Title

Chymase Inhibition Prevents Fibronectin and Myofibrillar Loss and Improves Cardiomyocyte Function and LV Torsion Angle in Dogs with Isolated Mitral Regurgitation.

Publication/Presentation Date

10-12-2010

Abstract

BACKGROUND: The left ventricular (LV) dilatation of isolated mitral regurgitation (MR) is associated with an increase in chymase and a decrease in interstitial collagen and extracellular matrix. In addition to profibrotic effects, chymase has significant antifibrotic actions because it activates matrix metalloproteinases and kallikrein and degrades fibronectin. Thus, we hypothesize that chymase inhibitor (CI) will attenuate extracellular matrix loss and LV remodeling in MR.

METHODS AND RESULTS: We studied dogs with 4 months of untreated MR (MR; n=9) or MR treated with CI (MR+CI; n=8). Cine MRI demonstrated a >40% increase in LV end-diastolic volume in both groups, consistent with a failure of CI to improve a 25% decrease in interstitial collagen in MR. However, LV cardiomyocyte fractional shortening was decreased in MR versus normal dogs (3.71±0.24% versus 4.81±0.31%; P

CONCLUSIONS: These results suggest that chymase disrupts cell surface-fibronectin connections and FAK phosphorylation that can adversely affect cardiomyocyte myofibrillar structure and function. The greater effect of CI on epicardial versus endocardial titin and noncollagen cell surface proteins may be responsible for the increase in torsion angle in chronic MR.

Volume

122

Issue

15

First Page

1488

Last Page

1495

ISSN

1524-4539

Disciplines

Cardiology | Medical Sciences | Medical Specialties | Medicine and Health Sciences

PubMedID

20876440

Department(s)

Department of Medicine, Department of Medicine Fellows and Residents, Department of Medicine Faculty

Document Type

Article