J Mol Cell Cardiol 31, 457–466 (1999) Article No. jmcc.1998.0887, available online at http://www.idealibrary.com on Regulation of Cardiac Fibroblast Extracellular Matrix Production by Bradykinin and Nitric Oxide Noel N. Kim, Sonia Villegas, Sonya R. Summerour and Francisco J. Villarreal Departments of Medicine and Bioengineering, University of California at San Diego, San Diego, CA 92103, USA (Received 20 July 1998; accepted in revised form 16 November 1998) N. N. K, S. V, S. R. S F. J. V. Regulation of Cardiac Fibroblast Extracellular Matrix Production by Bradykinin and Nitric Oxide. Journal of Molecular and Cellular Cardiology (1999) 31, 457–466. The beneficial effects of angiotensin-converting enzyme inhibitors on ameliorating cardiac fibrosis have been partially attributed to their ability to prevent the degradation of kinins. The potential role of bradykinin and the related signaling molecule nitric oxide (NO) in modulating extracellular matrix (ECM) production was examined in primary cultures of adult rat cardiac fibroblasts. Treatment of fibroblasts with 5 n bradykinin for 24 h led to a reduction in steady-state mRNA levels for fibronectin (34±7%) and collagens type I (19±8%) and type III (48±4%), as determined by Northern blot analysis. The NO synthase inhibitor -NAME attenuated the reduction observed in fibronectin and collagen mRNA levels in response to bradykinin. The NO donor DETA NONOate (100 ) mimicked the effects of bradykinin on ECM mRNA levels. Protein levels of soluble fibronectin, assessed in conditioned medium by ELISA, were decreased by 14±4% and 21±4% after 48 h treatment with 1 bradykinin and 100 DETA NONOate, respectively. Bradykinin stimulated intracellular cGMP accumulation 73.7±10.3% after 10 min of treatment. Cell proliferation rates at 48 h were unaffected by bradykinin, but were reduced by 26±12% by 100 DETA NONOate. These data indicate that bradykinin downregulates ECM protein production in cardiac fibroblasts and suggest that NO and the related signaling molecule cGMP may play an important role in mediating this reponse. 1999 Academic Press K W: Bradykinin; Nitric oxide; Collagen; Fibronectin; Cardiac fibrosis; Cardiac remodeling; Angio- tensin-converting enyzyme inhibitors. in light of the fact that the abnormal accumulation Introduction of ECM proteins in the interstitium (fibrosis) has been associated with the development of patho- Fibroblasts are the most abundant cell type in the heart and play a major role in synthesizing logical hypertrophy in the heart. These structural changes in myocardial ECM leads to alterations in components of the cardiac extracellular matrix (ECM) (Eghbali et al., 1998). The cellular behavior the physical properties of heart tissue and can potentially contribute to altered ventricular func- and function of cardiac fibroblasts are critical de- terminants in effecting structural changes (re- tion and the development of heart failure (for review see Weber, 1997). modeling) within the myocardium. Elucidating the cellular and molecular mechanisms that mediate In the clinical setting, angiotensin-converting enzyme inhibitors (ACEI), initially used as anti- cardiac tissue remodeling is particularly important Please address all correspondence to: Francisco J. Villarreal, UCSD Medical Center, 200 West Arbor Dr. 8412, San Diego, CA 92103- 8412, USA. 0022–2828/99/020457+10 $30.00/0 1999 Academic Press