Inorganic nitrate attenuates cardiac dysfunction: roles for xanthine oxidoreductase and nitric oxide.

BACKGROUND AND PURPOSE: NO is a vasodilator and independent modulator of cardiac remodelling. Commonly, in cardiac disease (e.g., heart failure), endothelial dysfunction (synonymous with NO deficiency) has been implicated in increased BP, cardiac hypertrophy and fibrosis. Currently, no effective therapies replacing NO have succeeded in the clinic. Inorganic nitrate (NO3 - ), through chemical reduction to nitrite and then to NO, exerts potent BP lowering, but whether it might be useful in treating undesirable cardiac remodelling is not known. EXPERIMENTAL APPROACH: We analysed demographics in a nested age- and sex-matched case-control study of hypertensive patients with or without left ventricular hypertrophy (NCT03088514) and assessed the effects of dietary nitrate in mouse models of cardiac dysfunction. KEY RESULTS: Lower plasma nitrite concentrations and vascular dysfunction accompanied cardiac hypertrophy and fibrosis in patients. In mouse models of cardiac remodelling, restoration of circulating nitrite levels using dietary nitrate improved endothelial dysfunction through targeting the xanthine oxidoreductase-driven increase in levels of H2 O2 and superoxide, and decreased cardiac fibrosis through NO-mediated block of SMAD phosphorylation leading to improvements in cardiac structure and function. CONCLUSIONS AND IMPLICATIONS: Dietary nitrate offers easily translatable therapeutic options for delivery of NO and thereby treatment of cardiac dysfunction.

Endogenously generated arachidonate-derived ligands for TRPV1 induce cardiac protection in sepsis.

The severity of cardiac dysfunction predicts mortality in sepsis. Activation of transient receptor potential vanilloid receptor type (TRPV)-1, a predominantly neuronal nonselective cation channel, has been shown to improve outcome in sepsis and endotoxemia. However, the role of TRPV1 and the identity of its endogenous ligands in the cardiac dysfunction caused by sepsis and endotoxemia are unknown. Using TRPV1-/- and TRPV1+/+ mice, we showed that endogenous activation of cardiac TRPV1 during sepsis is key to limiting the ensuing cardiac dysfunction. Use of liquid chromatography-tandem mass spectrometry lipid analysis and selective inhibitors of arachidonic metabolism suggest that the arachidonate-derived TRPV1 activator, 20-hydroxyeicosateraenoic acid (20-HETE), underlies a substantial component of TRPV1-mediated cardioprotection in sepsis. Moreover, using selective antagonists for neuropeptide receptors, we show that this effect of TRPV1 relates to the activity of neuronally released cardiac calcitonin gene-related peptide (CGRP) and that, accordingly, administration of CGRP can rescue cardiac dysfunction in severe endotoxemia. In sum activation of TRPV1 by 20-HETE leads to the release of CGRP, which protects the heart against the cardiac dysfunction in endotoxemia and identifies both TRPV1 and CGRP receptors as potential therapeutic targets in endotoxemia.-Chen, J., Hamers, A. J. P., Finsterbusch, M., Massimo, G., Zafar, M., Corder, R., Colas, R. A., Dalli, J., Thiemermann, C., Ahluwalia, A. Endogenously generated arachidonate-derived ligands for TRPV1 induce cardiac protection in sepsis.