Dietary nitrate improves cardiac contractility via enhanced cellular Ca2+ signaling

• Published in: Basic research in cardiology Vol. 111; no. 3; p. 34
• Main Authors: Pironti, Gianluigi, Ivarsson, Niklas, Yang, Jiangning, Farinotti, Alex Bersellini, Jonsson, William, Zhang, Shi-Jin, Bas, Duygu, Svensson, Camilla I., Westerblad, Håkan, Weitzberg, Eddie, Lundberg, Jon O., Pernow, John, Lanner, Johanna, Andersson, Daniel C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2016
• Subjects: Animals; Blotting, Western; Calcium Signaling - physiology; Cardiology; Diet; Heart - drug effects; Heart - physiology; Isolated Heart Preparation; Male; Medicin och hälsovetenskap; Medicine; Medicine & Public Health; Mice; Mice, Inbred C57BL; Myocardial Contraction - drug effects; Myocardial Contraction - physiology; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - physiology; Nitrates - pharmacology; Original Contribution; Patch-Clamp Techniques; Calcium; Diet; Cardiac; Contractility
• ISSN: 0300-8428; 1435-1803; 1435-1803
• DOI: 10.1007/s00395-016-0551-8

The inorganic anion nitrate (NO 3 − ), which is naturally enriched in certain vegetables (e.g., spinach and beetroot), has emerged as a dietary component that can regulate diverse bodily functions, including blood pressure, mitochondrial efficiency, and skeletal muscle force. It is not known if dietary nitrate improves cardiac contractility. To test this, mice were supplemented for 1–2 weeks with sodium nitrate in the drinking water at a dose similar to a green diet. The hearts from nitrate-treated mice showed increased left ventricular pressure and peak rate of pressure development as measured with the Langendorff heart technique. Cardiomyocytes from hearts of nitrate-treated and control animals were incubated with the fluorescent indicator Fluo-3 to measure cytoplasmic free [Ca 2+ ] and fractional shortening. Cardiomyocytes from nitrate-treated mice displayed increased fractional shortening, which was linked to larger Ca 2+ transients. Moreover, nitrate hearts displayed increased protein expression of the l -type Ca 2+ channel/dihydropyridine receptor and peak l -type Ca 2+ channel currents. The nitrate-treated hearts displayed increased concentration of cAMP but unchanged levels of cGMP compared with controls. These findings provide the first evidence that dietary nitrate can affect the expression of important Ca 2+ handling proteins in the heart, resulting in increased cardiomyocyte Ca 2+ signaling and improved left ventricular contractile function. Our observation shows that dietary nitrate impacts cardiac function and adds understanding to inorganic nitrate as a physiological modulator.