3,5-Diiodothyropropionic Acid

3,5-Diiodothyropropionic acid (DITPA) is an inotropic thyroid hormone analogue of L-thyroxine that binds to the thyroid hormone receptors TRα and TRβ (Kas = 2.4 and 4.06 x 107 M-1, respectively, for human recombinant receptors).1 DITPA increases mRNA expression of α-myosin heavy chain (α-MHC) in primary rat cardiomyocytes (EC50 = ~0.5 μM). Ex vivo, DITPA prevents myocardial infarction-induced loss of contractility in rabbit cardiomyocytes when administered at a dose of 3.75 mg/kg per day.2 DITPA (3.75 mg/kg per day) increases expression of VEGF, basic fibroblast growth factor (bFGF), angiopoietin-1, and angiopoietin-1 receptor (Tie-2) as well as angiogenesis in non-infarcted cardiac tissue in rats.3 It also decreases infarct size expansion, stimulates arteriolar growth, and inhibits ventricular remodeling post-myocardial infarction in rats when administered at a dose of 3.5 mg/kg per day.4