UMLS:C0406810 - FACTA Search

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Query: UMLS:C0406810 (NAME)
13,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were performed in the opossum to define the role of the L-arginine-nitric oxide (NO) pathway in lower esophageal sphincter (LES) relaxation to swallowing and vagal stimulation in viv and intramural nerve stimulation in vitro. In vivo, L-NAME, a water soluble NO synthase (NOS) inhibitor, caused antagonism of LES relaxation due to reflex-induced swallowing. L-NAME (20 mg/kg i.v.) reduced the amplitude of swallow induced relaxation from 88% to 28%. LES relaxation due to electrical stimulation of peripheral end of decentralized vagus nerve was also antagonized. The effects of L-NAME were reversed by L-arginine, but not by D-arginine. L-NAME treatment did not antagonize LES relaxation to intravenous administration of isoproterenol. In vitro, NO and sodium nitroprusside (SNP) caused a decrease in the sphincter tone. The relaxing effect caused by NO and SNP was not antagonized by tetrodotoxin or omega-conotoxin. Inhibitors of NO synthase, L-NMMA and L-NNA, caused slight increase in the spontaneous resting LES tone and concentration-dependent antagonism of electrical field stimulation (EFS) induced LES relaxation. L-NNA (10(-4)M) abolished EFS induced LES relaxation at low frequencies (less than 5 Hz) and antagonized the relaxation to a value 20% of the control at 20 Hz. The antagonistic action of L-NMMA and L-NNA was unaffected by D-arginine but was reversed by L-arginine. The inhibitory effect of NO, SNP, or two other putative inhibitory neurotransmitters (VIP and CGRP) on the LES was not antagonized by L-NNA. These studies show that inhibitors of NO synthase selectively antagonize LES relaxation to all three modes of intramural inhibitory nerve stimulation including physiological swallowing. These studies suggest that the L-arginine-nitric oxide pathway is involved in physiological relaxation of the LES.
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PMID:Role of nitric oxide in lower esophageal sphincter relaxation to swallowing. 137 90

1 We have determined the dermal microvascular effects of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 100 nmol/site), endothelin-1 (ET-1, 0.1-10 pmol/site) and ET-3 (0.1-30 pmol/site) in rats with streptozotocin (STZ)-induced diabetes mellitus. Cutaneous blood flow changes as measured by a 133xenon (133Xe) clearance technique, were determined in diabetic rats four weeks after treatment with streptozotocin (STZ) and compared with responses measured in normal rats four weeks after treatment with saline. 2 Resting skin blood flow was similar in diabetic and in normal rats, as measured by 133Xe clearance and laser Doppler flowmetry. 3 Intradermal NG-nitro-L-arginine methyl ester (L-NAME) reduced skin blood flow in normal rats by 55.2 +/- 2.6% as measured by 133Xe clearance, (n = 9). L-NAME was significantly less effective in diabetic rats, inducing a 40.9 +/- 7.7% decrease in blood flow (n = 9, P less than 0.05). The enantiomer D-NAME had no effect in either group of rats. 4 Low doses of ET-1 and ET-3 injected intradermally induced dose-dependent decreases in blood flow, measured by 133Xe clearance, which were similar in both groups of rats. However, the responses to the highest doses of ET-1 (10 pmol/site) and ET-3 (10 and 30 pmol/site) were significantly reduced in the diabetic compared with the normal rats (P less than 0.05).In addition vasoconstriction to the highest doses of vasopressin (0.3 and 3 pmol/site) and vasodilatation to the neuropeptide calcitonin gene-related peptide (CGRP, 1O pmol/site) were similarly reduced in the diabetic rats (P <0.05).5. The decrease in blood flow induced by submaximal doses of ET-1 was enhanced by co-injection with L-NAME (100 nmol/site) in both diabetic and normal rats. However, this enhanced response was significantly reduced in the diabetic rats (P<0.05). A similar pattern of responses were observed to ET-3 in the presence and absence of L-NAME.6. These results indicate that the cutaneous microvasculature of rats with STZ-induced diabetes responds differently to intradermal ET-1 and ET-3 compared with normal rats; a similarly altered vascular reactivity was observed with vasopressin and CGRP. Hence, the diabetic microcirculation has impaired responses to several vasoconstrictors and a vasodilator. The effect of the nitric oxide synthase inhibitor L-NAME is also suppressed in the diabetics, suggesting that there may be decreased local production of, or response, to nitric oxide.
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PMID:Altered microvascular reactivity to endothelin-1, endothelin-3 and NG-nitro-L-arginine methyl ester in streptozotocin-induced diabetes mellitus. 139 77

1. The aim of this study was to investigate whether the hypotensive effect of rat alpha-calcitonin gene-related peptide (alpha CGRP) in conscious rats is mediated by endothelium-derived nitric oxide (NO) or the opening of adenosine 5'-triphosphate (ATP)-sensitive potassium (KATP) channels. 2. Dose-mean arterial pressure (MAP)-response curves of alpha CGRP were examined in the presence of vehicle, phenylephrine, KATP channel antagonist glibenclamide or NO synthase inhibitors, NG-nitro-L-arginine methyl ester (L-NAME) and NG-nitro-D-arginine methyl ester (D-NAME). Dose-MAP-response curves for sodium nitroprusside were also constructed in the presence and absence of L-NAME and D-NAME. 3. alpha CGRP and nitroprusside produced dose-dependent reductions in MAP which were potentiated by phenylephrine. Both L-NAME and D-NAME attenuated the depressor response to alpha CGRP but not nitroprusside. 4. Dose-MAP-response curves for pinacidil, a KATP-channel activator, were also examined in the presence of glibenclamide or vehicle. Glibenclamide attenuated pinacidil- but not alpha CGRP-induced reductions in MAP. 5. It is concluded that the hypotensive effects of alpha CGRP are partially mediated via endothelium-derived NO but not via the opening of KATP channels.
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PMID:Mechanism of the vasodilator action of calcitonin gene-related peptide in conscious rats. 150 30

The possible modulatory role of nitric oxide (NO) in neurogenic edema formation in rat paw skin, induced by electrical stimulation of the saphenous nerve, was investigated by using two NO synthase inhibitors, NG-nitro-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI). Both L-NAME (100 mg/kg IV, P < .05) and 7-NI (10 mg/kg IV, P < .05) caused an L-arginine (100 mg/kg IV, P < .01)-reversible inhibition of neurogenic edema as measured by 125I-albumin accumulation, whereas D-NAME (inactive enantiomer of L-NAME) and 6-aminoindazole (structurally similar to 7-NI) were without inhibitory effect. L-NAME produced the predicted vasopressor effect (before, 115 +/- 18 mm Hg; 5 minutes after, 174 +/- 18 mm Hg; n = 6; P < .05), whereas 7-NI showed no significant increase in blood pressure (before, 96 +/- 9 mm Hg; 5 minutes after, 102 +/- 10 mm Hg; n = 6), and neither L-NAME nor 7-NI had any effect on basal or vasodilator calcitonin gene-related peptide (CGRP, 10 pmol per site)-stimulated local blood flow in rat skin, as measured by laser Doppler flowmetry. Furthermore, systemic and local 7-NI had no effect on edema formation induced by local administration of substance P (with or without CGRP) and histamine (with or without CGRP) in rat skin. Since 7-NI blocks edema produced by stimulation of the saphenous nerve, it is suggested that release of NO is involved in neurogenic edema formation, but the vasodilator action of NO is unimportant in this context.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Essential role for nitric oxide in neurogenic inflammation in rat cutaneous microcirculation. Evidence for an endothelium-independent mechanism. 753 19

1. Effects of the alpha 2-adrenoceptor agonists, UK14304 and clonidine, the 5-HT1 receptor agonist, sumatriptan and the kappa-opioid receptor agonist, GR103545, on sensory neurotransmission in histamine-contracted guinea-pig isolated pulmonary artery (GPPA) have been studied. 2. Electrical field stimulation (EFS) induced frequency-dependent relaxations of histamine-contracted GPPA, which were attenuated by tetrodotoxin and capsaicin pretreatment but not by the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME). 3. Substance P (0.3 microM) induced relaxations which were subject to rapid tachyphylaxis. Neither the NK1 receptor antagonist, (+/-)-CP 96,345, nor desensitization to substance P had any effect of EFS-induced relaxations of histamine-contracted GPPA. 4. Calcitonin gene-related peptide (CGRP; 3 and 30 nM) induced concentration-dependent relaxations of histamine-contracted GPPA. The putative CGRP receptor antagonist, CGRP8-37 (1 microM), markedly attenuated EFS-induced relaxations as well as relaxations induced by a low concentration of CGRP. 5. Sumatriptan (0.1 and 1 microM) and the selective kappa-opioid receptor agonist, GR103545 (10 and 100 nM) had no effect on EFS-induced relaxations of histamine-contracted GPPA. In contrast, the alpha 2-adrenoceptor agonists UK14304 (1-100 nM) and clonidine (300 nM) attenuated responses to EFS, the attenuation of UK14304 (100 nM) being reversed by yohimbine (300 nM). 6. It is concluded that in GPPA, where a presynaptic inhibition of sensory neurotransmission by alpha 2-adrenoceptor activation could be shown, there was no evidence for such modulation by either sumatriptan-sensitive 5-HT1 receptors or kappa-opioid receptors.
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PMID:Sensory nerve-mediated relaxation of guinea-pig isolated pulmonary artery: prejunctional modulation by alpha 2-adrenoceptor agonists but not sumatriptan. 768 95

1. Male, Long Evans rats were chronically instrumented with pulsed Doppler flow probes and intravascular catheters to permit assessment of the regional haemodynamic responses to human and rat adrenomedullin, to compare the responses to human adrenomedullin to those of human alpha-CGRP in the absence and presence of the CGRP1-receptor antagonist, human alpha-CGRP [8-37], and to determine the involvement of nitric oxide (NO)-mediated mechanisms in the responses to human adrenomedullin, relative to human alpha-CGRP. 2. Human and rat adrenomedullin (0.3, 1, and 3 nmol kg-1, i.v.) caused dose-dependent hypotension and tachycardia, accompanied by increases in renal, mesenteric and hindquarters flows and vascular conductances. At the lowest dose only, the hypotensive and mesenteric vasodilator effects of rat adrenomedullin were significantly greater than those of human adrenomedullin. 3. Human alpha-CGRP at a dose of 1 nmol kg-1 caused hypotension, tachycardia and increases in hindquarters flow and vascular conductance, but reduction in renal and mesenteric flows, and only transient vasodilatations in these vascular beds. These effects were substantially inhibited by human alpha-CGRP [8-37] (100 nmol kg-1 min-1), but those of human adrenomedullin (1 nmol kg-1) were not; indeed, the mesenteric haemodynamic effects of the latter peptide were enhanced by the CGRP1-receptor antagonist. 4. In the presence of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 183 nmol kg-1 min-1), there was only a slight, but significant, inhibition of the hindquarters hyperaemic vasodilator effect of human adrenomedullin, but not that of human alpha-CGRP. 5. These results indicate that the marked regional vasodilator effects of human (and rat) adrenomedullin are largely independent of NO and, in vivo, do not involve CGRP1-receptors.
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PMID:Regional haemodynamic effects of human and rat adrenomedullin in conscious rats. 773 84

Mechanisms involved in central thyrotropin-releasing hormone (TRH) analogue RX-77368-induced prevention of gastric lesions were investigated in urethan-anesthetized rats. Gastric lesions were induced by intragastric administration of ethanol (4 ml/kg) and assessed 1 h later by macroscopic visualization using computerized image analysis. RX-77368 (3, 5, and 10 ng) microinjected into the dorsal motor nucleus of the vagus (DMN) decreased ethanol-induced gastric lesions by 79, 68, and 61%, respectively. RX-77368 at 1.5, 15, or 30 ng into the DMN or at 3 or 10 ng into the nucleus of the solitary tract, hypoglossal nucleus, or reticular field was ineffective in preventing mucosal damage. The protective effect of RX-77368 (3 ng into the DMN) was partly inhibited by peripheral injection of indomethacin and completely blocked by atropine, the calcitonin gene-related peptide antagonist, CGRP-(8-37), and NG-nitro-L-arginine methyl ester (L-NAME). L-arginine, but not D-arginine, reversed the effect of L-NAME. RX-77368 (3 ng into the DMN) enhanced gastric prostaglandin E2 (PGE2) release. These data indicate that low doses of TRH analogue act in the DMN to induce gastric protection against ethanol injury through muscarinic-, PGE2-, CGRP-, and nitric oxide-dependent mechanisms.
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PMID:Low doses of TRH analogue act in the dorsal motor nucleus to induce gastric protection in rats. 859 29

1. RR may act as a preferential capsaicin antagonist in the pig nasal mucosa in vivo. However, the present data reveal a narrow concentration range for the selective actions of RR. Moreover, RR has systemic cardiovascular side effects despite local i.a. infusion in the IMA. 2. Acoustic rhinometry is a useful method for investigations of changes in nasal cavity volume in the pig in vivo. 3. The NK1-receptor antagonist RP-67,580 lacks NK1-receptor blocking properties in the pig in vivo. In contrast, CP-96,345 and SR 140.333 significantly blocked SP-mediated vascular effects in the pig nasal mucosa and superficial skin, indicating species dependent NK1-receptor selectivity. Capsaicin-induced vasodilatation in the IMA was not attenuated after administration of CP-96,345 and SR 140.333 whereas the superficial blood flow in the nasal mucosa and skin was slightly reduced. The CGRP-receptor antagonist hCGRP 8-37 markedly reduced the capsaicin-evoked vascular effects in the pig nasal mucosa and superficial skin. 4. Vanilloid receptors, as revealed by 3H-RTX binding, are present in the pig nasal mucosa although with different characteristics compared to vanilloid receptors in the pig dorsal horn. Capsaicin, RTX and LA evoked vasodilatation in the pig nasal mucosa in a similar fashion, indicating activation of sensory nerves. The LA (proton)-evoked vasodilatation was significantly attenuated after local i.a. infusion of hCGRP 8-37, closely resembling the results obtained from the capsaicin challenge before and after CGRP-receptor blockade. Capsazepine did not reduce the capsaicin-and LA-evoked vasodilation in the pig nasal mucosa. This agrees well with the observation that capsazepine did not inhibit RTX binding to vanilloid receptors in pig nasal mucosal membranes. 5. Capsaicin desensitisation of the human nasal mucosa attenuated the subjective pain response as well as the reduction of the cross-sectional area in the nasal cavity evoked by LA and hypertonic saline. This finding gives further support to the hypothesis that protons may act as endogenous ligands to the vanilloid receptor also in man. 6. Systemic administration of the NOS inhibitor L-NNA significantly reduced basal nasal V Con and increased C Vol in the pig. The effects evoked by L-NNA were similar in magnitude to those of phenylephrine and UK 14304, although of much longer duration. Administration of L-NNA did not reduce the vasodilator responses to SP and ACh, suggesting that these substances may mediate their vascular effects via one or several other mechanisms beside the NO/cGMP pathway. Moreover, capsaicin-, VIP-, and nitroprusside-evoked vasodilatation was not reduced after NOS inhibition. 7. Heavy physical exercise and alpha-adrenoceptor agonists reduce nasal cavity NO levels acutely in man. This may be due to a reduced supply of substrates for NO synthesis in the paranasal sinus epithelium, the primary NO production site in the upper airways. However, prolonged use of the alpha 2-adrenoceptor agonist oxymetazoline for 10 days, did not reduce basal nasal cavity NO levels. Nasal cavity NO levels and C Vol were not altered after topical administration of the NOS inhibitor L-NAME. Nor did we see any change in C Vol after local challenge with NO gas in the nasal cavity. The present results indicate that the human nasal mucosa is largely insensitive to NO gas in contrast to the bronchial mucosa and lung. 9. In conclusion, the present results suggest that vanilloid receptors are present on sensory nerves in the pig nasal mucosa and that LA (protons) may act as an endogenous ligand to this receptor. Sensory neuropeptides, especially CGRP, may be of importance for nasal congestion upon sensory nerve activation. Hence, selective, non-peptide CGRP-receptor antagonists may be of potential use in nasal disorders characterised by nasal congestion. NO is of importance for basal nasal vascular regulation. However, whether NOS inhibitors have potential as useful nasal de
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PMID:Sensory neuropeptides and nitric oxide in nasal vascular regulation. 880 Mar 74

1 Non-adrenergic non-cholinergic (NANC) vasodilator nerves regulate tone in certain vascular beds. We have investigated the mechanisms of the NANC dilator response in the isolated small mesenteric artery of the rabbit by use of the tension myograph. 2 Small second or third order (150-300 microm in diameter) arteries of the rabbit mesenteric bed were mounted in a Mulvany tension myograph. Responses to electrical field stimulation (EFS) and exogenous vasodilators were investigated. 3 EFS (0.5-16 Hz, 10 V, 0.3 ms for 5 s), in the presence of guanethidine (5 microM) and atropine (1 microM) produced frequency-dependent relaxation of small arteries. Pretreatment with tetrodotoxin (1 microM) abolished the relaxation and desensitization with capsaicin (10 microM) strongly inhibited the relaxation. 4 Pretreatment with a P2Y-purinoceptor antagonist, basilen blue (3 microM) or a human calcitonin gene-related peptide (hCGRP) receptor antagonist, hCGRP8-37 (1 microM) suppressed the NANC relaxation by approximately 40-60 % in each case and combined pretreatment almost abolished the relaxation. 5 The EFS-induced relaxation was suppressed by endothelium-removal, pretreatment with the soluble guanylyl cyclase inhibitor ODQ (1 microM) and the NO scavenger oxyhaemoglobin (OxyHb; 20 microM) but not by NO synthase inhibitors NG-nitro-L-arginine methyl ester (L-NAME; 300 microM) or NG-nitro-L-arginine (L-NOARG; 300 microM). Combined pretreatment with ODQ and CGRP8-37 almost abolished the relaxation. 6 A P2Y-purinoceptor agonist, 2-methylthio ATP, produced endothelium-dependent relaxation which was inhibited by L-NAME and ODQ (1 microM), whilst hCGRP produced endothelium-independent and ODQ-insensitive relaxation. 7 Ultraviolet light (320 nm, 5 shots over 20 s) produced relaxation that was blocked by both OxyHb and ODQ but not by NG-monomethyl-L-arginine (L-NMMA, 300 microM). 8 The present study suggests that EFS-induced NANC relaxation of the mesenteric small artery of the rabbit is mediated mainly by capsaicin-sensitive sensory C-fibres and that both ATP and CGRP are involved. The action of ATP released by EFS appears to be endothelium-dependent and involve activation of soluble guanylyl cyclase, but is resistant to inhibitors of NO synthase. The response to CGRP is endothelium-independent. These results show that ATP and CGRP account fully for the NANC relaxation of this vessel type and that the endothelium is involved in NANC-induced relaxation. The endothelium-dependent part of the response is consistent with the release of NO, either from NO synthase, incompletely inhibited by the NO synthase inhibitors, or by some preformed stores.
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PMID:Endothelium-dependent sensory NANC vasodilatation: involvement of ATP, CGRP and a possible NO store. 948 20

The mechanism of prostaglandin E2-, prostaglandin F2alpha- and latanoprost acid (13,14-dihydro-17-phenyl-18,19,20-trinor-prostaglandin F2alpha)-induced relaxation of the rabbit submental vein was studied. Prostaglandin E2 caused maximum relaxation of endothelin-1 precontracted vessels (EC50: 1.8 x 10(-8) M). Much of the relaxation could be abolished by denuding the endothelium with the nitric oxide synthase inhibitor, L-NAME (N(G)-Nitro-L-arginine methylester). CGRP-(8-37) (calcitonin gene-related peptide fragment (8-37)), a calcitonin gene-related peptide receptor antagonist, exhibited a partial blocking effect, whereas the tachykinin NK1 receptor blocker, GR 82334 ([D-Pro9[Spiro-gamma-Lactam]Leu10,Trp11]physalaemin (1-11)), markedly attenuated the response. Both prostaglandin F2alpha and the relatively selective FP receptor agonist, latanoprost acid, caused relaxation of the veins to about 50% of the precontracted state in the presence of GR 32191B ([1R-[1alpha(Z),2beta,3beta,5alpha]]-(+)-7-[5-([1,1'-b iphenyl]-4-ylmethoxy)-3-hydroxy-2-(1-piperidinyl)cyclopentyl]-4-he ptenoic acid), a thromboxane receptor antagonist (EC50: for prostaglandin F2alpha 7.9 x 10(-9) M, and for latanoprost acid 4.9 x 10(-9) M). L-NAME, as well as denuding the endothelium, completely abolished the effect. In addition, most or at least a large part of the relaxation was also blocked by CGRP-(8-37) as well as GR 82334. These results indicate that the FP receptor-mediated relaxation of veins is based on release of nitric oxide in addition to involvement of calcitonin gene-related peptide and substance P, or some other tachykinin, probably released from perivascular sensory nerves. The more pronounced relaxation induced by prostaglandin E2 could be due to vasodilator EP receptors in the smooth muscle layer of the veins.
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PMID:Mechanism of prostaglandin E2-, F2alpha- and latanoprost acid-induced relaxation of submental veins. 953 15

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