Role of the Lipid Peroxidation Product, 4-Hydroxynonenal, in the Development of Nitrate Tolerance

Abstract

Tolerance to nitrates such as nitroglycerin (GTN) is associated with oxidative stress, inactivation of aldehyde dehydrogenase 2 (ALDH2), and decreased GTN-induced cGMP accumulation and vasodilation. We hypothesized that GTN-induced inactivation of ALDH2 results in increased 4-hydroxy-2-nonenal (HNE) adduct formation of key proteins involved in GTN bioactivation, and, consequently, an attenuated vasodilator response to GTN (i.e., tolerance). We used an in vivo GTN tolerance model, a cell culture model of nitrate action, and Aldh2(-/-) mice to assess whether GTN exposure resulted in HNE adduct formation, and whether exogenous HNE affected GTN-induced relaxation and cGMP accumulation. Immunoblot analysis indicated a marked increase in HNE adduct formation in GTN-tolerant porcine kidney epithelial cells (PK1) and in aortae from GTN-tolerant rats and untreated Aldh2(-/-) mice. Preincubation of PK1 cells with HNE resulted in a dose-dependent decrease in GTN-induced cGMP accumulation, and pretreatment of isolated rat aorta with HNE resulted in dose-dependent decreases in the vasodilator response to GTN, thus mimicking GTN-tolerance. Pretreatment of aortae from Aldh2(-/-) mice with 10 μM HNE resulted in a desensitized vasodilator response to GTN. In the in vivo rat tolerance model, changes in HNE adduct formation correlated well with the onset of GTN tolerance and tolerance reversal. Furthermore, coadministration of an HNE scavenger during the tolerance induction protocol completely prevented HNE adduct formation and GTN tolerance but did not prevent the inactivation of ALDH2. The data are consistent with a novel mechanism of GTN tolerance suggesting a primary role of HNE adduct formation in the development of GTN tolerance.

The effect of vitamin C on nitroglycerin‐mediated vasodilation in individuals with and without the aldehyde dehydrogenase 2 polymorphism

“…We investigated an alternative role of ALDH-2 as the housekeeping enzyme that prevents the accumulation of intracellular reactive oxygen species and cytotoxic aldehydes during GTN bioactivation. 26 Using this construct, the lack of ALDH-2 function blunts the response to GTN, not because of its central role in GTN bioactivation, but because the lack of this detoxifying enzyme interferes with the function of other GTN bioactivating enzyme and/or decreases the bioavailability of nitric oxide or nitric oxide moiety which results from the GTN bioactivation process. We made use of a polymorphism of ALDH-2 that is present in up to 50% of the East Asian population, 20 a genetic variant that eliminates most, if not all ALDH-2 activity.…”

Nicotinamide Ameliorates Amyloid Beta-Induced Oxidative Stress-Mediated Neuroinflammation and Neurodegeneration in Adult Mouse Brain

“…Oxidative stress [34], (Aβ 1-42 -induced oxidative stress), has been documented in various (in vitro and in vivo) models of neurological disorders [35][36][37]. Neuroprotective agents [38] and emerging antioxidants as therapeutics still provide hope and are receiving increased attention [39,40].…”

Metabolomics-Driven Elucidation of Cellular Nitrate Tolerance Reveals Ascorbic Acid Prevents Nitroglycerin-Induced Inactivation of Xanthine Oxidase

“…The role of ALDH2 in GTN bioactivation has been recently questioned because siRNA-mediated knockouts and overexpression of ALDH2 had no significant effect on cGMP production in porcine epithelial cells ( D’souza et al, 2013 ). It has been proposed that ALDH2 acts as a scavenger of HNE and other reactive species, but in fact does not directly metabolize GTN ( D’souza et al, 2014 ). If ALDH2 activity is impaired, oxidative stress levels will rise and lead to inactivation of XO and reduced GTN bioactivation.…”