Inhibition of matrix metalloproteinases prevents peroxynitrite-induced contractile dysfunction in the isolated cardiac myocyte

Br J Pharmacol. 2008 Feb;153(4):676-83. doi: 10.1038/sj.bjp.0707621. Epub 2007 Dec 10.

Abstract

Background and purpose: The potent oxidant peroxynitrite (ONOO(-)) induces mechanical dysfunction in the intact heart in part through activation of matrix metalloproteinase-2 (MMP-2). This effect may be independent of the proteolytic actions of MMPs on extracellular matrix proteins. The purpose of this study was to examine the effects of ONOO(-) on contractile function at the level of the single cardiac myocyte and whether this includes the action of MMPs.

Experimental approach: Freshly isolated ventricular myocytes from adult rats were superfused with Krebs-Henseleit buffer at 21 degrees C and paced at 0.5 Hz. Contractility was measured using a video edge-detector. ONOO(-) or decomposed ONOO(-) (vehicle control) were co-infused over 40 min to evaluate the contraction cease time (CCT). The effects of ONOO(-) on intracellular [Ca(2+)] were determined in myocytes loaded with calcium green-1 AM. MMP-2 activity was measured by gelatin zymography.

Key results: ONOO(-) (30-600 microM) caused a concentration-dependent reduction in CCT. Myocytes subjected to 300 microM ONOO(-) had a shorter CCT than decomposed ONOO(-) (14.9+1.5 vs 32.2+3.5 min, n=7-8; P<0.05) and showed increased MMP-2 activity. The MMP inhibitors doxycycline (100 microM) or PD 166793 (2 microM) reduced the decline in CCT induced by 300 microM ONOO(-). ONOO(-) caused shorter calcium transient cease time and significant alterations in intracellular [Ca(2+)] homoeostasis which were partially prevented by doxycycline.

Conclusions and implications: This is the first demonstration that inhibition of MMPs protects the cardiac myocyte from ONOO(-)-induced contractile failure via an action unrelated to proteolysis of extracellular matrix proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Cardiac Pacing, Artificial
  • Doxycycline / pharmacology*
  • Enzyme Activation
  • Homeostasis
  • Hydroxamic Acids / pharmacology*
  • Male
  • Matrix Metalloproteinase 2 / metabolism
  • Matrix Metalloproteinase Inhibitors*
  • Myocardial Contraction / drug effects*
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / enzymology
  • Myocytes, Cardiac / metabolism
  • Oligopeptides / pharmacology*
  • Peroxynitrous Acid / metabolism*
  • Protease Inhibitors / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Time Factors

Substances

  • (R)-2-(4'-bromo-biphenyl-4-sulfonyl-amino)-3-methyl-butyric acid
  • Hydroxamic Acids
  • Matrix Metalloproteinase Inhibitors
  • Oligopeptides
  • Protease Inhibitors
  • Peroxynitrous Acid
  • Matrix Metalloproteinase 2
  • Mmp2 protein, rat
  • Doxycycline
  • Calcium