The effect of low molecular weight heparin (fragmin) on myocardial neutrophil accumulation and infarct size in a rat model of myocardial infarction.
BACKGROUND
Heparin molecules possess immunomodulating properties, which are thought to complement their established antithrombotic activity. The purpose of this study was to evaluate whether the antiinflammatory properties of low molecular weight heparin (LMWH) can attenuate polymorphonuclear neutrophil accumulation and infarct size in a rat model of myocardial infarction.


METHODS
Myocardial infarction was induced by ligating the left main coronary artery. LMWH (fragmin 500 anti-FXa u/kg) or vehicle (saline) were administered subcutaneously thirty minutes prior to coronary artery occlusion. Significant anticoagulant activity was attained with LMWH for more than eight hours. Twenty-four hours later, neutrophil accumulation and infarct size were determined by measuring left ventricular free wall myeloperoxidase and residual creatine kinase activity, respectively.


RESULTS
As compared with rats administered vehicle, myeloperoxidase activity was insignificantly decreased in rats treated with LMWH (1.24 +/- 0.28 u/g vs 1.66 +/- 0.15 u/g, P = 0.16. Infarct size was also not significantly different between the groups (62.48 +/- 3.5% and 50.67 +/- 7.2% of left ventricular free wall with vehicle and LMWH, respectively, P = 0.1).


CONCLUSIONS
The authors conclude that LMWH does not significantly reduce myocardial neutrophil accumulation and infarct size twenty-four hours after myocardial infarction in the rat.
Hasdai
D
D
Neufeld Cardiac Research Institute, Sheba Medical Center and Sackler Medical School, Tel Aviv University, Israel.
Varda-Bloom
N
N
Blumberg
N
N
Ohad
D
D
Kornowski
R
R
Battler
A
A
D000818:Animals; D000925:Anticoagulants / Q000008:administration & dosage*; D017985:Dalteparin / Q000008:administration & dosage*; D004195:Disease Models, Animal; D006321:Heart / Q000187:drug effects*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000473:pathology; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000925:Anticoagulants; D017985:Dalteparin