Profibrotic influence of high glucose concentration on cardiac fibroblast functions: effects of losartan and vitamin E

• Published in: American journal of physiology. Heart and circulatory physiology 2005-01, Vol.288 (1), p.H227-H234
• Main Authors: Asbun, Juan, Manso, Ana Maria, Villarreal, Francisco J
• Format: Article
• Language: English
• Subjects: Angiotensin II - pharmacology; Angiotensin II Type 1 Receptor Blockers - pharmacology; Animals; Antioxidants - pharmacology; Cells, Cultured; Collagen Type I - metabolism; Dose-Response Relationship, Drug; Fibroblasts - drug effects; Fibroblasts - metabolism; Fibroblasts - physiology; Fibrosis; Glucose - administration & dosage; Glucose - pharmacology; Leucine - metabolism; Losartan - pharmacology; Male; Matrix Metalloproteinases - metabolism; Myocardium - cytology; Osmolar Concentration; Proline - metabolism; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1 - genetics; RNA, Messenger - metabolism; Vitamin E - pharmacology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00340.2004

Department of Medicine, University of California at San Diego, La Jolla, California Submitted 8 April 2004 ; accepted in final form 26 August 2004 Long-standing diabetes can result in the development of cardiomyopathy, which can be accompanied by myocardial fibrosis. Although exposure of cultured kidney and skin fibroblasts to high glucose (HG) concentration is known to increase collagen synthesis, little is known about cardiac fibroblasts (CFs). Therefore, we determined the influence of HG conditions on CF functions and the effects of losartan and vitamin E in these responses. We cultured rat CFs in either normal glucose (NG; 5.5 mM) or HG (25 mM) media and assessed changes in protein and collagen synthesis, matrix metalloproteinase (MMP) activity, and levels of mRNA for ANG II type 1 (AT 1 ) receptors. Results indicate that HG-level CFs synthesized more protein and collagen, and these effects were not due to changes in osmotic pressure. The addition of ANG II stimulated protein and collagen synthesis in NG-concentration but not HG-concentration CFs. Interestingly, losartan pretreatment blocked the HG- or ANG II-induced increases in both protein and collagen synthesis. HG or ANG II decreased total MMP activity. Decreases in MMP activity were blocked by losartan. AT 1 mRNA levels were upregulated with HG concentration. Vitamin E pretreatment blocked the effects of HG on total protein synthesis and stimulated MMP activity. Results suggest that HG levels may promote fibrosis by increasing CF protein and collagen synthesis and decreasing MMP activity. HG levels may cause these effects via the upregulation of AT 1 receptors, which can be blocked by losartan. However, vitamin E can alter HG concentration-induced changes in CF functions independently of AT 1 mRNA levels. diabetes; myocardial fibrosis; collagen; matrix metalloproteinase Address for reprint requests and other correspondence: F. J. Villarreal, UCSD Medical Center, 200 West Arbor Dr. 8412, San Diego, CA 92103-8412 ( fvillarr{at}ucsd.edu )