Comparative effects of two potentiating peptides (KPP and BPP9a) on kinin-induced rat paw edema

We have previously shown that KPP, a kinin potentiating peptide generated by tryptic digestion of human plasma proteins potentiated kinin effects on isolated smooth muscle preparations like guinea-pig ileum with high potency and specificity. We also obtained evidence suggesting that, unlike other potentiating peptides, KPP exerts its effect by a mechanism different from the inhibition of kinin metabolism by angiotensin converting enzyme, neutral endopeptidase and kininase I. Here we show the potentiating effect of KPP and of BPP9a, a potentiator derived from snake venom, towards the rat paw edema induced by bradykinin (BK). Our results show that: a) KPP is 25-fold more active than BPP9a in potentiating rat paw edema elicited by BK: b) like BPP9a, KPP is specific in potentiating kinin-induced edema, being ineffective in potentiating edema induced by histamine or serotonin; and c) DesArg9-BK (DABK) elicits a small edematogenic response which can be potentiated by both KPP and BPP9a.