Additive effect of TAK-491, a new angiotensin receptor blocker, and pioglitazone, in reducing myocardial infarct size

Purpose: We assessed the effects of TAK-491 (a newly designed potent and selective ARB) alone and in combination with pioglitazone (PIO) on myocardial infarct size (IS).

Methods: Rats received TAK-491 (0.3, 1, 3, or 10 mgkg(-1)d(-1)), PIO (1.0 or 2.5 mgkg(-1)d(-1)), or PIO 2.5 mgkg(-1)d(-1) with TAK-491 (1 or 3 mgkg(-1)d(-1)) for 4 days. On day 5 rats underwent 30-minute coronary artery occlusion and 4-hour reperfusion. Area at risk (AR) was assessed by blue dye and IS by TTC. Left ventricular (LV) dimensions and function was assessed by echocardiography 35 days after infarction.

Results: TAK (1.0-10 mgkg(-1)d(-1)), PIO (1.0 to 2.5 mgkg(-1)d(-1)), PIO2.5+TAK1.0, and PIO2.5+TAK3.0 significantly reduced IS. IS was the smallest in the TAK 10.0, followed by PIO+TAK 3.0. The protective effects of TAK and PIO were additive, as IS was smaller in the PIO2.5+TAK1.0 than in PIO 2.5 alone (p = 0.008) or TAK1.0 alone (p = 0.002); and in PIO2.5+TAK3.0 than in PIO alone (p < 0.001) or TAK3.0 alone (p < 0.001). TAK, PIO and their combination tended to attenuate LV remodeling and improved LV function 35 days after infarction; however, the differences among individual groups were not statistically significant. Both TAK-491 and PIO increased calcium-dependent nitric oxide synthase activity, whereas only PIO increased COX2 expression and activity. Both PIO and TAK-491 increased Akt, ERK 1/2 and eNOS phosphorylation and inhibited Bax activation.

Conclusions: TAK-491 and PIO independently limited myocardial IS in a dose-dependent fashion; and the effects were additive. The mechanism of protection and the role of TAK-491 in this clinical setting should be further investigated.