Are cardiovascular and sympathoadrenal effects of human “new pressor protein” preparations attributable to human coagulation -FXIIa?
“New pressor protein” (NPP) derived from normal human plasma is an extra renal enzyme that shares strong sequence homology with human coagulation -FXIIa. Under our bioassay conditions, human NPP (10–20 µl plasma equivalent/∼300 g rat iv) can raise the systolic blood pressure (SBP) by 40–50 mmHg, the diastolic blood pressure (DBP) by 15–20 mmHg, and the heart rate (HR) by 70–90 beats/min. Plasma epinephrine (of adrenal medullary origin) and norepinephrine rise by about 50- and 10-fold, respectively. Because -FXIIa is not normally associated with pressor properties, we endeavored to substantiate that the hypertensive effects of impure NPP preparations used in our experiments are attributable to their content of -FXIIa. We carried out comparisons with highly purified (>90%) commercial human -FXIIa and found that by gel filtration (Sephadex G-100 and G-75), NPP bioactivity appeared in the ∼30-kDa elution zone, consistent with the molecular mass of -FXIIa. Retention time using fast-protein
