5.3 INORGANIC NITRITE, CONDUIT ARTERIES & CENTRAL BLOOD PRESSURE

DOI

10.1016/j.artres.2013.10.026How to use a DOI?

Abstract

Background. Organic nitrates (e.g. nitroglycerin) are highly selective dilators of muscular conduit arteries. By contrast, the endogenous inorganic nitrite anion (NO₂⁻) is thought to be a hypoxia-dependent dilator of small resistance arterioles, via its reduction to vasodilating nitric oxide (NO) by deoxyhaemoglobin.

Objective. To establish selectivity of nitrite for resistance versus conduit arteries.

Methods and Results A series of forearm blood flow (FABF) studies were performed in healthy volunteers. Intra-brachial sodium nitrite (8.7 μmol/min) markedly increased radial artery diameter (assessed using ultrasound) by 37.6 ± 9.7% (P < 0.001), with HbO₂ ∼99%. Furthermore, nitrite (0.087–87 μmol/min) displayed similar selectivity as nitroglycerin (0.003–1 μg/min) for conduit arteries, compared to resistance arterioles (FABF). Intravenous administration of sodium nitrite (8.7 μmol/min) dilated the contralateral radial artery by 10.7 ± 1.8% (P < 0.01) and lowered central systolic blood pressure (BP) by ~12mmHg from 98.3 ± 12.3 to 86.7 ± 15.1 mmHg (P = 0.02) without any change in peripheral BP; nitrite also reduced augmentation index and pulse wave velocity. In contrast to nitrite’s effects on FABF, induction of hypoxia (breathing 12% O₂) paradoxically inhibited nitrite-induced dilatation of the radial artery to a similar extent as hyperoxia/ breathing 100% O₂ (both P < 0.001 compared to normoxia).

Conclusions. Contrary to expectation, inorganic nitrite is a normoxia-dependent selective conduit artery dilator with similar selectivity to nitroglycerin. A specific advantage of nitrite is that it lacks the problems of development of tolerance and endothelial dysfunction, which limit the efficacy of organic nitrates. The selective central BP-lowering effects of nitrite have therapeutic potential to reduce cardiovascular events.

Open Access

This is an open access article distributed under the CC BY-NC license.

TY  - JOUR
AU  - S. Omar
AU  - H. Fok
AU  - A. Nair
AU  - J. Hunt
AU  - B. Jiang
AU  - P. Chowienczyk
AU  - A.J. Webb
PY  - 2013
DA  - 2013/11/11
TI  - 5.3 INORGANIC NITRITE, CONDUIT ARTERIES & CENTRAL BLOOD PRESSURE
JO  - Artery Research
SP  - 168
EP  - 169
VL  - 7
IS  - 3-4
SN  - 1876-4401
UR  - https://doi.org/10.1016/j.artres.2013.10.026
DO  - 10.1016/j.artres.2013.10.026
ID  - Omar2013
ER  -