Abstract 12968: mitoTEMPO Improves Expression of Pulmonary Artery Soluble Guanylate Cyclase β1 and Lowers Exercise Associated Elevations in Pulmonary Artery Pressures in a Rat Model of Combined Pre- and Post-Capillary Pulmonary Hypertension

Introduction: Exercise induced pulmonary hypertension (EIPH) portends worse prognosis compared to isolated resting PH. Exercise increases mitochondrial reactive oxygen species (mROS) production in peripheral blood mononuclear cells of patients with heart failure. Metabolic syndrome related mROS contribute to EIPH by decreasing the expression of the vasodilatory enzyme soluble guanylate cyclase (sGC) via downregulating an sGC transcription factor, namely nuclear factor Y alpha (NFYA; Satoh et al in press). Hypothesis: mROS scavenging with mitoTEMPO will restore sGC expression and ameliorate EIPH in a rat model of combined pre-and post-capillary pulmonary hypertension (CpcPH). Methods: Obese ZSF1 rats treated with sugen were used to model CpcPH. Half received mitoTEMPO (2mM) for 2 weeks. CpcPH rats treated with vehicle and lean ZSF1 rats served as controls (n=6/group). Hemodynamics were evaluated at rest and during treadmill exercise. Cardiac function was assessed using Doppler-echocardiography. We cultured pulmonary artery vascular smooth muscle cells (PAVSMCs) from lean rats in palmitate, glucose and insulin (PGI) containing media to simulate the metabolic syndrome milieu. Cells were treated with vehicle or mitoTEMPO. Expression of sGCβ1 and NFYA in pulmonary arteries of animals and in cultured cells was quantified by Western Blot. Data were analyzed with repeated measures two-way ANOVA. Results: MitoTEMPO significantly improved EIPH by reducing pulmonary vascular resistance (fig1A), significantly improved right ventricular function (fig1B) and significantly restored NFYA/sGCβ1 expression in pulmonary arteries (fig1C) and PAVSMCs of rats with CpcPH (fig1D). MitoTEMPO significantly blunted PGI-induced downregulation of NFYA and sGCβ1 in PAVSMCs from lean rats (fig1E). Conclusions: Mitochondria targeted antioxidants can improve EIPH in CpcPH by restoring NFYA/sGCβ1 expression, identifying a potential therapeutic target for CpcPH.