Metabolic studies of C3 in man

The results of metabolic studies with radioactively labelled C3 in 14 healthy individuals are presented. Plasma volume determined by labelled C3 was generally higher than when determined by labelled albumin, and different batches of C3 behaved differently during the early part of the experiments. These phenomena are probably caused by C3 inhomogenities which are difficult to detect by usual biochemical and immunological methods. We have, therefore, excluded the first 24 h of the experiments from the mathematical analysis. In this way, rather narrow limits for the metabolic parameters have been obtained.