Abstract Ligation of the main left coronary artery in mice serves as a model for myocardial infarction (MI). We tested whether plasma concentrations of heart-type fatty acid-binding protein (H-FABP) and/or cardiac tro- ponin T (cTnT) discriminate between infarcted and sham-operated mice and allow estimation of infarct size. Mice were subjected to coronary artery ligation or sham surgery and release curves of H-FABP and cTnT were determined. At 4 h after surgery the mean (±SD) H-FABP plasma concentration was 461±134 μg/l (n=10) in MI and 185±51 μg/l (n=6; P<0.001) in sham-operated mice. By 24 h after surgery H-FABP levels had returned to normal in both groups. cTnT plasma concentrations increased up to 48 h after MI to 13.5±6.2 μg/l (n=6; P<0.001) compared with 0.031±0.063 μg/l (n=7) in sham-operated mice. Linear regression analysis revealed a significant correlation between plasma H-FABP at 4 h and infarct size assessed 7 days after surgery. Plasma cTnT did not correlate significantly with infarct size. In conclusion, plasma cTnT concentration at 48 h after in- farction can be used to distinguish MI from sham mice, whereas H-FABP concentration at 4 h can be used for stratification of animals according to infarct size. Key words Diagnostic Techniques · Myocardial ischaemia · Mice Introduction Permanent occlusion of the main left coronary artery in mice results in antero-apical myocardial infarct (MI) with features such as ventricular dilation, wall thinning and septum hypertrophy which are highly comparable to those in rats [15]. In most experiments animals are strati- fied into groups with different interventions. To distin- guish between sham-operated and infarcted animals and to construct groups with comparable infarct sizes at the start of each study, a method is needed not only to con- firm the presence of MI, but also to quantify infarct size. Ideally, both parameters should be available at an early time. In patients, several criteria have been defined by the World Health Organisation [31] for diagnosing acute MI including electrocardiographic changes and increases in plasma concentrations of cardiac proteins. Clinically, the enzymes aspartate aminotransferase (ASAT), creatine kinase (CK) and lactate dehydrogenase (LDH) are used as plasma markers for the detection of cardiac injury. Although isoforms of CK and LDH, like CK-MB, LDH 1 and LDH 2 , are highly expressed in myo- cardium, these markers are not cardiac specific. Increased levels of these enzymes are also observed in clinical set- tings without myocardial injury (e.g. trauma and various inflammatory myopathies) [1, 17]. Recently, new plasma marker proteins such as myoglobin, heart-type fatty acid- binding protein (H-FABP) and cardiac troponin T and troponin I (cTnT/cTnI) have been introduced, allowing a faster and better diagnosis [10, 19, 22, 28, 30]. H-FABP and myoglobin are detectable in the circulation 4 h after the onset of anginal complaint, which makes them useful as early markers [1, 26]. Although cTnT and cTnI are re- leased only slowly into the circulation these markers are more specific for myocardial injury than CK and LDH [2, 6, 9, 11, 18]. Thus, both H-FABP (as an early marker) and cTnT/cTnI (as a specific marker) are potential candi- dates for biochemical determination of myocardial dam- age after experimental coronary artery ligation in mice. FABPs are present in the cytoplasm of fatty acid-utili- sing cells in liver, skeletal muscle and heart [21]. They W.M. Aartsen ( ✉ ) · J.F.M. Smits Department of Pharmacology and Toxicology, Cardiovascular Research Institute Maastricht (CARIM), Universiteit Maastricht, PO Box 616, NL-6200 MD Maastricht, The Netherlands e-mail: wendy.aartsen@farmaco.unimaas.nl Tel.: +31-433881342, Fax: +31-433884149 M.M.A.L. Pelsers · J.F.C. Glatz Department of Physiology, CARIM, Universiteit Maastricht, Maastricht, The Netherlands W.T. Hermens CARIM, Universiteit Maastricht, Maastricht, The Netherlands M.J.A.P. Daemen Department Pathology, CARIM, Universiteit Maastricht, Maastricht, The Netherlands Pflügers Arch – Eur J Physiol (2000) 439:416–422 © Springer-Verlag 2000 Digital Object Identifier (DOI) 10.1007/s004249900180 ORIGINAL ARTICLE W.M. Aartsen · M.M.A.L. Pelsers · W.T. Hermens J.F.C. Glatz · M.J.A.P. Daemen · J.F.M. Smits Heart fatty acid binding protein and cardiac troponin T plasma concentrations as markers for myocardial infarction after coronary artery ligation in mice Received: 15 July 1999 / Accepted: 27 September 1999 / Published online: 30 October 1999