Mechanisms of cerebral vasodilation by superoxide, hydrogen peroxide, and peroxynitrite

1996 ◽  
Vol 271 (3) ◽  
pp. H1262-H1266 ◽  
Author(s):  
E. P. Wei ◽  
H. A. Kontos ◽  
J. S. Beckman
Keyword(s):  
Hydrogen Peroxide ◽  
Potassium Channels ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Calcium Activated Potassium Channels ◽  
Cerebral Arterioles ◽  
Cerebral Vasodilation ◽  
Vasodilator Action ◽  
Ly 83583 ◽  
Dose Dependent

We investigated the role of potassium channels in the vasodilator action of hydrogen peroxide, peroxynitrite, and superoxide on cerebral arterioles. We studied the effect of topical application of these agents in anesthetized cats equipped with cranial windows. Hydrogen peroxide and peroxynitrite induced dose-dependent dilation that was inhibited by glyburide, an inhibitor of ATP-sensitive potassium channels. Superoxide, generated by xanthine oxidase acting on xanthine in the presence of catalase, also induced dose-dependent dilation of cerebral arterioles that was unaffected by glyburide but inhibited completely by tetraethylammonium chloride, an inhibitor of calcium-activated potassium channels. The vasodilations from hydrogen peroxide, peroxynitrite, or superoxide were unaffected by inhibition of soluble guanylate cyclase with LY-83583. The findings provide pharmacological evidence that hydrogen peroxide and peroxynitrite reversibly dilate cerebral arterioles by activating ATP-sensitive potassium channels, probably through an oxidant mechanism, whereas superoxide dilates cerebral arterioles by opening calcium-activated potassium channels. Activation of soluble guanylate cyclase is not a mediator of the vasodilator action of these agents in cerebral arterioles.

Responses of cerebral arterioles in diabetic rats to activation of ATP-sensitive potassium channels

1993 ◽  
Vol 265 (1) ◽  
pp. H152-H157 ◽  
Author(s):  
W. G. Mayhan ◽  
F. M. Faraci
Keyword(s):  
Nitric Oxide ◽  
Diabetes Mellitus ◽  
Potassium Channels ◽  
Diabetic Rats ◽  
Nonspecific Effect ◽  
Pial Arterioles ◽  
Calcium Activated Potassium Channels ◽  
Cerebral Arterioles

The goal of this study was to determine whether responses of pial arterioles to activation of ATP-sensitive potassium channels are altered during diabetes mellitus. We measured changes in diameter of pial arterioles in vivo in nondiabetic and diabetic rats (streptozotocin; 50–60 mg/kg ip; studied 3–4 mo after streptozotocin) in response to RP52891, an activator of ATP-sensitive potassium channels. RP52891 (1.0 microM) dilated pial arterioles in nondiabetic rats by 16 +/- 1% but constricted pial arterioles in diabetic rats by 2 +/- 2% (means +/- SE; P < 0.05 vs. response in nondiabetic rats). Dilatation of pial arterioles in nondiabetic rats in response to RP52891 was inhibited by glibenclamide (1.0 microM) but was not altered by NG-monomethyl-L-arginine (1.0 microM), apamin (0.1 microM), or charybdotoxin (50 nM). Thus dilatation of pial arterioles in response to RP52891 appears to be due to activation of ATP-sensitive potassium channels and does not involve nitric oxide or calcium-activated potassium channels. To determine whether impaired dilatation of pial arterioles in response to RP52891 in diabetic rats was related to a nonspecific effect of diabetes mellitus on vasodilatation, we measured diameter of pial arterioles in nondiabetic and diabetic rats in response to nitroglycerin. Nitroglycerin (1.0 microM) dilated pial arterioles by 12 +/- 1% in nondiabetic rats and 16 +/- 2% in diabetic rats (P > 0.05). Thus impaired dilatation of pial arterioles in diabetic rats in response to RP52891 also is not related to a nonspecific effect of diabetes mellitus on vasodilatation.(ABSTRACT TRUNCATED AT 250 WORDS)

α2-Adrenergic-mediated tubular NO production inhibits thick ascending limb chloride absorption

2001 ◽  
Vol 281 (4) ◽  
pp. F679-F686 ◽  
Author(s):  
Craig F. Plato ◽  
Jeffrey L. Garvin
Keyword(s):  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Chloride Transport ◽  
Receptor Activation ◽  
Inhibitory Effect ◽  
No Production ◽  
Thick Ascending Limb ◽  
Chloride Absorption ◽  
Ly 83583

Stimulation of α2-adrenergic receptors inhibits transport in various nephron segments, and the thick ascending limb of the loop of Henle (THAL) expresses α2-receptors. We hypothesized that selective α2-receptor activation decreases NaCl absorption by cortical THALs through activation of NOS and increased production of NO. We found that the α2-receptor agonist clonidine (10 nM) decreased chloride flux ( J Cl) from 119.5 ± 15.9 to 67.4 ± 13.8 pmol · mm−1 · min−1 (43% reduction; P < 0.02), whereas removal of clonidine from the bath increased J Cl by 20%. When NOS activity was inhibited by pretreatment with 5 mM N G-nitro-l-arginine methyl ester, the inhibitory effects of clonidine on THAL J Clwere prevented (81.7 ± 10.8 vs. 71.6 ± 6.9 pmol · mm−1 · min−1). Similarly, when the NOS substrate l-arginine was deleted from the bath, addition of clonidine did not decrease THAL J Cl from control (106.9 ± 11.6 vs. 132.2 ± 21.3 pmol · mm−1 · min−1). When we blocked the α2-receptors with rauwolscine (1 μM), we found that the inhibitory effect of 10 nM clonidine on THAL J Cl was abolished, verifying that α2, rather than I1, receptors mediate the effects of clonidine in the THAL. We investigated the mechanism of NOS activation and found that intracellular calcium concentration did not increase in response to clonidine, whereas pretreatment with 150 nM wortmannin abolished the clonidine-mediated inhibition of THAL J Cl, indicating activation of phosphatidylinositol 3-kinase and the Akt pathway. We found that pretreatment of THALs with 10 μM LY-83583, an inhibitor of soluble guanylate cyclase, blocked clonidine-mediated inhibition of THAL J Cl. In conclusion, α2-receptor stimulation decreases THAL J Cl by increasing NO release and stimulating guanylate cyclase. These data suggest that α2-receptors act as physiological regulators of THAL NO synthesis, thus inhibiting chloride transport and participating in the natriuretic and diuretic effects of clonidine in vivo.

Nitric oxide-mediated excitatory effect on neurons of dorsal motor nucleus of vagus

1994 ◽  
Vol 266 (1) ◽  
pp. G154-G160 ◽  
Author(s):  
R. A. Travagli ◽  
R. A. Gillis
Keyword(s):  
Nitric Oxide ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Spontaneous Discharge ◽  
Motor Nucleus ◽  
Excitatory Effect ◽  
Dorsal Motor Nucleus ◽  
Ly 83583 ◽  
Spontaneous Firing Rate

The purpose of our study was to explore whether nitric oxide was involved as an intercellular messenger in the dorsal motor nucleus of the vagus (DMV). To achieve this purpose we examined DMV motoneurons of the rat in vitro with the use of the extracellular cell-attached recording technique. The motoneurons, in general, exhibit a spontaneous discharge and when exposed to NO-producing drugs (i.e., 3-300 microM L-arginine and 10-100 microM S-nitroso-N-acetylpenicillamine) exhibit a concentration-related increase in their spontaneous firing rate. Because NO activates soluble guanylate cyclase and increases guanosine 3',5'-cyclic monophosphate (cGMP), we tested dibutyryl-cGMP (30-300 microM) and found that it also excites DMV neurons. Perfusion of the DMV neurons with N omega-nitro-L-arginine (300 microM), an inhibitor of NO synthase (NOS), and with NO scavenger, reduced hemoglobin (1 microM), counteracted the excitatory effect of L-arginine and N-methyl-D-aspartate (NMDA). Perfusion of the preparation with LY-83583 (10 microM), an inhibitor of guanylate cyclase, also counteracted the effects of L-arginine and NMDA. These data indicate that NOS is present in DMV neurons, and that the excitatory effect of NMDA on these neurons is due in part to formation of NO and the resulting accumulation of cGMP in DMV neurons.

Evidence for NO ⋅ redox form of nitric oxide as nitrergic inhibitory neurotransmitter in gut

1998 ◽  
Vol 275 (5) ◽  
pp. G1185-G1192 ◽  
Author(s):  
Raj K. Goyal ◽  
Xue D. He
Keyword(s):  
Nitric Oxide ◽  
Potassium Channel ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Slow Component ◽  
Circular Muscle ◽  
Exact Nature ◽  
Channel Blockers ◽  
Inhibitory Neurotransmitter ◽  
Ly 83583

A nitric oxide (NO)-like product of thel-arginine NO synthase pathway has been shown to be a major inhibitory neurotransmitter that is involved in the slow component of the inhibitory junction potential (IJP) elicited by stimulation of nonadrenergic, noncholinergic nerves. However, the exact nature of the nitrergic transmitter, the role of cGMP, and the involvement of a potassium or a chloride conductance in the slow IJP remain unresolved. We examined the effects of soluble guanylate cyclase inhibitors LY-83583 and 1 H-[1,2,4]oxadiazolo[4,3- a]quinoxalin-1-one (ODQ), potassium-channel blockers and putative chloride-channel blockers diphenylamine-2-carboxylate (DPC) and niflumic acid (NFA) on the hyperpolarization elicited by an NO ⋅ donor, diethylenetriamine/NO adduct (DNO), NO in solution, and an NO+ donor, sodium nitroprusside (SNP), in the guinea pig ileal circular muscle. Effects of these blockers on purinergic (fast) and nitrergic (slow) IJP were also examined. DNO-induced hyperpolarization and nitrergic slow IJP were suppressed by LY-83583 or ODQ and DPC or NFA but not by the potassium-channel blocker apamin. In contrast, hyperpolarization caused by SNP or solubilized NO gas and purinergic fast IJP were antagonized by apamin but not by inhibitors of guanylate cyclase or chloride channels. These results demonstrate biological differences in the actions of different redox states of NO and suggest that NO ⋅ is the nitrergic inhibitory neurotransmitter.

Hydrogen peroxide elicits pulmonary arterial relaxation and guanylate cyclase activation

1987 ◽  
Vol 252 (4) ◽  
pp. H721-H732 ◽  
Author(s):  
T. M. Burke ◽  
M. S. Wolin
Keyword(s):  
Hydrogen Peroxide ◽  
Guanylate Cyclase ◽  
Superoxide Anion ◽  
Vascular Tone ◽  
Soluble Guanylate Cyclase ◽  
Compound I ◽  
Cyclase Activation ◽  
Arterial Relaxation ◽  
Pulmonary Arterial ◽  
Guanylate Cyclase Activation

Hydrogen peroxide produces concentration-dependent relaxation of precontracted isolated bovine intrapulmonary arterial rings by a mechanism which is independent of the endothelium or prostaglandin mediators. Relaxant responses to hydrogen peroxide concentrations of up to 100 microM were markedly attenuated by the inhibitor of soluble guanylate cyclase activation, methylene blue (10 microM). Micromolar concentrations of hydrogen peroxide elicit time- and concentration-dependent increase in arterial levels of guanosine 3',5'-cyclic monophosphate that are associated with decreases in force. Soluble guanylate cyclase activity is markedly activated by enzymatically generated hydrogen peroxide in a manner that is most closely associated with the concentration of catalase present in the assay, by a mechanism that is inhibited by superoxide anion and the inactivation of catalase. Our data are most consistent with the involvement of compound I, a species of catalase formed during the metabolism of peroxide, in the mechanism of guanylate cyclase activation. The nature of this mechanism of arterial relaxation suggests that it could contribute to the regulation of pulmonary vascular tone by oxygen tension.

Rat mesenteric arterial dilator response to 11,12-epoxyeicosatrienoic acid is mediated by activating heme oxygenase

2006 ◽  
Vol 291 (4) ◽  
pp. H1999-H2002 ◽  
Author(s):  
David Sacerdoti ◽  
Massimo Bolognesi ◽  
Marco Di Pascoli ◽  
Angelo Gatta ◽  
John C. McGiff ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Heme Oxygenase ◽  
Biological Activities ◽  
Soluble Guanylyl Cyclase ◽  
Mesenteric Arteries ◽  
Epoxyeicosatrienoic Acid ◽  
Response Curves ◽  
Vasodilator Response ◽  
Calcium Activated Potassium Channels ◽  
Vasodilator Action

11,12-Epoxyeicosatrienoic acid (11,12-EET), a potent vasodilator produced by the endothelium, acts on calcium-activated potassium channels and shares biological activities with the heme oxygenase/carbon monoxide (HO/CO) system. We examined whether activation of HO mediates the dilator action of 11,12-EET, and that of the other EETs, on rat mesenteric arteries. Dose-response curves (10−9 to 10−6 M) to 5,6-EET, 8,9-EET, 11,12-EET, 14,15-EET, and ACh (10−9 to 10−4 M) were evaluated in preconstricted (10−6 mol/l phenylephrine) mesenteric arteries (<350 μm diameter) in the presence or absence of 1) the cyclooxygenase inhibitor indomethacin (2.8 μM), 2) the HO inhibitor chromium mesoporphyrin (CrMP) (15 μM), 3) the soluble guanylyl cyclase (GC) inhibitor ODQ (10 μM), and 4) the calcium-activated potassium channel inhibitor iberiotoxin (25 nM). The vasodilator response to 11,12-EET was abolished by CrMP and iberiotoxin, whereas indomethacin and ODQ had no effect. In contrast, the effect of ACh was attenuated by ODQ but not by CrMP. The vasodilator effect of 8,9-EET, like that of 11,12-EET, was greatly attenuated by HO inhibition. In contrast, the mesenteric vasodilator response to 5,6-EET was independent of both HO and GC, whereas that to 14,15-EET demonstrated two components, an HO and a GC, of equal magnitude. Incubation of mesenteric microvessels with 11,12-EET caused a 30% increase in CO release, an effect abolished by inhibition of HO. We conclude that the rat mesenteric vasodilator action of 11,12-EET is mediated via an increase in HO activity and an activation of calcium-activated potassium channels.

Hydrogen peroxide-induced pulmonary vasodilation: role of guanosine 3',5'-cyclic monophosphate

1991 ◽  
Vol 261 (6) ◽  
pp. L393-L398 ◽  
Author(s):  
T. Burke-Wolin ◽  
C. J. Abate ◽  
M. S. Wolin ◽  
G. H. Gurtner
Keyword(s):  
Hydrogen Peroxide ◽  
Guanylate Cyclase ◽  
Pulmonary Circulation ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Arteries ◽  
Phosphodiesterase Inhibitor ◽  
Cyclic Monophosphate ◽  
Pulmonary Vasodilation ◽  
Dependent Inhibition ◽  
Relaxant Response

Hydrogen peroxide (H2O2), but not tertbutyl hydroperoxide, produces a concentration-dependent vasodilation of the pulmonary circulation in isolated saline perfused rabbit lungs when pulmonary arterial pressures (PAP) are raised with the thromboxane analogue U-46619. This vasodilation was enhanced in the presence of indomethacin, suggesting that H2O2 possesses both a prostaglandin-mediated constrictor and an additional dilator mechanism. In isolated rabbit intrapulmonary arteries the endothelium did not alter the dose-dependent relaxation of arterial rings to H2O2, and indomethacin enhanced the relaxant response of the peroxide. The decrease in PAP and relaxation of isolated pulmonary arteries observed with H2O2 was attenuated with 10 microM methylene blue, an inhibitor of soluble guanylate cyclase activation. M & B 22948, a guanosine 3',5'-cyclic monophosphate (cGMP)-selective phosphodiesterase inhibitor, enhanced the vasodilation or relaxation to the peroxide in both preparations. These changes were not endothelium dependent. Inhibition of the cGMP-associated endothelium-derived relaxant factor (EDRF) with nitro-L-arginine, did not alter relaxation of arterial rings to peroxide. Thus H2O2 appears to produce pulmonary vasodilation through the activation of guanylate cyclase and accumulation of cGMP. Both H2O2 and EDRF may function as tonic stimulators of guanylate cyclase in the pulmonary circulation and contribute to the maintenance of low basal pressures.

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