title: Cardiac troponin T content in heart and skeletal muscle and in blood samples from ApoE/LDL receptor double knockout mice.
abstract: BACKGROUND
  The isolated perfused mouse heart is a useful experimental model, and cardiac troponin T (cTnT) in coronary effluent may be a sensitive marker of myocardial damage. In recent years, the apolipoprotein E/low-density lipoprotein receptor double knockout (apoE/LDLr KO) mice have become valuable tools in atherosclerosis research. The aim of the study was to validate measurements of cTnT in heart, skeletal muscle, and serum of apoE/LDLr KO mice.
  
  
  METHODS
  Wild-type C57BL/6J mice were fed with standard diet, and apoE/LDLr KO mice were fed an atherogenic diet. Blood was sampled from the jugular vein or the thoracic cavity. Heart and femoral skeletal muscle were sampled and homogenized. cTnT was measured with the third-generation cTnT assay (Troponin T STAT) on Elecsys 2010 immunoassay analyser (Roche Diagnostics).
  
  
  RESULTS
  Median serum cTnT in samples from the thoracic cavity of C57BL/6J mice was about 20-90 times higher, and from ApoE/LDLr KO mice about 30 times higher than serum cTnT in samples from the external jugular vein. There was no difference in cTnT content (microg cTnT/g heart muscle) in hearts from C57BL/6J and apoE/LDLr KO mice. The median cTnT content in skeletal muscle was less than 0.1% of the cTnT content in heart muscle.
  
  
  CONCLUSIONS
  There is no difference in cTnT content of heart muscle comparing C57BL/6J and ApoE/LDLr KO mice, which have larger hearts. Sampling from the thoracic cavity causes unacceptably high cTnT levels. Serum cTnT in samples from the jugular vein is only slightly elevated. Elevated baseline levels of cTnT in mice are not caused by troponin T from skeletal muscle.
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Huddinge University Hospital, Sweden. christian.lowbeer@medilab.se
authors.forename: Christian
authors.initials: C
authors.lastname: Löwbeer
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Forsberg
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tokuno
authors.forename: Anne-Louise
authors.initials: AL
authors.lastname: Hemdahl
authors.forename: Sven A
authors.initials: SA
authors.lastname: Gustafsson
authors.forename: Guro
authors.initials: G
authors.lastname: Valen
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency; D001161:Arteriosclerosis / Q000175:diagnosis*; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D001800:Blood Specimen Collection / Q000379:methods; D004195:Disease Models, Animal; D007601:Jugular Veins; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000737:chemistry*; D009206:Myocardium / Q000737:chemistry*; D011973:Receptors, LDL / Q000172:deficiency; D013909:Thorax / Q000098:blood supply; D020107:Troponin T / Q000032:analysis* / Q000097:blood
chemical_list: D001057:Apolipoproteins E; D015415:Biomarkers; D011973:Receptors, LDL; D020107:Troponin T