natriuretic-peptide--c-type and Arteriosclerosis

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: Achondroplasia; Animals; Arteriosclerosis; Cell Division; Chondrogenesis; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Endothelium, Vascular; Guanylate Cyclase; Humans; Natriuretic Peptide, C-Type; Receptors, Atrial Natriuretic Factor; Regeneration; Vasoconstriction

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

We recently reported that C-type natriuretic peptide (CNP) occurs in vascular endothelial cells and acts as a vascular-type natriuretic peptide. In the present study, we stimulated the cGMP cascade in proliferating smooth muscle cells (SMCs), in which particulate guanylate cyclase-B, the specific receptor for CNP, is predominantly expressed, by use of an adenovirus encoding rat CNP cDNA (Ad.CNP). In the Ad.CNP-treated cultured SMCs, CNP caused the growth inhibition of SMCs at G(1) phase with an early increase of p21(CIP1/WAF1) expression and subsequent upregulation of p16(INK4a). The expression of smooth muscle myosin heavy chain-2, which is the molecular marker of highly differentiated SMCs, was reinduced in the Ad.CNP-treated SMCs. The Ad.CNP-treated SMCs also reexpressed particulate guanylate cyclase-A, which shows high affinity to atrial and brain natriuretic peptide and is exclusively expressed in well-differentiated SMCs. CNP, which was overexpressed in rabbit femoral arteries in vivo at the time of balloon injury, significantly suppressed neointimal formation. Furthermore, an enhancement of the expression of smooth muscle myosin heavy chain-2 occurred in the residual neointima. In addition, early regeneration of endothelial cells was observed in the Ad.CNP-infected group. Thus, stimulation of cGMP cascade in proliferating dedifferentiated SMCs can induce growth inhibition and redifferentiation of SMCs with accelerated reendothelialization.

Topics: Adenoviridae; Angiography; Animals; Arteries; Arteriosclerosis; Catheterization; Cell Cycle Proteins; Cell Differentiation; Cells, Cultured; Endothelium, Vascular; Male; Muscle, Smooth, Vascular; Myosin Heavy Chains; Natriuretic Peptide, C-Type; Rabbits; Rats; Regeneration; RNA, Messenger; Transfection

Insulin resistance has been highlighted as a common causal factor for glucose intolerance, hypertension and dyslipidemia, all of which are cardiovascular risk factors. A new class of antidiabetic agents, thiazolidinediones (TZDs), has been developed and demonstrated to improve insulin sensitivity. TZDs are high affinity ligands for peroxisome proliferator-activated receptor gamma (PPARgamma), the crucial transcription factor for adipocytes. Recent studies showed that PPARgamma is also expressed in monocytes/macrophages and is suggested to be involved in atherosclerosis. We could detect PPARgamma gene transcript in several cultured endothelial cells (human aortic endothelial cells (HAoECs), human coronary artery endothelial cells (HCAECs), human umbilical vein endothelial cells (HUVECs) and bovine carotid artery endothelial cells (BAECs)) as well as human coronary arteries we examined. Since endothelial dysfunction is critical for atherosclerosis, we investigated the effects of TZDs, troglitazone (TRO) and pioglitazone (PIO), on endothelial cell growth and secretion of C-type natriuretic peptide (CNP), which we demonstrated as a novel endothelium-derived relaxing peptide, and endothelin (ET), a potent vasoconstrictor, using HAoECs, HCAECs, HUVECs and BAECs. When all these cultured endothelial cells were daily treated with TRO and PIO for 5 days, both TRO and PIO (10(-8)M) significantly stimulated (3)H-thymidine incorporation of all these endothelial cells. In contrast, higher dose of TRO and PIO (10(-5)M) significantly suppressed DNA synthesis. TRO and PIO also exerted the compatible effect on the increase of cell numbers. TRO and PIO significantly enhanced CNP secretion from BAECs. In contrast, ET secretion from BAECs was suppressed by both TRO and PIO in a dose-dependent manner. The results of the present study suggest that TZDs modulate endothelial functions, including regulation of endothelial cell growth and secretion of endothelium-derived vasoactive substances, which affect vascular tone and remodeling in the process of atherosclerosis.

Topics: Animals; Arteriosclerosis; Carotid Arteries; Cattle; Cell Division; Cells, Cultured; Chromans; Coronary Vessels; Dose-Response Relationship, Drug; Endothelins; Endothelium, Vascular; Gene Expression; Humans; Hypoglycemic Agents; Natriuretic Peptide, C-Type; Pioglitazone; Radioimmunoassay; Receptors, Cytoplasmic and Nuclear; Thiazoles; Thiazolidinediones; Transcription Factors; Troglitazone; Vasodilator Agents; Vasomotor System

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

1. We investigated the effect of local administration of type-C natriuretic peptide (CNP) on the endothelial dysfunction and development of an atheroma-like neointima induced by a peri-arterial collar in rabbits. 2. Peri-arterial collars were placed on both common carotid arteries allowing local treatment of the collared region with either CNP (10 micromol/L) or saline. After 7 days, uncollared (control) and collared sections were taken from both arteries for pharmacological and morphological analysis. 3. Application of the collar markedly attenuated (P < 0.05) endothelium-dependent vasorelaxation induced by acetylcholine (ACh); inhibition of 5-hydroxytryptamine contraction was 80+/-5% in control sections compared with 44+/-4% in collared sections from the same arteries. Local infusion of CNP (10 micromol/L) into the collar restored ACh-induced vasorelaxation (74+/-3% from collared arteries + CNP vs 77+/-2% from control sections from the same arteries). 4. Type-C natriuretic peptide treatment also reduced (P < 0.05) intimal thickening compared with contralateral collared arteries (intima/media ratio 0.06+/-0.01 vs 0.16+/-0.01). 5. These results provide evidence that locally administered CNP is effective in preventing the endothelial dysfunction and development of a neointima in this model.

Topics: Acetylcholine; Animals; Arteriosclerosis; Carotid Arteries; Endothelium, Vascular; In Vitro Techniques; Male; Natriuretic Peptide, C-Type; Nitroprusside; Rabbits

Neutral endopeptidase 24.11 (NEP), widely distributed in the body, hydrolyzes and inactivates a number of endogenous vasoactive peptides, some of which could alter various functions of cells present in the arterial wall. Recently NEP has been found to exist in the vascular endothelium. The aim of this study was to assess the influence of chronic NEP inhibition by daily administration of UK79300 (candoxatril), an orally active NEP inhibitor (NEPI), on the development of atherosclerotic changes in high-cholesterol-fed rabbits. Male New Zealand White rabbits were fed for 8 weeks as follows: normal rabbit diet (Normal, n = 15), 1.5% cholesterol diet (Cholesterol, n = 15), or 1.5% cholesterol diet containing NEPI (20 mg.kg-1.d-1) (Cholesterol+NEPI, n = 15). At the end of the dietary period, NEPI treatment was found to suppress the surface area of the aorta covered by plaques (% surface area: Cholesterol, 59 +/- 6 versus Cholesterol+NEPI, 36 +/- 7, P < .01) and decreased contents of cholesterol and cholesterol esters in the aortas. NEPI also reduced plasma total cholesterol by 27% of Cholesterol rabbits (1781 +/- 130 mg/dL). The endothelial function, estimated by the endothelium-dependent relaxation of the isolated aortas in response to acetylcholine, was preserved in Cholesterol+NEPI rabbits compared with that in Cholesterol rabbits. NEP enzymatic activities in plasma and the particulate fraction of the homogenates from the aortas in Cholesterol rabbits were both increased, 3.1- and 3.9-fold, respectively, above those in Normal rabbits, but the activities in Cholesterol+NEPI rabbits were significantly lower than those in Cholesterol rabbits. UK73967, an active form of UK79300, or phosphoramidon partly reversed the atherosclerotic impairment of relaxation of the isolated thoracic aortic rings from Cholesterol rabbits in response to exogenous additions of C-type natriuretic peptide (CNP) and substance P, which are NEP substrates known to exist endogenously in the vascular endothelium. The results suggest that the increased NEP activity plays a significant role in atherogenesis, and NEPIs might be therapeutically useful in the prevention of atherosclerosis. Reduction of plasma cholesterol and suppression of degradations in the arteries of endogenously released CNP, substance P, or possibly other kinins known to have anti-atherosclerotic actions may at least partially contribute to the inhibitory effects of NEPIs on atherosclerotic changes.

Topics: Administration, Oral; Animals; Aorta, Thoracic; Arteriosclerosis; Atrial Natriuretic Factor; Body Weight; Cholesterol, Dietary; Diet, Atherogenic; Drug Evaluation, Preclinical; Enzyme Inhibitors; Glycopeptides; Hemodynamics; Hypercholesterolemia; Indans; Lipids; Male; Natriuretic Peptide, C-Type; Neprilysin; Nitroprusside; Organ Culture Techniques; Propionates; Proteins; Rabbits; Substance P; Vasodilation

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