The influence of geomagnetic variations on the formation of nitric oxide in exhaled air in human

The content of nitric oxide in exhaled air in healthy persons has been studied. It was shown that nitric oxide in exhaled air is formed from saliva nitrite due to the nitrite reductase activity of mouth cavity microflora. A relationship between the nitric oxide level and age, arterial pressure, and geomagnetic field indices was established. It was shown that the level of nitric oxide diminishes with age. A negative correlation between the nitric oxide content in exhaled air and arterial pressure (systolic and diastolic) was found. It was assumed that nitric oxide from the mouth can penetrate into the lungs and then to the blood where it can influence the vessel tonus. It was shown that the negative relationship took place between nitric oxide level in the air and Ki-indices of geomagnetic field on the day of measurement or the day preceding the measurement. The data obtained suggest that nitric oxide is involved in processes causing infarcts and insults in periods of magnetic storms.     

Fonsecaea monophora色素毒力性研究

目的探讨黑色素是否为Fonsecaea monophora的一个重要毒力因子。方法从Fonsecaea monophora的分生孢子突变株(CBS122845)传代接种产生白色突变株(CBS 125149)。透射电子显微镜(TEM)下观察到黑色素是位于分生孢子细胞壁表面上的电子致密颗粒。通过碱-酸法提取来自两个不同菌株的细胞壁色素颗粒。建立不同菌株或色素颗粒与活化巨噬细胞(RAW264.7)共培养体系,通过实时荧光相对定量PCR检测i-NOS基因的表达,格里斯法检测一氧化氮(NO)的表达结果,ELISA检测IL-12、TNF-α、IL-10的表达结果。结果色素型分生孢子和其色素颗粒能够降低巨噬细胞诱导型一氧化氮合酶(I-NOS)基因的表达和抑制一氧化氮的合成(P<0.05)。提高Th2细胞因子表达,同时抑制Th1细胞因子表达(P<0.05)。结论黑色素可能是Fonsecaea monophora逃避巨噬细胞对其氧化应激的重要机制。同时黑色素下调Th1免疫应答,可能利于真菌的持续感染。     

Factors that increase the contractile tone of the ductus arteriosus also regulate its anatomic remodeling

Permanent closure of the full-term newborn ductus arteriosus (DA) occurs only if profound hypoxia develops within the vessel wall during luminal obliteration. We used fetal and newborn baboons and lambs to determine why the immature DA fails to remodel after birth. When preterm newborns were kept in a normoxic range (Pa(O(2)): 50-90 mmHg), 86% still had a small patent DA on the sixth day after birth; in addition, the preterm DA wall was only mildly hypoxic and had only minimal remodeling. The postnatal increase in Pa(O(2)) normally induces isometric contractile responses in rings of DA; however, the excessive inhibitory effects of endogenous prostaglandins and nitric oxide, coupled with a weaker intrinsic DA tone, make the preterm DA appear to have a smaller increment in tension in response to oxygen than the DA near term. We found that oxygen concentrations, beyond the normoxic range, produce an additional increase in tension in the preterm DA that is similar to the contractile response normally seen at term. We predicted that preterm newborns, kept at a higher Pa(O(2)), would have increased DA tone and would be more likely to obliterate their lumen. We found that preterm newborns, maintained at a Pa(O(2)) >200 mmHg, had only a 14% incidence of patent DA. Even though DA constriction was due to elevated Pa(O(2)), obliteration of the lumen produced profound hypoxia of the DA wall and the same features of remodeling that were observed at term. DA wall hypoxia appears to be both necessary and sufficient to produce anatomic remodeling in preterm newborns.     

Role of reactive oxygen and nitrogen species in the vascular responses to inflammation

Inflammation is a complex and potentially life-threatening condition that involves the participation of a variety of chemical mediators, signaling pathways, and cell types. The microcirculation, which is critical for the initiation and perpetuation of an inflammatory response, exhibits several characteristic functional and structural changes in response to inflammation. These include vasomotor dysfunction (impaired vessel dilation and constriction), the adhesion and transendothelial migration of leukocytes, endothelial barrier dysfunction (increased vascular permeability), blood vessel proliferation (angiogenesis), and enhanced thrombus formation. These diverse responses of the microvasculature largely reflect the endothelial cell dysfunction that accompanies inflammation and the central role of these cells in modulating processes as varied as blood flow regulation, angiogenesis, and thrombogenesis. The importance of endothelial cells in inflammation-induced vascular dysfunction is also predicated on the ability of these cells to produce and respond to reactive oxygen and nitrogen species. Inflammation seems to upset the balance between nitric oxide and superoxide within (and surrounding) endothelial cells, which is necessary for normal vessel function. This review is focused on defining the molecular targets in the vessel wall that interact with reactive oxygen species and nitric oxide to produce the characteristic functional and structural changes that occur in response to inflammation. This analysis of the literature is consistent with the view that reactive oxygen and nitrogen species contribute significantly to the diverse vascular responses in inflammation and supports efforts that are directed at targeting these highly reactive species to maintain normal vascular health in pathological conditions that are associated with acute or chronic inflammation.     

Nitric oxide-an endothelial cell survival factor

Due to its unique position in the vessel wall, the endothelium acts as a barrier and thereby controls adhesion, aggregation and invasion of immune competent cells. Apoptosis of endothelial cells may critically disturb the integrity of the endothelial monolayer and contribute to the initiation of proinflammatory events. Endothelial cell apoptosis is counteracted by nitric oxide synthesised by the endothelium nitric oxide synthase (eNOS). Thus, nitric oxide inhibits endothelial cell apoptosis induced by proinflammatory cytokines and proatherosclerotic factors including reactive oxygen species and angiotensin II. The apoptosis-suppression may contribute to the profound anti-inflammatory and anti-atherosclerotic effects of endothelial-derived NO. Furthermore, the support of endothelial cell survival by NO may further play a central role for the pro-angiogenic effects of NO.     

Depression by relaxin of neurally induced contractile responses in the mouse gastric fundus

The peptide hormone relaxin, which attains high circulating levels during pregnancy, has been shown to depress small-bowel motility through a nitric oxide (NO)-mediated mechanism. In the present study we investigated whether relaxin also influences gastric contractile responses in mice. Female mice in proestrus or estrus were treated for 18 h with relaxin (1 microg s.c.) or vehicle (controls). Mechanical responses of gastric fundal strips were recorded via force-displacement transducers. Evaluation of the expression of nitric oxide synthase (NOS) isoforms was performed by immunohistochemistry and Western blot. In control mice, neurally induced contractile responses elicited by electrical field stimulation (EFS) were reduced in amplitude by addition of relaxin to the organ bath medium. In the presence of the NO synthesis inhibitor l-NNA, relaxin was ineffective. Direct smooth muscle contractile responses were not influenced by relaxin or l-NNA. In strips from relaxin-pretreated mice, the amplitude of neurally induced contractile responses was also reduced in respect to the controls, while that of direct smooth muscle contractions was not. Further addition of relaxin to the bath medium did not influence EFS-induced responses, whereas l-NNA did. An increased expression of NOS I and NOS III was observed in gastric tissues from relaxin-pretreated mice. In conclusion, the peptide hormone relaxin depresses cholinergic contractile responses in the mouse gastric fundus by up-regulating NO biosynthesis at the neural level.     

RhoA/Rho kinase and nitric oxide modulate the agonist-induced pulmonary artery diameter response time

We studied the amplitude and response time (RT; time to 50% of maximal response) of pulmonary vasoreactivity and investigated whether the characteristics of pulmonary vasoreactivity could be modulated by endothelium removal, nitric oxide (NO) synthase inhibition [N(G)-nitro-L-arginine (L-NNA)], RhoA activation [lysophosphatidic acid (LPA)] and Rho kinase inhibition (Y-27632). Slow acetylcholine-induced pulmonary vasodilation (262 +/- 5 s) was not due to the RT of endothelial NO release (45-55 s) and was always longer than RT in renal arteries (15 +/- 4 s). The rate-determining step is located in the smooth muscle cells. This was confirmed by the existing differences between the RT of the NO solution and KCl-induced renal and pulmonary vasoreactivity in endothelium-denuded arteries. We found that the pulmonary contractile amplitude increases and the RT decreases by L-NNA or LPA. In contrast, Y-27632 reduced the contractile amplitude and increased the RT in pulmonary arteries. These phenomena were dependent on the contractile stimulus (phenylephrine or KCl). In conclusion, slow pulmonary vasoreactivity is a smooth muscle cell characteristic that can be enhanced by RhoA and NO or endothelium removal. These effects were counteracted by Rho kinase inhibition. We show a role for RhoA/Rho kinase and NO in the modulation of pulmonary vascular reactivity.     

Critical role of endothelial cell-derived nitric oxide synthase in sickle cell disease-induced microvascular dysfunction

Superoxide, which can limit nitric oxide bioavailability, has been implicated in blood cell-vessel wall interactions observed in sickle cell transgenic (beta(S)) mice. Here we report that nonselective chemical inhibition of nitric oxide synthase isoforms dramatically reduces the enhanced leukocyte and platelet adhesion normally observed in cerebral venules of beta(S) mice. Although genetic deficiency of vascular wall inducible nitric oxide synthase does not alter adhesion responses in beta(S) mice, a significant attenuation is noted in beta(S) mice with vascular wall endothelial nitric oxide synthase (eNOS) deficiency, while the adhesion responses are exacerbated when eNOS is overexpressed in microvessels. The eNOS-mediated enhancement of blood cell adhesion is reversible by pretreatment with sepiapterin (which generates the eNOS cofactor tetrahydrobiopterin) or polyethyleneglycol-superoxide dismutase, implicating a role for eNOS-dependent superoxide production. These findings suggest that an imbalance between eNOS-derived nitric oxide and superoxide, both generated by the vessel wall, is critical to the proinflammatory and prothrombogenic phenotype that is assumed by the microvasculature in sickle cell disease.     

Chemo- and Mechano-Induced Reactions of Vascular Smooth Muscles in Rats with Chronic Insufficiency of Cerebral Dopamine: Effect of Co-Enzyme Q<Subscript>10</Subscript>

In experiments on isolated preparations of segments of the aorta and portal vein, we demonstrated that endothelium-dependent reactions of vascular smooth muscles (SMs) are suppressed in rats subjected to destruction of the nigro-striatal dopaminergic system in the left hemisphere (model of hemiparkinsonims). Under such conditions, the amplitude of relaxation of SMs of the wall of the thoracic aorta upon the action of the endothelium-dependent vasodilator acetylcholine iodide was four times smaller, while the latency demonstrated a 3.5-fold increase, as compared with the control. The amplitude of relaxation of vascular SMs after application of the endothelium-independent vasodilator sodium nitroprusside remained practically unchanged. In addition, preliminary stretching-induced increments of the amplitude of phasic contractions of the portal vein demonstrated a 2.5-fold decrease; this increment reached the maximum at smaller additional loadings, while the rigidity of the vascular wall increased. In animals that obtained a preparation of coenzyme Q₁₀ (10 mg/kg) with food during one month, contractile reactions of vascular SMs partly recovered. The amplitude of endothelium-dependent relaxation of the aorta increased, the latency of this reaction shortened, stretching-induced increments of the amplitude of phasic contractions increased, and the rigidity of the vascular wall dropped. We conclude that the functional state of the endothelium is worsened, and the vascular reactivity is modified under conditions of chronic insufficiency of nigro-striatal dopamine. It seems probable that oxidative stress is one of the main reasons for such changes. Coenzyme Q₁₀ significantly normalized abnormal vascular reactions (perhaps, due, to a considerable extent, to its antioxidant properties).     

Melanin in a Meristematic Mutant of Fonsecaea monophora Inhibits the Production of Nitric Oxide and Th1 Cytokines of Murine Macrophages

Melanin is a complex polymer which is secreted outside or constitutes the structure of fungal cell wall. It is considered as an important virulence factor in opportunistic pathogenic fungi. In this study, one albino mutant (CBS 125149) was generated from a parent meristematic mutant (CBS 122845) of Fonsecaea monophora. Transmission electron microscopy profiles showed that melanin in the parent strains appeared as electron-dense granules which located on the cell wall surface. We extracted the cell wall fractions from the two different strains by an alkali–acid method. The different strains or its cell wall fractions were interacted with the activated RAW264.7. The pigmented strain and its cell wall fraction could reduce the expression of inducible nitric oxide synthase gene and inhibit the synthesis of nitric oxide in vitro (P < 0.05). Exacerbated Th2 and inhibited Th1 response occurred in the interaction between activated RAW264.7 and the pigmented strain or its cell wall fraction. Collectively, our results suggest that melanin plays an important role in escaping the killing of oxidative burst in vitro. The exacerbated Th2 response probably accelerates the persistence of the fungus.     

Short-term exposure to homocysteine depresses rat aortic contractility by an endothelium-dependent mechanism

The effect of short-term exposure to homocysteine (Hcy) on the contractile characteristics of rat aortic tissue was assessed both in vitro and in vivo. The contractile response of Hcy-treated aortic rings in culture for 1 or 4 days was unchanged from control responses. By comparison, aortic rings from animals injected with Hcy showed marked attenuation of response compared with controls injected with saline, cysteine or methionine. The contractile response to K+ was decreased within 24 hours of Hcy injection, whereas the response to both K+ (-27%) and noradrenaline (-56%) was significantly decreased by 4 days. In contrast, the contractile response to phorbol-12,13-dibutyrate was not different between Hcy and control groups. Intimal rubbing completely restored the responsiveness of Hcy-treated tissue to K+ and noradrenaline. By comparison, L-NAME only partially restored contractile responsiveness, while the cyclooxygenase inhibitor indomethacin had no effect on contractile attenuation induced by Hcy. Western blot analysis showed a 2-fold increase of endothelial nitric oxide synthase (eNOS) and a 3-fold increase in inducible nitric oxide synthase (iNOS) protein expression in the aortic endothelial cells from Hcy-injected rats. The results indicate an early detectable effect of Hcy on the in vivo contractile properties of vascular smooth muscle. The effect is endothelium-mediated and may vary depending on the agonist studied. The mechanism is uncertain but appears to involve increased nitric oxide (NO) production. Finally, the data suggest that attenuation of contraction may not be due to a direct effect of Hcy but that the compound is modified or acts indirectly in vivo.     

The microscopic anatomy and ultrastructure of the contractile vessel in the sipunculan Themiste hexadactyla (Satô, 1930) (Sipuncula: Sipunculidea)

The microscopic anatomy and ultrastructure of the contractile vessel of the sipunculan Themiste hexadactyla (Satô, 1930) from Vostok Bay (the Sea of Japan) were studied by histological and electron microscope methods. The ultrastructural features of the internal (endothelium) and external (coelothelium) lining of the contractile vessel are described and illustrated. Numerous macromolecular filters, the so-called “double diaphragms,” were found in the external coelothelium facing the cavity of the trunk coelom. This suggests a possible filtration from the tentacular coelom into the trunk coelom though the contractile vessel wall. The microscopic peculiarities of the main tube of the contractile vessel and its numerous lateral branches twining around several internal organs are described in detail. The contractile vessel is polyfunctional: it can act as the main reservoir for the cavity fluid during the withdrawal of the tentacular crown and performs the functions of the distribution system in sipunculans.     

Nitric Oxide as an Orthograde Cotransmitter at Central Synapses of Aplysia: Responses of Isolated Neurons in Culture

Nitric oxide serves as an orthograde synaptic cotransmitterbetween identified neurons in the cerebral ganglion of Aplysia.Nitric oxide synthase, the enzyme that produces nitric oxide,is localized in a few specific neurons in the ganglia, includingneuron C2. Guanylyl cyclase the target enzyme of nitric oxide,is found in neurons C4 and MCC, which are synaptic followersof C2. Stimulation of C2 causes a vsEPSP in these neurons thatis reduced to 50% of its amplitude by nitric oxide synthaseinhibitors and guanylyl cyclase inhibitors. The remaining portionof the vsEPSP is mediated by histamine. Thus, nitric oxide andhistamine act as orthograde cotransmitters in producing thevsEPSP. Both cotransmitters cause closure of a background potassiumchannel, which depolarizes the neuron and enhances its responseto synaptic inputs. Exogenous nitric oxide (released by nitricoxide donor molecules) and histamine mimic the vsEPSP's depolarizationand decreased membrane conductance. When neurons C4 or MCC areisolated in cell culture they respond just as they do in theganglion, i.e., the nitric oxide response but not the histamineresponse is blocked by guanylyl cyclase inhibitors, and themembrane conductance is decreased by both histamine and nitricoxide. Aplysia hemolymph partially suppresses the response tonitric oxide, due to nitric oxide scavenging by hemocyanin,which contains copper and is the equivalent of hemoglobin. NeuronC2 followers that are hyperpolarized by histamine are insensitiveto nitric oxide. Thus, only select follower neurons respondto both transmitters.     

Simulated microgravity promotes nitric oxide-supported angiogenesis via the iNOS-cGMP-PKG pathway in macrovascular endothelial cells

Angiogenesis is a physiological process involving the growth of blood vessel in response to specific stimuli. The present study shows that limited microgravity treatments induce angiogenesis by activating macrovascular endothelial cells. Inhibition of nitric oxide production using pharmacological inhibitors and inducible nitric oxide synthase (iNOS) small interfering ribo nucleic acid (siRNA) abrogated microgravity induced nitric oxide production in macrovascular cells. The study further delineates that iNOS acts as a molecular switch for the heterogeneous effects of microgravity on macrovascular, endocardial and microvascular endothelial cells. Further dissection of nitric oxide downstream signaling confirms that simulated microgravity induces angiogenesis via the cyclic guanosine monophosphate (cGMP)-PKG dependent pathway.     

Mechanisms of blood flow-induced vascular enlargement

Chronic changes in wall shear stress lead to vascular remodeling, characterized by increased vascular wall diameter and thickness, to restore wall shear stress values to baseline. Release of nitric oxide from endothelial cells exposed to excessive shear is a fundamental step in the remodeling process, and potentially triggers a cascade of events, including growth factor induction and matrix metalloproteinase activation, that together contribute to restructuralization of the vessel wall. Understanding these processes could help explain how changes in blood vessel wall structure occur in the context of atherosclerosis or aortic aneurisms.     

Invited review: cGMP-dependent protein kinase signaling mechanisms in smooth muscle: from the regulation of tone to gene expression.

cGMP is a second messenger that produces its effects by interacting with intracellular receptor proteins. In smooth muscle cells, one of the major receptors for cGMP is the serine/threonine protein kinase, cGMP-dependent protein kinase (PKG). PKG has been shown to catalyze the phosphorylation of a number of physiologically relevant proteins whose function it is to regulate the contractile activity of the smooth muscle cell. These include proteins that regulate free intracellular calcium levels, the cytoskeleton, and the phosphorylation state of the regulatory light chain of smooth muscle myosin. Other studies have shown that vascular smooth muscle cells (VSMCs) that are cultured in vitro may cease to express PKG and will, coincidentally, acquire a noncontractile, synthetic phenotype. The restoration of PKG expression to the synthetic phenotype VSMC results in the cells acquiring a more contractile phenotype. These more recent studies suggest that PKG controls VSMC gene expression that, in turn, regulates phenotypic modulation of the cells. Therefore, the regulation of PKG gene expression appears to be linked to phenotypic modulation of VSMC. Because several vascular disorders are related to the accumulation of synthetic, fibroproliferative VSMC in the vessel wall, it is likely that changes in the activity of the nitric oxide/cGMP/PKG pathway is involved the development of these diseases.     

The influence of nitric oxide on the regulation of plasminogen activator inhibitor type 1 and tissue-type plasminogen activator expression

Nitric oxide produced in various human tissues by nitric oxide synthase is involved in the regulation of many physiological processes. Mechanism of its action is diverse. The most important physiological activity of nitric oxide is guanylate cyclase activation and an increase of cGMP synthesis. At low concentrations NO plays a pivotal role in vessel relaxation and possesses antithrombotic, antiproliferative and anti-inflammatory features as well. An excessive production of nitric oxide can disturb vascular hemostasis and contribute to development of cardiovascular diseases. Studies provide that NO also participate in fibrynolysis regulation by the influence on the PAI-1 and t-PA expression, what may have important clinical implications. The aim of this review is to present current knowledge about the role of nitric oxide in the regulation of these plasminogen activation system factors.     

Hemoglobin α in the blood vessel wall

Hemoglobin has been studied and well characterized in red blood cells for over 100 years. However, new work has indicated that the hemoglobin α subunit (Hbα) is also found within the blood vessel wall, where it appears to localize at the myoendothelial junction (MEJ) and plays a role in regulating nitric oxide (NO) signaling between endothelium and smooth muscle. This discovery has created a new paradigm for the control of endothelial nitric oxide synthase activity, nitric oxide diffusion, and, ultimately, vascular tone and blood pressure. This review discusses the current knowledge of hemoglobin׳s properties as a gas exchange molecule in the bloodstream and extrapolates the properties of Hbα biology to the MEJ signaling domain. Specifically, we propose that Hbα is present at the MEJ to regulate NO release and diffusion in a restricted physical space, which would have powerful implications for the regulation of blood flow in peripheral resistance arteries.     

The role of nitric oxide in mediating nonadrenergic, noncholinergic relaxation in rat pulmonary artery.

Experiments were undertaken to investigate the existence of inhibitory nonadrenergic, noncholinergic (i-NANC) nerve activity by using in vitro functional and immunohistochemical techniques in rat main pulmonary arterial rings. Vessels precontracted with phenylephrine (3 microM) relaxed in response to electrical field stimulation (EFS) (50 V, 0.2 ms, 0.1-10 Hz for 5 s) in the presence of atropine (1 microM) and guanethidine (1 microM). Tetrodotoxin (0.3 microM) abolished this response, indicating that it is neuronal in origin. l-NAME (30 microM), methylene blue (10 microM), and removal of endothelium significantly reduced the EFS-induced relaxations. The inhibitory action of l-NAME was completely reversed by l-arginine (1 mM) but not by d-arginine (1 mM). Moreover l-arginine alone potentiated the magnitude of the relaxations elicited by EFS. On the other hand, immunohistochemical work clearly demonstrated the existence of neuronal nitric oxide synthase in the pulmonary artery vessel wall. All these results are consistent with the suggestion that nitric oxide is the likely mediator of this vasodilatation. However, the incomplete blockade of the responses by l-NAME gives evidence of an additional inhibitory NANC neurotransmitter(s) mediating the residual relaxation, which requires further experiments to clarify its nature.