BACKGROUND: Thyroid hormone can have positive effects on the cardiovascular 
system but its therapeutic potential is limited secondary to its adverse 
effects. DITPA (3,5-diiodothyroproprionic acid) is a synthetic thyroid hormone 
analog with positive inotropic effects similar to thyroid hormone but with 
minimal systemic effects. DITPA has previously been shown to reduce pathologic 
remodeling and improve cardiac output following myocardial infarction; however, 
few studies have examined the role of DITPA in determining infarct size or the 
early inflammatory response following myocardial ischemia. We examined the role 
of DITPA in the acute phase following infarction.
MATERIALS AND METHODS: Mice were subjected to surgical induction of myocardial 
infarction and were then randomized to receive daily injections of DITPA or 
vehicle control. After 3 d, animals were sacrificed and infarct size was 
determined by H and E staining. Myocardial macrophage and neutrophil 
accumulation was determined by immunofluorescent staining. Immunoblotting and 
enzyme-linked immunosorbent assay (ELISA) were used to examine the levels of 
intercellular adhesion molecule-1 (ICAM-1), keratinocyte-derived chemokine (KC), 
monocyte chemoattractant protein (MCP-1), and interleukin 6 (IL-6) in 
homogenates from the ischemic tissue.
RESULTS: Compared with vehicle control, DITPA treated animals had smaller 
infarcts (52.1%±5.7% versus 37.3%±3.6%, P<0.05) and decreased macrophage (32±4 
versus 14±1 cells/HPF, P<0.05, and neutrophil (14±2 versus 7±1 cells/HPF, 
P<0.05) accumulation. Myocardial ICAM-1, (2.37±0.4 versus 1.1±0.2, P<0.05), KC 
levels (33.32±12.4 pg/mg, versus 21.24±8.9 pg/mg, P<0.05), and IL-6 levels 
(112.3±78 pg/mg versus 37.3±25.9 pg/mg, P<0.05) were also reduced in the DITPA 
treated group, while MCP-1 levels were equivalent between groups.
CONCLUSIONS: Treatment with DITPA attenuates the acute inflammatory response and 
reduces myocardial infarct size. The reduction in myocardial ICAM-1, KC, and 
IL-6 levels in the DITPA group was associated with a decrease in macrophage and 
neutrophil accumulation.