends upon the state of protein depletion or pool size and upon the rates of synthesis and degradation of albumin (1)(2)(3)(4)(5)(6). Much of the infused protein can be accounted for by increased nitrogen excretion in the urine (2)(3)(4); the remainder has been assumed to be stored in intravascular or extravascular areas (1)(2)(3)(4)(5)(6).…”