Contributions of ACE and mast cell chymase to endogenous angiotensin II generation and leucocyte recruitment in vivo

Aims In vitro studies suggest that mast cell chymase (MCP) is more important than angiotensin-converting enzyme (ACE) for generating angiotensin II (Ang II) within the cardiovascular system. We investigated in vivo the relative contributions of ACE and MCP to leucocyte recruitment induced by endogenously generated Ang II. Methods and results Exposure of the murine cremasteric microcirculation of C57BL/6 mice to Ang I (100 nM for 4 h) induced leucocyte–endothelium interactions. Either losartan (an Ang II receptor-1 antagonist, AT1) or enalapril (an ACE inhibitor), but not chymostatin (a chymase inhibitor), inhibited Ang I-induced responses. Mast cell degranulation with compound 48/80 (CMP48/…