1. Haemaccel is a synthetic polymer of partially degraded gelatin and a widely used plasma volume expander.
2. The effect of a 17.5 g infusion of Haemaccel on protein excretion was investigated in four normal subjects.
3. The urinary excretion of two low molecular weight proteins, retinol-binding protein and β2-microglobulin, increased 1000- and 500-fold respectively above the values found after administration of saline as a control. The urinary excretion of albumin did not change significantly (P > 0.5).
4. In the hour after Haemaccel administration the excretion of the two low molecular weight proteins approached at least 50% of a predicted filtered load.
5. This effect of Haemaccel may be due to inhibition of proximal tubular uptake or transport of the two proteins. Absence of any effect on albumin excretion suggests alternative mechanisms for its tubular reabsorption.
6. Haemaccel may be a valuable new agent for the study of renal tubular protein metabolism.
