Search results for "arginine"
showing 10 items of 389 documents
Influence of nitric oxide on neurogenic contraction and relaxation of the human gastroepiploic artery.
2003
Abstract Background The objective of this study was to characterize the neurogenic contraction and relaxation of the human gastroepiploic artery and to determine whether the responses are mediated by nitric oxide (NO) from neural or endothelial origin. Methods Rings of human gastroepiploic artery were obtained from 18 patients (12 men, 6 women) undergoing gastrectomy. The rings were suspended in organ baths for isometric recording of tension. We studied the contractile and relaxant responses to electrical field stimulation. Results In arteries under resting conditions, electrical field stimulation (2 to 8 Hz) caused frequency-dependent contractions that were of greater magnitude in arteries…
Polyamines are increased in obese children and are related to markers of oxidative/nitrosative stress and angiogenesis.
2011
Polyamines (putrescine, spermidine, and spermine) are polycationic amines derived from arginine, which is the precursor of nitric oxide (NO). Due to the close relationship between the metabolism of polyamines and NO metabolism, the alteration in polyamine homeostasis can affect the NO bioavailability at the endothelium.The objective of the study was to test the hypothesis that childhood obesity is associated with a significant modification of blood polyamines and to investigate the presence of correlation between these molecules, circulating markers of oxidative and nitrosative stress, and endothelial dysfunction.This was an observational analytical case-control study conducted at one terti…
Modulation of adrenergic contraction of dog pulmonary arteries by nitric oxide and prostacyclin.
1999
Abstract The aim of this work was to investigate the influence of endothelium-derived nitric oxide and prostaglandins on the contractile responses of isolated dog pulmonary arteries to electrical field stimulation and noradrenaline. Electrical field stimulation (1–8 Hz, 20 v, 0.25 ms duration, for 30 s) produced frequency-dependent contractions that were abolished by tetrodotoxin, guanethidine and, prazosin (all at 10−6 M). Noradrenaline induced concentration-dependent contractions with an EC50 of 1.85 × 10−6 M. The increases in tension induced by electrical stimulation and noradrenaline were of greater magnitude in arteries denuded of endothelium. In segments with endothelium, NG-nitro- l …
Contribution of endothelin receptors and cyclooxygenase-derivatives to the altered response of the rabbit renal artery to endothelin-1 in diabetes
2006
Abstract The influence of diabetes on regulatory mechanisms and specific receptors implicated in the response of isolated rabbit renal artery to endothelin-1 was examined. Endothelin-1 induced a concentration-dependent contraction that was less potent in arteries from diabetic rabbits than in arteries from control rabbits. Endothelium removal or NG-nitro- l -arginine (L-NOARG) enhanced contractions to endothelin-1 either in control and diabetic arteries. Indomethacin inhibited endothelin-1-induced response in control arteries, but enhanced it in diabetic arteries. In contrast to that observed in rubbed and in L-NOARG treated arteries, in the presence of indomethacin the contractile action o…
Endogenous nitric oxide is responsible for the early loss of P450 in cultured rat hepatocytes
1998
AbstractLoss of P450 during the early hours of monolayer formation is known to be the more serious limitation of primary cultured hepatocytes as an adequate model for the study of drug metabolism, toxicity and P450 induction. This study reports that endogenous nitric oxide (NO) formation is activated shortly after isolation by the classical collagenase-based liver perfusion methods. Both rapid P450 loss and aerobic mitochondrial energy metabolism impairment – with subsequent changes on glucose metabolism – are directly related to the high local generation of the radical at this stage. These effects can be reverted by the sole addition of NO biosynthesis inhibitors during liver perfusion and…
Elevated levels of asymmetric dimethylarginine in chronic heart failure: a pathophysiologic link between oxygen radical load and impaired vasodilator…
2010
Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide-dependent vasodilation. In 113 patients with chronic heart failure (CHF) and 26 controls, ADMA level was studied in relation to peripheral blood flow and vasodilator capacity. Further, the effects of allopurinol on concentrations of reactive oxygen species (ROS) and ADMA and peripheral vasodilator capacity were tested in a double-blind design. ADMA level was found to be elevated in CHF patients as compared with controls and increased in parallel with New York Heart Association (NYHA) class and exercise capacity (all P < 0.0001). The level of ADMA predicted resting blood flow (P < 0.05) and postischemic vasodilator…
Asymmetric dimethylarginine (ADMA) and hyperhomocysteinemia in patients with acute myocardial infarction
2006
We sought to investigate the association between increased levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, and total plasma homocysteinemia (tHcy) in patients with acute myocardial infarction (AMI).In 138 patients hospitalized for AMI24 h on admission, serum levels of ADMA, its symmetric stereoisomer (SDMA) and tHcy were measured.ADMA was positively associated with SDMA (p0.001) and tHcy (p=0.03) but not with estimated glomerular filtration rates (eGFR, p=0.96), while tHcy strongly correlated with eGFR (p=0.002) and SDMA (p0.001). By multiple linear regression, SDMA but not ADMA was independently associated with tHcy (p=0.005).Our findings sugges…
Involvement of nitric oxide-soluble guanylyl cyclase pathway in the control of maximal dentate gyrus activation in the rat.
2006
Summary Nitric oxide=soluble Guanylyl cyclase (NO=sGC) pathway on the maximal dentate gyrus activation (MDA) was studied in rats. The cerebral NO levels were modified by administrating 7-Nitroindazole (7-NI), a selective inhibitor of neuronal NOS, and L-arginine, a precursor of the synthesis of NO. 1H-[1,2,4]Oxadiazole[4,3-a]quinoxalin-1-one (ODQ), a specific inhibitor of the NO-sGC pathway, was administered to study the involvement of cGMP pathway. The epileptic activity of the dentate gyrus was obtained through the repetitive stimulation of the angular bundle; MDA parameters studied were: onset time, MDA duration and post-stimulus afterdischarge (AD) duration. 7-NI caused an increase of M…
Nitric oxide-sensitive guanylyl cyclase inhibits acetylcholine release and excitatory motor transmission in the guinea-pig ileum
1997
Abstract This study examined the mechanism through which nitric oxide inhibits the release of acetylcholine and excitatory motor neurotransmission in the guinea-pig ileum. The selective inhibitor of nitric oxide-sensitive guanylyl cyclase, 1 H -[1,2,4]oxadiazolo[4,3- a ]quinoxalin-1-one (ODQ), concentration-dependently enhanced both basal release (−log EC 50 : 6.8) and electrically (10 Hz) -evoked release (−log EC 50 : 6.0) of [ 3 H]acetylcholine from longitudinal muscle-myenteric plexus preparations preincubated with [ 3 H]choline. The increase by ODQ of basal release appeared to be exocytotic since it was prevented by tetrodotoxin (300 nM) and absence of calcium from the superfusion mediu…
Inhibition by interleukin-1 beta of noradrenaline release in rat spleen: involvement of lymphocytes, NO and opioid receptors.
1995
Effects of indomethacin, N omega-nitro-L-arginine (NNA) and naloxone, and of pretreatment with cyclophosphamide (CY), on the interleukin (IL)-1 beta induced inhibition of exocytotic noradrenaline release were investigated in the isolated, vascularly perfused spleen of the rat. Neurotransmitter release was evoked by perivascular electrical stimulation (4 Hz) and the overflow of endogenous noradrenaline was determined by HPLC with electrochemical detection. Perfusion of the spleen with Tyrode's solution containing IL-1 beta (100 pg/ml) for 90 min caused an inhibition of the stimulation-evoked noradrenaline overflow which persisted for at least 20 min after washout of the IL. The evoked overfl…