Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1 We investigated the peripheral haemodynamic effects of human alpha-calcitonin gene-related peptide (CGRP) following administration of endothelin-1 or NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide production, in conscious, chronically-instrumented, Long Evans rats. 2 Infusion of endothelin-1 (3 nmol kg-1 h-1) caused hypertension, bradycardia and renal, mesenteric and hindquarters vasoconstrictions. Co-infusion of human alpha-CGRP (1.5 nmol kg-1 h-1) reduced the hypertension and abolished the hindquarters vasoconstriction caused by endothelin-1 but the renal and mesenteric vasoconstrictor actions of endothelin-1 were not affected. 3 Infusion of human alpha-CGRP (15 nmol kg-1 h-1) in the presence of endothelin-1 caused hypotension and hyperaemic vasodilatation in the hindquarters; the mesenteric vasoconstrictor effects of endothelin-1 were diminished, but there was only a transient reversal of the renal vasoconstrictor effects of endothelin-1. 4 Pretreatment with the non-peptide angiotensin II receptor antagonist, DuP 753 (10 mg kg-1), caused slight hypotension associated with renal, mesenteric and hindquarters vasodilatations, but DuP 753 did not affect responses to endothelin-1 infusion. However, under these conditions co-infusion of human alpha-CGRP (15 nmol kg-1 h-1) caused a sustained reversal of the renal vasoconstrictor effects of endothelin-1. 5 These results indicate that the failure of human alpha-CGRP to cause sustained reversal of the renal vasoconstrictor effects of endothelin-1 in the absence of DuP 753 was due to activation of the reninangiotensin system (possibly as a consequence of the hypotension). 6. In the second experiment, L-NAME (l0mgkg-1) caused renal, mesenteric and hindquarters vasoconstrictions similar to those seen in the presence of endothelin-1. However, the renal vasoconstrictor effects of L-NAME were reversed completely by human alpha-CGRP (l5nmolkg- h-1), even though the latter caused hypotension comparable to that seen in the presence of endothelin-1. These results are consistent with a lack of functional activation of the renin-angiotensin system by human alpha-CGRP in the presence of L-NAME. 7. The vasoconstrictor effects of L-NAME on the hindquarters were completely reversed by infusion of human alpha-CGRP, but hindquarters flow and vascular conductance did not rise above baseline levels. Hence these results indicate the hindquarters hyperaemic vasodilator effects of human alpha-CGRP seen in the presence of endothelin-1 were contributed to by nitric oxide-mediated mechanisms.
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PMID:Haemodynamic effects of human alpha-calcitonin gene-related peptide following administration of endothelin-1 or NG-nitro-L-arginine methyl ester in conscious rats. 187 60

Stroke-prone spontaneously hypertensive rats (SHRSP) develop severe hypertension and cerebrovascular lesions. We investigated the influence of dietary supplementation with L-arginine, an amino acid precursor of endothelium-derived nitric oxide, on blood pressure and stroke in these rats. L-Arginine, administered in the saline drinking solution at 2 or 6 g/l starting at 8.7 weeks of age, was without effect on blood pressure, cerebrovascular lesions, or longevity despite continuous treatment through 14 weeks of age. These findings do not support a beneficial influence of dietary arginine in the cerebrovascular pathology of SHRSP.
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PMID:Dietary arginine fails to protect against cerebrovascular damage in stroke-prone hypertensive rats. 188 30

1. The effects on blood pressure and on pressor responses to noradrenaline (NA), of NG-monomethyl-L-arginine (L-NMMA) and NG-nitro-L-arginine methyl ester (L-NAME), inhibitors of the L-arginine/nitric oxide pathway, were investigated in anaesthetized rats receiving an infusion of bacterial endotoxin (E. coli lipopolysaccharide, LPS). 2. Infusion of LPS (10 mg kg-1 h-1) for 50 min had no effect on mean arterial blood pressure (MABP) but induced a reduction in responsiveness to noradrenaline (100 ng-1 micrograms kg-1). L-NMMA (30 mg kg-1), but not D-NMMA, caused an increase in MABP of approximately 30 mmHg and restored responses to NA. This effect was reversed by L- but not D-arginine (100 mg kg-1). 3. In LPS-treated rats, blood pressure responses to NA were only marginally increased by the cyclooxygenase inhibitor, indomethacin (5 mg kg-1). L-NAME (1 mg kg-1) caused a similar increase in MABP and restored pressor responses to NA both in the presence and absence of indomethacin. 4. Co-infusion of vasopressin (100 ng kg-1, for 10 min) with LPS (10 mg kg-1 h-1) in order to reproduce the hypertensive effect of L-NMMA and L-NAME increased pressor responsiveness to 100 and 300 ng kg-1 NA but not to 1 microgram kg-1 NA. 5. Infusion of sodium nitroprusside (30 micrograms kg-1 min-1) decreased responsiveness to NA even when the hypotension was corrected by co-infusion of vasopressin (50 ng kg-1 min-1). 6. These results demonstrate that the restoration of vascular responsiveness to NA in LPS-treated anaesthetized rats by inhibitors of the L-arginine/nitric oxide pathway is stereospecific and reversible. Furthermore, the experiments involving indomethacin suggest that although cyclo-oxygenase products of arachidonic acid may contribute to the development of LPS-induced hyporeactivity, the effect of L-NAME is unlikely to involve inhibition of the cyclo-oxygenase pathway. Comparison of NA responsiveness during vasopressin and L-NMMA/L-NAME-induced hypertension shows that increasing the blood pressure may modify LPS-induced hyporeactivity, but cannot account for the complete restoration of responses to NA by L-NMMA and L-NAME. These observations suggest that activation of nitric oxide formation from L-arginine makes a direct contribution to the production of vascular hyporeactivity by LPS in vivo.
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PMID:The effect of inhibitors of the L-arginine/nitric oxide pathway on endotoxin-induced loss of vascular responsiveness in anaesthetized rats. 190 34

The effects of cilazaprilat were assessed on endothelium-dependent relaxations and contractions in isolated canine arteries. In coronary arteries incubated with indomethacin, cilazaprilat potentiated endothelium-dependent relaxations to bradykinin. In superfusion-perfusion bioassay studies with femoral arteries, cilazaprilat augmented the release of nonprostanoid endothelium-derived relaxing factors caused by bradykinin. To verify whether this effect was solely due to inhibition of the converting enzyme, the effects of cilazaprilat on responses to a variety of endothelium-dependent vasoactive agents were assessed. Endothelium-dependent relaxations to acetylcholine, thrombin, and vasopressin were not altered significantly by cilazaprilat. However, those induced by ADP and aggregating platelets were enhanced significantly by the compound. Endothelium-dependent relaxations to ADP-beta-S were augmented significantly but to a lesser extent. Furthermore, in the presence of the nitric oxide synthase antagonist NG-nitro-L-arginine, ADP-beta-S still caused small relaxations that were possibly mediated by endothelium-derived hyperpolarizing factor. These relaxations were augmented by cilazaprilat. Thus, the augmentation of purinergic relaxations may involve an increased production of endothelium-derived relaxing factors in addition to the protection of ADP from breakdown. Cilazaprilat did not affect endothelium-dependent contractions to acetylcholine or the calcium ionophore A23187 in canine basilar arteries, previously shown to be mediated by superoxide anions. Thus, cilazaprilat is not a scavenger of superoxide anion. Because this agent potentiates endothelium-dependent relaxations to bradykinin, ADP, and aggregating platelets, the present study suggests that, in addition to the lowering of plasmatic levels of angiotensin II, the antihypertensive and cardioprotective effects of cilazaprilat are mediated through an increased production of endothelium-derived relaxing factors.
Hypertension 1991 Oct
PMID:Effects of the converting enzyme inhibitor cilazaprilat on endothelium-dependent responses. 191 98

The effect of nitric oxide (NO) pathway inhibitor, NG-monomethyl-L- arginine (L-NMMA), on arterial blood pressure was examined in spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto rats (WKYs) to investigate whether the vasodilating effect of basal levels of NO, one of the endothelium-derived relaxing factors, is preserved during the development of hypertension. L-NMMA (1-100 mg/kg i.v.) produced dose-dependent increase in arterial pressure and bradycardia in anesthetized and conscious SHRs and WKYs. L-Arginine, a precursor of NO, inhibited the pressor response to L-NMMA. The L-NMMA-induced increases in arterial pressure in both 5- to 6- and 12- to 13-week (wk)-old anesthetized SHRs were similar to those of age-matched WKY controls; rather, the increase was significantly larger in 53- to 54-wk-old SHRs than in the age-matched WKYs. In conscious SHRs (13-14 wk-old), L-NMMA induced larger hypertensive effect than in the age-matched WKYs. The amplitude of acetylcholine (ACh)-induced hypotension was somewhat larger in 5- to 6- and 12- to 13-wk-old anesthetized SHRs compared with the age-matched WKY controls. The duration of the hypotension in 5- to 6- and 12- to 13-wk-old anesthetized SHRs was similar to the age-matched WKY controls. L-NMMA significantly reduced the duration of the ACh-induced hypotension; an effect which was recovered by L-arginine. However, L-NMMA did not decrease the amplitude of the hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:NG-monomethyl-L-arginine-induced pressor response at developmental and established stages in spontaneously hypertensive rats. 192 Jan 34

Nitric oxide first captured the interest of biologists when this inorganic molecule was found to activate cytosolic guanylate cyclase and stimulate cyclic guanosine monophosphate (GMP) formation in mammalian cells. Further studies led to the finding that nitric oxide causes vascular smooth muscle relaxation and inhibition of platelet aggregation by mechanisms involving cyclic GMP and that several clinically used nitrovasodilators owe their biological actions to nitric oxide. Nitric oxide possesses physicochemical and pharmacological properties that make it an ideal candidate for a short-term regulator or modulator of vascular smooth muscle tone and platelet function. Nitric oxide is synthesized by various mammalian tissues including vascular endothelium, macrophages, neutrophils, hepatic Kupffer cells, adrenal tissue, cerebellum, and other tissues. Nitric oxide is synthesized from endogenous L-arginine by a nitric oxide synthase system that possesses different cofactor requirements in different cell types. The nitric oxide formed diffuses out of its cells of origin and into nearby target cells, where it binds to the heme group of cytosolic guanylate cyclase and thereby causes enzyme activation. This interaction represents a novel and widespread signal transduction mechanism that links extracellular stimuli to the biosynthesis of cyclic GMP in nearby target cells. The small molecular size and lipophilic nature of nitric oxide enable communication with nearby cells containing cytosolic guanylate cyclase. The extent of transcellular communication is limited by the short half-life of nitric oxide, thereby ensuring a localized response. Labile nitric oxide-generating molecules such as S-nitrosothiols may be involved as precursors or effectors. Further research will provide a deeper understanding of the biology of nitric oxide and the nature of associated pathophysiological states.
Hypertension 1990 Nov
PMID:Nitric oxide. A novel signal transduction mechanism for transcellular communication. 197 98

We detected a novel vasoconstrictor in an arginine esterase fraction separated from fractions containing tonin and other esterases that were obtained from a rat submandibular gland extract. When tested on isolated rabbit aorta rings, the substance caused dose-related contractions that were slow in onset, long-lasting, and difficult to reverse by rinsing. The substance acts directly on vascular smooth muscle, since preincubation with plasma or intact endothelium is not required. The fact that the constrictor was destroyed by heat and incubation with pronase suggests that it is a protein. Molecular sieving indicates an estimated molecular weight of 24,000 Da. It has a neutral isoelectric point that is higher than the pI of tonin, from which it can be separated by anion exchange chromatography. A small amount of the vasoconstrictor was obtained by gel filtration and eluted from isoelectric focusing polyacrylamide gels. The purified substance showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was a potent vasoconstrictor; an estimated concentration of 2.5 nM induced contraction of isolated rabbit aorta rings ranging from 15% to 40% of the maximum contraction obtained by 60 mM KCl. Contraction was completely blocked by 1 mM (p-amidinophenyl)methanesulfonyl fluoride, a serine protease inhibitor. Contractile activity was not affected by hirudin, a thrombin inhibitor, but was completely inhibited by soybean trypsin inhibitor and blunted by aprotinin; thus it may be a trypsin-like serine protease. Purified vasoconstrictor preparation showed hydrolyzing activity on Pro-Phe-Arg-methyl-coumarin amide, a kallikrein substrate. We conclude that a novel vasoconstrictor serine protease is present in the rat submandibular gland.
Hypertension 1991 Jan
PMID:A potent vasoconstrictor in the rat submandibular gland. 198 78

An in vitro bioassay system was developed to study endothelium-mediated, shear stress-induced, or flow-dependent generation of endothelium-derived relaxing factor (EDRF). Monolayers of aortic endothelial cells were grown on a rigid and large surface area of microcarrier beads and were packed in a small column perfused with Krebs bicarbonate solution. The perfusate was allowed to superfuse three endothelium-denuded target pulmonary arterial strips arranged in a cascade. Fluid shear stress caused a flow-dependent release of EDRF from the endothelial cells. The action of EDRF was abolished by oxyhemoglobin and methylene blue, and the generation of EDRF in response to shear stress was markedly inhibited or abolished by NG-nitro-L-arginine, by NG-amino-L-arginine, by calcium-free extracellular medium, and by depleting endothelial cells of endogenous L-arginine. Addition of L-arginine to arginine-deficient but not arginine-containing endothelial cells rapidly restored the capacity of shear stress and bradykinin to generate EDRF. These observations indicate that fluid shear stress causes the generation of EDRF with properties of nitric oxide from aortic endothelial cells and that the bioassay system described may be useful for studying the mechanism of mechanochemical coupling that leads to nitric oxide generation.
Hypertension 1991 Feb
PMID:Shear stress-induced release of nitric oxide from endothelial cells grown on beads. 199 51

Inhibition of active sodium transport by ouabain was found to cause concentration- and time-dependent impairment of acetylcholine-induced relaxation in human resistance arteries with a significant effect at 100 pM. The reduced acetylcholine response was attributable to inhibition of the NG-monomethyl L-arginine-sensitive but not the indomethacin-sensitive component of relaxation. Relaxation by sodium nitroprusside was not affected by ouabain, suggesting that inhibition of sodium transport, directly or indirectly, must affect synthesis or release of endothelium-derived relaxing factor rather than its effector pathway. These results do not support the existence of an additional endothelium-derived relaxing factor other than endothelium-derived relaxing factor, which is dependent on sodium pump activity. The finding that inhibition of sodium transport has a profound effect on vascular relaxation may have implications in the pathogenesis of certain forms of hypertension.
Hypertension 1991 May
PMID:Effect of ouabain on endothelium-dependent relaxation of human resistance arteries. 202 6

Nitric oxide (NO) has been identified as a naturally-occurring metabolite in mammalian systems, formed from the amino acid arginine in response to a variety of physiological stimuli. It appears to function in cell-cell communication and may act either directly or through the stimulation of cyclic GMP synthesis in the regulation of such diverse functions as smooth muscle relaxation, inhibition of platelet aggregation and adhesion, central nervous system activity, and cytostasis. The significant role(s) could have important biomedical implications since perturbations in the biosynthesis, release or actions of NO could lead to hypertension, CNS dysfunction or increased susceptibility to infection. Understanding the enzymology and regulation of this pathway in various tissues may lead to development of pharmacological agents specifically designed for the rational control of nitric oxide formation and action.
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PMID:Nitric oxide. New discoveries, biomedical implications. 202 96


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