Cardiovascular Research 2011-12-01

Substance P induces adverse myocardial remodelling via a mechanism involving cardiac mast cells.

Giselle C Meléndez, Jianping Li, Brittany A Law, Joseph S Janicki, Scott C Supowit, Scott P Levick

文献索引：Cardiovasc. Res. 92(3) , 420-9, (2011)

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摘要

Substance P and neurokinin A (NKA) are sensory nerve neuropeptides encoded by the TAC1 gene. Substance P is a mast cell secretagogue and mast cells are known to play a role in adverse myocardial remodelling. Therefore, we wondered whether substance P and/or NKA modulates myocardial remodelling via a mast cell-mediated mechanism.Volume overload was induced by aortocaval fistula in TAC1(-/-) mice and their respective wild types. Left ventricular internal diameter of wild-type (WT) fistulas increased by 31.9%; this was prevented in TAC1(-/-) mice (4.2%). Matrix metalloproteinase (MMP) activity was significantly increased in WT fistula mice and was prevented in TAC1(-/-) mice. Myocardial collagen volume fraction was decreased in WT fistula mice; this collagen degradation was not observed in the TAC1(-/-) group. There were no significant differences between any groups in tumour necrosis factor (TNF)-α or cell death. Cardiac mast cells were isolated from rat hearts and stimulated with substance P or NKA. We found that these cells degranulated only to substance P, via the neurokinin-1 receptor. To determine the effect of substance P on mast cells in vivo, volume overload was created in Sprague-Dawley rats treated with the NK-1 receptor antagonist L732138 (5 mg/kg/day) for a period of 3 days. L732138 prevented: (i) increases in cardiac mast cell density; (ii) increased myocardial TNF-α; and (iii) collagen degradation.Our studies suggest that substance P may be important in mediating adverse myocardial remodelling secondary to volume overload by activating cardiac mast cells, leading to increased TNF-α and MMP activation with subsequent degradation of the extracellular matrix.