The effects of experimental malnutrition on albumin metabolism and distribution in rabbits

In order to determine the extent to which the concentration of albumin in plasma is maintained at the expense of the extravascular pool during protein-energy malnutrition, the rates of exchange between albumin in plasma (IA) and the extravascular pool (EA) and consequently the distribution of albumin between intravascular and extravascular pools (expressed as EA:IA) were measured in protein-energy-depleted and control rabbits. The fractional rates of synthesis (FSR) and catabolism (FCR), the concentration of albumin and the plasma volume (PV) were also measured. In animals in which protein-energy intake was reduced by 58% the concentration of albumin in plasma remained unchanged, whereas FCR decreased by 38% and FSR by 30%. No significant changes in EA:IA or PV were found. We conclude that albumin concentration during protein-energy depletion is not maintained at the expense of extravascular albumin, but by parallel changes in the rates of catabolism and synthesis.