Kininase I-type carboxypeptidases enhance nitric oxide production in endothelial cells by generating bradykinin B1 receptor agonists

Kininase I-type carboxypeptidases convert native kinin agonists for B2 receptors into B1 receptor agonists by specifically removing the COOH-terminal Arg residue. The membrane localization of carboxypeptidase M (CPM) and carboxypeptidase D (CPD) make them ideally situated to regulate kinin activity. Nitric oxide (NO) release from human lung microvascular endothelial cells (HLMVEC) was measured directly in real time with a porphyrinic microsensor. Bradykinin (1–100 nM) elicited a transient (5 min) peak of generation of NO that was blocked by the B2 antagonist HOE 140, whereas B1 agonist des-Arg10-kallidin caused a small linear increase in NO over 20 min. Treatment of HLMVEC with 5 ng/ml interleukin-1β and 200 U/ml interferon-γ for 16 h upregulated B1 receptors as shown by an approximately fourfold increase in prolonged (>20 min) output of NO in response to des-Arg10-kallidin, which was blocked by the B1antagonist des-Arg10-Leu9-kallidin. B2 receptor agonists bradykinin or kallidin also generated prolonged ...