Melina Lopez1,2, Pedro F Malacarne1,2, Anna Gajos-Draus3, Xinxin Ding4, Andreas Daiber2,5, Jon O Lundberg6, Stefan Offermanns7, Ralf P Brandes1,2, Flávia Rezende1,2. 1. Institute for Cardiovascular Physiology, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany. 2. German Center for Cardiovascular Research (DZHK), Partner site Rhein Main, Frankfurt am Main, Germany. 3. Department of Clinical Physiology, National Science Centre, Kraków, Poland. 4. Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, Arizona, USA. 5. Zentrum für Kardiologie - Kardiologie 1, Labor für Moleculare Kardiologie, Johannes Gutenberg University, Mainz, Germany. 6. Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden. 7. Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
Abstract
BACKGROUND AND PURPOSE: Organic nitrates such as nitroglycerin (NTG) or pentaerythritol tetranitrate (PETN) have been used for over a century in the treatment of angina or ischaemic heart disease. These compounds are prodrugs which release their nitrovasodilators upon enzymic bioactivation by aldehyde dehydrogenase (ALDH2) or cytochromes P450 (CYP). Whereas ALDH2 is known to directly activate organic nitrates in vessels, the contribution of vascular CYPs is unknown and was studied here. EXPERIMENTAL APPROACH: As all CYPs depend on cytochrome P450 reductase (POR) as electron donor, we generated a smooth muscle cell-specific, inducible knockout mouse of POR (smcPOR-/- ) to investigate the contribution of POR/CYP to vascular biotransformation of organic nitrates. KEY RESULTS: Microsomes containing recombinant CYPs expressed in human vascular tissues released nitrite from NTG and PETN with CYP2C9 and CYP2C8 being most efficient. SFK525, a CYP suicide inhibitor, blocked this effect. smcPOR-/- mice exhibited no obvious cardiovascular phenotype (normal cardiac weight and endothelium-dependent relaxation) and plasma and vascular nitrite production was similar to control (CTL) animals. NTG- and PETN-induced relaxation of isolated endothelium-intact or endothelium-denuded vessels were identical between CTL and smcPOR-/- . Likewise, nitrite release from organic nitrates in aortic rings was not affected by deletion of POR in smooth muscle cells (SMCs). In contrast, inhibition of ALDH2 by benomyl (10 μM) inhibited NTG-induced nitrite production and relaxation. Deletion of POR did not modulate this response. CONCLUSIONS AND IMPLICATIONS: Our data suggest that metabolism by vascular CYPs does not contribute to the pharmacological function of organic nitrates.
BACKGROUND AND PURPOSE: Organic nitrates such as nitroglycerin (NTG) or pentaerythritol tetranitrate (PETN) have been used for over a century in the treatment of angina or ischaemic heart disease. These compounds are prodrugs which release their nitrovasodilators upon enzymic bioactivation by aldehyde dehydrogenase (ALDH2) or cytochromes P450 (CYP). Whereas ALDH2 is known to directly activate organic nitrates in vessels, the contribution of vascular CYPs is unknown and was studied here. EXPERIMENTAL APPROACH: As all CYPs depend on cytochrome P450 reductase (POR) as electron donor, we generated a smooth muscle cell-specific, inducible knockout mouse of POR (smcPOR-/- ) to investigate the contribution of POR/CYP to vascular biotransformation of organic nitrates. KEY RESULTS: Microsomes containing recombinant CYPs expressed in human vascular tissues released nitrite from NTG and PETN with CYP2C9 and CYP2C8 being most efficient. SFK525, a CYP suicide inhibitor, blocked this effect. smcPOR-/- mice exhibited no obvious cardiovascular phenotype (normal cardiac weight and endothelium-dependent relaxation) and plasma and vascular nitrite production was similar to control (CTL) animals. NTG- and PETN-induced relaxation of isolated endothelium-intact or endothelium-denuded vessels were identical between CTL and smcPOR-/- . Likewise, nitrite release from organic nitrates in aortic rings was not affected by deletion of POR in smooth muscle cells (SMCs). In contrast, inhibition of ALDH2 by benomyl (10 μM) inhibited NTG-induced nitrite production and relaxation. Deletion of POR did not modulate this response. CONCLUSIONS AND IMPLICATIONS: Our data suggest that metabolism by vascular CYPs does not contribute to the pharmacological function of organic nitrates.
Authors: Elisabetta Marini; Marta Giorgis; Marta Leporati; Barbara Rolando; Konstantin Chegaev; Loretta Lazzarato; Massimo Bertinaria; Marco Vincenti; Antonella Di Stilo Journal: Antioxidants (Basel) Date: 2022-01-16