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ABSTRACT Valeriana wallichii DC (Valerianaceae), popularly named as Indian valerian has been shown to exist as three chemotypes. The present study evaluated the antidepressant like effect of root essential oil [...]

There is evidence that nitric oxide (NO) is required for the normal increases in skeletal muscle glucose uptake during contraction, but the mechanisms involved have not been elucidated. We examined whether NO regulates glucose uptake during skeletal muscle contractions via cGMP-dependent or cGMP-independent pathways. Isolated extensor digitorum longus (EDL) muscles from mice were stimulated to contract ex vivo, and potential NO signaling pathways were blocked by the addition of inhibitors to the incubation medium. Contraction increased (P < 0.05) NO synthase (NOS) activity (40%) and dichlorofluorescein (DCF) fluorescence (a marker of oxidant levels; 95%), which was prevented with a NOS inhibitor [N.sup.G]-monomethyl-L-arginine (L-NMMA), and antioxidants [nonspecific antioxidant, N-acetylcysteine (NAC); thiol-reducing agent, DTT], respectively. L-NMMA and NAC both attenuated glucose uptake during contraction by 50% (P < 0.05), and their effects were not additive. Neither the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-l-one, which prevents the formation of cGMP, the cGMP-dependent protein (PKG) inhibitor Rp-8-bromo-[beta]-phenyl-l,N2ethenoguanosine 3',5'-cyclic monophosphorothioate sodium salt nor white light, which breaks S-nitrosylated bonds, affects glucose uptake during contraction; however, DTT attenuated (P < 0.05) contraction-stimulated glucose uptake (by 70%). NOS inhibition and antioxidant treatment reduced contraction-stimulated increases in protein S-glutathionylation and tyrosine nitration (P < 0.05), without affecting AMPK or p38 MAPK phosphorylation. In conclusion, we provide evidence to suggest that NOS-derived oxidants regulate skeletal muscle glucose uptake during ex vivo contractions via a cGMP/PKG-, AMPK-, and p38 MAPK-independent pathway. In addition, it appears that NO and ROS may regulate skeletal muscle glucose uptake during contraction through a similar pathway. reactive oxygen species; peroxynitrite; S-glutathionylation; AMP-activated protein kinase doi: 10.1152/ajpregu.00433.2010

The objective of this study was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned, and regional renal blood flow was determined by positron emission tomography (PET) scanning using [H.sub.2][sup.15]O as tracer. Measurements were performed at baseline, during constant intravenous infusion of nitric oxide (NO) donor glyceryl nitrate and after intravenous injection of NO synthase inhibitor [N.sup.[omega]]-monomethyl-L-arginine (L-NMMA). Using the CT image, the kidney pole areas were delineated as volumes of interest (VOI). In the data analysis, tissue layers with a thickness of one voxel were eliminated stepwise from the external surface of the VOI (voxel peeling), and the blood flow subsequently was determined in each new, reduced VOI. Blood flow in the shrinking VOIs decreased as the number of cycles of voxel peeling increased. After 4-5 cycles, blood flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 [+ or -] 0.17 ml x g [tissue.sup.-1] x [min.sup.-1] during the control period; it increased during infusion of glyceryl nitrate to 2.97 [+ or -] 0.18 ml x g [tissue.sup.-1] x [min.sup.-1] (P < 0.05) and decreased after L-NMMA injection to 1.57 [+ or -] 0.17 ml x g [tissue.sup.-1] x [min.sup.-1] (P < 0.05). Cortical blood flow was 4.67 [+ or -] 0.31 ml x g [tissue.sup.-1] x [min.sup.-1] during control, unchanged by glyceryl nitrate, and decreased after L-NMMA [3.48 [+ or -] 0.23 ml x [(g x min).sup.-1], P < 0.05]. PET/CT scanning allows identification of a renal medullary region in which the measured blood flow is 1) low, 2) independent of reduction in the VOI, and 3) reactive to changes in systemic NO supply. The technique seems to provide indices of renal medullary blood flow in humans. blood pressure; humans; renal medulla; renal perfusion; PET/CT; L-NMMA; glyceryl nitrate

Upon agonist stimulation, endothelial cells trigger smooth muscle relaxation through the release of relaxing factors such as nitric oxide (NO). Endothelial cells of mouse aorta are interconnected by gap junctions made of connexin40 (Cx40) and connexin37 (Cx37), allowing the exchange of signaling molecules to coordinate their activity. Wild-type ([Cx40.sup.+/+]) and hypertensive Cx40-deficient mice ([Cx40.sup.-/-]), which also exhibit a marked decrease of Cx37 in the endothelium, were used to investigate the link between the expression of endothelial connexins (Cx40 and Cx37) and endothelial nitric oxide synthase (eNOS) expression and function in the mouse aorta. With the use of isometric tension measurements in aortic rings precontracted with U-46619, a stable thromboxane A2 mimetic, we first demonstrate that ACh- and ATP-induced endothelium-dependent relaxations solely depend on NO release in both [Cx40.sup.+/+] and [Cx40.sup.-/-] mice, but are markedly weaker in [Cx40.sup.-/-] mice. Consistently, both basal and ACh-or ATP-induced NO production were decreased in the aorta of Cx40 / mice. Altered relaxations and NO release from aorta of [Cx40.sup.-/-] mice were associated with lower expression levels of eNOS in the aortic endothelium of [Cx40.sup.-/-] mice. Using immunoprecipitation and in situ ligation assay, we further demonstrate that eNOS, Cx40, and Cx37 tightly interact with each other at intercellular junctions in the aortic endothelium of [Cx40.sup.+/+] mice, suggesting that the absence of Cx40 in association with altered Cx37 levels in endothelial cells from [Cx40.sup.-/-] mice participate to the decreased levels of eNOS. Altogether, our data suggest that the endothelial connexins may participate in the control of eNOS expression levels and function. connexin40; connexin37; endothelium-dependent relaxation; endothelial nitric oxide synthase doi: 10.1152/ajpheart.00029.2010.

Functional studies show that increased renal nitric oxide (NO) mediates the renal vasodilation and increased glomerular filtration rate that occur during normal pregnancy. We investigated whether changes in the constitutive NO synthases (NOS), endothelial (eNOS) and neuronal (nNOS), were associated with the increased renal NO production in normal midterm pregnancy in the rat. In kidneys from midterm pregnant (MP: 11-13 days gestation), late-term pregnant (LP: 18-20 days gestation), and similarly aged virgin (V) rats, transcript and protein abundance for eNOS and the nNOS[alpha] and nNOS[beta] splice variants, as well as the rate of L-arginine-to-L-citrulline conversion, were determined as a measure of NOS activity. At MP, renal cortical abundance of the total eNOS protein and phosphorylated ([Ser.sup.1177]) eNOS was reduced, and L-arginine-to-L-citrulline conversion in the cortical membrane fraction was decreased; these declines were also seen in LP. There were no changes in the eNOS transcript. In contrast, L-arginine-to-L-citrulline conversion in the soluble fraction of renal cortex increased at MP and then declined at LP. This MP increase was ablated by S-methylthiocitrulline, a nNOS inhibitor. Using Western blotting, we did not detect a change in the protein abundance or transcript of the 160-kDa nNOS[alpha], but protein abundance and transcript of the nNOS[beta] were increased at MP in cortex. Collectively, these studies suggest that the soluble nNOS[beta] is responsible for the increased renal cortical NO production during pregnancy. endothelial nitric oxide synthase; neuronal nitric oxide synthase; L-arginine-to-L-citrulline conversion; S-methylthiocitrulline; splice variants doi: 10.1152/ajprenal.00300.20l0.

S-nitrosothiols are nitric oxide (NO)-derived molecules found in biological systems. They have been variously discussed as both NO reservoirs and as major actors in NO-dependent, but cGMP-independent, signal transduction. Although S-nitrosation of specific cysteine residues has been suggested to represent a novel redox-based signaling mechanism, the exact mechanisms of S-nitrosothiol formation under (patho)physiological conditions and the determinants of signaling specificity have not yet been established. Here we examined the sensitivity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) to inhibition by S-nitrosocysteine (CysNO) and NO both intracellularly and in isolation. Bovine aortic endothelial cells (BAECs) and purified GAPDH preparations were treated with CysNO or NO, and enzymatic activity was monitored. Intracellular GAPDH was irreversibly inhibited upon CysNO administration, whereas treatment with NO resulted in a DTT-reversible inhibition of the enzyme. Purified GAPDH was inhibited by both CysNO and NO, but the inhibition pattern was diametrically opposite to that observed in the cells; CysNO-dependent inhibition was reversed with DTT, whereas NO-dependent inhibition was not. In the presence of GSH, NO inhibited purified GAPDH in a DTT-reversible way. Our data suggest that in response to CysNO treatment, cellular GAPDH undergoes S-nitrosation, which results in an irreversible inhibition of the enzyme under turnover conditions. In contrast, NO inhibits the enzyme via oxidative mechanisms that do not involve S-nitrosation and are reversible. In summary, our data show that GAPDH is a target for CysNO- and NO-dependent inhibition; however, these two agents inhibit the enzyme via different mechanisms both inside the cell and in isolation. Additionally, the differences observed between the cellular system and purified protein strongly imply that the intracellular environment dictates the mechanism of inhibition. nitric oxide; S-nitrosation; S-nitrosocysteine doi: 10.1152/ajpheart.00472.2010.

It has been shown that angiotensin (ANG)-(1-7) activates nitric oxide synthase (NOS) in isolated ventricular myocytes from normotensive rats. Since many ANG-(1-7) actions are enhanced in situations of increased ANG II activity, as in hypertension, in this study we investigated the in vivo effect of ANG-(1-7) on NOS activity and expression of endothelial (eNOS), neuronal (nNOS), and inducible NOS (iNOS) in ventricles from spontaneously hypertensive rats (SHR). Rats were subjected to a 60-min ANG-(1-7) infusion (0.35 nmol/min); controls received saline. NOS activity was measured using the NADPH diaphorase histochemical method and by the conversion of L-[[sup.14]C]arginine to citrulline, and NOS phosphorylation and expression were determined using Western blotting. In SHR, ANG-(1-7) infusion diminished mean arterial pressure from 180 [+ or -] 9 to 146 [+ or -] 9 mmHg (P < 0.05), and this effect was prevented by nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor. In addition, NOS activity and eNOS phosphorylation were increased by ANG-(1-7) infusion. Ventricular eNOS and nNOS expression were increased 67.4 [+ or -] 6.4 and 51 [+ or -] 10%, respectively, by ANG-(1-7), whereas iNOS was not changed. In another set of experiments, we evaluated the mechanism by which ANG-(1-7) modifies NOS activity. Isolated ventricle slices preincubated with ANG-(1-7) showed an increase in NOS activity and eNOS phosphorylation, which was blocked by an [AT.sub.2] and a bradykinin [B.sub.2] receptor antagonist, but not by the Mas receptor antagonist. Our results show that in rats in a hypertensive state, ANG-(1-7) infusion upregulates cardiac NOS expression and activity through an [AT.sub.2]- and bradykinin-dependent mechanism. In this way ANG-(1-7) may eficit its cardioprotective action and contribute to some of the counterregulatory [AT.sub.2] receptor effects that oppose the [AT.sub.1] receptor-mediated effects. receptors; hypertension; heart; bradykinin doi: 10.1152/ajpheart.00850.2009.