CARDIAC TROPONIN-T IS A SENSITIVE, SPECIFIC BIOMARKER OF CARDIAC INJURY IN LABORATORY-ANIMALS

A reliable serum assay that can discriminate between cardiac and skele tal muscle injury is not available for diagnostic use in laboratory an imals. We tested and supported the hypotheses that serum cardiac tropo nin T (cTnT) was widely applicable in laboratory animals as a biomarke r of cardiac injury arising from various causes; that it increased in proportion to severity of cardiac injury; and that it was more cardios pecific than creatine kinase (GM) or lactate dehydrogenase (LD) isozym e activities, In canine and rat models of myocardial infarction, cTnT concentration increased 1,000- to 10,000-fold and was highly correlate d with infarct size within 8 h of injury. Serum CR and LD isozymes wer e substantially less effective biomarkers and, in contrast to cTnT, we re ineffective markers in the presence of moderate skeletal muscle inj ury with resulting serum CK activity >5,000 U/L. Using these animal mo dels, and mouse and ferret models, we also showed cTnT to be an effect ive biomarker in doxorubicin cardiotoxicosis, traumatic injury, ischem ia, and cardiac puncture, Reference range serum concentrations for all species were at the detection limit of the assay, except those for mi ce, in which they were slightly increased, possibly because mice were used to generate assay monoclonal antibodies. We conclude that cTnT is a powerful biomarker in laboratory animals for the sensitive and spec ific detection of cardiac injury arising from various causes.