Venoconstrictor activity of some precursor fractions of stable plasma protein solution

Stable plasma protein solution (SPPS) is a 5% solution of human plasma albumin and some globulins. Rapid infusion of some batches of SPPS and analogous solutions prepared by similar processes induce paradoxical hypotensive reactions. In the current experiments, a number of precursor fractions of a single batch of SPPS were examined for kininogen content and for venoconstrictor activity on the isolated central vein of the rabbit ear. Unheated SPPS contained both venoconstrictor activity and kininogen. Among the various precursor fractions examined, Cohn fraction II + III (a precursor of fraction III-0) contained the greatest venoconstrictor activity. There was no evidence of kininogen depletion during the stages of fractionation examined but some generation of venoconstrictor material. Column chromatography suggested a molecular weight of approximately 1,500 for the major active material in unheated SPPS. It appears possible that the 14-amino acid hypotensive peptide present in fraction III-0 may also be present in SPPS, where it may contribute to the hypotensive effects of this solution.