P4.16 THE MYOTROPHOBLAST OF THE RAT PLACENTA: EX VIVO STUDY OF NITRIC OXIDE SYNTHASE INHIBITION

2015 ◽  
Vol 12 (C) ◽  
pp. 19
Author(s):  
Ilana Ariel ◽  
Galina Skarzinski ◽  
Vitali Belzer ◽  
Wiessam Abu-Ahmad ◽  
Zaid Abassi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Ex Vivo ◽  
Oxide Synthase ◽  
Ex Vivo Study

Glucose uptake during contraction in isolated skeletal muscles from neuronal nitric oxide synthase μ knockout mice

2015 ◽  
Vol 118 (9) ◽  
pp. 1113-1121 ◽  
Author(s):  
Yet Hoi Hong ◽  
Tony Frugier ◽  
Xinmei Zhang ◽  
Robyn M. Murphy ◽  
Gordon S. Lynch ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Nitric Oxide Synthase ◽  
Glucose Uptake ◽  
Ex Vivo ◽  
Organ Bath ◽  
Skeletal Muscle Glucose Uptake ◽  
Nos Inhibitor ◽  
Amp Activated Protein Kinase ◽  
Oxide Synthase

Inhibition of nitric oxide synthase (NOS) significantly attenuates the increase in skeletal muscle glucose uptake during contraction/exercise, and a greater attenuation is observed in individuals with Type 2 diabetes compared with healthy individuals. Therefore, NO appears to play an important role in mediating muscle glucose uptake during contraction. In this study, we investigated the involvement of neuronal NOSμ (nNOSμ), the main NOS isoform activated during contraction, on skeletal muscle glucose uptake during ex vivo contraction. Extensor digitorum longus muscles were isolated from nNOSμ−/−and nNOSμ+/+mice. Muscles were contracted ex vivo in a temperature-controlled (30°C) organ bath with or without the presence of the NOS inhibitor NG-monomethyl-l-arginine (L-NMMA) and the NOS substrate L-arginine. Glucose uptake was determined by radioactive tracers. Skeletal muscle glucose uptake increased approximately fourfold during contraction in muscles from both nNOSμ−/−and nNOSμ+/+mice. L-NMMA significantly attenuated the increase in muscle glucose uptake during contraction in both genotypes. This attenuation was reversed by L-arginine, suggesting that L-NMMA attenuated the increase in muscle glucose uptake during contraction by inhibiting NOS and not via a nonspecific effect of the inhibitor. Low levels of NOS activity (∼4%) were detected in muscles from nNOSμ−/−mice, and there was no evidence of compensation from other NOS isoform or AMP-activated protein kinase which is also involved in mediating muscle glucose uptake during contraction. These results indicate that NO regulates skeletal muscle glucose uptake during ex vivo contraction independently of nNOSμ.

scholarly journals Depolarization of mitochondria in neurons promotes activation of nitric oxide synthase and generation of nitric oxide

2016 ◽  
Vol 310 (9) ◽  
pp. H1097-H1106 ◽  
Author(s):  
Prasad V. G. Katakam ◽  
Somhrita Dutta ◽  
Venkata N. Sure ◽  
Samuel M. Grovenburg ◽  
Angellica O. Gordon ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Cortical Neurons ◽  
Ex Vivo ◽  
Cerebral Arteries ◽  
Resonance Spectroscopy ◽  
No Production ◽  
Cultured Neurons ◽  
Mitochondrial Depolarization ◽  
Oxide Synthase

The diverse signaling events following mitochondrial depolarization in neurons are not clear. We examined for the first time the effects of mitochondrial depolarization on mitochondrial function, intracellular calcium, neuronal nitric oxide synthase (nNOS) activation, and nitric oxide (NO) production in cultured neurons and perivascular nerves. Cultured rat primary cortical neurons were studied on 7–10 days in vitro, and endothelium-denuded cerebral arteries of adult Sprague-Dawley rats were studied ex vivo. Diazoxide and BMS-191095 (BMS), activators of mitochondrial KATP channels, depolarized mitochondria in cultured neurons and increased cytosolic calcium levels. However, the mitochondrial oxygen consumption rate was unaffected by mitochondrial depolarization. In addition, diazoxide and BMS not only increased the nNOS phosphorylation at positive regulatory serine 1417 but also decreased nNOS phosphorylation at negative regulatory serine 847. Furthermore, diazoxide and BMS increased NO production in cultured neurons measured with both fluorescence microscopy and electron spin resonance spectroscopy, which was sensitive to inhibition by the selective nNOS inhibitor 7-nitroindazole (7-NI). Diazoxide also protected cultured neurons against oxygen-glucose deprivation, which was blocked by NOS inhibition and rescued by NO donors. Finally, BMS induced vasodilation of endothelium denuded, freshly isolated cerebral arteries that was diminished by 7-NI and tetrodotoxin. Thus pharmacological depolarization of mitochondria promotes activation of nNOS leading to generation of NO in cultured neurons and endothelium-denuded arteries. Mitochondrial-induced NO production leads to increased cellular resistance to lethal stress by cultured neurons and to vasodilation of denuded cerebral arteries.

scholarly journals Islet constitutive nitric oxide synthase and glucose regulation of insulin release in mice

1999 ◽  
Vol 163 (1) ◽  
pp. 39-48 ◽  
Author(s):  
B Akesson ◽  
R Henningsson ◽  
A Salehi ◽  
I Lundquist
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Insulin Release ◽  
Ex Vivo ◽  
Insulin Response ◽  
Glucose Regulation ◽  
Nos Inhibitor ◽  
Oxide Synthase

We have studied, by a combined in vitro and in vivo approach, the relation between the inhibitory action of N(G)-nitro-l-arginine methyl ester (L-NAME), a selective inhibitor of nitric oxide synthase (NOS), on the activity of islet constitutive NOS (cNOS) and glucose regulation of islet hormone release in mice. The cNOS activity in islets incubated in vitro at 20 mM glucose was not appreciably affected by 0.05 or 0.5 mM L-NAME, but was greatly suppressed (-60%) by 5 mM L-NAME. Similarly, glucose-stimulated insulin release was unaffected by the lower concentrations of L-NAME but greatly enhanced in the presence of 5 mM of the NOS inhibitor. In incubated islets inhibition of cNOS activity resulted in a modestly enhanced insulin release in the absence of glucose, did not display any effect at physiological or subphysiological glucose concentrations, but resulted in a markedly potentiated insulin release at hyperglycaemic glucose concentrations. In the absence of glucose, glucagon secretion was suppressed by L-NAME. The dynamics of glucose-induced insulin release and (45)Ca(2+) efflux from perifused islets revealed that L-NAME caused an immediate potentiation of insulin release, and a slight increase in (45)Ca(2+) efflux. In islets depolarized with 30 mM K(+) in the presence of the K(+)(ATP) channel opener, diazoxide, L-NAME still greatly potentiated glucose-induced insulin release. Finally, an i.v. injection of glucose to mice pretreated with L-NAME was followed by a markedly potentiated insulin response, and an improved glucose tolerance. In accordance, islets isolated directly ex vivo after L-NAME injection displayed a markedly reduced cNOS activity. In conclusion, we have shown here, for the first time, that biochemically verified suppression of islet cNOS activity, induced by the NOS inhibitor L-NAME, is accompanied by a marked potentiation of glucose-stimulated insulin release both in vitro and in vivo. The major action of NO to inhibit glucose-induced insulin release is probably not primarily linked to changes in Ca(2+) fluxes and is exerted mainly independently of membrane depolarization events.

EX VIVO EXPRESSION OF NITRIC OXIDE SYNTHASE ISOFORMS (eNOS/iNOS) AND CALMODULIN IN HUMAN PENILE CAVERNOSAL CELLS

1998 ◽  
Vol 160 (6 Part 1) ◽  
pp. 2210-2215 ◽  
Author(s):  
MAHADEVAN RAJASEKARAN ◽  
DEBASIS MONDAL ◽  
KRISHNA AGRAWAL ◽  
I-LI CHEN ◽  
WAYNE HELLSTROM ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Ex Vivo ◽  
Oxide Synthase

Aldehyde dehydrogenase, nitric oxide synthase and superoxide in ex vivo nitrate tolerance in rat aorta

2004 ◽  
Vol 496 (1-3) ◽  
pp. 141-149 ◽  
Author(s):  
Ivan S de la Lande ◽  
Jacqueline M Stepien ◽  
Andrew C Philpott ◽  
Patrick A Hughes ◽  
Irene Stafford ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Aldehyde Dehydrogenase ◽  
Ex Vivo ◽  
Rat Aorta ◽  
Nitrate Tolerance ◽  
Oxide Synthase

7-Nitroindazole attenuates vasodilation from cerebellar parallel fiber stimulation but not acetylcholine

1996 ◽  
Vol 270 (4) ◽  
pp. R914-R919 ◽  
Author(s):  
C. Iadecola ◽  
G. Yang ◽  
S. Xu
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Ex Vivo ◽  
Neuronal Nitric Oxide Synthase ◽  
Selective Inhibition ◽  
Ringer Solution ◽  
Systemic Arterial Pressure ◽  
T Test ◽  
Nitric Oxide Donor ◽  
Oxide Synthase

We used the relatively selective inhibitor of neuronal nitric oxide synthase 7-nitroindazole (7-NI) to test the hypothesis that the increases in local cerebellar blood flow (BFcrb) elicited by activation of the cerebellar parallel fibers (PF) are mediated by neuronal production of nitric oxide. In halothane-anesthetized rats, the cerebellar cortex was exposed and superfused with Ringer solution (37 degrees C; pH 7.3-7.4). The PF were stimulated electrically (100 microA, 30 Hz, 40 s), while BFcrb was monitored at the site of stimulation by a laser-Doppler flow probe. In vehicle-treated rats (n = 5), PF stimulation increased BFcrb by 61 +/- 5% (P < 0.05; analysis of variance and Tukey's test). 7-NI attenuated the increase in BFcrb dose dependently (10-100 mg/kg i.p.; n = 5 animals/dose) and by 55 +/- 7% at 100 mg/kg (P < 0.05). The attenuation of the response to PF stimulation was correlated with the degree of inhibition of calcium-dependent brain nitric oxide synthase activity, measured ex vivo by the citrulline assay (n = 21). 7-NI also attenuated the cerebrovasodilation elicited by hypercapnia (PCO2 = 50-60 mmHg) but did not affect the vasodilation evoked by acetylcholine (10 microM; n = 4; P > 0.05; t-test), a response mediated by endothelial nitric oxide synthase. 7-NI did not attenuate the BFcrb increase evoked by the nitric oxide donor S-nitroso-N-acetylpenicillamine (1 mM; n = 5; P > 0.05; t-test). Similarly, 7-NI did not affect resting systemic arterial pressure. These observations suggest that selective inhibition of neuronal nitric oxide synthase by 7-NI attenuates the increases in BFcrb evoked by PF stimulation. The findings provide additional support to the hypothesis that the increase in BFcrb evoked by PF stimulation is mediated, in part, by glutamate-induced activation of neuronal nitric oxide synthase.

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