AN INHIBITOR FROM CORN BLOCKS THE HYPOTENSIVE ACTION OF PLASMA-PROTEIN FRACTION AND ACTIVE HAGEMAN-FACTOR

Rapid infusion of certain lots of plasma protein fraction (PPF) into surgical patients can cause a severe fall in blood pressure. These lots contain the .apprx. 30,000 dalton Hageman factor fragment (HFf), a potent activator of prekallikrein. The hypotensive effect of PPF could be due to the generation of bradykinin from the patients'' kininogen. Strong evidence supporting the theory that HFf is the hypotensive agent in PPF was obtained using a specific inhibitor of HFf isolated from corn. I.v. infusion of implicated lots of PPF or purified HFf causes a pronounced fall in the blood pressure of anesthetized rats pretreated with the kininase inhibitor SQ14225 [captopril]. The hypotensive effect of both PPF and HFf is blocked when they are preincubated with the specific HFf inhibitor. HFf is at least the trigger, if not the sole agent, responsible for the hypotensive action of implicated lots of PPF.