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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidemiologic studies have demonstrated hypertension is one of the risk factors of atherosclerosis, but the underlying mechanism is complex and still controversial. Salt-sensitivity is an important characteristic demonstrated in a subgroup of hypertension, since the factors relating to salt-sensitivity also influence smooth muscle hypertrophy and proliferation which are essential processes of atherosclerosis. Insulin resistance is also involved in the causal relationship between hypertension and atherosclerosis, because accumulating data indicate a central role of insulin resistance in patients with hypertension, glucose-intolerance and dyslipidemia. Vasoacting substances give direct effects on not only the tension but also the growth of smooth muscle cells, namely vasodilators, such as nitric oxide and atrial natriuretic peptides inhibit the proliferation of smooth muscle cells. On the other hand, vasoconstrictors such as angiotensin II, vasopressin and endothelin promote the proliferation of smooth muscle cells. The factors which influence both tension and proliferation of smooth muscle cells may play a central role in the relationship between hypertension and atherosclerosis.
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PMID:[The role of hypertension as a risk factor of atherosclerosis]. 769 22

The bioavailability of nitric oxide (NO) in the human coronary circulation at rest and after acetylcholine (ACH)-induced vasodilation was investigated in 32 patients with angiographically normal coronary arteries. The effects of intracoronary L-NG monomethyl arginine (L-NMMA) were investigated at rest and after ACH, sodium nitroprusside, and adenosine. L-NMMA (64 mumol/min) increased resting coronary vascular resistance by 22% (P < 0.001), reduced distal epicardial coronary artery diameter by 12.6% (P < 0.001), and inhibited ACH-induced coronary epicardial and microvascular vasodilation. These effects were reversed with intracoronary L-arginine. L-NMMA did not inhibit dilation in response to sodium nitroprusside and adenosine. 23 patients were exposed to one or more coronary risk factors. The vasoconstrictor effect of L-NMMA on the epicardial and microvessels was greater in patients free of risk factors: Coronary vascular resistance was 36% higher in patients without risks, compared to 17% higher in patients with risks (P < 0.05). Both epicardial and microvascular dilator effects of ACH were greater in patients without risk factors, and the inhibition of these effects by L-NMMA was also greater in patients without risk factors. Thus: (a) NO contributes importantly to resting epicardial and coronary microvascular tone, (b) coronary vascular dilation in response to ACH is predominantly due to increased production of NO, and (c) despite the absence of angiographic evidence of atherosclerosis, exposure to coronary risk factors is associated with reduced resting and stimulated bioavailability of NO from the human coronary circulation.
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PMID:Nitric oxide activity in the human coronary circulation. Impact of risk factors for coronary atherosclerosis. 770 83

Endothelins (ET) are a family of peptides with potent biological properties. Endothelial cells produce exclusively ET-1 while other tissues produce ET-2 and ET-3. The production of ET requires an increase in intracellular Ca2+. This increase can be induced by physical chemicals (i.e. hypoxia) or receptor-operated stimuli (i.e. thrombin, angiotensin II, arginine vasopressin, transforming growth factor beta 1, interleukin-1). Most of ET is released abluminally towards vascular smooth muscle and less luminally. The main vascular effect of ET are vasodilation (transient), profound and sustained vasoconstriction as well as proliferation of vascular smooth muscle. These biological effects are mediated by distinct receptors. Three ET receptors have been cloned, i.e. ETA-, ETB- and ETC-receptors. In vascular tissue ETA-receptors are expressed on vascular smooth muscle and responsible for vasoconstriction. ETB-receptors are expressed on endothelium and linked to nitric oxide and/or prostacyclin release. Activation of these receptors explains the transient vasodilation with intraluminal application of ET. Vascular smooth muscle cells can express ETB-receptors which contribute to ET-induced vasoconstriction particularly at lower concentrations. The role of the recently cloned ETC-receptor in the vasculature is still uncertain. ET production is increased (as judged from circulating plasma levels) in vascular disease and atherosclerosis in particular, in myocardial infarction and heart failure, pulmonary hypertension and renal disease. ET production is increased in arterial hypertension remains controversial. Non-peptidic ET antagonists have been developed which either block ETA- receptors or ETA- and ETB-receptors simultaneously. The advantage of ETA-receptors is that they leave the endothelium-dependent vasodilation to ET (via ETB-receptor) intact. However, ETB-mediated contraction remains unaffected by these antagonists. In contrast ETA-/ETB-antagonists fully prevent ET-induced vasoconstriction, however, they also inhibit the endothelial effects of the peptide. ET antagonists interfere with the effects of ET in isolated vascular tissue (including that obtained from humans) as well as in vivo. In humans, ETA as well as ETA-/ETB-antagonists inhibit endothelin-induced vasoconstriction. Hence in summary ET are a family of potent peptides with profound effects in the vasculature. Several studies suggest a role of ET in cardiovascular disease. The newly developed ET-antagonists are potent and selective tools to delineate the (patho-)physiological roles of ET and may become a new class of cardiovascular drugs.
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PMID:Endothelin and endothelin antagonists: pharmacology and clinical implications. 771 86

Nitric oxide (NO) is a highly reactive free radical with a multitude of organ specific regulatory functions. Since 1985, NO has been the subject of numerous research efforts and as a result, has been found to play a major role in the cardiovascular, pulmonary, gastrointestinal, immune, and central nervous systems. In addition, deranged NO synthesis is the basis for a number of pathophysiologic states, such as atherosclerosis, pulmonary hypertension, pyloric stenosis, and the hypertension associated with renal failure. Traditional NO donors such as sodium nitroprusside and new pharmacologic NO adducts such as S-nitrosothiols may serve as exogenous sources of NO for the treatment of NO-deficient pathologic states. This review is an attempt to acquaint the surgical community with the fundamentals of NO biochemistry and physiology. Increased knowledge of its functions in normal homeostasis and pathologic states will enable physicians to better understand these disease processes and utilize new pharmacologic therapies.
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PMID:The emerging multifaceted roles of nitric oxide. 891 85

Postmenopausal women (PMW) have an increased risk of cardiovascular disease that is attenuated by hormone replacement therapy (HRT). Inasmuch as hypertension and atherosclerosis are associated with diminished endothelium-derived nitric oxide (NO), we investigated whether HRT augments NO release in PMW. We determined serum levels of nitrite/nitrate (NO2 + NO3) at baseline and during the 6th, 12th, and 24th months of the study in two groups of PMW. One group (HRT-PMW, n = 13) received continuous transdermal administration of 17 beta-estradiol (Estraderm-TTS-50) supplemented with oral norethisterone acetate (NETA) on days 1 through 12 of each month, and the other group (control PMW, n = 13) did not receive HRT. Blood samples in the HRT-PMW group were collected without regard to whether subjects were taking NETA at the time of blood sampling. Serum NO2 + NO3 levels increased in HRT-PMW for the duration of the study, whereas serum NO2 + NO3 levels remained unchanged in control PMW. When all samples regardless of timing of collection with respect to NETA treatment were included in the statistical analysis, the change in NO2 + NO3 levels in HRT-PMW was significantly greater compared with the change in control PMW (P = .037). Likewise, when only those samples collected when estradiol-treated subjects were not taking oral NETA were included in the statistical analysis, the change in NO2 + NO3 levels in the HRT-PMW group remained significant (P = .047) compared with control PMW.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Circulating nitric oxide (nitrite/nitrate) levels in postmenopausal women substituted with 17 beta-estradiol and norethisterone acetate. A two-year follow-up study. 772 43

The recruitment of monocytes into the arterial wall is one of the earliest events in the pathogenesis of atherosclerosis. Since monocyte chemoattractant protein 1 (MCP-1) plays a key role in the subendothelial recruitment of monocytes, we tested whether nitric oxide (NO) modulates the expression of MCP-1 in cultured human endothelial cells. Inhibition of basal NO production by NG-nitro-L-arginine (L-NAG) upregulates endothelial MCP-1 mRNA expression (250 +/- 20%) and protein secretion. Exogenous addition of NO dose-dependently decreased MCP-1 mRNA expression and secretion. Changes in MCP-1 mRNA expression and protein secretion were paralleled by corresponding changes in chemotactic activity of cell-conditioned media for monocytes. An MCP-1 antibody reduced monocyte chemotactic activity by 85% and completely abolished the increased monocyte chemotactic activity induced by the inhibition of NO production. Elevation of endothelial cGMP levels had no significant effect on MCP-1 mRNA expression. Inhibition of basal endothelial NO production by L-NAG increased binding activity of a nuclear factor kappa B (NF-kappa B)-like transcriptional regulatory factor, whereas exogenous addition of NO decreased NF-kappa B-like binding activity during stimulation with tumor necrosis factor-alpha. Thus, NO modulates MCP-1 expression and monocyte chemotactic activity secreted by human umbilical vein endothelial cells (HUVECs) in culture. The activation of NF-kappa B-like transcriptional regulatory proteins by inhibition of NO suggests a molecular link between an oxidant-sensitive transcriptional regulatory mechanism and NO synthesis in HUVECs.
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PMID:Nitric oxide modulates the expression of monocyte chemoattractant protein 1 in cultured human endothelial cells. 775 69

Nitric oxide derived from the vascular endothelium and other cells of the cardiovascular system has important roles in physiological regulation of blood flow and may have pathophysiological functions in cardiovascular disease. Nitric oxide can be synthesised from L-arginine by any of three isoforms of nitric oxide synthase (NOS), and its interaction with prostacyclin, its proposed mechanisms of action and cytotoxicity are briefly reviewed in the context of cardiovascular function. Although nitric oxide can hyperpolarize vascular smooth muscle, activation of the endothelium can induce hyperpolarization and vasodilatation by other means. Nitric oxide has important roles in the physiological regulation of local blood flow and blood pressure, especially during exercise and in response to shear stresses and other local factors in arterioles. Nitric oxide is also involved in neurogenic control of the microcirculation through autonomic efferent nerves and it contributes to vasodilatation and inflammation associated with activation of sensory nerves. In pathological circumstances, excess nitric oxide produced by inducible NOS compromises circulatory function in septic shock, during transplant rejection, and during myocardial ischaemia and reperfusion injury. Immunosuppressant drugs like cyclosporin A inhibit the expression of NOS through complex intracellular intermediates. Disturbances in the activity of constitutive and inducible NOS in the artery wall accompany the development of atherosclerosis, vasospasm and thrombosis, and may contribute to some forms of hypertension and diabetic vascular disease. Reversing the nitric oxide defect with therapeutic agents including angiotensin-converting enzyme inhibitors offers promise in protecting against some manifestations of vascular disease.
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PMID:Nitric oxide in cardiovascular disorders. 777 76

So far pharmacological consequences of inhibition of thromboxane A2 (TXA2) synthase by imidazole derivatives (e.g., camonagrel or dazoxiben) were linked to suppression of platelet activity. Here we report that in patients with peripheral atherosclerosis or in cats with extracorporeal thrombogenesis treatment with camonagrel is associated with activation of fibrinolysis or thrombolysis. These phenomena seem to be related to the camonagrel-induced shift in metabolism of prostaglandin endoperoxides from TXA2 to prostacyclin (PGI2), although in an in vitro model the involvement of the L-arginine/nitric oxide pathway cannot be excluded. In cats camonagrel (10 mg/kg i.v.) produced not only a fall in TXB2 but also a rise in 6-keto-PGF1 alpha and no change in cyclic-GMP plasma levels. This points to PGI2 rather than to nitric oxide as an in vivo mediator of camonagrel-induced thrombolysis. The crucial role of endogenous PGI2 in the thrombolytic response to camonagrel in cats was evidenced by its blockade following pretreatment of animals with a megadose of aspirin (50 mg/kg i.v.) and lack of any effect on pretreatment with L-NAME (100 micrograms/kg/min, i.v.). Obviously TXA2 synthase inhibitors (e.g., camonagrel) and cyclo-oxygenase inhibitors (e.g., aspirin) antagonize each other in their anti-thrombotic actions and must not be administered at the same time. Furthermore, in patients camonagrel (800 mg orally) suppressed TXA2 generation by 99.5% and doubled the plasma level of 6-keto-PGF1 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The mechanism of anti-thrombotic, thrombolytic and fibrinolytic actions of camonagrel--a new thromboxane synthase inhibitor. 777 18

Nitric oxide (NO) synthesised by endothelial cells, plays a key role in the control of vascular tone. Its synthesis from L-arginine is assured by NO-synthase, the activity of which is dependent on intracellular calcium concentrations, which are themselves modulated by pharmacological (acetylcholine, serotonin, bradykinin...) or physical factors (shearing forces exerted by blood flow). NO acts by stimulating a soluble guanylate-cyclase of the smooth muscle cells in the vessel wall. Its vasodilator effect is therefore mediated by an increase in intracellular cyclic GMP concentration. The synthesis or liberation of NO by the endothelium may be decreased or abolished during many pathological processes (hypercholesterolaemia, atherosclerosis, systemic or pulmonary hypertension...). The significance of this abnormality of NO-mediated endothelium-dependent vasodilation in different pathological conditions has not been established. However, it is probably significant in view of the different properties of NO: vaso-relaxation, antiaggregant and inhibition of vascular smooth muscle growth. It is not yet known whether this abnormality is a cause or a consequence of the underlying disease. From the therapeutic point of view, NO is an active metabolite of nitrate derivatives, sodium nitroprussiate and molsidomine which therefore share the same mode of action as the so-called "endothelium-dependent" vasodilatoe agents. The inhalation of NO, which is increasingly used in neonatal and adult intensive care units, is an alternative therapeutic approach in many conditions associated with pulmonary hypertension.
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PMID:[Nitric oxide, from vascular physiology to therapeutics]. 778 35

Oxidized low-density lipoprotein (ox-LDL) plays an important role in the development of atherosclerosis and potentially influences the endothelial regulation of vasomotor tone. We have recently shown that lysophosphatidylcholine (LPC), a lysophospholipid contained in ox-LDL, has various pathophysiological effects. We further examined the role of LPC in the ox-LDL-induced vasoactivity in isolated pig coronary arteries. Copper-induced ox-LDL but not native LDL (n-LDL) elicited endothelium-dependent contraction during plateau contraction evoked by prostaglandin F2 alpha. Lipid extracted from ox-LDL (ox-LDL-lipid) also induced vasocontraction, but lipid of n-LDL (n-LDL-lipid) did not influence tone. When LPC was depleted from ox-LDL (i.e., defatted albumin- or phospholipase B-treated ox-LDL), vasocontraction was significantly attenuated. Synthetic palmitoyl LPC also induced endothelium-dependent vasocontraction, mimicking the response elicited by ox-LDL, but phosphatidylcholine, which exists in n-LDL and is converted to LPC during oxidative modification of LDL, did not influence the tone. Contraction to either ox-LDL or LPC was significantly attenuated by NG-monomethyl-L-arginine but not by indomethacin or superoxide dismutase. Forty minutes of incubation of coronary rings with either ox-LDL or LPC significantly attenuated endothelium-dependent vasorelaxation to thrombin without affecting vasorelaxation to endothelium-independent vasodilator nitroglycerin. In conclusion, LPC contained in lipid fraction of ox-LDL caused endothelium-dependent contraction and inhibited endothelium-dependent relaxation in isolated pig coronary arteries. The vasocontraction might be at least in part caused by LPC-mediated inhibition of endothelium-derived nitric oxide release.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:LPC in oxidized LDL elicits vasocontraction and inhibits endothelium- dependent relaxation. 781 Jul 42


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