Combination Sodium Nitrite and Hydralazine Therapy Attenuates Heart Failure With Preserved Ejection Fraction Severity in a “2‐Hit” Murine Model

Abstract

Background Recent studies have suggested that cardiac nitrosative stress mediated by pathological overproduction of nitric oxide (NO) via inducible NO synthase (iNOS) contributes to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). Other studies have suggested that endothelial NO synthase (eNOS) dysfunction and attenuated NO bioavailability contribute to HFpEF morbidity and mortality. We sought to further investigate dysregulated NO signaling and to examine the effects of a NO‐based dual therapy (sodium nitrite+hydralazine) following the onset of HFpEF using a “2‐hit” murine model. Methods and Results Nine‐week‐old male C57BL/6 N mice (n=15 per group) were treated concurrently with high‐fat diet and N(ω)‐nitro‐L‐arginine methyl ester (L‐NAME) (0.5 g/L per day) via drinking water for 10 weeks. At week 5, mice were randomized into either vehicle (normal saline) or combination treatment with sodium nitrite (75 mg/L in the drinking water) and hydralazine (2.0 mg/kg IP, BID). Cardiac structure and function were monitored with echocardiography and invasive hemodynamic measurements. Cardiac mitochondrial respiration, aortic vascular function, and exercise performance were also evaluated. Circulating and myocardial nitrite were measured to determine the bioavailability of NO. Circulating markers of oxidative or nitrosative stress as well as systemic inflammation were also determined. Severe HFpEF was evident by significantly elevated E/E', LVEDP, and Tau in mice treated with L‐NAME and HFD, which was associated with impaired NO bioavailability, mitochondrial respiration, aortic vascular function, and exercise capacity. Treatment with sodium nitrite and hydralazine restored NO bioavailability, reduced oxidative and nitrosative stress, preserved endothelial function and mitochondrial respiration, limited the fibrotic response, and improved exercise capacity, ultimately attenuating the severity of “two‐hit” HFpEF. Conclusions Our data demonstrate that nitrite, a well‐established biomarker of NO bioavailability and a physiological source of NO, is significantly reduced in the heart and circulation in the “2‐hit” mouse HFpEF model. Furthermore, sodium nitrite+hydralazine combined therapy significantly attenuated the severity of HFpEF in the “2‐hit” cardiometabolic HFpEF. These data suggest that supplementing NO‐based therapeutics with a potent antioxidant and vasodilator agent may result in synergistic benefits for the treatment of HFpEF.

Genetic Loss of Nicotinamide Nucleotide Transhydrogenase Prevents from Cardiometabolic Heart Failure with Preserved Ejection Fraction

“…Similarly, Schiattarella et al used C57Bl/6N mice for the initial establishment of this HFD+L-NAME model. 16 Intriguingly, although this initial report has been meticulously reproduced by several groups, 46,47 other unpublished reports were unable to reproduce it, prompting the initial inquiry of whether genetic sub-strain selection accounts for this phenotypic variation.…”

Impact of ovary-intact menopause in a mouse model of heart failure with preserved ejection fraction

“…This inconsistency together with the absent to mild HFpEF phenotype in female mice across both age and reproductive status foments broader concerns regarding the strength of the HFD + l -NAME combination to induce HFpEF. Although several works have leveraged this approach, phenotype severity does vary markedly ( 8 , 46 – 48 ). One work in particular tested 30 inbred strains of mice using this protocol and reported large strain-to-strain variability along with inconsistent sex differences ( 29 ).…”

Epigenetics in Heart Failure: Role of DNA Methylation in Potential Pathways Leading to Heart Failure with Preserved Ejection Fraction

“…While some animal data suggest that hydralazine plus sodium nitrite significantly attenuated the severity of HFpEF [48], the combination of hydralazine with isosorbide dinitrate in patients with HFpEF appears to have deleterious effects on myocardial remodeling and submaximal exercise, findings that do not support the routine use of hydralazine in patients with HFpEF [49].…”