RESEARCH Right Ventricular Physiology in Health and Disease Reversal of right ventricular failure by chronic (cid:2) 1A -subtype adrenergic agonist therapy

Reversal of right ventricular failure by chronic (cid:2) 1A -subtype adrenergic agonist therapy. Right ventricular (RV) failure (RVF) is a serious disease with no effective treatment available. We recently reported a disease prevention study showing that chronic stimulation of (cid:2) 1A -adrenergic receptors ( (cid:2) 1A -ARs), started at the time of RV injury, prevented the development of RVF. The present study used a clinically relevant disease reversal design to test if chronic (cid:2) 1A -AR stimulation, started after RVF was established, could reverse RVF. RVF was induced surgically by pulmonary artery constriction in mice. Two weeks after pulmonary artery constriction, in vivo RV fractional shortening as assessed by MRI was reduced by half relative to sham-operated controls (25 (cid:3) 2%, n (cid:4) 27, vs. 52 (cid:3) 2%, n (cid:4) 13, P (cid:5) 10 (cid:6) 11 ). Subsequent chronic treatment with the (cid:2) 1A -AR agonist A61603 for a further 2 wk resulted in a substantial recovery of RV fractional shortening (to 41 (cid:3) 2%, n (cid:4) 17, P (cid:5) 10 (cid:6) 7 by a paired t -test) along with recovery of voluntary exercise capacity. Mechanistically, chronic A61603 treatment resulted in increased activation of the prosurvival kinase ERK, increased abundance of the antiapoptosis factor Bcl-2, and decreased myocyte necrosis evidenced by a decreased serum level of cardiac troponin. Moreover, A61603 treatment caused increased abundance of the antioxidant glutathione peroxidase-1, decreased level of reactive oxygen species, and decreased oxidative modiﬁcation (carbonylation) of myoﬁlament proteins. Consistent with these effects, A61603 treatment resulted in increased force development by cardiac myoﬁlaments, which might have contributed to increased RV function. These ﬁndings suggest that the (cid:2) 1A -AR is a therapeutic target to reverse established RVF. chronic of (cid:2) 1A -adrenergic the agonist A61603 in recovery of in vivo RV function, improved exercise capacity, reduced oxidative stress-related carbonylation of contractile proteins, and increased myoﬁlament force generation. suggest the (cid:2) 1A -adrenergic receptor is a therapeutic target to treat RVF. Analysis of Quantiﬁcation of protein concentration was performed using the 660-nm protein assay (Thermo Scientiﬁc). Carbonylated myoﬁbrillar proteins were detected using the OxyBlot kit (EMD Millipore) according to the manufac- ture’s protocol. Protein carbonyl groups were derivatized by reaction with 2,4-dinitrophenylhydrazane for 15 min, neutralized, and loaded onto 12% SDS-PAGE gels for Western blot analysis. Protein was transferred to polyvinylidene ﬂuoride membranes. Membranes were stained with the MemCode Reversible Protein Stain Kit (Thermo Scientiﬁc) to ensure equal protein loading and transfer. Membranes were blocked with 5% skim milk and incubated with the anti-dinitrophenyl primary antibody (1:150) overnight at 4°C and then with goat anti-rabbit secondary antibody (1:150) in 5% nonfat skim milk for 1 h at room temperature. The immunoreactive bands were developed and analyzed according to the procedures described above. Carbonylated protein were the the per lane. conﬁrm the identity of the carbonylated bands, the was stripped blot strip- ping and reprobed with primary antibodies for actin Santa and tropo- myosin to Secondary antibody was a mouse IgG (cid:11) chain-binding This three each