Harald Schmidt

Publications

• Activation of TRPC6 channels is essential for lung ischaemia-reperfusion induced oedema in mice.

  Norbert Weissmann, Akylbek Sydykov, Hermann Kalwa, Ursula Storch, Beate Fuchs, Michael Mederos Y Schnitzler, Ralf P Brandes, Friedrich Grimminger, Marcel Meissner, Marc Freichel, [......], Oleg Pak, Karl-Heinz Krause, Ralph T Schermuly, Alison C Brewer, Harald H H W Schmidt, Werner Seeger, Ajay M Shah, Thomas Gudermann, Hossein A Ghofrani, Alexander Dietrich

  Nature communications. 01/2012; 3:649.

  Lung ischaemia-reperfusion-induced oedema (LIRE) is a life-threatening condition that causes pulmonary oedema induced by endothelial dysfunction. Here we show that lungs from mice lacking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox2(y/-)) or the classical transient receptor pote... [more] Lung ischaemia-reperfusion-induced oedema (LIRE) is a life-threatening condition that causes pulmonary oedema induced by endothelial dysfunction. Here we show that lungs from mice lacking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox2(y/-)) or the classical transient receptor potential channel 6 (TRPC6(-/-)) are protected from LIR-induced oedema (LIRE). Generation of chimeric mice by bone marrow cell transplantation and endothelial-specific Nox2 deletion showed that endothelial Nox2, but not leukocytic Nox2 or TRPC6, are responsible for LIRE. Lung endothelial cells from Nox2- or TRPC6-deficient mice showed attenuated ischaemia-induced Ca(2+) influx, cellular shape changes and impaired barrier function. Production of reactive oxygen species was completely abolished in Nox2(y/-) cells. A novel mechanistic model comprising endothelial Nox2-derived production of superoxide, activation of phospholipase C-γ, inhibition of diacylglycerol (DAG) kinase, DAG-mediated activation of TRPC6 and ensuing LIRE is supported by pharmacological and molecular evidence. This mechanism highlights novel pharmacological targets for the treatment of LIRE.
• 3.73

  Impact points

  Endothelial dysfunction after right coronary artery remodeling: a new pathogenetic role of eNOS uncoupling?

  Yanti Octavia, Kirstin Wingler, Harald H Schmidt, An L Moens

  Journal of applied physiology (Bethesda, Md. : 1985). 07/2011; 111(1):329; author reply 330.
• 4.29

  Impact points

  Measuring oxidative burden and predicting pharmacological response in coronary artery disease patients with a novel direct activator of haem-free/oxidised sGC.

  Ingo Ahrens, Jonathon Habersberger, Nadège Baumlin, Hongwei Qian, Belinda K Smith, Johannes-Peter Stasch, Christoph Bode, Harald H H W Schmidt, Karlheinz Peter

  Atherosclerosis. 06/2011; 218(2):431-4.

  The soluble guanylate cyclase (sGC) activator Cinaciguat (BAY 58-2667) represents a novel class of drugs that selectively activate oxidised sGC. The extent of oxidised sGC depends on the patient's oxidative burden. We here describe two platelet-based assays that allow determining the extent of o... [more] The soluble guanylate cyclase (sGC) activator Cinaciguat (BAY 58-2667) represents a novel class of drugs that selectively activate oxidised sGC. The extent of oxidised sGC depends on the patient's oxidative burden. We here describe two platelet-based assays that allow determining the extent of oxidised sGC and thus provide a basis for an individualised pharmacotherapy. Platelets obtained from patients with (n=12) and without (n=12) coronary artery disease (CAD) were examined by flow cytometry (P-selectin expression), and Western blots (vasodilator associated phosphoprotein, VASP-phosphorylation). Results were compared to maximal oxidation of sGC achieved by the oxidising agent ODQ (1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one). Treatment of platelets with Cinaciguat resulted in differential activation of oxidised sGC. Platelet P-selectin expression and VASP-phosphorylation revealed significant differences (p=0.012, p=0.039, respectively) between CAD and non-CAD patients. We describe platelet-based assays that allow the determination of patients' oxidative status and thus allow the prediction of pharmacological response to direct sGC activators.
• 3.71

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  Modulating endothelial nitric oxide synthase: a new cardiovascular therapeutic strategy.

  Yixuan Zhang, Stefan P Janssens, Kirstin Wingler, Harald H H W Schmidt, An L Moens

  American journal of physiology. Heart and circulatory physiology. 05/2011; 301(3):H634-46.

  The pathogenesis of many cardiovascular diseases is associated with reduced nitric oxide (NO) bioavailability and/or increased endothelial NO synthase (eNOS)-dependent superoxide formation. These findings support that restoring and conserving adequate NO signaling in the heart and blood vessels is a... [more] The pathogenesis of many cardiovascular diseases is associated with reduced nitric oxide (NO) bioavailability and/or increased endothelial NO synthase (eNOS)-dependent superoxide formation. These findings support that restoring and conserving adequate NO signaling in the heart and blood vessels is a promising therapeutic intervention. In particular, modulating eNOS, e.g., through increasing the bioavailability of its substrate and cofactors, enhancing its transcription, and interfering with other modulators of eNOS pathway, such as netrin-1, has a high potential for effective treatments of cardiovascular diseases. This review provides an overview of the possibilities for modulating eNOS and how this may be translated to the clinic in addition to describing the genetic models used to study eNOS modulation.
• 6.08

  Impact points

  Pathogenetic role of eNOS uncoupling in cardiopulmonary disorders.

  Jan F Gielis, Judy Y Lin, Kirstin Wingler, Paul E Y Van Schil, Harald H Schmidt, An L Moens

  Free radical biology & medicine. 04/2011; 50(7):765-76.

  The homodimeric flavohemeprotein endothelial nitric oxide synthase (eNOS) oxidizes l-arginine to l-citrulline and nitric oxide (NO), which acutely vasodilates blood vessels and inhibits platelet aggregation. Chronically, eNOS has a major role in the regulation of blood pressure and prevention of ath... [more] The homodimeric flavohemeprotein endothelial nitric oxide synthase (eNOS) oxidizes l-arginine to l-citrulline and nitric oxide (NO), which acutely vasodilates blood vessels and inhibits platelet aggregation. Chronically, eNOS has a major role in the regulation of blood pressure and prevention of atherosclerosis by decreasing leukocyte adhesion and smooth muscle proliferation. However, a disturbed vascular redox balance results in eNOS damage and uncoupling of oxygen activation from l-arginine conversion. Uncoupled eNOS monomerizes and generates reactive oxygen species (ROS) rather than NO. Indeed, eNOS uncoupling has been suggested as one of the main pathomechanisms in a broad range of cardiovascular and pulmonary disorders such as atherosclerosis, ventricular remodeling, and pulmonary hypertension. Therefore, modulating uncoupled eNOS, in particular eNOS-dependent ROS generation, is an attractive therapeutic approach to preventing and/or treating cardiopulmonary disorders, including protective effects during cardiothoracic surgery. This review provides a comprehensive overview of the pathogenetic role of uncoupled eNOS in both cardiovascular and pulmonary disorders. In addition, the related therapeutic possibilities such as supplementation with the eNOS substrate l-arginine, volatile NO, and direct NO donors as well as eNOS modulators such as the eNOS cofactor tetrahydrobiopterin and folic acid are discussed in detail.
• 4.40

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  Role of tetrahydrobiopterin (BH4) in hyperhomocysteinemia-induced endothelial dysfuction: new indication for this orphan-drug?

  Rinrada Kietadisorn, Bas L Kietselaer, Harald H H W Schmidt, An L Moens

  American journal of physiology. Endocrinology and metabolism. 03/2011; 300(6):E1176; author reply E1177-8.

  n/a.
• 4.59

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  Folic acid enlarges the armamentarium for the treatment of coronary vasospasm.

  Rio P Juni, Henk J Blom, Harald H Schmidt, An L Moens

  Journal of cellular physiology. 03/2011;
• 4.41

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  Fluorescence dequenching makes haem-free soluble guanylate cyclase detectable in living cells.

  Linda S Hoffmann, Peter M Schmidt, Yvonne Keim, Carsten Hoffmann, Harald H H W Schmidt, Johannes-Peter Stasch

  PloS one. 01/2011; 6(8):e23596.

  In cardiovascular disease, the protective NO/sGC/cGMP signalling-pathway is impaired due to a decreased pool of NO-sensitive haem-containing sGC accompanied by a reciprocal increase in NO-insensitive haem-free sGC. However, no direct method to detect cellular haem-free sGC other than its activation ... [more] In cardiovascular disease, the protective NO/sGC/cGMP signalling-pathway is impaired due to a decreased pool of NO-sensitive haem-containing sGC accompanied by a reciprocal increase in NO-insensitive haem-free sGC. However, no direct method to detect cellular haem-free sGC other than its activation by the new therapeutic class of haem mimetics, such as BAY 58-2667, is available. Here we show that fluorescence dequenching, based on the interaction of the optical active prosthetic haem group and the attached biarsenical fluorophor FlAsH can be used to detect changes in cellular sGC haem status. The partly overlap of the emission spectrum of haem and FlAsH allows energy transfer from the fluorophore to the haem which reduces the intensity of FlAsH fluorescence. Loss of the prosthetic group, e.g. by oxidative stress or by replacement with the haem mimetic BAY 58-2667, prevented the energy transfer resulting in increased fluorescence. Haem loss was corroborated by an observed decrease in NO-induced sGC activity, reduced sGC protein levels, and an increased effect of BAY 58-2667. The use of a haem-free sGC mutant and a biarsenical dye that was not quenched by haem as controls further validated that the increase in fluorescence was due to the loss of the prosthetic haem group. The present approach is based on the cellular expression of an engineered sGC variant limiting is applicability to recombinant expression systems. Nevertheless, it allows to monitor sGC's redox regulation in living cells and future enhancements might be able to extend this approach to in vivo conditions.
• 3.58

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  Folic Acid as a cardiovascular drug: dose matters.

  Rinrada Kietadisorn, Harald H Schmidt, An L Moens

  The American journal of cardiology. 12/2010; 106(11):1673-4.
• 7.19

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  Oxidative stress and endothelial dysfunction in aortas of aged spontaneously hypertensive rats by NOX1/2 is reversed by NADPH oxidase inhibition.

  Sven Wind, Knut Beuerlein, Melanie E Armitage, Ashraf Taye, Arun H S Kumar, Daniel Janowitz, Christina Neff, Ajay M Shah, Kirstin Wingler, Harald H H W Schmidt

  Hypertension. 09/2010; 56(3):490-7.

  Arterial hypertension is associated with increased levels of reactive oxygen species, which may scavenge endothelium-derived NO and thereby diminish its vasorelaxant effects. However, the quantitatively relevant source of reactive oxygen species is unclear. Thus, this potential pathomechanism is not... [more] Arterial hypertension is associated with increased levels of reactive oxygen species, which may scavenge endothelium-derived NO and thereby diminish its vasorelaxant effects. However, the quantitatively relevant source of reactive oxygen species is unclear. Thus, this potential pathomechanism is not yet pharmacologically targetable. Several enzymatic sources of reactive oxygen species have been suggested: uncoupled endothelial NO synthase, xanthine oxidase, and NADPH oxidases. Here we show that increased reactive oxygen species formation in aortas of 12- to 14-month-old spontaneously hypertensive rats versus age-matched Wistar Kyoto rats is inhibited by the specific NADPH oxidase inhibitor VAS2870 but neither by the xanthine oxidase inhibitor oxypurinol nor the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester. NADPH oxidase activity, as well as protein expression of its catalytic subunits, NOX1 and NOX2, was increased in the aortas of spontaneously hypertensive rats, whereas the expression of NOX4 protein, the most abundant NOX isoform, was not significantly changed. Impaired acetylcholine-induced relaxation of spontaneously hypertensive rat aortas was significantly improved by VAS2870. In conclusion, NOX1 and NOX2 but not NOX4 proteins are increased in aged spontaneously hypertensive rat aortas. Importantly, these NOX isoforms, in particular, ectopic expression of NOX1 in endothelial cells, appear to affect vascular function in an NADPH oxidase inhibitor-reversible manner. NADPH oxidases may, thus, be a novel target for the treatment of systemic hypertension.

• Diagnosis and individual treatment of cardiovascular diseases: targeting vascular oxidative stress.

  Melanie E Armitage, Mylinh La, Harald Hhw Schmidt, Kirstin Wingler

  Expert review of clinical pharmacology. 09/2010; 3(5):639-48.

  Cardiovascular diseases are the leading cause of death and disability worldwide, yet we do not fully understand their underlying causes to reliably identify and treat, let alone prevent, these diseases. The majority of therapeutic approaches are symptom orientated, and current practice often follows... [more] Cardiovascular diseases are the leading cause of death and disability worldwide, yet we do not fully understand their underlying causes to reliably identify and treat, let alone prevent, these diseases. The majority of therapeutic approaches are symptom orientated, and current practice often follows a 'one-fits-all' approach. New strategies are needed, which harness the potential of individualized medicine with its three major pillars: in vitro diagnostics for early identification of individuals at risk and monitoring of drug efficacy; molecular imaging for disease localization and monitoring; and innovative, mechanism-based drugs. One so far untargeted mechanism of cardiovascular disease is oxidative stress, that is, the increased occurrence of reactive oxygen species in the vascular wall that leads to endothelial dysfunction. We outline why previous antioxidant supplements do not work and suggest an alternative approach targeting the enzymatic sources of oxidative stress and using emerging biomarkers of oxidative stress. These and similar approaches may be applied to fewer patients but in a much more individualized, effective and cost-saving manner.
• 12.92

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  Post-stroke inhibition of induced NADPH oxidase type 4 prevents oxidative stress and neurodegeneration.

  Christoph Kleinschnitz, Henrike Grund, Kirstin Wingler, Melanie E Armitage, Emma Jones, Manish Mittal, David Barit, Tobias Schwarz, Christian Geis, Peter Kraft, [......], Anja Schrewe, Lore Becker, Valérie Gailus-Durner, Helmut Fuchs, Thomas Klopstock, Martin Hrabé de Angelis, Karin Jandeleit-Dahm, Ajay M Shah, Norbert Weissmann, Harald H H W Schmidt

  PLoS biology. 01/2010; 8(9).

  Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thu... [more] Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox4(-/-)) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox4(-/-) mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.

• Good stress, bad stress-the delicate balance in the vasculature.

  Kirstin Wingler, Harald H H W Schmidt

  Deutsches Ärzteblatt international. 10/2009; 106(42):677-84.

  BACKGROUND: Radicals have important physiological functions, for example, in immune defense and vasoprotection. However, they are also potentially dangerous waste products of cellular metabolism and they can contribute to the development of many different diseases. METHOD: Selective literature revie... [more] BACKGROUND: Radicals have important physiological functions, for example, in immune defense and vasoprotection. However, they are also potentially dangerous waste products of cellular metabolism and they can contribute to the development of many different diseases. METHOD: Selective literature review. RESULTS: The scientific understanding of radicals has not yet led to any therapeutic application. For many years, scavenging already formed radicals with antioxidants was considered to be the most promising therapeutic approach, but clinical trials based on this principle have yielded mostly negative results. Thus, entirely new approaches are needed. The goal should be to prevent the formation of harmful radicals, or to treat radical-related damage if it has already occurred. New diagnostic tools have the potential to identify those patients that are most likely to benefit from this form of treatment, as well as to document its success. CONCLUSIONS: A new generation of cardiovascular drugs is being developed for the prevention or the mechanism-based treatment of vascular damage caused by oxidative stress. This new therapy should go hand in hand with new diagnostics, in accordance with the principle of individualized medicine.
• 5.00

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  Translating the oxidative stress hypothesis into the clinic: NOX versus NOS.

  Melanie Armitage, Kirstin Wingler, Harald Schmidt, Mylinh La

  Journal of molecular medicine (Berlin, Germany). 10/2009;

  Cardiovascular diseases remain the leading cause of death in industrialised nations. Since the pathomechanisms of most cardiovascular diseases are not understood, the majority of therapeutic approaches are symptom-orientated. Knowing the molecular mechanism of disease would enable more targeted ther... [more] Cardiovascular diseases remain the leading cause of death in industrialised nations. Since the pathomechanisms of most cardiovascular diseases are not understood, the majority of therapeutic approaches are symptom-orientated. Knowing the molecular mechanism of disease would enable more targeted therapies. One postulated underlying mechanism of cardiovascular diseases is oxidative stress, i.e. the increased occurrence of reactive oxygen species such as superoxide. Oxidative stress leads to a dysfunction of vascular endothelium-dependent protective mechanisms. There is growing evidence that this scenario also involves impaired nitric oxide (NO)-cyclic GMP signalling. Out of a number of enzyme families that can produce reactive oxygen species, NADPH oxidases stand out, as they are the only enzymes whose sole purpose is to produce reactive oxygen species. This review focuses on the clinically validated targets of oxidative stress, NO synthase (NOS) and the NO receptor, soluble guanylate cyclase as well as the source of ROS, e.g. NADPH oxidases. We place recent knowledge in the function and regulation of these enzyme families into clinical perspective. For a comprehensive overview of the biology and pharmacology of oxidative stress and possible other sources and targets, we refer to other literature overviews.

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• 9.21

  Impact points

  Nitric Oxide-Independent Vasodilator Rescues Heme-Oxidized Soluble Guanylate Cyclase From Proteasomal Degradation.

  Sabine Meurer, Sylke Pioch, Tatjana Pabst, Nils Opitz, Peter M Schmidt, Tobias Beckhaus, Kristina Wagner, Simone Matt, Kristina Gegenbauer, Sandra Geschka, Michael Karas, Johannes-Peter Stasch, Harald H H W Schmidt, Werner Müller-Esterl

  Circulation research. 06/2009;

  Nitric oxide (NO) is an essential vasodilator. In vascular diseases, oxidative stress attenuates NO signaling by both chemical scavenging of free NO and oxidation and downregulation of its major intracellular receptor, the alphabeta heterodimeric heme-containing soluble guanylate cyclase (sGC). Oxid... [more] Nitric oxide (NO) is an essential vasodilator. In vascular diseases, oxidative stress attenuates NO signaling by both chemical scavenging of free NO and oxidation and downregulation of its major intracellular receptor, the alphabeta heterodimeric heme-containing soluble guanylate cyclase (sGC). Oxidation can also induce loss of the heme of sGC, as well as the responsiveness of sGC to NO. sGC activators such as BAY 58-2667 bind to oxidized/heme-free sGC and reactivate the enzyme to exert disease-specific vasodilation. Here, we show that oxidation-induced downregulation of sGC protein extends to isolated blood vessels. Mechanistically, degradation was triggered through sGC ubiquitination and proteasomal degradation. The heme-binding site ligand BAY 58-2667 prevented sGC ubiquitination and stabilized both alpha and beta subunits. Collectively, our data establish oxidation-ubiquitination of sGC as a modulator of NO/cGMP signaling and point to a new mechanism of action for sGC activating vasodilators by stabilizing their receptor, oxidized/heme-free sGC.
• 5.20

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  Distinct molecular requirements for activation or stabilization of soluble guanylyl cyclase upon haem oxidation-induced degradation.

  L S Hoffmann, P M Schmidt, Y Keim, S Schaefer, H H H W Schmidt, J P Stasch

  British journal of pharmacology. 06/2009;

  Background and purpose: In endothelial dysfunction, signalling by nitric oxide (NO) is impaired because of the oxidation and subsequent loss of the soluble guanylyl cyclase (sGC) haem. The sGC activator 4-[((4-carboxybutyl){2-[(4-phenethylbenzyl)oxy]phenethyl}amino)methyl[benzoic]acid (BAY 58-2667) ... [more] Background and purpose: In endothelial dysfunction, signalling by nitric oxide (NO) is impaired because of the oxidation and subsequent loss of the soluble guanylyl cyclase (sGC) haem. The sGC activator 4-[((4-carboxybutyl){2-[(4-phenethylbenzyl)oxy]phenethyl}amino)methyl[benzoic]acid (BAY 58-2667) is a haem-mimetic able to bind with high affinity to sGC when the native haem (the NO binding site) is removed and it also protects sGC from ubiquitin-triggered degradation. Here we investigate whether this protection is a unique feature of BAY 58-2667 or a general characteristic of haem-site ligands such as the haem-independent sGC activator 5-chloro-2-(5-chloro-thiophene-2-sulphonylamino-N-(4-(morpholine-4-sulphonyl)-phenyl)-benzamide sodium salt (HMR 1766), the haem-mimetic Zn-protoporphyrin IX (Zn-PPIX) or the haem-dependent sGC stimulator 5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine (BAY 41-2272). Experimental approach: The sGC inhibitor 1H-(1,2,4)-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) was used to induce oxidation-induced degradation of sGC. Activity and protein levels of sGC were measured in a Chinese hamster ovary cell line as well as in primary porcine endothelial cells. Cells expressing mutant sGC were used to elucidate the molecular mechanism underlying the effects observed. Key results: Oxidation-induced sGC degradation was prevented by BAY 58-2667 and Zn-PPIX in both cell types. In contrast, the structurally unrelated sGC activator, HMR 1766, and the sGC stimulator, BAY 41-2272, did not protect. Similarly, the constitutively haem-free sGC mutant beta(1)H105F was stabilized by BAY 58-2667 and Zn-PPIX. Conclusions: The ability of BAY 58-2667 not only to activate but also to stabilize oxidized/haem-free sGC represents a unique example of bimodal target interaction and distinguishes this structural class from non-stabilizing sGC activators and sGC stimulators such as HMR 1766 and BAY 41-2272, respectively.

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• Handbook of Experimental Pharmacology 191. cGMP: generators, effectors and therapeutic implications. Preface.

  H H H W Schmidt, F Hofmann, J P Stasch

  Handbook of experimental pharmacology. 02/2009;

• cGMP in the Vasculature.

  Barbara Kemp-Harper, Harald H H W Schmidt

  Handbook of experimental pharmacology. 02/2009;

  Cyclic guanosine 3', 5'-monophosphate (cGMP) plays an integral role in the control of vascular function. Generated from guanylate cyclases in response to the endogenous ligands, nitric oxide (NO) and natriuretic peptides (NPs), cGMP influences a number of vascular cell types and regulates va... [more] Cyclic guanosine 3', 5'-monophosphate (cGMP) plays an integral role in the control of vascular function. Generated from guanylate cyclases in response to the endogenous ligands, nitric oxide (NO) and natriuretic peptides (NPs), cGMP influences a number of vascular cell types and regulates vasomotor tone, endothelial permeability, cell growth and differentiation, as well as platelet and blood cell interactions. Reciprocal regulation of the NO-cGMP and NP-cGMP pathways is evident in the vasculature such that one cGMP generating system may compensate for the dysfunction of the other. Indeed, aberrant cGMP production and/or signalling accompanies many vascular disorders such as hypertension, atherosclerosis, coronary artery disease and diabetic complications. This chapter highlights the main vascular functions of cGMP, its role in disease and the resulting current and potential therapeutic applications. With respect to pulmonary hypertension, heart failure and erectile dysfunction, as well as cGMP signal transduction, the reader is specifically referred to other dedicated chapters.

• NO- and Haem-Independent Soluble Guanylate Cyclase Activators.

  Harald H H W Schmidt, Peter M Schmidt, Johannes-Peter Stasch

  Handbook of experimental pharmacology. 02/2009;

  Oxidative stress, a risk factor for several cardiovascular disorders, interferes with the NO/sGC/cGMP signalling pathway through scavenging of NO and formation of the strong intermediate oxidant, peroxynitrite. Under these conditions, endothelial and vascular dysfunction develops, culminating in dif... [more] Oxidative stress, a risk factor for several cardiovascular disorders, interferes with the NO/sGC/cGMP signalling pathway through scavenging of NO and formation of the strong intermediate oxidant, peroxynitrite. Under these conditions, endothelial and vascular dysfunction develops, culminating in different cardio-renal and pulmonary-vascular diseases. Substituting NO with organic nitrates that release NO (NO donors) has been an important principle in cardiovascular therapy for more than a century. However, the development of nitrate tolerance limits their continuous clinical application and, under oxidative stress and increased formation of peroxynitrite foils the desired therapeutic effect. To overcome these obstacles of nitrate therapy, direct NO- and haem-independent sGC activators have been developed, such as BAY 58-2667 (cinaciguat) and HMR1766 (ataciguat), showing unique biochemical and pharmacological properties. Both compounds are capable of selectively activating the oxidized/haem-free enzyme via binding to the enzyme's haem pocket, causing pronounced vasodilatation. The potential importance of these new drugs resides in the fact that they selectively target a modified state of sGC that is prevalent under disease conditions as shown in several animal models and human disease. Activators of sGC may be beneficial in the treatment of a range of diseases including systemic and pulmonary hypertension (PH), heart failure, atherosclerosis, peripheral arterial occlusive disease (PAOD), thrombosis and renal fibrosis. The sGC activator HMR1766 is currently in clinical development as an oral therapy for patients with PAOD. The sGC activator BAY 58-2667 has demonstrated efficacy in a proof-of-concept study in patients with acute decompensated heart failure (ADHF), reducing pre- and afterload and increasing cardiac output from baseline. A phase IIb clinical study for the indication of ADHF is currently underway.

• Nitric oxide-independent vasodilator rescues heme-oxidized soluble guanylate cyclase from proteosomal degradation

  Sabine Meurer, Sylke Pioch, Tatjana Pabst, Nils Opitz, Peter Schmidt, Tobias Beckhaus, Kristina Wagner, Simone Matt, Kristina Gegenbauer, Sandra Geschka, Michael Karas, Johannes-Peter Stasch, Harald Schmidt, Werner Müller-Esterl

  BMC Pharmacology. 01/2009;