RT Journal Article
SR Electronic
T1 Sustained Formation of Nitroglycerin-Derived Nitric Oxide by Aldehyde Dehydrogenase-2 in Vascular Smooth Muscle Without Added Reductants. Implications for the Development of Nitrate Tolerance
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP mol.117.110783
DO 10.1124/mol.117.110783
A1 Marissa Opelt
A1 Gerald Wolkart
A1 Emrah Eroglu
A1 Markus Waldeck-Weiermair
A1 Roland Malli
A1 Wolfgang F. Graier
A1 Alexander Kollau
A1 John T. Fassett
A1 Astrid Schrammel
A1 Bernd Mayer
A1 Antonius C. F. Gorren
YR 2018
UL http://molpharm.aspetjournals.org/content/early/2018/01/22/mol.117.110783.abstract
AB According to current views, oxidation of aldehyde dehydrogenase-2 (ALDH2) in the course of glyceryltrinitrate (GTN) biotransformation is essentially involved in vascular nitrate tolerance and explains the dependence of the reaction on added thiols. Using a novel fluorescent intracellular NO probe expressed in vascular smooth muscle cells (VSMC) we observed ALDH2-catalyzed formation of nitric oxide (NO) from GTN in the presence of exogenously added dithiothreitol (DTT), whereas only a short burst of NO, corresponding to a single turnover of ALDH2, occurred in the absence of DTT. This short burst of NO that is associated with oxidation of the reactive C302 residue in the active site was followed by formation of low nanomolar NO even without added DTT, indicating slow recovery of ALDH2 activity by an endogenous reductant. In addition to the thiol-reversible oxidation of ALDH2, thiol-refractive inactivation was observed, particularly under high-turnover conditions. Organ bath experiments with rat aortas showed that relaxation by GTN lasted longer than that caused by the NO donor diethylamine/NONOate, in line with the long-lasting nanomolar NO generation from GTN observed in VSMC. Our results suggest that an endogenous reductant with low efficiency allows sustained generation of GTN-derived NO in the low nanomolar range that is sufficient for vascular relaxation. On a longer time scale, mechanism-based, thiol-refractive irreversible inactivation of ALDH2, and possibly depletion of the endogenous reductant, will render blood vessels tolerant to GTN. Accordingly, full reactivation of oxidized ALDH2 may not occur in vivo and may not be necessary to explain GTN-induced vasodilation.