Immediate Hypersensitivity Elicits Renin Release from Cardiac Mast Cells

BACKGROUND: We recently reported that murine and cavian heart mast cells are a unique extrarenal source of renin. Ischemia/reperfusion releases this renin leading to local angiotensin formation and norepinephrine release. As mast cells are a primary target of hypersensitivity, we assessed whether anaphylactic mast cell degranulation also results in renin and norepinephrine release. METHODS: Hearts isolated from presensitized guinea pigs were challenged with antigen. RESULTS: Cardiac anaphylaxis was characterized by mast cell degranulation, evidenced by beta-hexosaminidase release and associated with renin and norepinephrine release. Mast cell stabilization with cromolyn or lodoxamide markedly attenuated the release of beta-hexosaminidase, renin and norepinephrine. Renin inhibition with BILA2157 did not affect mast cell degranulation, but attenuated norepinephrine release. CONCLUSIONS: Our findings disclose that immediate-type hypersensitivity elicits renin release from mast cells, activating a local renin-angiotensin system, thereby promoting norepinephrine release. As renin is stored in human heart mast cells, allergic reactions could initiate renin release, leading to local angiotensin formation and hyperadrenergic dysfunction.