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Huang AJ, Cummings SR, Ganz P, Schembri M, Raghunathan H, Vittinghoff E, Gibson CJ, Grady D. Efficacy of Continuous Transdermal Nitroglycerin for Treating Hot Flashes by Inducing Nitrate Cross-tolerance in Perimenopausal and Postmenopausal Women: A Randomized Clinical Trial. JAMA Intern Med 2023; 183:776-783. [PMID: 37273224 PMCID: PMC10242506 DOI: 10.1001/jamainternmed.2023.1977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/06/2023] [Indexed: 06/06/2023]
Abstract
Importance Due to the potential risks of long-term systemic estrogen therapy, many menopausal women are interested in nonhormonal treatments for vasomotor symptoms. Physiologic studies indicate that nitric oxide plays a key role in mediating hot flash-related vasodilation, suggesting that nonhormonal medications that induce nitrate tolerance in the vasculature may offer therapeutic benefit for vasomotor symptoms. Objective To determine whether uninterrupted administration of transdermal nitroglycerin (NTG) to induce nitrate cross-tolerance decreased the frequency or severity of menopause-related hot flashes. Design, Setting, and Participants This randomized, double-blinded, placebo-controlled clinical trial included perimenopausal or postmenopausal women reporting 7 or more hot flashes per day who were recruited from northern California by study personnel at a single academic center. Patients were randomized between July 2017 and December 2021, and the trial ended in April 2022 when the last randomized participant completed follow-up. Interventions Uninterrupted daily use of transdermal NTG (participant-directed dose titration from 0.2-0.6 mg/h) or identical placebo patches. Main Outcome Measures Validated symptom diaries assessing changes in any hot flash frequency (primary outcome) and moderate-to-severe hot flash frequency over 5 and 12 weeks. Results Among the 141 randomized participants (70 NTG [49.6%], 71 placebo [50.4%]; 12 [85.8%] Asian, 16 [11.3%] Black or African American, 15 [10.6%] Hispanic or Latina, 3 [2.1%] multiracial, 1 [0.7%] Native Hawaiian or Pacific Islander, and 100 [70.9%] White or Caucasian individuals), a mean (SD) of 10.8 (3.5) hot flashes and 8.4 (3.6) moderate-to-severe hot flashes daily was reported at baseline. Sixty-five participants assigned to NTG (92.9%) and 69 assigned to placebo (97.2%) completed 12-week follow-up (P = .27). Over 5 weeks, the estimated change in any hot flash frequency associated with NTG vs placebo was -0.9 (95% CI, -2.1 to 0.3) episodes per day (P = .10), and change in moderate-to-severe hot flash frequency with NTG vs placebo was -1.1 (95% CI, -2.2 to 0) episodes per day (P = .05). At 12 weeks, treatment with NTG did not significantly decrease the frequency of any hot flashes (-0.1 episodes per day; 95% CI, -1.2 to 0.4) or moderate-to-severe hot flashes (-0.5 episodes per day; 95% CI, -1.6 to 0.7) relative to placebo. In analyses combining 5-week and 12-week data, no significant differences in change in the frequency of any hot flashes (-0.5 episodes per day; 95% CI, -1.6 to 0.6; P = .25) or moderate-to-severe hot flashes (-0.8 episodes per day; 95% CI, -1.9 to 0.2; P = .12) were detected with NTG vs placebo. At 1 week, 47 NTG (67.1%) and 4 placebo participants (5.6%) reported headache (P < .001), but only 1 participant in each group reported headache at 12 weeks. Conclusions and Relevance This randomized clinical trial found that continuous use of NTG did not result in sustained improvements in hot flash frequency or severity relative to placebo and was associated with more early but not persistent headache. Trial Registration Clinicaltrials.gov Identifier: NCT02714205.
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Affiliation(s)
- Alison J. Huang
- Department of Medicine, University of California, San Francisco
| | - Steven R. Cummings
- Department of Medicine, University of California, San Francisco
- San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco
| | - Peter Ganz
- Department of Medicine, University of California, San Francisco
| | - Michael Schembri
- Department of Obstetrics and Gynecology, University of California, San Francisco
| | | | - Eric Vittinghoff
- Department of Epidemiology and Biostatistics, University of California, San Francisco
| | - Carolyn J. Gibson
- San Francisco VA Health Care System, San Francisco, California
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco
| | - Deborah Grady
- Department of Medicine, University of California, San Francisco
- Deputy Editor, JAMA Internal Medicine
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Pearson R, Butler A. Glyceryl Trinitrate: History, Mystery, and Alcohol Intolerance. Molecules 2021; 26:6581. [PMID: 34770988 PMCID: PMC8587134 DOI: 10.3390/molecules26216581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/27/2021] [Accepted: 10/27/2021] [Indexed: 11/23/2022] Open
Abstract
Glyceryl trinitrate (GTN) is one of the earliest known treatments for angina with a fascinating history that bridges three centuries. However, despite its central role in the nitric oxide (NO) story as a NO-donating compound, establishing the precise mechanism of how GTN exerts its medicinal benefit has proven to be far more difficult. This review brings together the explosive and vasodilatory nature of this three-carbon molecule while providing an update on the likely in vivo pathways through which GTN, and the rest of the organic nitrate family, release NO, nitrite, or a combination of both, while also trying to explain nitrate tolerance. Over the last 20 years the alcohol detoxification enzyme, aldehyde dehydrogenase (ALDH), has undoubtedly emerged as the front runner to explaining GTN's bioactivation. This is best illustrated by reduced GTN efficacy in subjects carrying the single point mutation (Glu504Lys) in ALDH, which is also responsible for alcohol intolerance, as characterized by flushing. While these findings are significant for anyone following the GTN story, they appear particularly relevant for healthcare professionals, and especially so, if administering GTN to patients as an emergency treatment. In short, although the GTN puzzle has not been fully solved, clinical study data continue to cement the importance of ALDH, as uncovered in 2002, as a key GTN activator.
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Affiliation(s)
- Russell Pearson
- School of Pharmacy & Bioengineering, Keele University, Newcastle-under-Lyme ST5 5BG, Staffordshire, UK
| | - Anthony Butler
- School of Psychology & Neuroscience, University of St Andrews, St Andrews KY16 9JP, UK;
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The novel organic mononitrate NDHP attenuates hypertension and endothelial dysfunction in hypertensive rats. Redox Biol 2017; 15:182-191. [PMID: 29268201 PMCID: PMC5735329 DOI: 10.1016/j.redox.2017.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/30/2017] [Accepted: 12/06/2017] [Indexed: 01/13/2023] Open
Abstract
Rationale Development and progression of cardiovascular diseases, including hypertension, are often associated with impaired nitric oxide synthase (NOS) function and nitric oxide (NO) deficiency. Current treatment strategies to restore NO bioavailability with organic nitrates are hampered by undesirable side effects and development of tolerance. In this study, we evaluated NO release capability and cardiovascular effects of the newly synthesized organic nitrate 1, 3-bis (hexyloxy) propan-2-yl nitrate (NDHP). Methods A combination of in vitro and in vivo approaches was utilized to assess acute effects of NDHP on NO release, vascular reactivity and blood pressure. The therapeutic value of chronic NDHP treatment was assessed in an experimental model of angiotensin II-induced hypertension in combination with NOS inhibition. Results NDHP mediates NO formation in both cell-free system and small resistance arteries, a process which is catalyzed by xanthine oxidoreductase. NDHP-induced vasorelaxation is endothelium independent and mediated by NO release and modulation of potassium channels. Reduction of blood pressure following acute intravenous infusion of NDHP was more pronounced in hypertensive rats (two-kidney-one-clip model) than in normotensive sham-operated rats. Toxicological tests did not reveal any harmful effects following treatment with high doses of NDHP. Finally, chronic treatment with NDHP significantly attenuated the development of hypertension and endothelial dysfunction in rats with chronic NOS inhibition and angiotensin II infusion. Conclusion Acute treatment with the novel organic nitrate NDHP increases NO formation, which is associated with vasorelaxation and a significant reduction of blood pressure in hypertensive animals. Chronic NDHP treatment attenuates the progression of hypertension and endothelial dysfunction, suggesting a potential for therapeutic applications in cardiovascular disease. The organic nitrate NDHP mediates NO formation in cell-free system and blood vessels. NDHP-mediated NO release is dependent on functional XOR. NDHP induces endothelium-independent vasorelaxation and significant reduction of blood pressure. NDHP-mediated vasorelaxation involves activation of NO/cGMP/PKG pathway and K+ channels (Kv and BKCa). Chronic treatment with NDHP attenuates the development of hypertension and endothelial dysfunction.
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To the Editor:. Menopause 2017; 24:118. [DOI: 10.1097/gme.0000000000000818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Huang AJ, Cummings SR, Schembri M, Vittinghoff E, Ganz P, Grady D. Continuous transdermal nitroglycerin therapy for menopausal hot flashes: a single-arm, dose-escalation trial. Menopause 2016; 23:330-4. [PMID: 26263283 PMCID: PMC4746109 DOI: 10.1097/gme.0000000000000520] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To describe the efficacy and tolerability of continuous nitroglycerin for treatment of hot flashes. METHODS Perimenopausal and postmenopausal women reporting at least seven hot flashes per day were recruited into a single-arm, dose-escalation trial of continuous transdermal nitroglycerin. Participants were started on a generic 0.1 mg/hour nitroglycerin patch applied daily without patch-free periods. During 4 weeks, participants escalated dosage weekly to 0.2, 0.4, or 0.6 mg/hour as tolerated, then discontinued nitroglycerin during the final week. Changes in hot flash frequency and severity were assessed using symptom diaries. Paired t tests examined change in outcomes between baseline and maximal-dose therapy and after discontinuation of nitroglycerin. RESULTS Of the 19 participants, mean age was 51.4 (±4.3) years. Women reported an average 10.6 (±3.0) hot flashes and 7.1 (±3.8) moderate-to-severe hot flashes per day at baseline. Eleven women escalated to 0.6 mg/hour, three to 0.4 mg/hour, two to 0.2 mg/hour, and one remained on 0.1 mg/hour nitroglycerin. Two discontinued nitroglycerin before the first outcomes assessment. Among the remaining 17 women, the average daily frequency of hot flashes decreased by 54% and the average frequency of moderate-to-severe hot flashes decreased by 69% from baseline to maximum-dose therapy (P < 0.001 for both). After discontinuing nitroglycerin, participants reported an average 23% increase in frequency of any hot flashes (P = 0.041) and 96% increase in moderate-to-severe hot flashes (P < 0.001). CONCLUSIONS Continuous nitroglycerin may substantially and reversibly decrease hot flash frequency and severity. If confirmed in a randomized blinded trial, it may offer a novel nonhormonal hot flash treatment.
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Affiliation(s)
- Alison J Huang
- 1Department of Medicine, University of California, San Francisco, California 2San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, California 3Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California 4Department of Epidemiology and Biostatistics, University of California, San Francisco, California
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Pharmacological characterization of the vasodilating effect induced by the ruthenium complex cis-[Ru(NO)(NO2)(bpy)2].(PF6)2. J Cardiovasc Pharmacol 2016; 65:168-75. [PMID: 25384194 DOI: 10.1097/fjc.0000000000000175] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nitric oxide (NO) can be found in different species and is a potent vasodilator. The ruthenium compound cis-[Ru(NO)(NO2)(bpy)2].(PF6)2 (BPY) can generate NO. This study aimed to investigate the BPY stability at physiological pH, the cellular mechanisms involved in BPY effect, NO species originating from BPY, and to verify how BPY affects blood pressure. Our results has shown that at pH 7.4 and 9.4, the NO coordinated to ruthenium (Ru-NO) is converted to nitrite (Ru-NO2) and remains stable. In aortic rings, the stable configuration of BPY (Ru-NO2) induces vascular relaxation in a concentration-dependent manner. Thus, further experiments were made with stable configuration of BPY (Ru-NO2). The relaxation induced by BPY was abolished in the presence of guanylyl cyclase inhibitor and decreased in the presence of potassium channel blocker. By using radicalar (NO) and nitroxyl (NO) scavenger, our results suggest that the BPY mainly release the radicalar species. By using fluorescence probes to detect intracellular NO concentration ([NO]i) and cytosolic Ca concentration ([Ca]c), we verified that in smooth muscle cells, BPY induces an increase in [NO]i and a decrease in [Ca]c. The intravenous bolus injection of 1.25, 2.5, and 5.0 mg/kg from stable configuration of BPY results in a decrease on basal blood pressure values. Taken together, our results indicated that the stable configuration of the compound BPY induces vascular relaxation in aorta because of NO release and decrease of [Ca]c in vascular smooth muscle cells. Also, the stable configuration is able to reduce the blood pressure in a dose-dependent manner.
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Queiroz TM, Mendes-Júnior LG, Guimarães DD, França-Silva MS, Nalivaiko E, Braga VA. Cardiorespiratory effects induced by 2-nitrate-1,3-dibuthoxypropan are reduced by nitric oxide scavenger in rats. Auton Neurosci 2013; 181:31-6. [PMID: 24418115 DOI: 10.1016/j.autneu.2013.12.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 11/26/2022]
Abstract
The search for new nitric oxide donors is warranted by the limitations of organic nitrates currently used in cardiology. The new organic nitrate 2-nitrate-1,3-dibuthoxypropan (NDBP) exhibited promising cardiovascular activities in previous studies. The aim of this study was to investigate the cardiorespiratory responses evoked by NDBP and to compare them to the clinically used organic nitrate nitroglycerine (NTG). Arterial pressure, heart rate and respiration were recorded in conscious adult male Wistar rats. Bolus i.v. injection of NDBP (1 to 15mg/kg; n=8) and NTG (0.1 to 5mg/kg; n=8) produced hypotension. NDBP induced bradycardia at all doses, while NTG induced tachycardia at three lower doses but bradycardia at higher doses. Hydroxocobalamin (20mg/kg; HDX), a NO scavenger, blunted hypotension induced by NDBP (15mg/kg), and its bradycardic effect (n=6). In addition, HDX blunted both hypotension and bradycardia induced by a single dose of NTG (2.5mg/kg; n=6). Both NDBP and NTG altered respiratory rate, inducing a biphasic effect with a bradypnea followed by a tachypnea; HDX attenuated these responses. Our data indicate that NDBP and NTG induce hypotension, bradycardia and bradypnea, which are mediated by nitric oxide release.
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Affiliation(s)
- Thyago M Queiroz
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB, Brazil
| | | | - Drielle D Guimarães
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB, Brazil
| | | | - Eugene Nalivaiko
- School of Biomedical Sciences and Pharmacy, University of Newcastle, NSW, Australia.
| | - Valdir A Braga
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB, Brazil
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Long-lasting Hypotensive Effect in Renal Hypertensive Rats Induced by Nitric Oxide Released From a Ruthenium Complex. J Cardiovasc Pharmacol 2012; 60:193-8. [DOI: 10.1097/fjc.0b013e31825bacc4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Paulo M, Rodrigues GJ, da Silva RS, Bendhack LM. A new NO donor failed to release NO and to induce relaxation in the rat basilar artery. Eur J Pharm Sci 2012; 45:344-50. [DOI: 10.1016/j.ejps.2011.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/01/2011] [Accepted: 12/01/2011] [Indexed: 11/28/2022]
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Rodrigues G, Cicillini S, Silva R, Bendhack L. Mechanisms underlying the vascular relaxation induced by a new nitric oxide generator. Nitric Oxide 2011; 25:331-7. [DOI: 10.1016/j.niox.2011.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Revised: 05/29/2011] [Accepted: 06/03/2011] [Indexed: 11/16/2022]
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Smajilovic S, Schaal-Jensen R, Jabbari R, Smajilovic U, Haunso S, Tfelt-Hansen J. Effect of intermittent versus continuous parathyroid hormone in the cardiovascular system of rats. Open Cardiovasc Med J 2010; 4:110-6. [PMID: 20461233 PMCID: PMC2866532 DOI: 10.2174/1874192401004010110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 03/08/2010] [Accepted: 03/10/2010] [Indexed: 11/22/2022] Open
Abstract
Objective: PTH increases ionic calcium concentration in the serum, acting primarily on bone and kidney cells through the type 1 PTH receptor. Interestingly, PTH stimulates bone formation when administrated intermittently but causes severe bone loss with continuous administration. Daily injections of PTH are used as the most promising anabolic agent in the treatment of severe osteoporosis. Elevated PTH is reported an independent risk factor for left ventricle hypertrophy. Design: in rats we investigated the effect of intermittent and continuous administration of PTH on blood pressure, heart rate and development of cardiac hypertrophy and fibrosis. Results: We did not find PTH to induce heart hypertrophy. In contrast, continuous administration of PTH the mRNA level of a hypertrophic marker gene, atrial natriuretic peptide. When comparing the effect of continuously versus injected PTH collagen 1 mRNA was significantly higher in continuously treated animals. Conclusion: our data demonstrated a decrease in heart rate upon continuous administration of PTH in rats. No changes in blood pressure were observed. Moreover, neither intermittent nor continuous administration of PTH induced ventricular hypertrophy. But continuous PTH induced a marker of collagen 1. Thus, these data did not reveal any negative effects of the injection of PTH on the cardiovascular system.
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Affiliation(s)
- Sanela Smajilovic
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Denmark
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Charakida M, Tousoulis D, Skoumas I, Pitsavos C, Vasiliadou C, Stefanadi E, Antoniades C, Latsios G, Siasos G, Stefanadis C. Inflammatory and thrombotic processes are associated with vascular dysfunction in children with familial hypercholesterolemia. Atherosclerosis 2008; 204:532-7. [PMID: 19004443 DOI: 10.1016/j.atherosclerosis.2008.09.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 06/21/2008] [Accepted: 09/19/2008] [Indexed: 01/04/2023]
Abstract
BACKGROUND Evidence suggests that children with familial hypercholesterolemia (FH) have endothelial dysfunction. Inflammatory and haemostatic abnormalities are associated with advanced atherosclerosis and increased cardiovascular events. However, it is unknown whether these abnormalities present in FH children and contribute to their vascular dysfunction. METHODS AND RESULTS We studied 38 children with FH (19 males, 19 females aged 14.8+/-0.9 years mean+/-S.E.) and 41 healthy children (controls; 22 males, 19 females aged 15.4+/-0.7 years). Endothelium-dependent reactive hyperemia (RH%) and endothelium-independent nitrate hyperemia dilatation (NH%) were measured by strain gauge plethysmography. Inflammatory and haemostatic parameters were assessed by ELISA. RH% and NH% were significantly reduced in FH compared to controls (91.3+/-9.3% vs. 120.4+/-10.6% and 53.6+/-3.8% vs. 74.5+/-7.4%, p<0.05 for both). Total cholesterol and lipoprotein (a) were increased in FH children compared to controls (282.3+/-8.8 mg/dl vs. 163.8+/-4.6 mg/dl and 11.0[4.6, 30.7]mg/dl vs. 5.24[2.63, 11.0]mg/dl median [IQR] respectively; p<0.001 for both). Intercellular cell adhesion molecule (ICAM-1) and interleukin 1 beta (IL-1 beta) serum levels were increased in FH compared to controls (p<0.05 and <0.001, respectively). Plasminogen activator inhibitor 1 (PAI-1) levels were also higher in FH children (p<0.001). Multivariate analysis revealed that reactive hyperemia was independently associated with nitrate-dependent reactive hyperemia (beta=0.597(0.199), p<0.01), PAI-1(beta=-6.78(2.65), p<0.05), log IL-1 beta (beta=-102.8 (30.2), p<0.01), age (beta=-5.06 (2.35), p<0.05) and FH status (beta=-25.2(10.6), p<0.05) (R(2) for the model: 0.63, p=0.001). CONCLUSIONS Inflammatory and haemostatic abnormalities are present in FH children and contribute to the endothelial dysfunction observed in these children.
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Affiliation(s)
- Marietta Charakida
- Cardiology Unit, Hippokration Hospital, Athens University Medical School, Athens, Greece.
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Mayer B, Beretta M. The enigma of nitroglycerin bioactivation and nitrate tolerance: news, views and troubles. Br J Pharmacol 2008; 155:170-84. [PMID: 18574453 PMCID: PMC2538691 DOI: 10.1038/bjp.2008.263] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 05/28/2008] [Accepted: 06/03/2008] [Indexed: 02/07/2023] Open
Abstract
Nitroglycerin (glyceryl trinitrate; GTN) is the most prominent representative of the organic nitrates or nitrovasodilators, a class of compounds that have been used clinically since the late nineteenth century for the treatment of coronary artery disease (angina pectoris), congestive heart failure and myocardial infarction. Medline lists more than 15 000 publications on GTN and other organic nitrates, but the mode of action of these drugs is still largely a mystery. In the first part of this article, we give an overview on the molecular mechanisms of GTN biotransformation resulting in vascular cyclic GMP accumulation and vasodilation with focus on the role of mitochondrial aldehyde dehydrogenase (ALDH2) and the link between the ALDH2 reaction and activation of vascular soluble guanylate cyclase (sGC). In particular, we address the identity of the bioactive species that activates sGC and the potential involvement of nitrite as an intermediate, describe our recent findings suggesting that ALDH2 catalyses direct 3-electron reduction of GTN to NO and discuss possible reaction mechanisms. In the second part, we discuss contingent processes leading to markedly reduced sensitivity of blood vessels to GTN, referred to as vascular nitrate tolerance. Again, we focus on ALDH2 and describe the current controversy on the role of ALDH2 inactivation in tolerance development. Finally, we emphasize some of the most intriguing, in our opinion, unresolved puzzles of GTN pharmacology that urgently need to be addressed in future studies.
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Affiliation(s)
- B Mayer
- Department of Pharmacology and Toxicology, Karl-Franzens-University Graz, Graz, Austria.
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Effects of chronic in vivo administration of nitroglycerine on ACh-induced endothelium-dependent relaxation in rabbit cerebral arteries. Br J Pharmacol 2007; 153:132-9. [PMID: 17965730 DOI: 10.1038/sj.bjp.0707562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE In the setting of nitrate tolerance, endothelium-dependent relaxation is reduced in several types of peripheral vessels. However, it is unknown whether chronic in vivo administration of nitroglycerine modulates such relaxation in cerebral arteries. EXPERIMENTAL APPROACH Isometric force and smooth muscle cell membrane potential were measured in endothelium-intact strips from rabbit middle cerebral artery (MCA) and posterior cerebral artery (PCA). KEY RESULTS ACh (0.1-10 microM) concentration-dependently induced endothelium-dependent relaxation during the contraction induced by histamine in both MCA and PCA. Chronic (10 days) in vivo administration of nitroglycerine reduced the ACh-induced relaxation in PCA but not in MCA, in the presence of the cyclooxygenase inhibitor diclofenac (3 microM). In the presence of the NO-synthase inhibitor N (omega)-nitro-L-arginine (L-NNA, 0.1 mM) plus diclofenac, in MCA from both nitroglycerine-untreated control and -treated rabbits, ACh (0.1-10 microM) induced a smooth muscle cell hyperpolarization and relaxation, and these were blocked by the small-conductance Ca(2+)-activated K(+)-channel inhibitor apamin (0.1 microM), but not by the large- and intermediate-conductance Ca(2+)-activated K(+)-channel inhibitor charybdotoxin (0.1 microM). In contrast, in PCA, ACh (<3 microM) induced neither hyperpolarization nor relaxation under these conditions, suggesting that the endothelium-derived relaxing factor is NO in PCA, whereas endothelium-derived hyperpolarizing factor (EDHF) plays a significant role in MCA. CONCLUSIONS AND IMPLICATIONS It is suggested that in rabbit cerebral arteries, the function of the endothelium-derived relaxing factor NO and that of EDHF may be modulated differently by chronic in vivo administration of nitroglycerine.
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Yin CC, Lin TK, Huang KT. Superoxide counteracts low-density lipoprotein-induced human aortic smooth muscle cell proliferation. J Biosci Bioeng 2007; 104:157-62. [DOI: 10.1263/jbb.104.157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 05/26/2007] [Indexed: 11/17/2022]
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Yamamoto T, Kajikuri J, Watanabe Y, Suzuki Y, Suzumori K, Itoh T. Chronic nitroglycerine administration reduces endothelial nitric oxide production in rabbit mesenteric resistance artery. Br J Pharmacol 2006; 146:534-42. [PMID: 16056230 PMCID: PMC1751186 DOI: 10.1038/sj.bjp.0706365] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
We investigated whether 10 days' in vivo treatment with nitroglycerine (NTG) would inhibit nitric oxide production by the endothelial cells of resistance arteries ex vivo and, if so, what the underlying mechanism might be. ACh increased the intracellular nitric oxide concentration ([NO]i; estimated using the nitric oxide-sensitive fluorescent dye diaminofluorescein-2) within the endothelial cells of rabbit mesenteric resistance arteries. This effect was significantly smaller in arteries isolated from NTG-treated rabbits than in those from control rabbits. The reduction in endothelial [NO]i in NTG-treated rabbits was prevented when olmesartan (blocker of type 1 angiotensin II receptors (AT1Rs)) was coadministered in vivo with NTG and also when the superoxide scavenger manganese (III) tetrakis-(4-benzoic acid) porphyrin (Mn-TBAP), the protein kinase C (PKC) inhibitor GF109203X or L-arginine (with or without the active form of folate (5-methyltetrahydrofolate)) was incubated with the arteries in vitro. Endothelial cell superoxide production (estimated by ethidium fluorescence) was greatly increased in arteries from NTG-treated rabbits. This was normalized by in vivo coadministration of olmesartan with NTG and also by in vitro application of Mn-TBAP or GF109203X (but not of 5-methyltetrahydrofolate+L-arginine). ACh increased the intracellular Ca2+ concentration (estimated using the Ca2+-sensitive dye Fura 2) within endothelial cells, the increase being not significantly different between NTG-treated rabbits and control rabbits. We conclude that in NTG-treated rabbits, endothelial nitric oxide production in mesenteric resistance arteries is reduced, possibly through a reduction in the bioavailability of L-arginine via an action mediated by superoxide. Activation of the AT1R-PKC pathway may be involved in increasing superoxide production.
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Affiliation(s)
- Tamao Yamamoto
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Junko Kajikuri
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Yoshimasa Watanabe
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Yoshikatsu Suzuki
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Kaoru Suzumori
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Takeo Itoh
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
- Author for correspondence:
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Otto A, Fontaine J, Berkenboom G. Ramipril treatment protects against nitrate-induced oxidative stress in eNOS-/- mice: An implication of the NADPH oxidase pathway. J Cardiovasc Pharmacol 2006; 48:842-9. [PMID: 16891913 DOI: 10.1097/01.fjc.0000238587.68239.52] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The development of nitrate tolerance has been found to be associated with vascular production of superoxide anion (O2-*), generated mainly by the eNOS and NADPH oxidase pathways. The aim of our study was to investigate whether long-term angiotensin-converting enzyme inhibition by ramipril is able to protect against nitrate tolerance in the aortas of eNOS-deficient (eNOS-/-) mice and to assess the implication of the NADPH oxidase pathway. Therefore, 3 types of treatment were given to wild-type (WT) and eNOS-/- mice: group 1 received ramipril for 5 weeks and a co-treatment with ramirpil plus nitroglycerine (NTG) during the last 4 days, group 2 received only NTG, and group 3 served as control. Relaxations to NTG (0.1 nmol/L to 0.1 mmol/L) were determined on U44619, a thromboxane analogue, precontracted rings, and O2-* production were assessed on aorta homogenates with the lucigenin-enhanced chemiluminescence technique. Cyclic guanosine monophosphate and reverse-transcriptase-polymerase chain reaction analyses were performed on whole mouse aortas. In WT group 2, the concentration-effect curves to NTG were significantly shifted to the right: the pD2 was 6.16 +/- 0.17 (n = 6) vs 6.81 +/- 0.10 (n = 6) in WT group 3 (not exposed to NTG; P < 0.05) and O2-* production was enhanced from 100% +/- 11% (n = 9) to 191% +/- 21% (n = 6; P < 0.01). In contrast, in WT group 1, the rightward shift was abolished: the pD2 value was 6.73 +/- 0.13 (n = 6; NS vs group 3 WT) and O2-* production was 117% +/- 6% (n = 7; NS vs group 3 WT). In eNOS groups 1 and 3, similar data were observed: the pD2 values were 7.58 +/- 0.08 and 7.38 +/- 0.11 (NS) vs 6.89 +/- 0.20 in eNOS group 2 (n = 6; P < 0.01). In the WT mice aortas, ramipril treatment significantly increased the cyclic guanosine monophosphate levels (reflecting nitric oxide availability), which returned to control values after in vivo co-treatment with a bradykinin BK2 antagonist (Icatibant). In both strains, candesartan, an AT1 blocker, was also able to protect against the development of nitrate tolerance. Moreover, before NTG exposure, ramipril treatment decreased p22phox and gp91phox (essential NADPH oxidase subunits) mRNA expression in aortas from both mice strains. In conclusion, long-term ramipril treatment in mice protects against the development of nitrate tolerance by counteracting NTG-induced increase in O2 production, which involves a direct interaction with the NADPH oxidase pathway and seems to be completely independent of the eNOS pathway.
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Affiliation(s)
- Anne Otto
- Physiology and Pharmacology Department, ERASME Hospital, Universite Libre de Bruxelles, Brussels, Belgium
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Adding LC, Agvald P, Andersson LI, Jonzon B, Hoogstraate J, Gustafsson LE. Direct gas measurements indicate that the novel cyclooxygenase inhibitor AZD3582 is an effective nitric oxide donor in vivo. Br J Pharmacol 2005; 145:679-87. [PMID: 15852032 PMCID: PMC1576184 DOI: 10.1038/sj.bjp.0706236] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. AZD3582 [4-(nitrooxy)butyl-(2S)-2-(6-methoxy-2-naphthyl)propanoate] is a COX-inhibiting nitric oxide donor that inhibits COX-1 and COX-2. It is as effective as naproxen in models of pain and inflammation, but causes less gastroduodenal damage. Nitric oxide (NO) is generated from AZD3582 in vitro, and this study sought to show that the drug donates NO in vivo. 2. In anaesthetised male New Zealand white rabbits, the endogenous NO concentration in exhaled air was reduced by N(G)-nitro-L-arginine methyl ester (L-NAME) (30 mg kg(- 1) i.v.) from 33.5+/-1.0 ppb (mean+/-s.e.m.; n=6 per group) to 3.0+/-1.0 ppb, while increasing blood pressure and reducing heart rate. AZD3582 (0.2, 0.6, 2.0 or 6.0 micromol kg(- 1) min(- 1)) given 30 min after L-NAME increased the concentration of NO in exhaled air (P<0.05), decreased blood pressure and increased heart rate in a dose-dependent manner versus L-NAME control values. The peak mean NO concentration obtained was 44+/-8.0 ppb. 3. In in situ-perfused rabbit lungs, L-NAME (185 micromol l(- 1)) reduced the NO concentration in exhaled air from 106+/-13 to 4.0+/-0.4 ppb (n=5). Addition of AZD3582 (6 micromol min(- 1)) to the perfusate produced an initial rapid increase in the NO concentration in exhaled air, followed by a sustained, but lower plateau. Infusion of L-NAME increased, and AZD3582 decreased, pulmonary arterial pressure. 4. In both anaesthetised rabbits and in the perfused lungs, brief periods of hypoxia increased NO concentrations generated by AZD3582. 5. We conclude that, in rabbits, AZD3582 donates NO in vivo with characteristics similar to those reported for nitroglycerin and isosorbide nitrates
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Affiliation(s)
- L Christofer Adding
- Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm, Sweden
| | - Per Agvald
- Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm, Sweden
| | - Lars I Andersson
- Research DMPK & Biomarkers, AstraZeneca R&D Södertälje, S-151 85 Södertälje, Sweden
| | - Bror Jonzon
- Experimental Medicine, AstraZeneca R&D Södertälje, S-151 85 Södertälje, Sweden
| | - Janet Hoogstraate
- Research DMPK & Biomarkers, AstraZeneca R&D Södertälje, S-151 85 Södertälje, Sweden
| | - Lars E Gustafsson
- Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm, Sweden
- Center for Allergy Research, Karolinska Institute, Stockholm, Sweden
- Author for correspondence:
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19
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Daiber A, Mülsch A, Hink U, Mollnau H, Warnholtz A, Oelze M, Münzel T. The oxidative stress concept of nitrate tolerance and the antioxidant properties of hydralazine. Am J Cardiol 2005; 96:25i-36i. [PMID: 16226933 DOI: 10.1016/j.amjcard.2005.07.030] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The hemodynamic and anti-ischemic effects of nitroglycerin (NTG) are rapidly blunted as a result of the development of nitrate tolerance. With initiation of NTG therapy, it is possible to detect neurohormonal activation and intravascular volume expansion. These so-called pseudotolerance mechanisms may compromise the vasodilatory effects of NTG. Long-term nitrate treatment also is associated with decreased vascular responsiveness caused by changes in intrinsic mechanisms of the tolerant vasculature itself. According to the oxidative stress concept, increased vascular superoxide (O2-) production and an increased sensitivity to vasoconstrictors secondary to activation of protein kinase C contribute to the development of tolerance. Nicotinamide adenine dinucleotide phosphate oxidase and the uncoupled endothelial nitric oxide synthase may be O2- -producing enzymes. Nitric oxide (NO) and O2-, both derived from NTG and the vessel wall, form peroxynitrite in a diffusion-limited rapid reaction. Peroxynitrite, O2-, or both may be responsible for the development of nitrate tolerance and cross-tolerance to direct NO donors (eg, sodium nitroprusside, sydnonimines) and endothelium-dependent NO synthase-activating vasodilators. Hydralazine is an efficient reactive oxygen species (ROS) scavenger and an inhibitor of O2- generation. When given concomitantly with NTG, hydralazine prevents the development of nitrate tolerance and normalizes endogenous rates of vascular O2- production. Recent experimental work has defined new tolerance mechanisms, including inhibition of the enzyme that bioactivates NTG (ie, mitochondrial aldehyde dehydrogenase isoform 2 [ALDH2]) and mitochondria as potential sources of ROS. NTG-induced ROS inhibit the bioactivation of NTG by ALDH2. Both mechanisms increase oxidative stress and impair NTG bioactivation, and now converge at the level of ALDH2 to support a new theory for NTG tolerance and NTG-induced endothelial dysfunction. The consequences of these processes for NTG downstream targets (eg, soluble guanylyl cyclase, cyclic guanosine monophosphate-dependent protein kinase), toxic effects contributing to endothelial dysfunction (eg, prostacyclin synthase inhibition) and novel applications of the antioxidant properties of hydralazine are discussed.
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Affiliation(s)
- Andreas Daiber
- The 2nd Medical Clinic, Department of Cardiology, Johannes Gutenberg University, Mainz, Germany
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20
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Kusama N, Kajikuri J, Watanabe Y, Suzuki Y, Katsuya H, Itoh T. Characteristics of attenuated endothelium-dependent relaxation seen in rabbit intrapulmonary vein following chronic nitroglycerine administration. Br J Pharmacol 2005; 145:193-202. [PMID: 15753949 PMCID: PMC1576130 DOI: 10.1038/sj.bjp.0706178] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 This study was undertaken to determine whether long-term in vivo administration of nitroglycerine (NTG) downregulates the endothelium-dependent relaxation induced by acetylcholine (ACh) in the rabbit intrapulmonary vein and, if so, whether the type 1 angiotensin II receptor (AT(1)R) blocker valsartan normalizes this downregulated relaxation. 2 In strips treated with the cyclooxygenase inhibitor diclofenac, ACh induced a relaxation only when the endothelium was intact. A small part of this ACh-induced relaxation was inhibited by coapplication of two Ca(2+)-activated K(+)-channel blockers (charybdotoxin (CTX)+apamin) and the greater part of the response was inhibited by the nitric-oxide-synthase inhibitor N(omega)-nitro-L-arginine (L-NNA). 3 The endothelium-dependent relaxation induced by ACh, but not the endothelium-independent relaxation induced by the nitric oxide donor NOC-7, was significantly reduced in NTG-treated rabbits (versus those in NTG-nontreated control rabbits). The attenuated relaxation was normalized by coapplication of valsartan with the NTG. 4 In the vascular wall, both the amount of localized angiotensin II and the production of superoxide anion were increased by in vivo NTG treatment. These variables were normalized by coapplication of valsartan with the NTG. 5 It is suggested that long-term in vivo administration of NTG downregulates the ACh-induced endothelium-dependent relaxation, mainly through an inhibition of endothelial nitric oxide production in the rabbit intrapulmonary vein. A possible role for AT(1)R is proposed in the mechanism underlying this effect.
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Affiliation(s)
- Nobuyoshi Kusama
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Kawasumi 1, Mizuho-ku, Nagoya 467-8601, Japan
- Department of Anesthesiology and Medical Crisis Management, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Junko Kajikuri
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Kawasumi 1, Mizuho-ku, Nagoya 467-8601, Japan
| | - Yoshimasa Watanabe
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Kawasumi 1, Mizuho-ku, Nagoya 467-8601, Japan
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Yoshikatsu Suzuki
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Hirotada Katsuya
- Department of Anesthesiology and Medical Crisis Management, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Takeo Itoh
- Department of Cellular and Molecular Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Kawasumi 1, Mizuho-ku, Nagoya 467-8601, Japan
- Author for correspondence:
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Janero DR, Bryan NS, Saijo F, Dhawan V, Schwalb DJ, Warren MC, Feelisch M. Differential nitros(yl)ation of blood and tissue constituents during glyceryl trinitrate biotransformation in vivo. Proc Natl Acad Sci U S A 2004; 101:16958-63. [PMID: 15550545 PMCID: PMC534729 DOI: 10.1073/pnas.0406075101] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO)-derived products may modify tissue constituents, forming S- and N-nitroso adducts and metal nitrosyls implicated in NO signaling. Nitrovasodilator drugs have been in widespread use for more than a century, yet their biotransformation pathways to NO and their effects as NO donors across tissues remain ill defined. By using a metabonomics approach (termed "NObonomics") for detailing the global NO-related metabolism of the cornerstone nitrovasodilator, glyceryl trinitrate (GTN; 0.1-100 mg/kg), in the rat in vivo, we find that GTN biotransformation elicits extensive tissue nitros(yl)ation throughout all major organ systems. The corresponding reaction products remained detectable hours after administration, and vascular tissue was not a major nitros(yl)ation site. Extensive heart and liver modifications involved both S- and N-nitrosation, and RBC S-nitrosothiol formation emerged as a sensitive indicator of organic nitrate metabolism. The dynamics of GTN-derived oxidative NO metabolites in blood did not reflect the nitros(yl)ation patterns in the circulation or in tissues, casting doubt on the usefulness of plasma nitrite/nitrate as an index of NO/NO-donor biodynamics. Target-tissue NO metabolites varied in amount and type with GTN dose, suggesting a dose-sensitive shift in the prevailing routes of GTN biotransformation ("metabolic shunting") from thiol nitrosation to heme nitrosylation. We further demonstrate that GTN-induced nitros(yl)ation is modulated by a complex, tissue-selective interplay of enzyme-catalyzed pathways. These findings provide insight into the global in vivo metabolism of GTN at pharmacologically relevant doses and offer an additional experimental paradigm for the NObonomic analysis of NO-donor metabolism and signaling.
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Affiliation(s)
- David R Janero
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118, USA
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22
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Bonaventura D, de S Oliveira F, Togniolo V, Tedesco AC, da Silva RS, Bendhack LM. A macrocyclic nitrosyl ruthenium complex is a NO donor that induces rat aorta relaxation. Nitric Oxide 2004; 10:83-91. [PMID: 15135361 DOI: 10.1016/j.niox.2004.03.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Revised: 03/17/2004] [Indexed: 11/20/2022]
Abstract
The vasorelaxation induced by a nitrosyl macrocyclic ruthenium complex, proposed as a new nitric oxide (NO) carrier, was studied in rat isolated aorta. The compound trans-[RuCl([15]aneN4)NO]2+ was characterized by elemental analysis, UV-visible spectrum, and infrared spectrum. Based on the electrochemical process, the reduction of the compound was followed by NO release, which was also observed using norepinephrine as a reducing agent and NO released was analyzed by a sensor. Vasorelaxation induced by this NO donor was studied and compared to those obtained with sodium nitroprusside (SNP). The relaxation induced by the compound was concentration-dependent in denuded rat aortas and occurred only in pre-contracted arteries with norepinephrine. The macrocyclic compound induced relaxation with a similar efficacy as SNP, although the potency of SNP was slightly greater. The time to reach maximum relaxation (595 s) was longer than that of SNP (195 s). Relaxation was completely abolished by oxyhemoglobin, a known NO scavenger.
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Affiliation(s)
- Daniella Bonaventura
- Laboratório de Farmacologia, Depto. de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP Av. do Café s/no, 14040-903 Ribeirão Preto, SP, Brazil
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23
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Abstract
Organic nitrates such as nitroglycerin (NTG) have been used as potent vasodilators in medicine for more than a century, but their biochemical mechanisms of action, particularly in relation to tolerance development, are still incompletely defined. Numerous candidate enzymes for NTG metabolism, as well as a multiplicity of tolerance mechanisms, have been proposed in the literature, but a consolidating hypothesis that links these phenomena together has not appeared. Here, we outline a "thionitrate oxidation hypothesis," which attempts to link nitrate bioactivation and tolerance development in an overall mechanism. We also attempt to compare and contrast the proposed mechanism against existing theories of nitrate action and tolerance. Interactions between organic nitrates, which have been thought of as endothelium-independent agents, and the vascular endothelium and endothelial nitric oxide synthase (eNOS) are also discussed.
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Affiliation(s)
- Ho-Leung Fung
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, New York 14260-1200, USA.
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24
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Ratz JD, Adams MA, Bennett BM. Effect of in vivo nitrate tolerance on hypersensitivity to NO donors after NO-synthase blockade. Can J Physiol Pharmacol 2002; 80:1106-18. [PMID: 12489930 DOI: 10.1139/y02-141] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Animals treated with nitric oxide synthase (NOS) inhibitors exhibit marked hypersensitivity to the blood pressure lowering effects of exogenous nitric oxide (NO) donors. We used this model as a sensitive index to evaluate the relative importance of reduced biotransformation of glyceryl trinitrate (GTN) to NO in the development of nitrate tolerance. NOS-blockade hypertension using N(G)-nitro-L-arginine methyl ester (L-NAME) caused a marked enhancement of the mean arterial pressure (MAP) decrease mediated by GTN in nontolerant rats. However, even large doses of GTN were unable to change the MAP in GTN-tolerant, NOS-blockade hypertensive animals. In contrast, the MAP responses to the spontaneous NO donor sodium nitroprusside (SNP) were completely unaltered in either tolerant rats or tolerant NOS-blockade hypertensive animals, indicating that NO-dependent vasodilatory mechanisms remain intact despite the development of GTN tolerance. The MAP-lowering effects of GTN in NOS-blockade hypertensive animals were restored 48 h after cessation of chronic GTN exposure. These alterations in the pharmacodynamic response to GTN during tolerance development and reversal were associated with parallel changes in the pattern of GTN metabolite formation, suggesting that the activity of one or more enzymes involved in nitrate metabolism was altered as a consequence of chronic GTN exposure. These findings suggest that the vasodilation resulting from the vascular biotransformation of GTN to NO (or a closely related species) is severely compromised in nitrate-tolerant animals, and that although other mechanisms may contribute to the vascular changes observed following the development of GTN tolerance, decreased GTN bioactivation is likely the most important.
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Affiliation(s)
- Jodan D Ratz
- Department of Pharmacology and Toxicology, Faculty of Health Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
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25
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Marcondes FG, Ferro AA, Souza-Torsoni A, Sumitani M, Clarke MJ, Franco DW, Tfouni E, Krieger MH. In vivo effects of the controlled NO donor/scavenger ruthenium cyclam complexes on blood pressure. Life Sci 2002; 70:2735-52. [PMID: 12269379 DOI: 10.1016/s0024-3205(02)01528-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ruthenium(II/III) complexes able to bind and release NO* were tested in vivo, in conscious Wistar rats instrumented for continuous blood pressure (BP) measurement and administration of in bolus injections (5 to 100 nmol/Kg i.v.) of trans-[Ru(II)Cl(NO+)(cyclam)](PF6)2 (cyclam-NO) or sodium nitroprusside (SNP). For normotensive rats, cyclam-NO produced a sustained 10% BP reduction of basal MAP during 7 +/- 0.4 to 11 +/- 0.3 min. In acute hypertensive rats, cyclam-NO produced BP reduction 3-fold larger than in normotensive rats and similar to that of SNP (maximal effect: 41 +/- 1.3 vs. 45 +/- 2.2 mmHg, respectively). However, the duration of the effect of cyclam-NO was 13 to 21-fold longer than that of SNP. The hypotensive effect of cyclam-NO was fully blocked in presence of continuous infusion of a NO* scavenger, carboxy-PTIO (6 mmol/Kg/min), or of the inhibitor of cGMP activation, methylene blue (83 nmol/Kg/min), or of the cyclam-NO precursor, trans-[RuCl(tfins)(cyclam)](tfms) (cyclam-tfms) (500 mmol/Kg/min). The long lasting BP reduction of cyclam-NO can be interpreted in terms of a slower rate of NO* release (k-NO = 2.2 x 10(-3) S(-1) at 35 degrees C) following chemical reduction (E(0') = 0.10 V vs NHE). In summary, cyclam-NO showed an hypotensive effect around 20 times longer than SNP in either normotensive or hypertensive rats, which was completely inhibited by methylene blue or carboxy-PTIO. Continuous infusion of cyclam-tfms completely blocked the hypotensive effect of cyclam-NO by scavenging the NO* released by the reduced cyclam-NO.
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Affiliation(s)
- Fabiana G Marcondes
- Departamento de Fisiologia e Biofisica, Instituto de Biologia UNICAMP, Barão Geraldo, Campinas-SP, Brazil
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Gruhn N, Boesgaard S, Andersen C, Aldershvile J. Nitroglycerin tolerance: different mechanisms in vascular segments with or without intact endothelial function. J Cardiovasc Pharmacol 2002; 40:201-9. [PMID: 12131549 DOI: 10.1097/00005344-200208000-00005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In vivo tolerance to nitroglycerin seems to be induced by an increase in vascular superoxide anion levels. In rabbits with normal endothelial function, in vivo induced tolerance is functionally reversed by ex vivo removal of the endothelium, probably due to a reduction in superoxide anion levels. However, the impact of in vivo endothelial dysfunction on tolerance development has not been examined. This study investigated how in vivo endothelium denudation affects the development of in vivo nitroglycerin tolerance. The effect of in vivo endothelium denudation was examined ex vivo (myograph experiments) after prolonged continuous nitroglycerin infusion in a conscious rat model. The vascular reactivity to nitroglycerin was studied in vivo in endothelium-denuded and corresponding endothelium-intact arteries. The results show that in vivo endothelium denudation does not affect the degree of tolerance development but significantly alters the effect of interventions targeted to inhibit tolerance development. In endothelium-intact vessels, superoxide dismutase and the angiotensin II receptor blocker losartan significantly inhibited tolerance-inducing properties of the prolonged nitroglycerin infusion (E[max, nitroglycerin] response in % of normal controls: nitroglycerin tolerant 70%, superoxide dismutase 93%, losartan 99%). This effect was absent in in vivo endothelium-denuded segments (nitroglycerin tolerant 57%, superoxide dismutase 72%, losartan 60%). These findings suggest that interventions against in vivo tolerance development, within the same animal, may elicit different results depending on the presence or absence of an in vivo dysfunctional endothelium.
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Affiliation(s)
- Nicolai Gruhn
- Medical Department B 2142, Division of Cardiology and Department of Pathology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
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27
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Csont T, CsonkA C, Onody A, Görbe A, Dux L, Schulz R, Baxter GF, Ferdinandy P. Nitrate tolerance does not increase production of peroxynitrite in the heart. Am J Physiol Heart Circ Physiol 2002; 283:H69-76. [PMID: 12063276 DOI: 10.1152/ajpheart.00817.2001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Clinical studies have suggested that long-term nitrate treatment does not improve and may even worsen cardiovascular mortality, and the possible role of nitrate tolerance has been suspected. Nitrate tolerance has been recently shown to increase vascular superoxide and peroxynitrite production leading to vascular dysfunction. Nevertheless, nitrates exert direct cardiac effects independent from their vascular actions. Therefore, we investigated whether in vivo nitroglycerin treatment leading to vascular nitrate tolerance increases cardiac formation of nitric oxide (NO), reactive oxygen species, and peroxynitrite, thereby leading to cardiac dysfunction. Nitrate tolerance increased bioavailability of NO in the heart without increasing formation of reactive oxygen species. Despite elevated myocardial NO, neither cardiac markers of peroxynitrite formation nor cardiac mechanical function were affected by nitroglycerin treatment. However, serum free nitrotyrosine, a marker for systemic peroxynitrite formation, was significantly elevated in nitroglycerin-treated animals. This is the first demonstration that, although the systemic effects of nitroglycerin may be deleterious due to enhancement of extracardiac peroxynitrite formation, nitroglycerin does not result in oxidative damage in the heart.
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Affiliation(s)
- Tamás Csont
- Cardiovascular Research Group, Department of Biochemistry, University of Szeged, Szeged, H-6720, Hungary
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28
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Gruhn N, Boesgaard S, Eiberg J, Bang L, Thiis J, Schroeder TV, Aldershvile J. Effects of large conductance Ca(2+)-activated K(+) channels on nitroglycerin-mediated vasorelaxation in humans. Eur J Pharmacol 2002; 446:145-50. [PMID: 12098596 DOI: 10.1016/s0014-2999(02)01826-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nitric oxide (NO)-induced vasorelaxation and the regulation of endothelial superoxide anion levels is partly mediated by vascular large conductance Ca(2+)-activated K(+) (BK(Ca)) channels. Nitroglycerin acts through the release of NO and its effect is modulated by changes in endothelial superoxide levels. This study examines the effect of BK(Ca) channel blockade on nitroglycerin-induced vasorelaxation in human arterial and venous vascular segments and whether responses to BK(Ca) channel blockade are influenced by the development of venous nitroglycerin tolerance. Dose-relaxation curves to nitroglycerin (10(-10)-10(-4) M) were obtained in segments of the saphenous vein and the left mammary artery. Studies were performed with and without pre-incubation with the BK(Ca) channel blocker iberiotoxin (10(-7) M) and venous tolerance to nitroglycerin were induced by a 24-h i.v. infusion (0.5 microg/kg/min). Iberiotoxin reduced the vasorelaxant effect of nitroglycerin (E(max)) by 60% in endothelium-intact arteries and 13% in endothelium-denuded arteries (P<0.05). Development of nitroglycerin tolerance did not affect the response to iberiotoxin in the venous vascular segments (P>0.05) and (compared to arterial segments) veins were less sensitive to BK(Ca) channel blockade (30% reduction in E(max)) or endothelial removal. The results suggest that primarily arterial effects of nitroglycerin are significantly inhibited by changes in the activity of the endothelial BK(Ca) channels. Although endothelial BK(Ca) are likely regulators of mechanisms underlying arterial tolerance development to nitroglycerin, they do not appear to play a role in human venous nitroglycerin tolerance development.
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Affiliation(s)
- Nicolai Gruhn
- Medical Department B 2142, Division of Cardiology, University of Copenhagen, Rigshospitalet Blegdamsvej 9, DK-2100, Copenhagen, Denmark
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29
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Minamiyama Y, Imaoka S, Takemura S, Okada S, Inoue M, Funae Y. Escape from tolerance of organic nitrate by induction of cytochrome P450. Free Radic Biol Med 2001; 31:1498-508. [PMID: 11728822 DOI: 10.1016/s0891-5849(01)00733-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The mechanism of organic nitrate tolerance is poorly defined. We studied the rat P450-catalyzed conversion of organic nitrate to nitric oxide (NO) by purified P450 isoforms relationship between P450 expression and nitrate tolerance following continuous infusion of organic nitrates in rats. The hypotensive effect of an nitroglycerin (NTG) bolus injection was abolished in rats that had been previously provided a continuous 48 h infusion of NTG. This effect was accompanied by a gradual but marked decrease in plasma and urinary nitrate levels following a peak at 18-24 h. Nitrate tolerance was reversible; the decline in the hypotensive effect and P450 levels observed after 2 d of continuous infusion was followed by restoration to control levels 2 d after cessation of the infusion. Similarly, the hypotensive action disappeared in P450-depleted, and -inhibited rats. At 48 h after infusion, NTG-induced NO generation of the vessels increased in acetone (a P450 inducer) -pretreated rats. The appearance and disappearance of P450 paralleled the conversion of organic nitrates to NO. Our observations indicate that nitrate tolerance is in large part the result of decreased P450 expression and activity. Interventions that maintain or increase P450 activity may be a strategy to provide relief from ischemic conditions in humans.
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Affiliation(s)
- Y Minamiyama
- Department of Biochemistry and Molecular Pathology, Osaka City University Graduate School of Medicine, Osaka, Japan.
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30
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Jurt U, Gori T, Ravandi A, Babaei S, Zeman P, Parker JD. Differential effects of pentaerythritol tetranitrate and nitroglycerin on the development of tolerance and evidence of lipid peroxidation: a human in vivo study. J Am Coll Cardiol 2001; 38:854-9. [PMID: 11527645 DOI: 10.1016/s0735-1097(01)01414-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
OBJECTIVES We investigated the development of nitrate tolerance after continuous exposure to nitroglycerin (GTN) as compared with pentaerythritol tetranitrate (PETN) in humans. BACKGROUND Sustained therapy with GTN causes tolerance and has been associated with increased production of free oxygen radicals by the endothelium. Pentaerythritol tetranitrate is an organic nitrate that has been used in the therapy of angina. There have been no investigations concerning the development of tolerance to PETN in humans. Animal investigations suggested that continuous therapy with PETN does not cause increased free radical production or hemodynamic tolerance. METHODS We randomized 30 healthy volunteers to continuous GTN (0.6 mg/h/24 h), long-acting PETN (60 mg orally three times a day) or no treatment (control group) for seven days. We studied systemic blood pressure responses and venous volume responses to GTN with strain-gauge plethysmography. The levels of cytotoxic aldehydes and isoprostanes were measured as markers of free radical-mediated lipid peroxidation. RESULTS Tolerance, as demonstrated by blood pressure and forearm plethysmography, developed in the GTN group and was absent in the PETN group (p < 0.05). Therapy with GTN was associated with a significant increase in plasma markers of lipid peroxidation. This response was not observed in those treated with PETN (isoprostanes: control: 38 +/- 5; GTN: 59 +/- 6; PETN: 38 +/- 3 microg/ml; p < 0.005). CONCLUSIONS Treatment with PETN does not cause tolerance and is not associated with evidence of increased free radical production.
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Affiliation(s)
- U Jurt
- Division of Cardiology, Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
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31
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Gruhn N, Aldershvile J, Boesgaard S. Tetrahydrobiopterin improves endothelium-dependent vasodilation in nitroglycerin-tolerant rats. Eur J Pharmacol 2001; 416:245-9. [PMID: 11290375 DOI: 10.1016/s0014-2999(01)00879-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Tolerance to nitroglycerin is caused by a nitroglycerin-mediated increase in vascular superoxide anion production. Administration of tetrahydrobiopterin (co-factor for endogenous nitric oxide (NO) formation) may potentially influence nitroglycerin tolerance in at least two different ways. Firstly, tetrahydrobiopterin may act as a scavenger of the nitroglycerin-mediated production of superoxide anions. Secondly, tetrahydrobiopterin may protect endothelial NO synthesis from the deleterious effects of increased oxidative stress. This study investigates whether in vivo nitroglycerin tolerance is affected by tetrahydrobiopterin supplementation and assesses the in vivo role of tetrahydrobiopterin in endogenous NO-mediated vasodilation in normal and nitroglycerin-tolerant rats. The results show that tetrahydrobiopterin does not affect nitroglycerin-derived, NO-mediated vasodilation, but reduces baseline mean arterial blood pressure (by 8 mm Hg, P<0.05) and normalizes endothelium-dependent responses to N(G)-monomethyl-L-arginine (L-NMMA) (from 7+/-1 to 22+/-4 mm Hg, P<0.05) in nitroglycerin-tolerant rats. It is concluded that altered bioavailability of tetrahydrobiopterin is involved in the pathophysiology of endothelial dysfunction seen in nitroglycerin tolerance.
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Affiliation(s)
- N Gruhn
- Medical Department B2142, Division of Cardiology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
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Tsuchiya K, Yoshizumi M, Houchi H, Mason RP. Nitric oxide-forming reaction between the iron-N-methyl-D-glucamine dithiocarbamate complex and nitrite. J Biol Chem 2000; 275:1551-6. [PMID: 10636843 DOI: 10.1074/jbc.275.3.1551] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The objective of this study was to elucidate the origin of the nitric oxide-forming reactions from nitrite in the presence of the iron-N-methyl-D-glucamine dithiocarbamate complex ((MGD)(2)Fe(2+)). The (MGD)(2)Fe(2+) complex is commonly used in electron paramagnetic resonance (EPR) spectroscopic detection of NO both in vivo and in vitro. Although it is widely believed that only NO can react with (MGD)(2)Fe(2+) complex to form the (MGD)(2)Fe(2+).NO complex, a recent article reported that the (MGD)(2)Fe(2+) complex can react not only with NO, but also with nitrite to produce the characteristic triplet EPR signal of (MGD)(2)Fe(2+).NO (Hiramoto, K., Tomiyama, S., and Kikugawa, K. (1997) Free Radical Res. 27, 505-509). However, no detailed reaction mechanisms were given. Alternatively, nitrite is considered to be a spontaneous NO donor, especially at acidic pH values (Samouilov, A., Kuppusamy, P., and Zweier, J. L. (1998) Arch Biochem. Biophys. 357, 1-7). However, its production of nitric oxide at physiological pH is unclear. In this report, we demonstrate that the (MGD)(2)Fe(2+) complex and nitrite reacted to form NO as follows: 1) (MGD)(2)Fe(2).NO complex was produced at pH 7.4; 2) concomitantly, the (MGD)(3)Fe(3+) complex, which is the oxidized form of (MGD)(2)Fe(2+), was formed; 3) the rate of formation of the (MGD)(2)Fe(2+).NO complex was a function of the concentration of [Fe(2+)](2), [MGD], [H(+)] and [nitrite].
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Affiliation(s)
- K Tsuchiya
- Free Radical Metabolite Section, Laboratory of Pharmacology and Chemistry, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
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Fink B, Dikalov S, Bassenge E. A new approach for extracellular spin trapping of nitroglycerin-induced superoxide radicals both in vitro and in vivo. Free Radic Biol Med 2000; 28:121-8. [PMID: 10656298 DOI: 10.1016/s0891-5849(99)00228-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Anti-ischemic therapy with nitrates is complicated by the induction of tolerance that potentially results from an unwanted coproduction of superoxide radicals. Therefore, we analyzed the localization of in vitro and in vivo, glyceryl trinitrate (GTN)-induced formation of superoxide radicals and the effect of the antioxidant vitamin C and of superoxide dismutase (SOD). Sterically hindered hydroxylamines 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CP-H) and 1-hydroxy-4-phosphonooxy-2,2,6,6-tetramethylpiperidin (PP-H) can be used for in vitro and in vivo quantification of superoxide radical formation. The penetration/incorporation of CP-H or PP-H and of their corresponding nitroxyl radicals was examined by fractionation of the blood and blood cells during a 1-h incubation. For monitoring in vivo, GTN-induced (130 microg/kg) O2*- formation CP-H or PP-H were continuously infused (actual concentration, 800 microM) for 90 to 120 min into rabbits. Formation of superoxide was determined by SOD- or vitamin C-inhibited contents of nitroxide radicals in the blood from A. carotis. The incubation of whole blood with CP-H, PP-H, or corresponding nitroxyl radicals clearly shows that during a 1-h incubation, as much as 8.3% of CP-H but only 0.9% of PP-H is incorporated in cytoplasm. Acute GTN treatment of whole blood and in vivo bolus infusion significantly increased superoxide radical formation as much as 4-fold. Pretreatment with 20 mg/kg vitamin C or 15,000 U/kg superoxide dismutase prevented GTN-induced nitroxide formation. The decrease of trapped radicals after treatment with extracellularly added superoxide dismutase or vitamin C leads to the conclusion that GTN increases the amount of extracellular superoxide radicals both in vitro and in vivo.
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Affiliation(s)
- B Fink
- Institute of Applied Physiology, University of Freiburg, Germany
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Agvald P, Adding LC, Gustafsson LE, Persson MG. Nitric oxide generation, tachyphylaxis and cross-tachyphylaxis from nitrovasodilators in vivo. Eur J Pharmacol 1999; 385:137-45. [PMID: 10607869 DOI: 10.1016/s0014-2999(99)00720-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitric oxide (NO) increments in exhaled air and changes in mean arterial pressure of anaesthetised rabbits were measured in order to study the NO generation from NO donors and tachyphylaxis in NO formation from nitroglycerin. Continuous infusions of isosorbide dinitrate, isosorbide-5-mononitrate and 3-morpholino-sydnonimine (SIN-1) evoked dose-dependent increases in exhaled NO, paralleled by decrements in mean arterial pressure. Repeated infusions of nitroglycerin resulted in attenuation (P<0.01) of the NO increase from a given dose. Concurrent infusions of isosorbide dinitrate, isosorbide-5-mononitrate or nitroglycerin reduced the amount of NO emanating from the bioconversion of a given dose nitroglycerin as measured in the expired air (P<0.01 for all drugs), indicating cross-tachyphylaxis. SIN-1 did not exhibit such cross-tachyphylaxis. In conclusion, measurements of exhaled NO can be a useful tool for exploration of nitrovasodilator tachyphylaxis. Cross-tachyphylaxis is only shared between some nitrovasodilators and is possibly not due to feedback from the generated NO.
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Affiliation(s)
- P Agvald
- Department of Physiology and Pharmacology, Division of Physiology, Karolinska Institute, S-171 77, Stockholm, Sweden.
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35
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Csont T, Szilvássy Z, Fülöp F, Nedeianu S, Páli T, Tosaki Á, Dux L, Ferdinandy P. Direct myocardial anti-ischaemic effect of GTN in both nitrate-tolerant and nontolerant rats: a cyclic GMP-independent activation of KATP. Br J Pharmacol 1999; 128:1427-34. [PMID: 10602321 PMCID: PMC1571777 DOI: 10.1038/sj.bjp.0702929] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We have recently demonstrated that glyceryl trinitrate (GTN) exerts a direct myocardial anti-ischaemic effect in both GTN-tolerant and nontolerant rats. Here we examined if this effect is mediated by GTN-derived nitric oxide (NO) and involves guanosine 3'5' cyclic monophosphate (cyclic GMP) and ATP-sensitive K+ channels (KATP). 2. Rats were treated with 100 mg kg-1 GTN or vehicle s.c. three times a day for 3 days to induce vascular GTN-tolerance or nontolerance. Isolated working hearts obtained from either GTN-tolerant or nontolerant rats were subjected to 10 min coronary occlusion in the presence of 10-7 M GTN or its solvent. 3. GTN improved myocardial function and reduced lactate dehydrogenase (LDH) release during coronary occlusion in both GTN-tolerant and nontolerant hearts. 4. Cardiac NO content significantly increased after GTN administration in both GTN-tolerant and nontolerant hearts as assessed by electron spin resonance. However, cardiac cyclic GMP content measured by radioimmunoassay was not changed by GTN administration. 5. When hearts from both GTN-tolerant and nontolerant rats were subjected to coronary occlusion in the presence of the KATP-blocker glibenclamide (10-7 M), the drug itself did not affect myocardial function and LDH release, however, it abolished the anti-ischaemic effect of GTN. 6. We conclude that GTN opens KATP via a cyclic GMP-independent mechanism, thereby leading to an anti-ischaemic effect in the heart in both GTN-tolerant and nontolerant rats.
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Affiliation(s)
- Tamás Csont
- Department of Biochemistry, Albert Szent-Györgyi Medical University, Dóm tér 9, H-6720 Szeged, Hungary
| | - Zoltán Szilvássy
- Department of Pharmacology, Medical University of Pécs, Pécs, Hungary
| | - Ferenc Fülöp
- Department of Pharmaceutical Chemistry, Albert Szent-Györgyi Medical University, Dóm tér 9, H-6720 Szeged, Hungary
| | - Saviana Nedeianu
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Tibor Páli
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Árpád Tosaki
- Department of Pharmacology, Medical University of Debrecen, Debrecen, Hungary
| | - László Dux
- Department of Biochemistry, Albert Szent-Györgyi Medical University, Dóm tér 9, H-6720 Szeged, Hungary
| | - Péter Ferdinandy
- Department of Biochemistry, Albert Szent-Györgyi Medical University, Dóm tér 9, H-6720 Szeged, Hungary
- Author for correspondence:
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36
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Murphy ME. Influence of redox compounds on nitrovasodilator-induced relaxations of rat coronary arteries. Br J Pharmacol 1999; 128:435-43. [PMID: 10510455 PMCID: PMC1571631 DOI: 10.1038/sj.bjp.0702777] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 Various classes of nitrovasodilators release nitric oxide (NO) through distinct reaction pathways, many of which involve endogenous reductants and/or oxidants. This study examined relaxations of isolated rat coronary arteries induced by spermine NONOate (SPNO), 3-morpholinosydnonimine (SIN-1), nitroprusside (NP), S-nitroso-N-acetylpenicillamine (SNAP) and nitroglycerin (NTG) in order to assess whether their potency was influenced by any of six redox compounds: 1 mM ascorbate, 1 mM dehydroascorbate, 0.1 mM dithiothreitol, 10 microM diamide, 0.1 mM ferrocyanide, and 0.1 mM ferricyanide. 2 Only SPNO spontaneously generated NO at measurable levels. These levels were decreased by the presence of ascorbate and dithiothreitol, which likewise decreased the potency of SPNO. 3 The potency of SIN-1 was unaffected by any redox compound except ferricyanide, which increased the potency not only of SIN-1, but also of other nitrovasodilators and NO-independent vasodilators. 4 The potency of NP was decreased by two structurally similar multivalent anions, ferrocyanide and ferricyanide, suggesting that NP metabolism requires ionic binding to tissue. 5 SNAP lost its potency in solutions containing ascorbate or dehydroascorbate. SNAP potency was also decreased by the glutathione oxidant, diamide, and by ferrocyanide and ferricyanide, suggesting that glutathione and ionic binding may be required for NO release. 6 NTG appeared to relax arteries via two pathways. One required only low concentrations of NTG and a labile endogenous factor that was preserved by dithiothreitol and eliminated by ferricyanide. A distinct second pathway required higher concentrations of NTG. 7 These distinct attributes of nitrovasodilator metabolism may underlie differences in regional specificity or tolerance development, and therefore might eventually be exploited in the development and use of nitrovasodilators.
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Affiliation(s)
- M E Murphy
- Department of Pharmacology and Neuroscience, The Albany Medical College, 47 New Scotland Avenue, Albany, New York, NY 12208-3479, USA.
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37
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De la Lande IS, Stafford I, Horowitz JD. Tolerance induction by transdermal glyceryl trinitrate in rats. Eur J Pharmacol 1999; 374:71-5. [PMID: 10422642 DOI: 10.1016/s0014-2999(99)00319-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mechanisms of mild glyceryl trinitrate tolerance in rats (transdermal application; 15 mg/day/2 days) were examined in isolated aortic rings contracted with phenylephrine. Tolerance to glyceryl trinitrate was comparable in both endothelium-intact and -denuded vessels; the maximum relaxation decreased to 70-80% and the EC50 increased 3-4-fold. There was minimal cross-tolerance to acetylcholine (1.7-fold increase in EC50) and none to sodium nitroprusside. The results suggest that mild tolerance to glyceryl trinitrate in rats is mediated by mechanisms which are predominantly endothelium-independent and which produce little activation of the cellular mechanism responsible for cross-tolerance.
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Affiliation(s)
- I S De la Lande
- Cardiology Unit, North Western Adelaide Health Service, The Queen Elizabeth Hospital, University of Adelaide, South Australia, Australia.
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Oroszi G, Szilvassy Z, Nemeth J, Ferdinandy P, Szolcsanyi J, Tosaki A. Interaction between capsaicin and nitrate tolerance in isolated guinea-pig heart. Eur J Pharmacol 1999; 368:R1-3. [PMID: 10193667 DOI: 10.1016/s0014-2999(99)00056-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Capsaicin-induced increases in heart rate and coronary flow were blocked by N(G)-nitro-L-Arg-methyl ester (30 mM) in Langendorff-perfused guinea-pig hearts. Neither heart rate nor coronary flow changed by capsaicin in hearts from animals made tolerant to the hypotensive effect of 30 microg/kg nitroglycerin by the administration of 50 mg/kg nitroglycerin subcutaneously 4 times a day over 3 days. We conclude that the effector function of sensory nerves may deteriorate in nitrate tolerance.
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Affiliation(s)
- G Oroszi
- Department of Pharmacology and Pharmacotherapy, Medical University of Pecs, Hungary.
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Lecour S, Maupoil V, Siri O, Tabard A, Rochette L. Electron spin resonance detection of nitric oxide generation in major organs from LPS-treated rats. J Cardiovasc Pharmacol 1999; 33:78-85. [PMID: 9890400 DOI: 10.1097/00005344-199901000-00012] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The increased production of nitric oxide (NO) has been implicated as the basis for myocardial dysfunction and the lack of response to vasoconstrictors during endotoxin shock induced by lipopolysaccharide (LPS). Our objective was to evaluate and compare NO production in major organs of rats treated with LPS, 1 or 14 mg/kg. A NO spin-trapping technique using electron spin resonance (ESR) spectroscopy has been used to study NO production in the liver, the kidney, the aorta, and the heart. The method was based on the trapping of NO by a metal-chelator complex consisting of N-methyl-D-glucamine dithiocarbamate (MGD) and reduced iron (Fe2+) to form a stable [(MGD)2-Fe2+-NO] complex, giving rise to a characteristic triplet ESR spectrum with g = 2.04 and aN = 12.65 G: Iron was quantified in the different organs to study the [(MGD)2-Fe2+] complex distribution. Six hours after intravenous injection of 1 or 14 mg/kg of LPS, we observed large increases in the [(MGD)2-Fe2+-NO] adduct signal in the liver, the kidney, and in the aorta, strongly suggesting an increased production of NO in these organs. The [(MGD)2-Fe2+-NO] adduct was also detected in the heart, 6 h after injection of LPS. Moreover, we observed dose-dependent increases in [(MGD)2-Fe2+-NO] adduct in the heart, whereas no changes were observed in the other organs. Concurrently, the [(MGD)2-Fe2+-NO] adduct was not detected in the blood from rats treated with LPS, although circulating nitrosylhemoglobin, nitrite, and nitrate levels increased. The spin-trapping technique allowed us to monitor organ-specific formation of NO after LPS administration and for the first time demonstrated direct NO production in aorta and heart of LPS-treated animals.
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Affiliation(s)
- S Lecour
- Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Facultés de Médecine et Pharmacie, Dijon, France
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Csont T, Páli T, Szilvássy Z, Ferdinandy P. Lack of correlation between myocardial nitric oxide and cyclic guanosine monophosphate content in both nitrate-tolerant and -nontolerant rats. Biochem Pharmacol 1998; 56:1139-44. [PMID: 9802323 DOI: 10.1016/s0006-2952(98)00167-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We studied the effect of nitroglycerin (NTG) on cardiac nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) content in nitrate-tolerant/nontolerant rats in vivo. The effect of the pharmacological blockade of endogenous NO synthesis and the effect of exogenous NO on cardiac cGMP were also examined. Rats were treated with 100 mg/kg of NTG and corresponding vehicle s.c. three times a day for 2.5 days to induce NTG-tolerance/nontolerance. Rats were then administered a single dose of s.c. 100 mg/kg of NTG to test the effect of NTG in tolerant/nontolerant states, respectively. Nontolerant rats treated with vehicle were controls, and nontolerant rats treated with the NO synthesis inhibitor NG-nitro-L-arginine (LNNA, 20 mg/kg) were negative controls. Another group of nontolerant rats treated i.v. with the direct NO donor sodium nitroprusside (SNP, 3 mg/kg) were positive controls. Cardiac NO assessed by electron spin resonance after in vivo spin-trapping increased 100-fold (P < 0.05) in the positive control, 10-fold (P < 0.05) in the NTG-tolerant group, and 4-fold (P < 0.05) in the single NTG group, when compared to controls. In the negative control group, NO was reduced to near the detection limit (four-fold reduction, P < 0.05). Cardiac cGMP measured by radioimmunoassay was increased significantly (two-fold, P < 0.05) only in the positive control group, and there were no differences among the other groups. This shows that: 1) in vivo cardiac bioconversion of NTG to NO is not impaired in nitrate tolerance; and 2) changes in cardiac NO content are not reflected by changes in cGMP content in nitrate-tolerant and -nontolerant rats.
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Affiliation(s)
- T Csont
- Department of Biochemistry, Albert Szent-Györgyi Medical University, Szeged, Hungary
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Abstract
Under basal conditions, nitric oxide (NO) modulates vascular tone, serves as an antithrombotic agent, and inhibits vascular smooth muscle cell proliferation. NO deficiency has been implicated in the pathophysiology of several vascular disorders, including hypertension, atherosclerosis, and restenosis, and provides a plausible biologic basis for the use of NO replacement therapy in these conditions. Treatment with conventional nitrate preparations is limited by a short therapeutic half-life, systemic absorption with potentially adverse hemodynamic effects, and drug tolerance. To overcome these limitations, novel delivery systems and novel NO donors have been developed that offer selective effects, a prolonged half-life, and a reduced incidence of tolerance.
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Affiliation(s)
- J A Leopold
- Whitaker Cardiovascular Institute, Boston Medical Center, MA 02118-2393, USA
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44
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Parker JD, Parker JO. Diuretic Therapy in Angina Pectoris: Effects on Nitrate Tolerance and Exercise Performance. Am J Cardiol 1998. [DOI: 10.1016/s0002-9149(97)00996-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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45
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Sütsch G, Kim JH, Bracht C, Kiowski W. Lack of cross-tolerance to short-term linsidomine in forearm resistance vessels and dorsal hand veins in subjects with nitroglycerin tolerance. Clin Pharmacol Ther 1997; 62:538-45. [PMID: 9390110 DOI: 10.1016/s0009-9236(97)90049-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Therapy with nitroglycerin is widely used in the treatment of angina pectoris, but development of tolerance is a major problem. Nitrovasodilators other than nitroglycerin may be less prone to induce vascular tolerance. This investigation was designed to test whether the alternative nitric oxide donor linsidomine maintains its vasodilator effects in the presence of nitroglycerin tolerance. METHODS We tested the vascular effects of nitroglycerin and linsidomine (SIN-1) in forearm resistance arteries (venous occlusion plethysmography) and hand veins (venous compliance technique) using a randomized, double-blind placebo-controlled regimen in 33 healthy subjects (age range, 22 to 38 years; mean age, 26 years) before and after 7 days of assignment to either 1 week of nitroglycerin administration (0.83 mg/hr) for induction of tolerance or placebo administration. RESULTS Vascular responses of both vascular beds to nitroglycerin (in veins: mean difference, 42.3%; confidence interval [CI], 3% to 81.7%; p < 0.05; in arteries: mean difference, 65.0%; CI, 38.9% to 91.1%; p < 0.01) but not to linsidomine (in veins: mean difference, -13.8%; CI, -53.5 to 25.8%; not significant; in arteries: -19.7%; CI, -33.7% to -5.6%; not significant) were attenuated in the nitroglycerin patch group, whereas the placebo group showed no differences to either nitroglycerin (in arteries: mean difference, -7.5%; CI, -44.6% to 29.6%; in veins: -10.6%; CI, -58.2% to 36.9%) or linsidomine (in arteries: 4.5%; CI, -12.8% to 21.7%; in veins: -13.1%; CI, -4.5% to 29.8%). CONCLUSION These results suggest that short-term administration of sydnonimines can overcome the loss of vascular relaxation associated with long-term nitroglycerin therapy.
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Affiliation(s)
- G Sütsch
- Department of Internal Medicine, University Hospital Zürich, Switzerland
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46
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Szilvassy Z, Ferdinandy P, Nagy I, Jakab I, Koltai M. The effect of continuous versus intermittent treatment with transdermal nitroglycerin on pacing-induced preconditioning in conscious rabbits. Br J Pharmacol 1997; 121:491-6. [PMID: 9179391 PMCID: PMC1564716 DOI: 10.1038/sj.bjp.0701163] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. Tolerance to the hypotensive effect of nitroglycerin (NG) blocks preconditioning induced by rapid ventricular pacing (RVP) in rabbits. In the present work the effect of continuous versus intermittent treatment with transdermal nitroglycerin on the pacing-induced preconditioning phenomenon was studied in conscious rabbits. 2. RVP (500 beats min-1 over 5 min) increased left ventricular end-diastolic pressure (LVEDP) from baseline 4.1 +/- 0.9 to postpacing 13.8 +/- 2.9 mmHg (P < 0.001) with a right intraventricular ST-segment elevation of 1.25 +/- 0.13 mV, two indicators of myocardial ischaemia. These changes were significantly attenuated when the RVP period was preceded by a preconditioning pacing of the same rate and duration with an interpacing interval of 5 min. 3. Protection by preconditioning was abolished when the animals had been made tolerant to the vasodilator effect of 30 micrograms kg-1 NG by the application of transdermal NG (approx. 0.07 mg kg-1 h-1) over 7 days. Furthermore, transdermal NG per se attenuated both RVP-induced ST-segment elevation and LVEDP-increase over the 7 day period. 4. With intermittent transdermal NG treatment (12 h 'patch on' vs 'patch off'), neither development of vascular tolerance nor attenuation of the NG- or preconditioning-induced anti-ischaemic effects were observed. However, the severity of pacing-induced myocardial ischaemia was significantly increased during the 'patch off' periods. 5. In a second set of experiments, postpacing changes in cardiac cyclic GMP and cyclic AMP levels were determined by means of radioimmunoassay in chronically instrumented anaesthetized open-chest rabbits with the same NG-treatment protocols. Preconditioning reduced postpacing increase in cyclic AMP with an increase in cyclic GMP concentrations in hearts of the untreated animals and in those given patches intermittently during both 'patch on' and 'patch off' periods. However, the preconditioning effect on either cyclic nucleotide was blocked in the tolerant animals. 6. Transdermal NG increased resting levels of both cardiac cyclic nucleotides in the non-tolerant but not in the tolerant state. The postpacing increase in cyclic AMP content was inhibited by transdermal NG, independent of vascular tolerance development, whereas an cyclic GMP content was exclusively seen in the non-tolerant animals. 7. We conclude that the anti-ischaemic effect of NG is independent of the cyclic GMP mechanism in the tolerant state. While intermittent NG therapy prevents development of vascular tolerance and preserves preconditioning, the nitrate-free periods yield an increased susceptibility of the heart to ischaemic challenges.
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Affiliation(s)
- Z Szilvassy
- 1st Department of Medicine, Albert Szent-Györgyi Medical University Szeged, Hungary
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Mülsch A, Bauersachs J, Schäfer A, Stasch JP, Kast R, Busse R. Effect of YC-1, an NO-independent, superoxide-sensitive stimulator of soluble guanylyl cyclase, on smooth muscle responsiveness to nitrovasodilators. Br J Pharmacol 1997; 120:681-9. [PMID: 9051308 PMCID: PMC1564520 DOI: 10.1038/sj.bjp.0700982] [Citation(s) in RCA: 186] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. We studied the effects of 3-(5'-hydroxymethyl-2'furyl)-1-benzyl indazole (YC-1) on the activity of purified soluble guanylyl cyclase (sGC), the formation of guanosine-3':5' cyclic monophosphate (cyclic GMP) in vascular smooth muscle cells (VSMC), and on the tone of rabbit isolated aortic rings preconstricted by phenylephrine (PE). In addition, we assessed the combined effect of YC-1, and either NO donors, or superoxide anions on these parameters. 2. YC-1 elicited a direct concentration-dependent activation of sGC (EC50 18.6 +/- 2.0 microM), which was rapid in onset and quickly reversible upon dilution. YC-1 altered the enzyme kinetics with respect to GTP by decreasing KM and increasing Vmax. Activation of sGC by a combination of sodium nitroprusside (SNP) and YC-1 was superadditive at low and less than additive at high concentrations, indicating a synergistic activation of the enzyme by both agents. A specific inhibitor of sGC, 1H-(1,2,4)-oxdiazolo-(4,3-a)-6-bromo-quinoxazin-1-one (NS 2028), abolished activation of the enzyme by either compound. 3. YC-1 induced a concentration-dependent increase in intracellular cyclic GMP levels in rat cultured aortic VSMC, which was completely inhibited by NS 2028. YC-1 applied at the same concentration as SNP elicited 2.5 fold higher cyclic GMP formation. Cyclic GMP-increases in response to SNP and YC-1 were additive. 4. YC-1 relaxed preconstricted endothelium-denuded rabbit aortic rings in a concentration-dependent manner (50% at 20 microM) and markedly increased cyclic GMP levels. Relaxations were inhibited by NS 2028. A concentration of YC-1 (3 microM), which elicited only minor effects on relaxation and cyclic GMP, increased the vasodilator potency of SNP and nitroglycerin (NTG) by 10 fold and markedly enhanced SNP- and NTG-induced cyclic GMP formation. 5. Basal and YC-1-stimulated sGC activity was sensitive to inhibition by superoxide (O-2) generated by xanthine/xanthine oxidase, and was protected from this inhibition by superoxide dismutase (SOD). YC-1-stimulated sGC was also sensitive to inhibition by endogenously generated (O-2 in rat preconstricted endothelium-denuded aortic rings. Relaxation to YC-1 was significantly attenuated in aortae from spontaneously hypertensive rats (SHR), which generated O-2 at a higher rate than aortae from normotensive Wistar Kyoto rats (WKY). SOD restored the vasodilator responsiveness of SHR rings to YC-1. 6. In conclusion, these results indicate that YC-1 is an NO-independent, O-2-sensitive, direct activator of sGC in VSMC and exerts vasorelaxation by increasing intracellular cyclic GMP levels. The additive or even synergistic responses to NO-donors and YC-1 in cultured VSMC and isolated aortic rings apparently reflect the direct synergistic action of YC-1 and NO on the sGC. The synergism revealed in this in vitro study suggests that low doses of YC-1 may be of therapeutic value by permitting the reduction of nitrovasodilator dosage.
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Affiliation(s)
- A Mülsch
- Zentrum der Physiologie, Johann-Wolfgang-Goethe Universität, Frankfurt, Germany
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