title: Endothelin-1 mediates cardiac mast cell degranulation, matrix metalloproteinase activation, and myocardial remodeling in rats.
abstract: The objective of this study was to determine whether elevated circulating levels of endothelin (ET)-1 are capable of mediating left ventricular (LV) mast cell degranulation and thereby induce matrix metalloproteinase (MMP) activation. After the administration of 20 pg/ml ET-1 to blood-perfused isolated rat hearts, LV tissue was analyzed for signs of mast cell degranulation and MMP activation. Relative to control, ET-1 produced extensive mast cell degranulation as well as a significant increase in myocardial water content (78.8 +/- 1.5% vs. 74.2 +/- 2.2%, P <0.01), a marked 107% increase in MMP-2 activity (P <0.05), and a substantial decrease in collagen volume fraction (0.69 +/- 0.09% vs. 0.99 +/- 0.04%, P <0.001). Although the myocardial edema would be expected to increase ventricular stiffness, compliance was not altered, and moderate ventricular dilatation was observed (end-diastolic volume at end-diastolic pressure of 0 mmHg of 330.2 +/- 22.1 vs. 298.9 +/- 17.4 microl in ET-1 treated vs. control, respectively, P=0.07). Additionally, pretreatment with the mast cell stabilizer nedocromil prevented ET-1-induced changes in MMP-2 activity, myocardial water content, collagen volume fraction, and end-diastolic volume. These findings demonstrate that ET-1 is a potent cardiac mast cell secretogogue and further indicate that ET-1-mediated mast cell degranulation is a potential mechanism responsible for myocardial remodeling.
authors.affiliation: Department of Anatomy, Physiology, and Pharmacology, 240A Greene Hall, Auburn Univ., Auburn, AL 36849-5518. murradb@auburn.edu
authors.forename: David B
authors.initials: DB
authors.lastname: Murray
authors.forename: Jason D
authors.initials: JD
authors.lastname: Gardner
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Brower
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Janicki
mesh_terms: D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects / Q000502:physiology*; D019332:Endothelin-1 / Q000097:blood / Q000494:pharmacology / Q000502:physiology*; D004789:Enzyme Activation; D008297:Male; D008407:Mast Cells / Q000502:physiology*; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020257:Ventricular Remodeling / Q000187:drug effects / Q000502:physiology*
chemical_list: D019332:Endothelin-1; D020782:Matrix Metalloproteinases