Indexed on: 25 Jan '17Published on: 25 Jan '17Published in: Toxicological sciences : an official journal of the Society of Toxicology
The skeletal muscle (SKM) injury biomarkers, skeletal troponin I (sTnI), myosin light chain 3 (Myl3), and creatine kinase muscle isoform (Ckm) have been shown recently to be more sensitive and specific for monitoring drug-induced SKM injury than the conventional biomarkers, aspartate transaminase (AST) and creatine kinase (CK) enzymatic assays in rat toxicology studies. To evaluate the utility of these SKM biomarkers across species, they were assessed in two dog models: a drug-induced injury study in Beagle dogs and a 160 km endurance exercise run completed by Alaskan sled dogs. In the drug-induced injury model, mean sTnI and Myl3 plasma levels were 6- and 18-fold, respectively, compared to baseline as early as Study Day (SD) 15, while mean plasma AST and CK levels did not increase, and biopsy samples were non-remarkable for histopathology prior to SD 29 when degeneration was first noted. Peak group mean plasma responses over baseline for sTnI, Myl3, and Ckm biomarkers were 96-, 103-, and 11-fold, respectively, compared to 2.5-fold for AST and 3.8-fold for CK-enzymatic assay. In the sled dog sustained exercise model, the peak response for all biomarkers was observed at the first sampling (2 h) after the completion of the run. The sTnI, Myl3, and Ckm mean fold peak values compared to baseline were 170-, 120-, and 150-fold, respectively, while AST increased 7-fold and CK-enzymatic increased 29-fold. These findings support the conclusion that sTnI, Myl3, and Ckm are sensitive early tissue leakage biomarkers for monitoring SKM injury and effects of exercise in dog, extending their utility across preclinical species beyond the rat, and provide further support to investigate their translational utility to clinical trial settings to monitor for drug-induced SKM injury and ensure patient safety.