Myagmar, B.-E. | bioRxiv Science

bioRxiv2026

Chronic therapy with α1A-adrenergic agonist reverses RV failure and mitochondrial dysfunction

Right ventricular failure (RVF) is a serious disease with a high mortality but no effective pharmacologic treatments. We reported RVF was reversed by chronic treatment with an 1A-adrenergic receptor (1A-AR) agonist. Recent studies suggest mitochondrial dysfunction contributes to RVF. Therefore, we investigated if reversal of RVF by chronic 1A-AR agonist treatment involved improved mitochondrial function. A mouse model of RVF caused by pulmonary artery constriction (PAC) for 2 wk was chronically treated for a further 2 wk. with a low dose of the 1A-AR agonist A61603 (10 ng/kg/day) or vehicle (no drug control). RV dysfunction was assessed from the fractional shortening of the RV outflow tract (RVOT FS). RVOT FS for sham controls (46.5 {+/-} 1.3 %, n = 9) was reduced 4 wk after PAC (27.6 {+/-} 1.5 %, n = 13, P < 0.0001), but was higher after PAC plus 2 wk A61603 treatment (34.5 {+/-} 0.6 %, n = 14, P < 0.001). RV myocardial respiration rate (O2 consumption) for sham controls (776 {+/-} 51 pM/s/mg, n = 9) was reduced 4 wk after PAC (493 {+/-} 28 pM/s/mg, n = 15, P <0.0001), but was higher after PAC plus 2 wk A61603 treatment (634 {+/-} 30 pM/s/mg, n = 11, P <0.05). RV myocardial ATP level for sham controls (3.3 {+/-} 0.1 mM, n = 10) was reduced 4 wk after PAC (1.9 {+/-} 0.1 mM, n = 6, P < 0.0001), but was higher after PAC plus 2 wk A61603 treatment (2.6 {+/-} 0.13 mM, n = 7, P < 0.01). In conclusion, reversal of RVF after chronic A61603 treatment involved reversal of mitochondrial dysfunction. Consistent with our previous studies, this study suggests that the 1A-AR is a therapeutic target to treat RVF. HighlightsRV failure is reported to involve mitochondrial dysfunction which might impair RV contraction by decreasing cardiomyocyte ATP level. Using the pulmonary artery constriction model of RV failure, we found that chronic treatment with an 1A-adrenergic receptor agonist increased RV myocardial respiration rate, increased RV myocardial ATP level, and increased RV function. These findings suggest that the 1A-adrenergic receptor is a therapeutic target for treating RV failure, and that the mechanism involves improved RV cardiomyocyte bioenergetic status.

physiology↗

bioRxiv2022

Cardiomyocyte alpha-1A adrenergic receptors mitigate post-infarct remodeling and mortality by constraining necroptosis

Activation of alpha-1-adrenergic receptors (1-ARs), particularly the 1A subtype, protects the murine heart against injury, whereas human studies show that 1-AR antagonists (-blockers) may increase the risk of heart failure. We created a cardiomyocyte-specific 1A-AR knockout mouse (cmAKO) to define the mechanisms underlying these effects and to elucidate whether they arise from cardiomyocyte 1A-ARs or systemic factors. Myocardial infarction (MI) resulted in 70% 7-day mortality in cmAKO compared to 10% in wild type (WT) mice. cmAKO mice exhibited exaggerated ventricular remodeling and increased cell death compared to WT mice 3 days post-MI, coupled to upregulation of canonical mediators of necroptosis: receptor-interacting protein (RIP) kinases RIP1 and RIP3 and mixed lineage kinase domain-like protein. An 1A-AR agonist mitigated ischemia-induced cardiomyocyte death and necroptotic signaling in vitro. A RIP1 antagonist abrogated the protective effects of 1A activation in vivo and in vitro. We found that patients at our center who were taking -blockers at the time of MI experienced a higher risk of mortality (hazard ratio 1.53, p=0.029) during 5-year follow-up, providing clinical correlation for our experimental data. Collectively our findings indicate that cardiomyocyte 1A-ARs constrain ischemia-induced necroptosis and suggest caution in the use of -blockers in patients at risk for MI.

pathology↗