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Contribution of aldehyde dehydrogenase to mitochondrial bioactivation of nitroglycerin: evidence for the activation of purified soluble guanylate cyclase through direct formation of nitric oxide.
Biochem J. 2005 Feb 01; 385(Pt 3):769-77.BJ

Abstract

Vascular relaxation to GTN (nitroglycerin) and other antianginal nitrovasodilators requires bioactivation of the drugs to NO or a related activator of sGC (soluble guanylate cyclase). Conversion of GTN into 1,2-GDN (1,2-glycerol dinitrate) and nitrite by mitochondrial ALDH2 (aldehyde dehydrogenase 2) may be an essential pathway of GTN bioactivation in blood vessels. In the present study, we characterized the profile of GTN biotransformation by purified human liver ALDH2 and rat liver mitochondria, and we used purified sGC as a sensitive detector of GTN bioactivity to examine whether ALDH2-catalysed nitrite formation is linked to sGC activation. In the presence of mitochondria, GTN activated sGC with an EC50 (half-maximally effective concentration) of 3.77+/-0.83 microM. The selective ALDH2 inhibitor, daidzin (0.1 mM), increased the EC50 of GTN to 7.47+/-0.93 microM. Lack of effect of the mitochondrial poisons, rotenone and myxothiazol, suggested that nitrite reduction by components of the respiratory chain is not essential to sGC activation. However, since co-incubation of sGC with purified ALDH2 led to significant stimulation of cGMP formation by GTN that was completely inhibited by 0.1 mM daidzin and NO scavengers, ALDH2 may convert GTN directly into NO or a related species. Studies with rat aortic rings suggested that ALDH2 contributes to GTN bioactivation and showed that maximal relaxation to GTN occurred at cGMP levels that were only 3.4% of the maximal levels obtained with NO. Comparison of sGC activation in the presence of mitochondria with cGMP accumulation in rat aorta revealed a slightly higher potency of GTN to activate sGC in vitro compared with blood vessels. Our results suggest that ALDH2 catalyses the mitochondrial bioactivation of GTN by the formation of a reactive NO-related intermediate that activates sGC. In addition, the previous conflicting notion of the existence of a high-affinity GTN-metabolizing pathway operating in intact blood vessels but not in tissue homogenates is explained.

Authors+Show Affiliations

Department of Pharmacology and Toxicology, Karl-Franzens-Universität Graz, Universitätsplatz 2, A-8010 Graz, Austria.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15377279

Citation

Kollau, Alexander, et al. "Contribution of Aldehyde Dehydrogenase to Mitochondrial Bioactivation of Nitroglycerin: Evidence for the Activation of Purified Soluble Guanylate Cyclase Through Direct Formation of Nitric Oxide." The Biochemical Journal, vol. 385, no. Pt 3, 2005, pp. 769-77.
Kollau A, Hofer A, Russwurm M, et al. Contribution of aldehyde dehydrogenase to mitochondrial bioactivation of nitroglycerin: evidence for the activation of purified soluble guanylate cyclase through direct formation of nitric oxide. Biochem J. 2005;385(Pt 3):769-77.
Kollau, A., Hofer, A., Russwurm, M., Koesling, D., Keung, W. M., Schmidt, K., Brunner, F., & Mayer, B. (2005). Contribution of aldehyde dehydrogenase to mitochondrial bioactivation of nitroglycerin: evidence for the activation of purified soluble guanylate cyclase through direct formation of nitric oxide. The Biochemical Journal, 385(Pt 3), 769-77.
Kollau A, et al. Contribution of Aldehyde Dehydrogenase to Mitochondrial Bioactivation of Nitroglycerin: Evidence for the Activation of Purified Soluble Guanylate Cyclase Through Direct Formation of Nitric Oxide. Biochem J. 2005 Feb 1;385(Pt 3):769-77. PubMed PMID: 15377279.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Contribution of aldehyde dehydrogenase to mitochondrial bioactivation of nitroglycerin: evidence for the activation of purified soluble guanylate cyclase through direct formation of nitric oxide. AU - Kollau,Alexander, AU - Hofer,Alexandra, AU - Russwurm,Michael, AU - Koesling,Doris, AU - Keung,Wing Ming, AU - Schmidt,Kurt, AU - Brunner,Friedrich, AU - Mayer,Bernd, PY - 2004/9/21/pubmed PY - 2005/7/30/medline PY - 2004/9/21/entrez SP - 769 EP - 77 JF - The Biochemical journal JO - Biochem J VL - 385 IS - Pt 3 N2 - Vascular relaxation to GTN (nitroglycerin) and other antianginal nitrovasodilators requires bioactivation of the drugs to NO or a related activator of sGC (soluble guanylate cyclase). Conversion of GTN into 1,2-GDN (1,2-glycerol dinitrate) and nitrite by mitochondrial ALDH2 (aldehyde dehydrogenase 2) may be an essential pathway of GTN bioactivation in blood vessels. In the present study, we characterized the profile of GTN biotransformation by purified human liver ALDH2 and rat liver mitochondria, and we used purified sGC as a sensitive detector of GTN bioactivity to examine whether ALDH2-catalysed nitrite formation is linked to sGC activation. In the presence of mitochondria, GTN activated sGC with an EC50 (half-maximally effective concentration) of 3.77+/-0.83 microM. The selective ALDH2 inhibitor, daidzin (0.1 mM), increased the EC50 of GTN to 7.47+/-0.93 microM. Lack of effect of the mitochondrial poisons, rotenone and myxothiazol, suggested that nitrite reduction by components of the respiratory chain is not essential to sGC activation. However, since co-incubation of sGC with purified ALDH2 led to significant stimulation of cGMP formation by GTN that was completely inhibited by 0.1 mM daidzin and NO scavengers, ALDH2 may convert GTN directly into NO or a related species. Studies with rat aortic rings suggested that ALDH2 contributes to GTN bioactivation and showed that maximal relaxation to GTN occurred at cGMP levels that were only 3.4% of the maximal levels obtained with NO. Comparison of sGC activation in the presence of mitochondria with cGMP accumulation in rat aorta revealed a slightly higher potency of GTN to activate sGC in vitro compared with blood vessels. Our results suggest that ALDH2 catalyses the mitochondrial bioactivation of GTN by the formation of a reactive NO-related intermediate that activates sGC. In addition, the previous conflicting notion of the existence of a high-affinity GTN-metabolizing pathway operating in intact blood vessels but not in tissue homogenates is explained. SN - 1470-8728 UR - https://www.unboundmedicine.com/medline/citation/15377279/Contribution_of_aldehyde_dehydrogenase_to_mitochondrial_bioactivation_of_nitroglycerin:_evidence_for_the_activation_of_purified_soluble_guanylate_cyclase_through_direct_formation_of_nitric_oxide_ DB - PRIME DP - Unbound Medicine ER -