Figure 7.

Chymotryptic Activity Within Cardiomyocytes and Mast Cells

(A and C) Chymotryptic activity within cardiomyocytes and mast cells (M) (deep blue color) with chymotryptic activity in adjacent LA myocytes identified by blue staining in the (A) cross section and by (C) blue dots largely between z discs associated with the myofibrils. (B and D) The increased chymotryptic activity is prevented by pre-treatment with a specific chymase inhibitor, especially in the chymase-laden mast cell in (B). (E) Immunohistochemistry of MR LA demonstrating chymase (red) within LA myocyte in the peri-nuclear areas (arrows) and sarcomeres in areas of desmin breakdown (arrowhead). (F) TEM immunogold image (40,000× demonstrating chymase (black dots) associated with myofibrillar breakdown (arrows) and mitochondria (m). Abbreviations as in Figures 1 and 3.