natriuretic-peptide--c-type and Hypertension

Natriuretic peptides (NPs) exert diverse effects on several biological and physiological systems, such as kidney function, neural and endocrine signaling, energy metabolism, and cardiovascular function, playing pivotal roles in the regulation of blood pressure (BP) and cardiac and vascular homeostasis. NPs are collectively known as anti-hypertensive hormones and their main functions are directed toward eliciting natriuretic/diuretic, vasorelaxant, anti-proliferative, anti-inflammatory, and anti-hypertrophic effects, thereby, regulating the fluid volume, BP, and renal and cardiovascular conditions. Interactions of NPs with their cognate receptors display a central role in all aspects of cellular, biochemical, and molecular mechanisms that govern physiology and pathophysiology of BP and cardiovascular events. Among the NPs atrial and brain natriuretic peptides (ANP and BNP) activate guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) and initiate intracellular signaling. The genetic disruption of Npr1 (encoding GC-A/NPRA) in mice exhibits high BP and hypertensive heart disease that is seen in untreated hypertensive subjects, including high BP and heart failure. There has been a surge of interest in the NPs and their receptors and a wealth of information have emerged in the last four decades, including molecular structure, signaling mechanisms, altered phenotypic characterization of transgenic and gene-targeted animal models, and genetic analyses in humans. The major goal of the present review is to emphasize and summarize the critical findings and recent discoveries regarding the molecular and genetic regulation of NPs, physiological metabolic functions, and the signaling of receptor GC-A/NPRA with emphasis on the BP regulation and renal and cardiovascular disorders.

Topics: Animals; Atrial Natriuretic Factor; Blood Pressure; Cardiovascular Diseases; Diabetes Complications; Hepatitis; Humans; Hypertension; Kidney; Mice; Natriuretic Peptide, C-Type; Polymorphism, Genetic; Protein Precursors; Receptors, Atrial Natriuretic Factor; Renin-Angiotensin System; Sodium

Hypertension management poses a major challenge to clinicians globally once non-drug (lifestyle) measures have failed to control blood pressure (BP). Although drug treatment strategies to lower BP are well described, poor control rates of hypertension, even in the first world, suggest that more needs to be done to surmount the problem. A major issue is non-adherence to antihypertensive drugs, which is caused in part by drug intolerance due to side effects. More effective antihypertensive drugs are therefore required which have excellent tolerability and safety profiles in addition to being efficacious. For those patients who either do not tolerate or wish to take medication for hypertension or in whom BP control is not attained despite multiple antihypertensives, a novel class of interventional procedures to manage hypertension has emerged. While most of these target various aspects of the sympathetic nervous system regulation of BP, an additional procedure is now available, which addresses mechanical aspects of the circulation. Most of these new devices are supported by early and encouraging evidence for both safety and efficacy, although it is clear that more rigorous randomized controlled trial data will be essential before any of the technologies can be adopted as a standard of care.

Topics: Angiotensin Receptor Antagonists; Antihypertensive Agents; Arteriovenous Shunt, Surgical; Baroreflex; Catheter Ablation; Clinical Trials as Topic; Deep Brain Stimulation; Elapid Venoms; Evidence-Based Medicine; Forecasting; Humans; Hypertension; Mineralocorticoid Receptor Antagonists; Natriuretic Peptide, C-Type; Neprilysin; Nerve Regeneration; Norepinephrine; Peptides; Renin-Angiotensin System; Sympathectomy; Transcutaneous Electric Nerve Stimulation; Vasoactive Intestinal Peptide

The natriuretic peptide (NP) family includes atrial natriuretic peptide (ANP), B-type natriuretic peptide, C-type natriuretic peptide and their receptors NPR-A, NPR-B and NPR-C. The effects exerted by this hormonal system in the control of cardiovascular, renal and endocrine functions have been extensively investigated. Moreover, the involvement of NP in the pathogenesis of cardiovascular diseases has been demonstrated. Among the NP components, NPR-C has been described, at the time of its discovery, as the clearance receptor of NP devoid of any physiological functions. Emerging roles of NPR-C, however, have been highlighted over the last few years in relation to its effects on the cardiovascular system and other organs. These effects appear to be directly mediated through distinct cAMP-dependent intracellular mechanisms. Moreover, evidence has been accumulated on a potential pathophysiological role of NPR-C in human diseases. Ongoing studies from our group are revealing its involvement in the mediation of antiproliferative effects exerted on vascular cells by a molecular variant of human ANP. Thus, a new appraisal of NPR-C is overcoming the traditional view of a mere clearance receptor. This review focuses on the most important evidence supporting an involvement of NPR-C in mediating some of the actions of NP and its direct implication in cardiovascular diseases. The current state of knowledge highlights the need of further studies to better clarify the specific roles of NPR-C in pathophysiological processes.

Topics: Atrial Natriuretic Factor; Cardiovascular Diseases; Humans; Hypertension; Natriuretic Peptide, C-Type; Obesity; Phenotype

The review analyzes the possible role of multioscillatory circadian system in the seasonal circadian variability of basic indices of cardiovascular system and probable mechanisms of development of changes in diurnal rhythms of the organism. It was postulated the close relationship between hemodynamic parameters and homeostatic mechanisms of circulation. The destruction of relationship may initiate the development of pathologic condition - desynchronizes. Studies suggest a potential role of relationship between circadian rhythms and secretion of vasoactive peptides, such as angiotensine, endothelins, sodium uretic peptide, endothelial relaxing factor and enkephalins, the circadian rhythmicity of receptor. It is suggested the necessity of investigation of circadian hemodynamic rhythms during desinchronoses formation in purpose of rational pharmacotherapy of different cardiovascular diseases.

Topics: Animals; Chronobiology Disorders; Circadian Rhythm; Hemodynamics; Humans; Hypertension; Natriuretic Peptide, C-Type; Opioid Peptides; Rats; Seasons

Topics: Adrenomedullin; Animals; Arteriosclerosis; Connexins; Cyclooxygenase 2 Inhibitors; Endothelium-Dependent Relaxing Factors; Epoprostenol; Humans; Hypertension; Natriuretic Peptide, C-Type; Nitric Oxide; Nitric Oxide Synthase Type III; Peptides

Topics: Atrial Natriuretic Factor; Biomarkers; Diagnostic Techniques, Endocrine; Heart Failure; Humans; Hypertension; Hyperthyroidism; Immunoradiometric Assay; Kidney Failure, Chronic; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Reference Values; Specimen Handling; Tachycardia, Supraventricular

Natriuretic peptide system plays a well-defined role in the regulation of blood pressure and fluid volume. Although the effects of natriuretic peptides (atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide) are mediated by specific biologic receptors, their plasma level is influenced by clearance receptors. It has been demonstrated that in hypertensive subjects plasma levels of natriuretic peptides are impaired; furthermore peptide receptor polymorphisms have been shown to be significantly associated with hypertension and cardiac hypertrophy. Studying normotensive subjects at high genetic risk of developing hypertension on the basis of family history makes it possible to investigate the role of natriuretic peptide system in the genesis of hypertension. It has been shown that plasma atrial and ventricular natriuretic peptide levels are significantly reduced in normotensive subjects with a family history of hypertension. Our study is the first one showing association among positive family history of essential hypertension and natriuretic peptide receptor polymorphisms. We identified a novel insertion/deletion polymorphism at position 15,129 in the 3'-untranslated region (3'-UTR) of NPRA receptor mRNA. The NPRA gene deletion variant is associated with hypertensive family history and higher systolic blood pressure. The "deletion 15129" variant might participate in the functional impairment of natriuretic peptide system defining an increased genetic susceptibility to hypertension.

Topics: Gene Deletion; Guanylate Cyclase; Humans; Hypertension; Natriuretic Agents; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Polymorphism, Genetic; Receptors, Atrial Natriuretic Factor

Most cardiovascular traits of interest can be defined as "complex traits," with the first step in the identification of genetic factors affecting such traits being the detection of quantitative trait loci (QTLs). Animal models have proven particularly useful in this regard. However, only very few of the QTLs identified to date have led to the identification of candidate genes. We describe an example of our own work where the combination of anatomical and a biochemical intermediate phenotypes have led to the identification of the natriuretic peptide precursor A (Nppa) gene as a candidate gene for left ventricular hypertrophy (LVH). Combined with the power of comparative genetics, these strategies will continue to improve the chances of finding candidate genes for cardiovascular traits such as susceptibility to heart diseases, hypertension, and hypertension-induced end-organ damage.

Topics: Animals; Atrial Natriuretic Factor; Genetic Predisposition to Disease; Genotype; Humans; Hypertension; Hypertrophy, Left Ventricular; Models, Animal; Natriuretic Peptide, C-Type; Phenotype; Protein Precursors; Quantitative Trait, Heritable

Topics: Arteriosclerosis; Heart Failure; Humans; Hypertension; Natriuretic Peptide, C-Type

Topics: Animals; Atrial Natriuretic Factor; Cardiovascular Diseases; Cattle; Dogs; Heart Failure; Humans; Hypertension; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; RNA, Messenger; Swine; Vasodilation

The endothelium produces a variety of substances that play important roles in regulation of the circulation and vascular wall homeostasis. The control of blood vessel wall homeostasis is achieved via production of vasorelaxants and vasoconstrictors. Among the vasorelaxants are nitric oxide (NO), prostacyclin, various endothelium-derived hyperpolarizing factors (EDHFs, such as cytochrome P-450 monooxygenase metabolites of arachidonic acid like epoxyeicosatrienoic acids, and endocannabinoids), and C-type natriuretic peptide. Among the vasoconstrictors we find endothelin-1 (ET-1) and endothelium-derived contracting factors (EDCF) that are cyclooxygenase products such as endoperoxides and thromboxanes. The endothelium, via these and other agents, also exerts a critical influence on the blood stream, particularly formed elements such as leucocytes and platelets, and on substances involved in blood coagulation. All these effects contribute to modulating the growth of the vascular wall in hypertension, and participate in the development of atherothrombotic complications associated with hypertension. Inhibition of NO production may induce elevation of blood pressure in experimental animals. However, even today, we do not have incontrovertible evidence of participation of NO, EDHFs or EDCFs, or other endothelial products, in the pathogenesis of hypertension, although there is evidence of abnormal endothelium-dependent relaxation in hypertension in many but not all hypertensives. It is unclear, however, to what extent this may precede hypertension or be a consequence of elevated blood pressure, possibly contributing to its complications. Also, it is often difficult to dissociate abnormal endothelium-dependent relaxation from confounding factors such as the presence of associated conditions like dyslipidaemia, diabetes, smoking, obesity, hyperhomocysteinaemia, and others, that are accompanied themselves by abnormal endothelium-dependent relaxation. There is some evidence for a role of ET-1 in blood pressure elevation in some experimental forms of hypertension, particularly severe, sodium-sensitive hypertension, in which it may play a role in accentuating rather than initiating blood pressure elevation. Endothelin-1 may play a similar role in human hypertension.

Topics: 8,11,14-Eicosatrienoic Acid; Cannabinoid Receptor Modulators; Cannabinoids; Endothelin-1; Endothelins; Endothelium, Vascular; Epoprostenol; Humans; Hypertension; Natriuretic Peptide, C-Type; Nitric Oxide; Oxidative Stress; Oxygen; Peroxides; Thromboxanes; Vasodilator Agents

Vasopeptidase inhibition is a new concept in cardiovascular therapy. It involves simultaneous inhibition with a single molecule of two key enzymes involved in the regulation of cardiovascular function, neutral endopeptidase (EC 24.11; NEP) and angiotensin-converting enzyme (ACE). Simultaneous inhibition of NEP and ACE increases natriuretic and vasodilatory peptides (including atrial natriuretic peptide [ANP], brain natriuretic peptide [BNP] of myocardial cell origin, and C-type natriuretic peptide [CNP] of endothelial cell origin) and increases the half-life of other vasodilator peptides including bradykinin and adrenomedullin. By simultaneously inhibiting the renin-angiotensin-aldosterone system and potentiating the natriuretic peptide system, vasopeptidase inhibitors (VPIs) reduce vasoconstriction and enhance vasodilation, thereby decreasing vascular tone and lowering blood pressure. Omapatrilat, a heterocyclic dipeptide mimetic, is a novel vasopeptidase inhibitor and a single molecule that simultaneously inhibits NEP and ACE with similar inhibition constants. Unlike ACE inhibitors, omapatrilat demonstrates antihypertensive efficacy in low-, normal-, and high-renin animal models. Unlike NEP inhibitors, omapatrilat provides a potent and sustained antihypertensive effect in spontaneously hypertensive rats (SHR), a model of human essential hypertension. In animal models of heart failure, omapatrilat is more effective than ACE inhibition in improving cardiac performance and ventricular remodeling and prolonging survival. Omapatrilat effectively reduces blood pressure, provides target-organ protection, and reduces morbidity and mortality from cardiovascular events in animal models. Omapatrilat is the first VPI to enter advanced USA clinical trials. Omapatrilat appears to be a safe, well-tolerated and effective antihypertensive in humans. Vasopeptidase inhibition is a novel and efficacious strategy for treating cardiovascular disorders, including hypertension and heart failure, that may offer advantages over currently available therapies.

Topics: Amino Acid Sequence; Angiotensin-Converting Enzyme Inhibitors; Animals; Atrial Natriuretic Factor; Blood Pressure; Humans; Hypertension; Molecular Sequence Data; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Neprilysin; Peptidyl-Dipeptidase A; Pyridines; Thiazepines

Topics: Animals; Atrial Natriuretic Factor; Heart Diseases; Hemodynamics; Humans; Hypertension; Natriuretic Peptide, C-Type

Natriuretic peptide system consists of three endogenous ligands, ANP (atrial natriuretic peptide), BNP (brain natriuretic peptide) and CNP (C-type natriuretic peptide), and three receptor subtypes, natriuretic peptide receptor (NPR)-A or guanylate cyclase (GC)-A and NPR-B or GC-B and C receptor (NPR-C). ANP and BNP are mainly secreted from the atrium and ventricle of the heart respectively to act as cardiac hormones whereas CNP is secreted from the endothelium to act as an endothelium-derived relaxing peptide. ANP and BNP regulate body fluid and blood pressure to reduce cardiac pre- and after-load. Recent molecular biology and developmental biotechnology demonstrated the physiological role of ANP and BNP for the determination of basal blood pressure. CNP can modulate the phenotype of vascular smooth muscle cells to regulate vascular remodeling. Therefore, natriuretic peptide system is implicated in the pathophysiology of hypertension, congestive heart failure atherosclerosis and renal diseases. Clinical application of natriuretic peptide system is actively going on progress. Determination of plasma ANP and BNP levels are useful for the evaluation of congestive heart failure, cardiac hypertrophy and acute myocardial infarction. Infusion of ANP improves acute heart failure. Application of NEP (neutral endopeptidase) inhibitor for the treatment of congestive heart failure and hypertension is under clinical trial.

Topics: Animals; Atrial Natriuretic Factor; Cell Differentiation; Guanylate Cyclase; Humans; Hypertension; Muscle, Smooth, Vascular; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Nitric Oxide; Proteins; Receptors, Atrial Natriuretic Factor; Signal Transduction

Natriuretic peptides are produced in the brain, heart and vasculature, and cause vasodilation, sodium excretion, and diuresis. Recent advances indicate that they play important roles in blood-pressure homeostasis, both in normal and in pathophysiological conditions. Although therapeutic interventions which elevate plasma natriuretic peptide levels do not have great antihypertensive efficacy, animal studies suggest that they may be useful in combination treatment strategies.

Topics: Animals; Atrial Natriuretic Factor; Humans; Hypertension; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins; Receptors, Peptide

Topics: Aldosterone; Angiotensin II; Animals; Atrial Natriuretic Factor; Cardiac Output, Low; Central Nervous System; Dogs; Humans; Hypertension; Male; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins; Rats; Renin; Renin-Angiotensin System; Sheep

Topics: Animals; Atrial Natriuretic Factor; Blood Pressure; Cardiovascular Agents; Humans; Hypertension; Natriuretic Peptide, C-Type

The natriuretic peptide family consists of three members: atrial natriuretic peptide, brain natriuretic peptide, and C-type natriuretic peptide. Atrial and brain natriuretic peptides possess similar effects, causing natriuresis, vasodilation, and suppression of the renin-angiotensin-aldosterone system. C-type natriuretic peptide has been suggested to exert its predominant effect on the vasculature, eliciting vasodilation and inhibiting the proliferation of vascular smooth muscle cells. Numerous studies have broadened our current knowledge of the regulation of natriuretic peptide gene expression, biosynthesis, and secretion, as well as structure of specific receptors. This has led to a better understanding of the renal, cardiovascular, and endocrine actions of natriuretic peptides in both normal and pathophysiological states, including hypertensive disease. Development of nonpeptide neutral endopeptidase inhibitors and antagonists for natriuretic peptide receptors may reveal the range of potential therapeutic application of atrial and other natriuretic peptides in hypertension.

Topics: Animals; Atrial Natriuretic Factor; Hemodynamics; Humans; Hypertension; Kidney; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins

Topics: Atrial Natriuretic Factor; Humans; Hypertension; Natriuresis; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins

Topics: Animals; Atrial Natriuretic Factor; Humans; Hypertension; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins

Topics: Animals; Atrial Natriuretic Factor; Drug Therapy, Combination; Humans; Hypertension; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Neprilysin; Nerve Tissue Proteins; Peptide Fragments

Topics: Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Blood Pressure; Humans; Hypertension; Molecular Sequence Data; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Signal Transduction

Hypertension underlies endothelial dysfunction, and activation of vasorelaxation signaling with low dependence on nitric oxide (NO) represents a good alternative for vascular modulation. C-type natriuretic peptide (CNP) causes relaxation by increasing cyclic guanosine 3',5'-monophosphate (cGMP) or Gi-protein activation through its natriuretic peptide receptor-B or -C, respectively. We have hypothesized that CNP could exerts its effects and could overcome endothelial dysfunction in two kidney-one clip (2K-1C) hypertensive rat aorta. Here, we investigate the intracellular signaling involved in CNP effects in hypertension.. The 2K-1C hypertension was induced in male Wistar rats (200 g). CNP-induced vascular relaxation and cGMP production were investigated in rat thoracic aortas. The natriuretic peptide receptor-B and -C localization was evaluated by immunofluorescence. Calcium mobilization was assessed in endothelial cells from rat aortas.. CNP induced similar relaxation in normotensive and 2K-1C hypertensive rat aortas, which increased after endothelium removal. CNP-induced relaxation involved natriuretic peptide receptor-B and -C activation in 2K-1C rats. Nitric oxide synthase (NOS) and soluble guanylyl cyclase (sGC) counter-regulated CNP-particulate GC (pGC) activation in aortas. CNP reduced endothelial calcium and increased cGMP production, which was lower in 2K-1C. CNP-induced cGMP-dependent protein kinase (PKG) and sarcoplasmic/endoplasmic reticulum Ca. Our results indicated CNP triggered relaxation through its natriuretic peptide receptor-B and -C in 2K-1C rat aortas, and that CNP-induced relaxation overcomes endothelial dysfunction in hypertension. In addition, NOS and sGC activities counter-regulate CNP-pGC activation to induce vascular relaxation.

Topics: Animals; Blood Pressure; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Endothelial Cells; Endothelium, Vascular; Guanylate Cyclase; Hypertension; Kidney; Male; Natriuretic Peptide, C-Type; Natriuretic Peptides; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Wistar; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Surgical Instruments; Vasodilation

Inflammation and fibrosis are key mechanisms in cardiovascular remodeling. C-type natriuretic peptide (CNP) is an endothelium-derived factor with a cardiovascular protective role, although its in-vivo effect on cardiac remodeling linked to hypertension has not been investigated. The aim of this study was to determine the effects of chronic administration of CNP on inflammatory and fibrotic cardiac mechanisms in normotensive Wistar rats and spontaneously hypertensive rats (SHR).. Twelve-week-old male SHR and normotensive rats were infused with CNP (0.75 μg/h/100 g) or isotonic saline (NaCl 0.9%) for 14 days (subcutaneous micro-osmotic pumps). Echocardiograms and electrocardiograms were performed, and SBP was measured. After treatment, transforming growth factor-beta 1, Smad proteins, tumor necrosis factor-alpha, interleukin-1 and interleukin-6, nitric oxide (NO) system and 2-thiobarbituric acid-reactive substances were evaluated in left ventricle. Histological studies were also performed.. SHR showed lower cardiac output with signs of fibrosis and hypertrophy in left ventricle, higher NO-system activity and more oxidative damage, as well as higher pro-inflammatory and pro-fibrotic markers than normotensive rats. Chronic CNP treatment-attenuated hypertension and ventricular hypertrophy in SHR, with no changes in normotensive rats. In left ventricle, CNP induced an anti-inflammatory and antifibrotic response, decreasing both pro-fibrotic and pro-inflammatory cytokines in SHR. In addition, CNP reduced oxidative damage as well as collagen content, and upregulated the NO system in both groups.. Chronic CNP treatment appears to attenuate hypertension and associated end-organ damage in the heart by reducing inflammation and fibrosis.

Topics: Animals; Blood Pressure; Heart; Hypertension; Inflammation; Male; Myocardium; Natriuretic Peptide, C-Type; Rats; Rats, Inbred SHR; Rats, Wistar

The aim of this study was to determine whether exogenous administration of C-type natriuretic peptide (CNP) induces functional and morphological vascular changes in spontaneously hypertensive rats (SHR) compared with normotensive rats. Male 12-week-old normotensive Wistar and SHR were administered with saline (NaCl 0.9%) or CNP (0.75 μg/h/100 g) for 14 days (subcutaneous micro-osmotic pumps). Systolic blood pressure (SBP) was measured in awake animals and renal parameters were evaluated. After decapitation, the aorta was removed, and vascular morphology, profibrotic markers, and vascular reactivity were measured. In addition, nitric oxide (NO) system and oxidative stress were evaluated. After 14-days of treatment, CNP effectively reduced SBP in SHR without changes in renal function. CNP attenuated vascular remodeling in hypertensive rats, diminishing both profibrotic and pro-inflammatory cytokines. Also, CNP activated the vascular NO system and exerted an antioxidant effect in aortic tissue of both groups, diminishing superoxide production and thiobarbituric acid-reactive substances, and increasing glutathione content. These results show that chronic treatment with CNP attenuates the vascular damage development in a model of essential hypertension, inducing changes in fibrotic, inflammatory, oxidative, and NO pathways that could contribute to beneficial long-term effects on vascular morphology, extracellular matrix composition, and function. The knowledge of these effects of CNP could lead to improved therapeutic strategies to not only control BP but also reduce vascular damage, primarily responsible for the risk of cardiovascular events.

Topics: Animals; Aorta; Blood Pressure; Cytokines; Glutathione; Hypertension; Kidney; Male; Natriuretic Agents; Natriuretic Peptide, C-Type; Nitric Oxide; Oxidative Stress; Rats; Rats, Inbred SHR; Rats, Wistar; Superoxides; Vasoconstriction

Peripheral vascular resistance has a major impact on arterial blood pressure levels. Endothelial C-type natriuretic peptide (CNP) participates in the local regulation of vascular tone, but the target cells remain controversial. The cGMP-producing guanylyl cyclase-B (GC-B) receptor for CNP is expressed in vascular smooth muscle cells (SMCs). However, whereas endothelial cell-specific CNP knockout mice are hypertensive, mice with deletion of GC-B in vascular SMCs have unaltered blood pressure.. Intravital microscopy studies revealed that the vasodilatatory effect of CNP increases toward small-diameter arterioles and capillaries. CNP consistently did not prevent endothelin-1-induced acute constrictions of proximal arterioles, but fully reversed endothelin effects in precapillary arterioles and capillaries. Here, the GC-B receptor is expressed both in endothelial and mural cells, ie, in pericytes. It is notable that the vasodilatatory effects of CNP were preserved in mice with endothelial GC-B deletion, but abolished in mice lacking GC-B in microcirculatory SMCs and pericytes. CNP, via GC-B/cGMP signaling, modulates 2 signaling cascades in pericytes: it activates cGMP-dependent protein kinase I to phosphorylate downstream targets such as the cytoskeleton-associated vasodilator-activated phosphoprotein, and it inhibits phosphodiesterase 3A, thereby enhancing pericyte cAMP levels. These pathways ultimately prevent endothelin-induced increases of pericyte calcium levels and pericyte contraction. Mice with deletion of GC-B in microcirculatory SMCs and pericytes have elevated peripheral resistance and chronic arterial hypertension without a change in renal function.. Our studies indicate that endothelial CNP regulates distal arteriolar and capillary blood flow. CNP-induced GC-B/cGMP signaling in microvascular SMCs and pericytes is essential for the maintenance of normal microvascular resistance and blood pressure.

Topics: Animals; Arterial Pressure; Biosensing Techniques; Calcium Signaling; Cells, Cultured; Cyclic GMP; Endothelial Cells; Fluorescence Resonance Energy Transfer; Genetic Predisposition to Disease; Hypertension; Mice, Inbred C57BL; Mice, Knockout; Microcirculation; Microvessels; Natriuretic Peptide, C-Type; Paracrine Communication; Pericytes; Phenotype; Receptor, Platelet-Derived Growth Factor beta; Receptors, Atrial Natriuretic Factor; Vasodilation; Vasodilator Agents

We previously reported the secretion of C-type natriuretic peptide (CNP) from vascular endothelial cells and proposed the existence of a vascular natriuretic peptide system composed of endothelial CNP and smooth muscle guanylyl cyclase-B (GC-B), the CNP receptor, and involved in the regulation of vascular tone, remodeling, and regeneration. In this study, we assessed the functional significance of this system in the regulation of blood pressure in vivo using vascular endothelial cell-specific CNP knockout and vascular smooth muscle cell-specific GC-B knockout mice. These mice showed neither the skeletal abnormality nor the early mortality observed in systemic CNP or GC-B knockout mice. Endothelial cell-specific CNP knockout mice exhibited significantly increased blood pressures and an enhanced acute hypertensive response to nitric oxide synthetase inhibition. Acetylcholine-induced, endothelium-dependent vasorelaxation was impaired in rings of mesenteric artery isolated from endothelial cell-specific CNP knockout mice. In addition, endothelin-1 gene expression was enhanced in pulmonary vascular endothelial cells from endothelial cell-specific CNP knockout mice, which also showed significantly higher plasma endothelin-1 concentrations and a greater reduction in blood pressure in response to an endothelin receptor antagonist than their control littermates. By contrast, vascular smooth muscle cell-specific GC-B knockout mice exhibited blood pressures similar to control mice, and acetylcholine-induced vasorelaxation was preserved in their isolated mesenteric arteries. Nonetheless, CNP-induced acute vasorelaxation was nearly completely abolished in mesenteric arteries from vascular smooth muscle cell-specific GC-B knockout mice. These results demonstrate that endothelium-derived CNP contributes to the chronic regulation of vascular tone and systemic blood pressure by maintaining endothelial function independently of vascular smooth muscle GC-B.

Topics: Animals; Blood Pressure; Disease Models, Animal; Endothelium, Vascular; Hypertension; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Natriuretic Peptide, C-Type; Vasoconstriction; Vasodilation

B-type natriuretic peptide (BNP)-natriuretic peptide receptor A (NPR-A) receptor signalling inhibits cardiac sympathetic neurotransmission, although C-type natriuretic peptide (CNP) is the predominant neuropeptide of the nervous system with expression in the heart and vasculature. We hypothesized that CNP acts similarly to BNP, and that transgenic rats (TGRs) with neuron-specific overexpression of a dominant negative NPR-B receptor would develop heightened sympathetic drive.. C-type natriuretic peptide reduces cardiac sympathetic neurotransmission via a reduction in neuronal calcium signalling and NE release through the NPR-B receptor. Situations impairing CNP-NPR-B signalling lead to hypertension, tachycardia, and impaired left ventricular systolic function secondary to sympatho-excitation.

Topics: Animals; Arterial Pressure; Calcium Signaling; Genetic Predisposition to Disease; Heart; Heart Rate; Hypertension; Natriuretic Peptide, C-Type; Norepinephrine; Phenotype; Rats, Sprague-Dawley; Rats, Transgenic; Receptors, Atrial Natriuretic Factor; Stellate Ganglion; Sympathetic Nervous System; Synaptic Transmission; Systole; Tachycardia, Ventricular; Time Factors; Tyrosine 3-Monooxygenase; Ventricular Dysfunction, Left; Ventricular Function, Left

Bradykinin-potentiating peptides (BPPs) from the South American pit viper snake venom were the first natural inhibitors of the human angiotensin I-converting enzyme (ACE) described. The pioneer characterization of the BPPs precursor from the snake venom glands by our group showed for the first time the presence of the C-type natriuretic peptide (CNP) in this same viper precursor protein. The confirmation of the BPP/CNP expression in snake brain regions correlated with neuroendocrine functions stimulated us to pursue the physiological correlates of these vasoactive peptides in mammals. Notably, several snake toxins were shown to have endogenous physiological correlates in mammals. In the present work, we expressed in bacteria the BPPs domain of the snake venom gland precursor protein, and this purified recombinant protein was used to raise specific polyclonal anti-BPPs antibodies. The correspondent single protein band immune-recognized in adult rat brain cytosol was isolated by 2D-SDS/PAGE and/or HPLC, before characterization by MS fingerprint analysis, which identified this protein as superoxide dismutase (SOD, EC 1.15.1.1), a classically known enzyme with antioxidant activity and important roles in the blood pressure modulation. In silico analysis showed the exposition of the BPP-like peptide sequences on the surface of the 3D structure of rat SOD. These peptides were chemically synthesized to show the BPP-like biological activities in ex vivo and in vivo pharmacological bioassays. Taken together, our data suggest that SOD protein have the potential to be a source for putative BPP-like bioactive peptides, which once released may contribute to the blood pressure control in mammals.

Topics: Amino Acid Sequence; Angiotensin-Converting Enzyme Inhibitors; Animals; Antibodies; Antihypertensive Agents; Blood Pressure; Bothrops; Escherichia coli; Gene Expression; Guinea Pigs; Heart Rate; Hypertension; Male; Mice; Models, Molecular; Molecular Sequence Data; Natriuretic Peptide, C-Type; Protein Precursors; Rats; Rats, Inbred SHR; Rats, Wistar; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Superoxide Dismutase; Teprotide

To evaluate the vascular endothelium in patients with cardiopulmonary disease, by studying the levels of endothelin-1 (ET-1) and C-type natriuretic peptide (CNP).. Examinations were conducted in 212 dwellers of the Astrakhan Region, including 40 patients with chronic obstructive pulmonary disease (COPD) concurrent with hypertensive disease (HD), 40 patients with COPD concurrent with coronary heart disease (CHD), 27 somatically healthy individuals, 35 patients with Stage II HD, 35 patients with Functional Classes II and III CHD, and 35 patients with moderate and severe COPD.. The patients with COPD concurrent with HD and CHD were found to have endothelial dysfunction manifesting itself in the overproduction of ET-1 and CNP. The level of CNP was statistically significantly higher in the COPD + HD group than in the HD and COPD groups whereas in the COPD + HD group the level of ET-1 remained comparable to that in the COPD and HD groups. This indicates that CNP is a more sensitive indirect marker of endothelial dysfunction and that nitric oxide deficiency is aggravated in the concurrence of COPD and HD as compared to a mononosological entity (HD, COPD).. The concurrence of COPD and CHD is more unfavorable for the development and severity of endothelial dysfunction, which may lead to mutual aggravation syndrome, the rapider progression of the diseases, and the increased frequency of complications.

Topics: Comorbidity; Coronary Disease; Disease Progression; Endothelin-1; Endothelium, Vascular; Female; Humans; Hypertension; Male; Middle Aged; Natriuretic Peptide, C-Type; Predictive Value of Tests; Prognosis; Pulmonary Disease, Chronic Obstructive

The aim of the present work was to establish a time-course correlation between vascular and autonomic changes that contribute to the development of hypertension during ethanol ingestion in rats. For this, male Wistar rats were subjected to the intake of increasing ethanol concentrations in their drinking water during four weeks. Ethanol effects were investigated at the end of each week. Mild hypertension was already observed at the first week of treatment, and a progressive blood pressure increase was observed along the evaluation period. Increased pressor response to phenylephrine was observed from first to fourth week. α1-Adrenoceptor protein in the mesenteric bed was enhanced at the first week, whereas β2-adrenoceptor protein in the aorta was reduced after the second week. In the third week, ethanol intake facilitated the depressor response to sodium nitroprusside, whereas in the fourth week it reduced nitrate content in aorta and increased it plasma. The bradycardic component of the baroreflex was impaired, whereas baroreflex tachycardia was enhanced at the third and fourth weeks. AT1A receptor and C-type natriuretic peptide (CNP) mRNAs in the nucleus tractus solitarius were increased at the fourth week. These findings suggest that increased vascular responsiveness to vasoconstrictor agents is possibly a link factor in the development and maintenance of the progressive hypertension induced by ethanol consumption. Additionally, baroreflex changes are possibly mediated by alterations in angiotensinergic mechanisms and CNP content within the brainstem, which contribute to maintaining the hypertensive state in later phases of ethanol ingestion. Facilitated vascular responsiveness to nitric oxide seems to counteract ethanol-induced hypertension.

Topics: Alcohol Drinking; Animals; Baroreflex; Blood Pressure; Heart Rate; Hypertension; Male; Natriuretic Peptide, C-Type; Nitric Oxide; Nitroprusside; Phenylephrine; Rats; Rats, Wistar; Receptor, Angiotensin, Type 1

To study the relationship between C-type natriuretic peptide (NT-proCNP) and other natriuretic peptides, such as pro-atrial natriuretic peptide [proANP(1-98)] and N-terminal pro-brain natriuretic peptide (NT-proBNP), in the elderly, investigating also their correlation with other traditional clinical markers of the hypertensive condition.. NT-proCNP, NT-proBNP and proANP(1-98) were measured in 57 elderly patients. They were hypertensive patients (n = 36) and normotensive controls (n = 21). Their anthropometric parameters, including Winsor's index and total and high-density lipoprotein cholesterol, were determined.. A diagnostic role of NT-proBNP in hypertensive patients was detected by a model of logistic regression, which gave a significant result [odds ratio (OR) 1.0115, P = 0.0184]. By this model the area (AUC) under the receiver-operating characteristic (ROC) curve was 0.69 ± 0.071 (P = 0.0075). On the basis of the ROC curve, the calculated serum NT-proBNP cut-off for the prediction of hypertension was greater than 164 pmol/l - the value being provided with a sensitivity of 89% coupled with a specificity of 55%. NT-proCNP and proANP(1-98) did not predict the hypertensive condition, although significant correlations were detected with serum lipid profile and creatinine levels.. By using the logistic regression analysis, NT-proBNP was identified as a significant predictor of hypertension, whereas NT-proCNP and proANP circulating levels were not shown to reliably predict the hypertensive condition. Further validation by means of larger cohort studies is undoubtedly needed to assess the use of all three peptides to increase the performance of a possible test for the prediction of the hypertensive condition in humans.

Topics: Aged; Aged, 80 and over; Anthropometry; Atrial Natriuretic Factor; Biomarkers; Case-Control Studies; Cholesterol; Creatinine; Female; Humans; Hypertension; Male; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Natriuretic Peptides; Peptide Fragments; Sensitivity and Specificity

The aim was to study the effects of C-type natriuretic peptide (CNP) on mean arterial pressure (MAP) and the cardiovascular nitric oxide (NO) system in spontaneously hypertensive rats (SHR), and to investigate the signaling pathways involved in this interaction. SHR and WKY rats were infused with saline or CNP. MAP and nitrites and nitrates excretion (NO(x)) were determined. Catalytic NO synthase (NOS) activity and endothelial (eNOS), neuronal (nNOS) and inducible NOS (iNOS) were measured in the heart and aorta artery. NOS activity induced by CNP was determined in presence of: iNOS or nNOS inhibitors, NPR-A/B natriuretic peptide receptors blocker and Gi protein and calmodulin inhibitors. CNP diminished MAP and increased NO(x) in both groups. Cardiovascular NOS activity was higher in SHR than in WKY. CNP increased NOS activity, but this activation was lower in SHR. CNP had no effect on NOS isoforms expression. iNOS and nNOS inhibitors did not modify CNP-induced NOS activity. NPR-A/B blockade induced no changes in NOS stimulation via CNP in both tissues. Cardiovascular NOS response to CNP was reduced by Gi protein and calmodulin inhibitors in both groups. CNP interacts with NPR-C receptors, activating Ca-calmodulin eNOS via Gi protein. NOS response to CNP is impaired in the heart and aorta of SHR. Alterations in the interaction between CNP and NO would be involved in the maintenance of high blood pressure in this model of hypertension.

Topics: Animals; Antihypertensive Agents; Hypertension; Male; Myocardium; Natriuretic Peptide, C-Type; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Inbred SHR

Topics: Atrial Natriuretic Factor; Biomarkers; Heart Failure; Humans; Hypertension; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Renal Insufficiency

We conducted an association study between genetic variants of C-type natriuretic peptide gene (CNP) and hypertension in a Japanese population. We found four genetic variants, two in the promoter region, one missense mutation, and one in the 3'-untranslated region (3'-UTR), and genotyped all four variants in 2,006 subjects recruited from the Suita study. One of the variants, G2628A in 3'-UTR, was found to be associated with blood pressure. Multiple logistic analyses indicated that the genotype of the G2628A polymorphism (GG=1, GA+AA=2) (p=0.0034), sex (p=0.0288), alcohol consumption (p=0.0002), age (p<0.0001), and body mass index (p<0.0001) were predictors of hypertension. The odds ratio of the GA+AA genotype over the GG genotype for hypertension was 1.40 (p=0.0034, 95% confidence interval (CI) 1.12-1.75). Multiple logistic analyses in a younger subpopulation aged below 65 years indicated that the odds ratio of the GA+AA genotype over the GG genotype for hypertension was 1.58 (p=0.0024, 95%CI 1.18-2.12). Thus, the CNP G2628A polymorphism made an even greater contribution to hypertension in the younger subpopulation.

Topics: Age Distribution; Aged; Blood Pressure; Female; Genetic Predisposition to Disease; Genotype; Humans; Hypertension; Male; Middle Aged; Natriuretic Peptide, C-Type; Polymorphism, Single Nucleotide

Excess oxidative stress is one of the major metabolic abnormalities on vascular walls in hypertension and atherosclerosis. In order to further elucidate the endothelial function under oxidative stress, the effect of hydrogen peroxide (H2O2) on expression of two novel endothelium-derived vasorelaxing peptides, C-type natriuretic peptide (CNP) and adrenomedullin (AM) from bovine carotid artery endothelial cells (BCAECs) was examined.. BCAECs were treated with H2O2 (0.1-1.0 mmol/ l) and/or an antioxidant, N-acetylcysteine (NAC) (5-10 mmol/l), and incubated for 48 h. The concentrations of CNP and AM were measured with the specific radioimmuno assays that we originally developed. CNP and AM mRNA expressions were also examined by reverse transcription-polymerase chain reaction (RT-PCR).. Treatment of BCAECs with 0.5 and 1 mmol/l H2O2 induced 9-and 10-fold increases of CNP concentration in the media. Addition of 10 mmol/l NAC significantly suppressed the effect of H2O2 by 52%. RT-PCR analysis showed that CNP mRNA expression in BCAECs was also rapidly augmented within 1 h with H2O2 (1 mmol/l) treatment, and reached a peak at 3 h to show a 10-fold increase. AM secretion from BCAECs also increased to two-fold with exposure to 0.5 mmol/l H2O2, accompanied with the augmented level of AM mRNA. NAC 10 mmol/l completely suppressed the effect of H2O2 on AM secretion.. In this study, it has been demonstrated that H2O2 augments endothelial secretion of the two endothelium-derived relaxing peptides, CNP and AM. Our findings suggest the increased secretion of CNP and AM from endothelium under oxidative stress may function to compensate the impaired nitric oxide-dependent vasorelaxation in hypertension and atherosclerosis.

Topics: Acetylcysteine; Adrenomedullin; Animals; Antioxidants; Arteriosclerosis; Base Sequence; Cattle; Cells, Cultured; DNA Primers; Endothelium, Vascular; Gene Expression; Humans; Hydrogen Peroxide; Hypertension; Natriuretic Peptide, C-Type; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Peptides; RNA, Messenger; Vasodilation

Cyclosporine (CysA), a potent immunosuppressant, is associated with hypertension and nephrotoxicity. Neutral endopeptidase (NEP) degrades vasoactive peptides, including the natriuretic peptides and endothelin-1 (ET-1). We conducted the present study to determine whether or not the NEP inhibitor, ecadotril, prevents cyclosporine-induced hypertension and to clarify the mechanisms responsible for the hypotensive effects of ecadotril.. We studied the chronic effects of ecadotril (30 mg/kg per day) on blood pressure; the production of ET-1 and C-type natriuretic peptide (CNP); endothelial nitric oxide synthase (eNOS) activity; and the expression of messenger RNA (mRNA), for each substance in blood vessels of CysA-induced hypertensive rats.. CysA (25 mg/kg per day) given for 4 weeks increased the blood pressure from 116 +/- 14 mmHg to 159 +/- 15 mmHg, in rats. This increase was blunted by the co-administration of ecadotril (blood pressure: 134 +/- 14 mmHg). CysA increased plasma NEP activity. CysA increased the production of ET-1 and the expression of ET-1 mRNA without affecting CNP synthesis and endothelin converting enzyme (ECE)-1 mRNA expression. CysA decreased the eNOS activity and eNOS mRNA levels. Addition of the NEP inhibitor decreased the synthesis of ET-1 and ET-1 mRNA levels and increased the eNOS activity and the eNOS mRNA levels. Vascular CNP synthesis and ECE-1 mRNA expression in rats treated with ecadotril did not differ from those in rats treated with CysA and ecadotril.. These results indicate that chronic NEP inhibition may prevent the CysA-induced hypertension by decreasing local ET-1 synthesis and partly increasing vascular nitric oxide production.

Topics: Animals; Blood Pressure; Blotting, Southern; Cyclosporine; DNA Probes; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Hypertension; Male; Natriuretic Peptide, C-Type; Neprilysin; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Polymerase Chain Reaction; Protease Inhibitors; Rats; Rats, Inbred WKY; RNA, Messenger; Thiorphan

C-type natriuretic peptide (CNP) is a potent, endothelial-derived relaxant and growth-inhibitory factor. Accelerated vascular disease is an important cause of morbidity in cardiac transplant recipients, and endothelial dysfunction is now well recognized in patients with cardiovascular disease. CNP has not previously been investigated following cardiac transplantation. We therefore studied plasma levels of immunoreactive CNP in patients early and late after heart transplantation, compared with levels in healthy subjects. We measured CNP in extracted human plasma using an antibody against human CNP-(1-22). CNP levels were significantly elevated in 13 cardiac recipients 2 weeks post-transplant [2.64+/-0.26 pmol/l (mean+/-S.E.M.)] compared with those in the normal healthy subjects (0.62+/-0.04 pmol/l; n=20, P<0.001). Plasma levels of CNP were also significantly elevated in a second group of established cardiac transplant recipients (1.15+/-0.07 pmol/l; n=46) studied 1-13 years post-transplant when compared with the healthy subjects (P<0.001). In the group studied later after transplantation, CNP levels were significantly associated with systolic blood pressure (P<0.05) and were higher in patients with angiographic post-transplant coronary artery disease (P=0.032). In conclusion, these findings clearly demonstrate that CNP is elevated soon after cardiac transplantation and remains raised in patients even several years post-transplant. CNP may be important as a circulating or local hormone involved in vascular contractile function and in the pathophysiology of cardiac allograft vasculopathy following heart transplantation.

Topics: Adolescent; Adult; Aged; Case-Control Studies; Coronary Disease; Female; Heart Transplantation; Humans; Hypertension; Male; Middle Aged; Natriuretic Peptide, C-Type; Postoperative Complications; Ventricular Function, Left

To investigate the changes and clinical significance of plasma type C natriuretic peptide (CNP) concentration in patients with pregnancy induced hypertension (PIH).. Plasma CNP levels were detected by radioimmunoassay in 89 patients with PIH, 193 normal pregnant women and 46 normal non-pregnant women. Outcomes were statistically analyzed by one-way analysis of variance and Student-Nawman-Kenls (SNK) test.. The plasma CNP levels in patients with PIH [(30.51 +/- 33.61) ng/L] were significantly higher than those of normal non-pregnant women and normal pregnancies [(17.15 +/- 3.82) ng/L, (19.43 +/- 5.13) ng/L, respectively; F = 13.61, P < 0.01]. There was significant difference among plasma CNP levels from patients with mild, moderate, and severe PIH (P < 0.0001).. The changes of plasma CNP levels are believed to be the reflection of patients in progression of PIH and can be used as a biochemical marker for judging the progression and guiding the therapy of PIH.

Topics: Adult; Female; Humans; Hypertension; Natriuretic Peptide, C-Type; Pregnancy; Pregnancy Complications, Cardiovascular; Radioimmunoassay

-Tacrolimus (FK 506) is a powerful, widely used immunosuppressant. The clinical utility of FK 506 is complicated by substantial hypertension and nephrotoxicity. To clarify the mechanisms of FK 506-induced hypertension, we studied the chronic effects of FK 506 on the synthesis of endothelin-1 (ET-1), the expression of mRNA of ET-1 and endothelin-converting enzyme-1 (ECE-1), the endothelial nitric oxide synthase (eNOS) activity, and the expression of mRNA of eNOS and C-type natriuretic peptide (CNP) in rat blood vessels. In addition, the effect of the specific endothelin type A receptor antagonist FR 139317 on FK 506-induced hypertension in rats was studied. FK 506, 5 mg. kg-1. d-1 given for 4 weeks, elevated blood pressure from 102+/-13 to 152+/-15 mm Hg and increased the synthesis of ET-1 and the levels of ET-1 mRNA in the mesenteric artery (240% and 230%, respectively). Little change was observed in the expression of ECE-1 mRNA and CNP mRNA. FK 506 decreased eNOS activity and the levels of eNOS mRNA in the aorta (48% and 55%, respectively). The administration of FR 139317 (10 mg. kg-1. d-1) prevented FK 506-induced hypertension in rats. These results indicate that FK 506 may increase blood pressure not only by increasing ET-1 production but also by decreasing NO synthesis in the vasculature.

Topics: Animals; Aorta, Abdominal; Aspartic Acid Endopeptidases; Azepines; Base Sequence; Blood Pressure; Blotting, Southern; Data Interpretation, Statistical; DNA, Complementary; Endothelin-1; Endothelin-Converting Enzymes; Hypertension; Immunosuppressive Agents; Indoles; Kidney; Male; Mesenteric Artery, Superior; Metalloendopeptidases; Molecular Sequence Data; Natriuretic Peptide, C-Type; Nitric Oxide Synthase; Polymerase Chain Reaction; Rats; Rats, Inbred WKY; RNA, Messenger; Tacrolimus

To measure plasma levels of C-type natriuretic peptide in women with normal pregnancies and those complicated by gestational hypertension and preeclampsia.. We collected venous plasma samples from 20 women with normal pregnancies, 15 with gestational hypertension, and nine with preeclampsia. Gestational ages ranged from 26-39 weeks. We measured C-type natriuretic peptide concentrations by radioimmunoassay. Statistical comparisons were made by one-way analysis of variance and Tukey test.. The mean plasma concentration of C-type natriuretic peptide in the women with normal pregnancy was 7.1 +/-2.5 pg/mL, in those with gestational hypertension 9.6+/-4.2 pg/mL, and in those with preeclampsia 8.1+/-2.4 pg/mL. There were no statistically significant differences between groups. The statistical power to detect a difference of 3 pg/mL at the 5% significance level was 78% for the group with gestational hypertension and 64% for the preeclamptic group.. Our results suggest that C-type natriuretic peptide plasma levels are not significantly different in normal pregnancies and those complicated by gestational hypertension or preeclampsia. In hypertensive pregnancy disorders, C-type natriuretic peptide showed a distinct course compared with atrial natriuretic peptide and brain natriuretic peptide.

Topics: Adult; Female; Gestational Age; Humans; Hypertension; Natriuretic Peptide, C-Type; Pre-Eclampsia; Pregnancy; Pregnancy Complications, Cardiovascular; Radioimmunoassay

To investigate the roles of brain angiotensin II and C-type natriuretic peptide (CNP) in the hypertensive mechanism of deoxycorticosterone acetate (DOCA)-salt hypertension.. We injected 50 microg/kg CV-11 974, an angiotensin II type-1 receptors antagonist, 30 nmol/kg CNP-22, or the vehicle (artificial cerebrospinal fluid) into the cerebral ventricle or intravenously 5 min before the intracerebroventricular infusion of 1.5 mol/I NaCl solution for 30 min into either male normotensive Wistar rats or DOCA-salt hypertensive rats anesthetized with urethane, and their arterial pressures and heart rates were continuously recorded. Blood (2 ml) was collected at the end of the infusion for the measurement of plasma concentration of arginine vasopressin. We infused 10 or 50 microg/kg per day CV-11 974, 10 or 50 nmol/kg per day CNP-22, or the vehicle (1 microl/h) into the cerebral ventricles of DOCA-salt hypertensive rats for 7 days by using osmotic minipumps, and measured their systolic arterial pressures, pulse rates, and urinary excretions of vasopressin.. Intracerebroventricular pre-administrations of CV-11 974 and of CNP-22 inhibited increases in mean arterial pressure, heart rate, and plasma vasopressin concentration induced by intracerebroventricular infusion of 1.5 mol/l NaCl into normotensive rats; increases in hemodynamics and plasma level of vasopressin induced by intracerebroventricular infusion of 1.5 mol/l NaCl were suppressed by intracerebroventricular pre-injections of CV-11 974, but not of CNP-22, into DOCA-salt hypertensive rats. Continuous intracerebroventricular infusions of 50 microg/kg per day CV-11 974 attenuated hypertension in DOCA-salt treated rats, accompanied by a reduction in urinary excretion of vasopressin. Continuous intracerebroventricular infusions of 50 nmol/kg per day CNP-22, however, affected neither hypertension nor urinary excretion of vasopressin in DOCA-salt hypertensive rats.. Brain angiotensin II could play a role in the pressor mechanism of DOCA-salt hypertension by increasing release of vasopressin via type 1 receptors. That brain CNP has an inhibitory effect on release of vasopressin in acute experiments indicates that the impairment of this inhibitory effect of brain CNP on secretion of vasopressin could be involved in the pathogenesis of DOCA-salt hypertension in rats.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Arginine Vasopressin; Benzimidazoles; Biphenyl Compounds; Blood Pressure; Brain; Desoxycorticosterone; Hypertension; Infusions, Parenteral; Injections, Intravenous; Injections, Intraventricular; Male; Natriuretic Peptide, C-Type; Rats; Rats, Wistar; Sodium Chloride; Tetrazoles

Atrial (ANP) and C-type (CNP) natriuretic peptides have been found in brain regions associated with fluid homeostasis and blood pressure. Since chronic moderate ethanol consumption has been shown to prevent the age-dependent increase in blood pressure in experimental animals, the objective of the present studies was to investigate the effect of ethanol (20% (v/v) for 8 months) on the total content and concentration of ANP and CNP in the brain of spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Ethanol increased the content and concentration of both ANP and CNP in the hypothalamus, pons and medulla of SHR rats. In contrast, in the WKY rats ethanol had no effect on the levels of ANP in any of the brain regions studies, but enhanced the concentration of CNP in the hypothalamus and medulla. Thus, ethanol induced changes in the content of natriuretic peptides in distinct brain regions associated with control of cardiovascular activity. Such changes may be partially responsible for the effect of chronic moderate ethanol consumption on blood pressure.

Topics: Aging; Alcohol Drinking; Animals; Blood Pressure; Brain Chemistry; Hypertension; Hypothalamus; Iodine Radioisotopes; Male; Medulla Oblongata; Natriuretic Peptide, C-Type; Pons; Proteins; Radioimmunoassay; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Species Specificity

Three atrial natriuretic peptide (ANP) receptors, ANP(A), ANP(B), and ANP(C), have been identified in the heart, suggesting that natriuretic peptides may have direct effects on cardiac function. To characterize the possible role of atrial natriuretic peptide (ANP) in the regulation of its own secretion, we studied here the effects of ANP (greater affinity for ANP(A) than for ANP(B) receptors) and C-type natriuretic peptide (CNP), a potent activator of ANP(B) receptors, on the release of atrial peptides under basal conditions and during acute volume expansion in conscious normotensive Sprague-Dawley rats. The effects of HS-142-1, a nonpeptide ANP(A) and ANP(B) receptor antagonist, on volume load-induced atrial peptide release in 1-yr-old conscious normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were also studied. As an index of secretion of atrial peptides from the heart, plasma levels of N-terminal fragment of pro-ANP (NT-ANP) were measured. In Sprague-Dawley rats, i.v. infusion of ANP for 30 min in doses of 0.3 and 1.0 microg/kg x min blocked the plasma immunoreactive NT-ANP (IR-NT-ANP) response to volume load (P < 0.001), whereas CNP had no significant effect. Neither ANP nor CNP infusion had any effect on plasma IR-NT-ANP levels under basal conditions. Bolus administration of HS-142-1 increased baseline plasma IR-ANP concentrations in both WKY and SHR strains (WKY: 3 mg/kg, 46 +/- 8 pmol/liter, P < 0.001; SHR: 1 mg/kg, 26 +/- 9 pmol/liter, P < 0.01; SHR: 3 mg/kg, 40 +/- 12 pmol/liter, P < 0.01). The corresponding increases in plasma IR-NT-ANP concentrations in the SHR in response to administration of HS-142-1 were 0.17 +/- 0.06 nmol/liter (P < 0.01) and 0.40 +/- 0.14 nmol/liter (P < 0.01). Moreover, HS-142-1 (3 mg/kg) augmented plasma IR-ANP and IR-NT-ANP responses to acute volume load in WKY rats. In contrast, HS-142-1 did not enhance the plasma IR-ANP response to acute volume load in SHR and resulted in a smaller increase in the plasma IR-NT-ANP concentration in SHR than in WKY rats. In conclusion, the findings that ANP, but not CNP, inhibited volume expansion-stimulated NT-ANP release and that HS-142-1, an antagonist of guanylate cyclase-linked natriuretic peptide receptors, increased plasma ANP and NT-ANP concentrations show that endogenous ANP directly modulates its own release via ANP(A) receptors in vivo. Furthermore, this modulation of acute volume expansion-induced atrial peptide release appears to be altered in

Topics: Animals; Atrial Natriuretic Factor; Blood Pressure; Blood Volume; Hemodynamics; Hypertension; Male; Natriuretic Peptide, C-Type; Peptide Fragments; Polysaccharides; Proteins; Rats; Rats, Inbred WKY; Rats, Sprague-Dawley; Receptors, Atrial Natriuretic Factor

We compared the abundance and sensitivity of atrial natriuretic peptides (ANP) receptors in the brains of spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats and examined the effect of blood pressure on the abundance of brain ANP receptors in several other experimental rat models. Brain slices from SHR generated more guanosine 3',5'-cyclic monophosphate in response to ANP than brain slices from WKY rats. No differences were found in brain particulate guanylate cyclase activity in both strains of rats. In rat brain homogenates, we observed that ANP bound in a specific and saturable fashion to samples from WKY rats, but not in samples from SHR. In vitro receptor autoradiography revealed that ANP binding was reduced in the subfornical organ, the choroid plexus, and the paraventricular nucleus of SHR compared with WKY rat brains. Correction of hypertension in SHR or induction of hypertension in other strains did not affect ANP binding in any of these brain regions. Altogether, our data suggest that the increased sensitivity of SHR brains to the action of ANP may be a consequence of factors other than the abundance of receptors and that it is not secondary to the elevation of blood pressure.

Topics: 1-Methyl-3-isobutylxanthine; Animals; Atrial Natriuretic Factor; Brain; Cyclic GMP; Guanylate Cyclase; Hypertension; Hypothalamus; In Vitro Techniques; Kinetics; Male; Natriuretic Peptide, C-Type; Organ Specificity; Proteins; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley; Receptors, Atrial Natriuretic Factor; Reference Values; Regression Analysis

A genetic model of salt-resistant hypertension has been developed recently through disruption of the guanylyl cyclase-A (GC-A) natriuretic peptide receptor gene (Lopez, M. J., Wong, S. K., Kishimoto, I., Dubois, S., Mach, V., Friesen, J., Garbers, D. L., and Beuve, A. (1995) Nature 378, 65-68). These genetically altered mice were used to determine which of the natural peptides with natriuretic peptide-like structures regulate blood pressure through the GC-A receptor. Atrial natriuretic peptide (ANP) or B-type natriuretic peptide (BNP) half-maximally relaxed precontracted aortic rings in wild-type mice at about 24 nM, but failed to relax such aortas in GC-A null mice, even at micromolar concentrations. C-type natriuretic peptide (CNP), in contrast, caused half-maximal relaxation at concentrations of 335 and 146 nM in aortas from either wild-type or null mice, respectively, suggesting that this peptide acted through a receptor other than GC-A. Since the in vitro results with aortic smooth muscle do not necessarily reflect the physiology of the smaller blood vessels important in blood pressure regulation, the blood pressures of conscious mice infused with the various peptides were determined. ANP caused decreases in blood pressure when infused at rates of 500 ng/kg/min, a rate which resulted in a plasma concentration of 0.8 nM. In the null mice, in contrast, ANP failed to lower blood pressure even at infusion rates of 50 microg/kg/min. Much higher infusion rates for CNP (50 microg/kg/min), which yielded final plasma concentrations of 18.3 nM, were required to lower blood pressure in wild-type mice, but the effects of CNP were not altered in GC-A null mice. Thus, two natriuretic peptides (ANP, BNP) act through GC-A whereas another (CNP) acts through another receptor to regulate blood pressure.

Topics: Animals; Aorta; Atrial Natriuretic Factor; Blood Pressure; Dose-Response Relationship, Drug; Guanylate Cyclase; Hypertension; In Vitro Techniques; Mice; Mice, Mutant Strains; Muscle Relaxation; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Proteins; Receptors, Atrial Natriuretic Factor; Signal Transduction

Biological actions of natriuretic peptide (NP) are determined by the condition of the receptor as well as that of the hormone. Although we previously demonstrated in hypertensive rats the up-regulation of NP-A receptor that mediates various biological actions of NPs, the pathophysiologic significance of NP-C receptor, another subtype thought to be related to clearance of NPs and possibly to biological actions, remains unknown. In the present study, we determined NP-C receptor messenger RNA (mRNA) level in the aortic tissue of stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and in cultured aortic smooth muscle cells by ribonuclease protection assay. The aortic NP-C receptor mRNA level in SHR-SP/Izm was significantly lower than that in the control WKY/Izm. Oral administration of an angiotensin (Ang) II receptor (AT1) antagonist, TCV-116, but not a calcium channel blocker, manidipine, reversed the down-regulated NP-C receptor mRNA in SHR-SP/Izm to the level in WKY/Izm, whereas the latter was more potent in decreasing the blood pressure. In cultured aortic smooth muscle cells, the NP-C receptor was the predominant subtype. Ang II decreased the NP-C receptor mRNA level in a dose-dependent manner, but this effect was reversed by an AT1 antagonist, CV-11974. Neither the NP-A nor NP-B receptor mRNA level was altered by Ang II. These findings indicate that vascular NP-C receptor is down- regulated via Ang-II-mediated mechanism in SHR-SP/Izm. The phenomenon, together with the up-regulation of the NP-A receptor, may play an important role in counteracting hypertension by enhancing the action of NPs.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Benzimidazoles; Biphenyl Compounds; Calcium Channel Blockers; Cells, Cultured; Dihydropyridines; Down-Regulation; Guanylate Cyclase; Hypertension; Male; Muscle, Smooth, Vascular; Natriuretic Peptide, C-Type; Nitrobenzenes; Piperazines; Proteins; Rats; Rats, Inbred SHR; Rats, Wistar; Receptors, Atrial Natriuretic Factor; RNA, Messenger; Tetrazoles

Hypertension is commonly associated with diabetes mellitus. The aim of the present study was to explore the pathophysiological significance of the natriuretic peptide (NP) system in hypertension associated with genetically obese/hyperglycemic Wistar fatty rats. The messenger RNA (mRNA) levels of the two biologically active NP receptors, NP-A receptor [more specific for atrial natriuretic peptide (ANP)] and NP-B receptor [more specific for C-type natriuretic peptide (CNP)], and CNP mRNA levels were determined in the aorta and kidney by ribonuclease protection assay. Plasma ANP levels were determined by RIA. Both NP-A and NP-B receptor mRNA levels in the aortae of Wistar fatty rats were double those in Wistar lean rats. Plasma ANP levels and CNP mRNA levels in the aorta of Wistar fatty rats were also significantly higher than those in Wistar lean rats. In contrast, there was no significant difference in renal levels of the mRNA for both NP receptors and CNP between the two strains. Administration of a NP-A and -B receptor antagonist, HS-142-1, to Wistar fatty rats resulted in a significant increase in systolic blood pressure and a larger decrease in plasma cGMP level than that in Wistar lean rats, with no difference in the extents of decrease in urine volume and urinary sodium excretion between the two strains. These results suggest that both the ANP/NP-A system and the CNP/NP-B system in vessels are up-regulated at the level of gene expression and may, thus, play an important role in counteracting the hypertension associated with diabetes mellitus.

Topics: Animals; Aorta; Atrial Natriuretic Factor; Blood Vessels; Cyclic GMP; Diuresis; Guanylate Cyclase; Hyperglycemia; Hypertension; Kidney; Male; Natriuresis; Natriuretic Peptide, C-Type; Obesity; Polysaccharides; Proteins; Rats; Rats, Wistar; Receptors, Atrial Natriuretic Factor; RNA, Messenger

The influence of neutral endopeptidase (NEP) inhibition with (S)-thiorphan on the hormonal, renal, and blood-pressure-lowering effects of an infusion of atrial (ANP), brain (BNP), and C-type natriuretic peptide (CNP) was evaluated in hypertensive transgenic rats (TGR) harboring an additional mouse renin gene (TGR(m(Ren2)27)). These TGR possess an activated natriuretic peptide system as compared with Sprague-Dawley rats (SDR), used in this study as control. (S)-Thiorphan significantly decreased blood pressure in anesthetized TGR but not in anesthetized SDR during the 60-min infusion period. Exogenously administered ANP decreased blood pressure in SDR with no significant effects in TGR after 60 min. In contrast, BNP infusion significantly decreased blood pressure in TGR, while changes in SDR were not significant. The blood pressure was further decreased after combined infusion of ANP and BNP with (S)-thiorphan in TGR. No effect on blood pressure was registered during infusion of CNP in either experimental group. The plasma levels of ANP, BNP, and cGMP were higher in TGR than in SDR, whereas plasma renin activity was lower. Co-administration of ANP, BNP, or CNP with the NEP inhibitor (S)-thiorphan potentiated the plasma ANP, BNP, and cGMP. Infusion of ANP alone did not affect BNP plasma levels of TGR and vice versa. In contrast, CNP infusion increased ANP plasma levels in both TGR and SDR. Renal excretion of sodium and cGMP increased after infusion of (S)-thiorphan and ANP or BNP in both TGR and SDR. The combination of ANP and (S)-thiorphan had a slightly greater effect on urinary excretion of sodium and cGMP in TGR than either compound alone, but the effects were more pronounced in SDR than in TGR. Finally, infusion of CNP alone and in combination with (S)-thiorphan influenced the excretion of sodium and cyclic GMP only slightly. These results indicate that inhibition of neutral endopeptidase by (S)-thiorphan potentiates the hemodynamic and renal effects of natriuretic peptides ANP and BNP, and to some extent those of CNP, in hypertensive TGR and normotensive SDR. In contrast to ANP and BNP, infusion of CNP had no effect on the blood pressure in anesthetized TGR or SDR. Inhibition of NEP therefore seems to be a promising way to potentiate endogenous levels of natriuretic peptides, which may be of therapeutic benefit in cardiovascular diseases such as hypertension or heart failure.

Topics: Animals; Animals, Genetically Modified; Atrial Natriuretic Factor; Blood Pressure; Cyclic GMP; Disease Models, Animal; Drug Therapy, Combination; Electrolytes; Hypertension; Mice; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Neprilysin; Protease Inhibitors; Proteins; Rats; Rats, Sprague-Dawley; Renin; Sodium; Thiorphan

1. Hyperglycaemia is believed to be a major cause of diabetic vascular complications such as accelerated atherosclerosis. In order to elucidate the effect of hyperglycaemia on vascular response in spontaneously hypertensive rats (SHR), the natriuretic peptides receptor responses to vascular smooth muscle cells (VSMC) which are thought to suppress atherosclerosis were studied under high glucose (HG:22.2 mmol/L) conditions. 2. The total number of cells in SHR is higher and natriuretic peptides receptor response is smaller than that of cells in the Wistar-Kyoto (WKY) rat. Membrane bound protein kinase C (PKC) activity in HG or SHR is higher compared to that of cells in normal glucose (NG:5.6 mmol/L) or WKY. Cells cultured in HG for at least 2 passages had higher total cell number and receptor mediated cGMP formation were suppressed compared to cells cultured in NG both in SHR and WKY. Specific PKC inhibitor PKC (19-36) 1 mu mol/L prevented HG induced suppression of natriuretic peptides response. 3. These results show that hyperglycaemia may be linked to suppressed natriuretic peptides receptor response which is caused by increased PKC activity both in WKY and SHR. This suppressed response may cause the accelerated atherosclerosis by hyperglycaemia.

Topics: Animals; Cells, Cultured; Cyclic GMP; Glucose; Hypertension; Muscle, Smooth, Vascular; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Protein Kinase C; Proteins; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Atrial Natriuretic Factor; Receptors, Peptide

Vascular remodelling is central to the pathophysiology of hypertension and atherosclerosis. Recent evidence suggests the pivotal role of vasoactive substances occurring in the blood vessel, such as angiotensin II (AII), in the control of vascular growth. We recently discovered that C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, is produced by vascular endothelial cells and can act as an endothelium-derived relaxing peptide. We also demonstrated gene expression of CNP and the ANP-B receptor, which is one of the three subtypes of the natriuretic peptide receptor and is specific to CNP in blood vessels in vivo. Thus, we propose the existence of a "vascular natriuretic peptide system (NPS)" similar to the vascular renin-angiotensin system (RAS). The present study showed that CNP exerted a growth-inhibitory action and antagonised the growth-promoting action of AII, which was mediated through the AII subtype 1 receptor in cultured vascular smooth muscle cells. In neointimal lesions of rat carotid artery, CNP gene transcript was detectable 2 weeks after balloon injury, and ANP-B receptor gene expression was augmented. These findings suggest that the vascular NPS is activated in proliferative vascular lesions, suppressing further proliferation by antagonising the action of the vascular RAS.

Topics: Angiotensin II; Animals; Arteriosclerosis; Atrial Natriuretic Factor; Base Sequence; Cattle; Cell Division; Cells, Cultured; Endothelium, Vascular; Gene Expression Regulation; Guanylate Cyclase; Hypertension; Male; Molecular Sequence Data; Muscle, Smooth, Vascular; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptors, Atrial Natriuretic Factor; Renin-Angiotensin System; RNA; Stimulation, Chemical

To study the relationship between hypertension and the plasma levels of brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP), and to determine whether the plasma levels of BNP and CNP are correlated.. A cross-sectional study of the plasma levels of BNP and CNP in hypertensive patients and normotensive controls matched for age and sex was performed.. The hypertension research clinic in a teaching hospital and well-person risk factor screening clinics in general practice health centres.. Fifty-four subjects (29 hypertensive, 25 normotensive controls) took part in the study after giving their informed consent. Hypertensive patients (n = 19) were paired with normotensive controls (n = 19) matched for age and sex to form a subgroup before analysis of the plasma.. The plasma levels of BNP and CNP were determined by specific radioimmunoassays.. The mean plasma concentration of BNP was significantly higher in the hypertensive group than in the paired controls. In contrast, the mean plasma concentration of CNP was not significantly different in the hypertensive group than in the paired controls. Multiple regression analysis of all 54 subjects showed that the plasma level of BNP correlated significantly with age and systolic blood pressure, whereas the plasma level of CNP correlated significantly with sex, heart rate and alcohol intake. The CNP levels did not correlate significantly with either systolic or diastolic blood pressure, or with plasma brain natriuretic levels.. Hypertension is associated with raised BNP but not CNP plasma levels.

Topics: Aging; Blood Pressure; Cross-Sectional Studies; Epinephrine; Female; Humans; Hypertension; Male; Middle Aged; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Norepinephrine; Proteins; Radioimmunoassay; Reference Values; Sex Characteristics

We have previously reported that C-type natriuretic peptide (CNP), the third member of natriuretic family, was produced in vascular endothelial cells and hypothesized that CNP might be a local regulator of vascular tone and/or growth from endothelial cells. In order to clarify the pathophysiological significance of CNP in humans, we examined the presence of CNP in human circulation and determined plasma levels of CNP in patients with various cardiovascular disorders. The plasma level of CNP in healthy persons was 1.4 +/- 0.6 fmol/ml (n = 13). The plasma level of CNP was markedly increased in patients with septic shock (13.2 +/- 10.1 fmol/ml, n = 11), while there was no alteration in patients with congestive heart failure or hypertension. There was two-fold increase of the plasma CNP level in patients with chronic renal failure. These results indicate that CNP, which can be considered as an endothelium-derived relaxing peptide, is detectable in human circulation and suggest the pathophysiological significance of endothelial CNP in humans.

Topics: Aged; Atrial Natriuretic Factor; Biomarkers; Chromatography, Gel; Chromatography, High Pressure Liquid; Cross Reactions; Heart Failure; Humans; Hypertension; Kidney Failure, Chronic; Middle Aged; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Reference Values; Shock, Septic