doi: 10.1161/hy0202.103287
(Hypertension. 2002;39:591.)
© 2002 American Heart Association, Inc.
Scientific Contributions |
Interaction of O2- and NO in the Thick Ascending Limb
From the Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Hospital, Detroit, Mich.
Correspondence to Jeffrey L. Garvin, Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Hospital, 2799 W. Grand Boulevard, Detroit, MI 48202. E-mail jgarvin1{at}hfhs.org
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Abstract |
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Abstract— Nitric oxide (NO) is an important regulator of NaCl absorption by the thick ascending limb of the loop of Henle (THAL). The free radical superoxide (O2-) reacts with NO, decreasing its bioavailability. O2- is produced by mitochondria and various oxidases, some of which are present in the THAL. However, the ability of the THAL to produce O2- and its interaction with NO have not been studied. We hypothesized that NO bioavailability is decreased by O2-. THALs were isolated and perfused and NO production was measured with an NO-selective microelectrode. Addition of L-Arg (250 µmol/L), but not D-arginine, to the bath increased NO release by 34.8±11.8 pA (n=7). The response to L-Arg was completely abolished by the NO synthase inhibitor L-NAME (n=7). Scavenging THAL O2- with the superoxide dismutase (SOD) mimetic Tempol (50 µmol/L) increased L-Arg-induced NO release. At all concentrations of L-Arg tested (50, 100, 250, 500, and 750 µmol/L), further addition of Tempol to the bath significantly increased NO release by THALs. Addition of SOD (300 U/mL) to the bath increased L-Arg-induced NO levels by 82% (n=5; P<0.02). Pretreatment of THALs with the SOD inhibitor diethyl-dithiocarbamate (250 µmol/L) blunted L-Arg-induced NO release by 63% compared with untreated tubules (n=5; P<0.05). Finally, we tested the effect of Tempol on NO-induced inhibition of THAL chloride transport. Addition of L-Arg decreased THAL Cl- absorption by 35%. Subsequent addition of Tempol (50 µmol/L) to the bath further decreased Cl- absorption by 35% (n=6; P<0.05). We conclude that NO bioavailability in the THAL is decreased by O2-. In addition, we believe our studies are the first to show that endogenous O2- may act as a physiological regulator of nephron NaCl transport.
Key Words: nitric oxide • natriuresis
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Introduction |
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The thick ascending limb of the loop of Henle (THAL) plays an important role in the maintenance of NaCl homeostasis by reabsorbing 20% to 30% of filtered NaCl.1 Nitric oxide (NO) is an important regulator of THAL NaCl transport. We have previously shown that endogenous NO inhibits THAL NaCl absorption,2,3 consistent with the natriuretic and diuretic effects of NO observed in vivo.4,5 Therefore, factors affecting THAL NO production as well as NO bioavailability are of physiological significance.
NO rapidly reacts with the free radical superoxide (O2-) (K
7x109 mol/L/sec) to produce peroxynitrite (OONO-).6 O2- has been shown to decrease NO half-life in various tissues. Jones et al reported that O2- produced by activated neutrophils decreased NO released by lung epithelial cells.7 In the vasculature, O2- decreases endothelium-dependent relaxation,8,9 whereas superoxide dismutase (SOD) increases NO half-life and potentiates endothelium-dependent dilatation.10 Because both NO and O2- can exert physiological effects, the rate of production and the ratio of their concentrations are important in systems in which both radicals are produced.
O2- is produced by the reduction of molecular oxygen. Virtually all aerobically metabolizing cells are able to produce O2-, because 1 to 5% of oxygen consumed in mitochondrial respiration is reduced to O2.11 In addition, O2- production can be catalyzed by different enzymes such as xanthine oxidase (XO),12 nicotinamide adenine dinucleotide phosphate (NADPH) oxidase13 P450 monooxygenase,14 and other systems.15 The THAL contains large numbers of mitochondria. It also expresses some subunits of NADPH oxidase,16 and XO activity has been reported as well.17 However, it is not known whether the bioavailability of NO produced by the THAL is reduced by interaction with O2-, nor what effect this has on NaCl transport.
We have found that (1) NO bioavailability in the THAL is decreased by O2- and (2) scavenging O2- enhances the inhibitory effect of NO on THAL NaCl absorption. To our knowledge, these are the first data to show that O2- produced by a nephron segment can act as a physiological regulator of transport. Additionally, we report a new method for direct measurement of NO released by isolated, perfused tubules.
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Methods |
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Isolation and Perfusion of Rat Thick Ascending Limbs
Male Sprague-Dawley rats weighing 120 to 150 g (Charles River, Wilmington, Mass) were fed a diet containing 0.22% sodium and 1.1% potassium (Purina) for at least 5 days. On the day of the experiment, rats were anesthetized with ketamine (100 mg/kg body wt IP) and xylazine (20 mg/kg body wt IP), the abdominal cavity was opened, and the left kidney was bathed in ice-cold saline and removed. Coronal slices were placed in oxygenated physiological saline. Cortical THALs were dissected from the medullary rays under a stereomicroscope at 4 to 10°C, then transferred to a temperature-regulated chamber and perfused using concentric glass pipettes at 37±1°C as described previously.18
NO Release by Isolated, Perfused THALs
L-arginine (L-Arg), the substrate for NOS (Sigma), was added to THALs and NO release measured using an amperometric microelectrode selective for NO (inNO measuring system, Harvard Apparatus). For details, see expanded Methods section.
Measurement of Chloride Absorption
THALs ranging from 0.6 to 1.0 mm were mounted on concentric glass pipettes and perfused at 37°C as described previously.18 The perfusion rate was set at 5 to 10 nL/min-1/mm-1. Chloride concentrations in the perfusate and collected fluid were measured by microfluorometry.19 For details, see expanded Methods section.
Statistics
Results are expressed as mean±SEM. Data were evaluated with Student’s paired t-test when possible. In the protocol in which the response to L-arginine was studied in THALs pretreated with either vehicle or diethyldithiocarbamate (DETC), one-way ANOVA was used. P<0.05 was considered significant.
An expanded Methods section can be found in an online data supplement available at http://www.hypertensionaha.org.
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Results |
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To test whether NO bioavailability in the THAL is decreased by O2-, we first measured L-Arg-stimulated NO release by isolated, perfused THALs. We have shown that L-Arg decreases THAL transport via a nitric oxide synthase (NOS)-dependent pathway.2,3 However, we know of no direct measurements of NO produced by the THAL. An average increase in electrode output of 34.8±11.8 pA was observed when 250 µmol/L L-Arg was added to the bath (n=7) (Figure 1A). We found that the response to L-Arg was directly related to tubule length. When plotting NO response in pA versus THAL length in mm, a positive linear relationship was observed (r2=0.88) (Figure 1B). Consequently, all data are expressed as pA/mm of tubule length. The plot also indicates that the shortest THAL that can be used for these measurements is 0.55 mm.
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To make sure the response produced by L-Arg was caused by NO released from THALs, we tested whether inhibition of NOS could prevent this response. Pretreatment of THALs with L-
nitro-methylarginine (L-NAME) at 5 mmol/L completely abolished L-Arg-induced responses (n=6) (Figure 2). In addition, we tested whether the arginine isomer D-arginine could mimic the response caused by L-Arg; however, when D-arginine at 250 µmol/L was added to the bath, it did not significantly affect the baseline signal (n=6). Taken together, these data indicate that the response observed after adding L-Arg to the bath is caused by NO produced by NOS present in the THAL.
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The bioavailability of NO can be reduced by O2-,7,10 and the THAL possesses a large nimber of mitochondria as well as O2--producing oxidases.16,17 To study whether NO is degraded by O2-, we first tested whether decreasing the O2- concentration by scavenging with the SOD mimetic Tempol20 could increase the detectable amount of NO released after L-Arg stimulation. We found that adding 250 µmol/L L-Arg to the bath increased THAL NO by 46.1±8.4 pA/mm. Subsequent addition of 50 µmol/L Tempol to the bath significantly increased the signal to 75.5±10.1 pA/mm, a 64% increase in NO levels (n=5; P<0.01).
To test whether Tempol could increase NO levels over a wide range of L-Arg concentrations, we obtained a dose-response curve for L-Arg. Each L-Arg concentration (0, 50, 100, 250, 500, and 750 µmol/L) was tested in a separate group of tubules, and the effect of Tempol was studied in each group. At all concentrations tested, Tempol significantly increased the detectable amount of NO in the THAL, whereas in the absence of L-Arg, adding Tempol to the bath did not increase NO (Figure 3).
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The SOD mimetic Tempol scavenges both intracellular and extracellular O2-.20,21 We tested whether scavenging only extracellular O2- could increase NO levels. For this we used SOD, which has a molecular weight of 32 kDa and does not diffuse across the cell membrane. Adding 250 µmol/L L-Arg to the bath increased THAL NO production by 40.8±4.0 pA/mm. Subsequent addition of 300 U/mL SOD to the bath significantly increased the signal to 74.5±11.4 pA/mm, an 82% increase in NO levels (n=5; P<0.02) (Figure 4).
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To make sure O2- was being produced by the THAL and was not present in the bath, we generated a response to an NO donor (spermine NONOate) and then added SOD. Without a perfused tubule in the chamber, adding 300 U/mL SOD to the bath did not increase NO levels generated by spermine NONOate (data not shown).
A decrease in O2- concentration caused by Tempol and SOD increased NO levels in the THAL. We tested whether increasing O2- concentration in the THAL by inhibiting endogenous SOD could blunt L-Arg-induced NO release. Under control conditions, adding 250 µmol/L L-Arg to the bath increased NO release to 64.6±13.6 pA/mm (n=5). In contrast, when tubules were preincubated with the SOD inhibitor DETC at 250 µmol/L for 30 minutes, adding L-Arg only increased NO to 23.3±6.3 pA/mm, a 63% decrease in NO production compared with untreated tubules (n=5; P<0.01) (Figure 5). Taken together, these data indicate that NO bioavailability in the THAL is reduced by O2-.
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Because we found that endogenously produced O2- can decrease NO bioavailability in the THAL, we tested whether scavenging O2- could decrease THAL chloride absorption after stimulating NO production with L-Arg. Under basal conditions, THALs absorbed chloride at a rate of 167.2±16.6 pmol/min/mm. After adding 0.5 mmol/L L-Arg to the bath, chloride transport decreased to 106.5±9.5 pmol/min/mm, a 35% decrease. In the presence of L-Arg, adding 50 µmol/L Tempol to the bath further decreased THAL chloride absorption to 68.7±5.1 pmol/min/mm (n=6; P<0.03) (Figure 6). Control experiments showed no significant change in chloride absorption over time in the presence of L-Arg (data not shown).
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Discussion |
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Previous studies have shown that NO plays an important role in the regulation of sodium and fluid transport by the nephron. We have reported that endogenous NO inhibits THAL NaCl and bicarbonate absorption.2,3,22 However, no direct measurements of NO produced by the THAL have been made. Using an electrochemical method for detection of NO, we can now report for the first time that physiological concentrations of L-Arg induce NO production and release from isolated, perfused THALs. We found that NO release increased in a dose-dependent manner with higher concentrations of L-Arg. The minimum concentration of L-Arg that caused a measurable increase in NO release was 100 µmol/L, whereas the half-maximum response was 240 µmol/L and saturation occurred at concentrations greater than 500 µmol/L.
Because this was the first time that an electrochemical method was used to measure NO release by isolated, perfused kidney tubules, we examined the response of the electrode to D-Arg and the ability of L-NAME to block the response to L-Arg. We found that in the presence of the NOS inhibitor L-NAME, addition of L-Arg did not increase the electrical signal. Similarly, exposing THALs to D-arginine, which is not a substrate for NOS, did not change the signal. These data indicate that the response caused by L-Arg is due to NO and verify that this method is suitable for the detection of NO released by THALs.
Electrochemical detection of NO has been used several times for in vitro detection of NO.23,24 The selectivity of the sensor is given by the redox potential of NO at which the anode is maintained, and a gas-permeable membrane that coats the electrode surface. We chose to use the inNO measuring system by Harvard Apparatus because it is highly stable (lasting 
3 months) and highly sensitive (nmol/L range). Furthermore, only a small number of substances have been shown to interfere with electrochemical detection of NO.23 However, to obtain reproducible and accurate data one must isolate the electrode electrically and insulate it from temperature variations as described in detail in the expanded methods section. Without such precautions, detection of NO released from single renal tubules is impossible.
We hypothesized that NO bioavailability in the THAL is decreased by O2-. We first tested whether decreasing O2- concentration with Tempol, an SOD mimetic, could increase NO levels in the THAL. We found that adding Tempol to the bath significantly enhanced the detectable amount of NO released by THALs at all concentrations of L-Arg tested. These data appear to indicate that O2- produced by THALs reduces the bioavailability of NO. Even though Tempol has been reported to have pharmacological effects unrelated to scavenging O2-, this is unlikely in our system because at the concentration we used, Tempol has only been reported to scavenge O2-.25–28 In addition, similar concentrations of Tempol have been shown to increase the detectable amount of NO released by endothelial cells by dismutation of O2-.25 These data indicate that the increase in NO release caused by Tempol is most likely due to selective removal of O2-.
To make sure that NO bioavailability in THALs is decreased by O2-, we investigated the effect of altering O2- levels by adding or inhibiting SOD. Adding SOD to the bath significantly increased the detectable amount of NO released by THALs after L-Arg stimulation. We found that SOD, which only scavenges extracellular O2-, increased NO levels more than Tempol, which scavenges both intra- and extracellular O2-. This may be explained on the basis of a greater efficacy of SOD (K2x109 mol/L/sec) than Tempol (K6x105 mol/L/sec) to react with O2-.20 We also tested whether blocking SOD with the irreversible inhibitor DETC could decrease NO release by THALs. In THALs treated with DETC, L-Arg-induced NO release was 60% smaller compared with untreated tubules. These data support the hypothesis that NO bioavailability is decreased by endogenously produced O2-. Additionally, they indicate that Tempol acts only by scavenging O2- in our preparation.
Similar to our results, there have been many reports showing that O2- decreases the bioavailability of NO. In the vasculature, O2- decreases endothelium-dependent relaxation,8,9 whereas SOD increases NO half-life and potentiates endothelium-dependent dilatation.10 Inhibiting SOD with DETC decreases muscle relaxation induced by gaseous NO in the gastric fundus29 and by NO donors in coronary arteries.30 In other cell types such as epithelial cells7 and astrocytes,31 endogenously produced O2- decreases extracellular NO availability. Finally, in both normal and spontaneously hypertensive rats, the effects of an NO donor on TGF were enhanced by scavenging O2- with Tempol.32
We have previously shown that the source of NO in the THAL is likely to be endothelial NO synthase (eNOS),33 which is bound to the plasma membrane.34 While the source(s) of O2- in the THAL have not been identified to our knowledge, three major sources include the mitochondria, xanthine oxidase, and NAD(P)H oxidase. Mitochondria, which are present in large numbers in the THAL, are known to produce O2- during aerobic respiration.11,35 Xanthine oxidase activity has been detected in membrane fractions of isolated THALs,17 although its presence has not been confirmed at the protein level. A novel isoform of NADPH oxidase has been found in the renal cortex,36 and the major subunits of NADPH oxidase have been visualized in the THAL by immunological techniques.16 We found that SOD, which only scavenges extracellular O2-, increased the detectable amount of NO produced by THALs. This indicates that at least one source of O2- is external, or that there is leakage of intracellular O2- across the plasma membrane. Due to the high reactivity and negative charge of O2-, diffusion across the plasma membrane is highly improbable. Therefore, our data suggest the existence of a phagocyte-like NADPH oxidase in the THAL, although at present we know of no definitive evidence of O2- production by NADPH oxidase in the THAL.
In vivo experiments have shown that infusion of substances like acetylcholine, which causes NO release, into the renal artery increased urinary volume and sodium excretion.5,37,38 In addition, decreased water and sodium excretion has been reported when inhibitors of endogenous NO production were infused into the kidney.4,39–41 In these studies, the natriuretic and diuretic effects of NO were not accompanied by proportional changes in glomerular filtration rate or renal blood flow. These data indicate that NO regulates nephron transport; however, the specific nephron segment(s) affected by NO were not identified. By studying isolated nephron segments, we have shown that endogenously produced NO inhibits chloride and bicarbonate absorption by the THAL.2,22 In agreement with in vivo data, we found that the effects of NO were reversible and could be abolished by L-NAME, suggesting that NO is a physiological regulator of THAL transport.3,22
In vitro and in vivo data indicate that NO is an important regulator of THAL transport. Therefore, factors affecting NO bioavailability may be important for transport regulation in this segment. To determine the physiological role of endogenous O2- in the THAL, we examined whether Tempol could enhance the inhibitory effect of endogenous NO on THAL chloride absorption. We found that adding Tempol to the bath decreased THAL chloride absorption by 35% in the presence of L-Arg. Because Tempol increased L-Arg-stimulated NO levels in the THAL, the effects of Tempol on chloride absorption may be mediated by an increase in NO availability. However, preliminary data indicate that in the absence of L-Arg, Tempol decreased THAL chloride absorption (Ortiz and Garvin, unpublished observations), suggesting that O2- levels stimulate transport in the absence of NO. Thus, the effect of Tempol on chloride absorption in the presence of NO is more likely due to both an increase in NO bioavailability and a direct effect of O2-.
Little is known about the effect of interactions of NO and O2- on transport in other nephron segments. Some reports have implicated O2- in the regulation of physiological processes in the kidney. Lu and Wang42 found that the effect of NO on basolateral K+ channels in the collecting duct is modulated by O2-. A role for O2- in the regulation of tubuloglomerular feedback (TGF) has also been reported. Welch et al32 have shown that inhibition of TGF by NO in normal and spontaneously hypertensive rats is enhanced by scavenging O2- with Tempol. This effect may be due to a reduction of Na/K/2 Cl cotransport, because TGF is initiated by changes in cotransport activity. The ability of O2- to mitigate the actions of NO in both the vasculature and nephron segments may ultimately reduce urinary volume and sodium excretion. Recently, Zou et al43 reported that infusion of Tempol into the renal medulla enhanced urinary sodium excretion, and several investigators have reported that inhibition of NO production in this region has the opposite effect.44
We conclude that NO bioavailability in the THAL is decreased by O2-. In addition, we provide evidence showing for the first time that endogenous O2- may act as a physiological regulator of tubular NaCl transport.
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Acknowledgments |
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This work was supported in part by a grant from the National Institutes of Health Heart, Lung and Blood Institute (HL 28982). Dr Ortiz is the recipient of a fellowship grant from the American Heart Association. We thank Dr Ziad Taha from Innovative Instruments for custom preparation of the NO microelectrode.
Received September 22, 2001; first decision November 7, 2001; accepted November 21, 2001.
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References |
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1. Greger R, Velazquez H. The cortical thick ascending limb and early distal convoluted tubule in the urinary concentrating mechanism. Kidney Int. 1987; 31: 590–596.[Medline] [Order article via Infotrieve]
2. Ortiz PA, Garvin JL. NO inhibits NaCl absorption by rat thick ascending limb through activation of cGMP-stimulated phosphodiesterase. Hypertension. 2001; 37: 467–471.
3. Plato CF, Stoos BA, Wang D, Garvin JL. Endogenous nitric oxide inhibits chloride transport in the thick ascending limb. Am J Physiol. 1999; 276: F159–F163.[Medline] [Order article via Infotrieve]
4. Lahera V, Salom MG, Miranda-Guardiola F, Moncada S, Romero JC. Effects of NG-nitro-L-arginine methyl ester on renal function and blood pressure. Am J Physiol. 1991; 261: F1033–F1037.[Medline] [Order article via Infotrieve]
5. Majid DS, Williams A, Kadowitz PJ, Navar LG. Renal responses to intra-arterial administration of nitric oxide donor in dogs. Hypertension. 1993; 22: 535–541.
6. Huie RE, Padmaja S. The reaction of NO with superoxide. Free Radic Res Commun. 1993; 18: 195–199.[Medline] [Order article via Infotrieve]
7. Jones KL, Bryan TW, Jinkins PA, Simpson KL, Grisham MB, Owens MW, Milligan SA, Markewitz BA, Robbins RA. Superoxide released from neutrophils causes a reduction in nitric oxide gas. Am J Physiol. 1998; 275: L1120–L1126.[Medline] [Order article via Infotrieve]
8. Rubanyi GM, Vanhoutte PM. Oxygen-derived free radicals, endothelium, and responsiveness of vascular smooth muscle. Am J Physiol. 1986; 250: H815–H821.[Medline] [Order article via Infotrieve]
9. Rubanyi GM, Vanhoutte PM. Superoxide anions and hyperoxia inactivate endothelium-derived relaxing factor. Am J Physiol. 1986; 250: H822–H827.[Medline] [Order article via Infotrieve]
10. Gryglewski RJ, Palmer RM, Moncada S. Superoxide anion is involved in the breakdown of endothelium-derived vascular relaxing factor. Nature. 1986; 320: 454–456.[CrossRef][Medline] [Order article via Infotrieve]
11. Jamieson D, Chance B, Cadenas E, Boveris A. The relation of free radical production to hyperoxia. Annu Rev Physiol. 1986; 48: 703–719.[CrossRef][Medline] [Order article via Infotrieve]
12. Parks DA, Granger DN. Xanthine oxidase: biochemistry, distribution and physiology. Acta Physiol Scand Suppl. 1986; 548: 87–99.[Medline] [Order article via Infotrieve]
13. Babior BM. NADPH oxidase: an update. Blood. 1999; 93: 1464–1476.
14. Fulton D, McGiff JC, Wolin MS, Kaminski P, Quilley J. Evidence against a cytochrome P450-derived reactive oxygen species as the mediator of the nitric oxide-independent vasodilator effect of bradykinin in the perfused heart of the rat. J Pharmacol Exp Ther. 1997; 280: 702–709.
15. Kontos HA, Wei EP, Ellis EF, Jenkins LW, Povlishock JT, Rowe GT, Hess ML. Appearance of superoxide anion radical in cerebral extracellular space during increased prostaglandin synthesis in cats. Circ Res. 1985; 57: 142–151.
16. Chavrashvili T, Tojo A, Kitiyakara C, Wilcox CS. Expression and distribution of the five components of the classic NADPH oxidase in the kidney: comparison of SHR and WKY (Abstract). J Am Soc Nephrol. 99; 343A.
17. Pawelczyk T, Bizon D, Angielski S. The distribution of enzymes involved in purine metabolism in rat kidney. Biochim Biophys Acta. 1992; 1116: 309–314.[Medline] [Order article via Infotrieve]
18. Garvin JL, Burg MB, Knepper MA. Active NH4+ absorption by the thick ascending limb. Am J Physiol. 1988; 255: F57–F65.[Medline] [Order article via Infotrieve]
19. Garcia NH, Plato CF, Garvin JL. Fluorescent determination of chloride in nanoliter samples. Kidney Int. 1999; 55: 321–325.[CrossRef][Medline] [Order article via Infotrieve]
20. Krishna MC, Russo A, Mitchell JB, Goldstein S, Dafni H, Samuni A. Do nitroxide antioxidants act as scavengers of O2- or as SOD mimics? J Biol Chem. 1996; 271: 26026–26031.
21. Offer T, Russo A, Samuni A. The pro-oxidative activity of SOD and nitroxide SOD mimics. FASEB J. 2000; 14: 1215–1223.
22. Ortiz PA, Garvin JL. Autocrine effects of nitric oxide on HCO3- transport by rat thick ascending limb. Kidney Int. 2000; 58: 2069–2074.[CrossRef][Medline] [Order article via Infotrieve]
23. Christodoulou D, Kudo S, Cook JA, Krishna MC, Miles A, Grisham MB, Murugesan M, Ford PC, Wink DA. Electrochemical methods for detection of nitric oxide. Methods Enzymol. 1996; 268: 69–83.[Medline] [Order article via Infotrieve]
24. Taha Z, Kiechle F, Malinski T. Oxidation of nitric oxide by oxygen in biological systems monitored by porphyrinic sensor. Biochem Biophys Res Commun. 1992; 188: 734–739.[CrossRef][Medline] [Order article via Infotrieve]
25. Zollner S, Haseloff RF, Kirilyuk IA, Blasig IE, Rubanyi GM. Nitroxides increase the detectable amount of nitric oxide released from endothelial cells. J Biol Chem. 1997; 272: 23076–23080.
26. Monti E, Supino R, Colleoni M, Costa B, Ravizza R, Gariboldi MB. Nitroxide TEMPOL impairs mitochondrial function and induces apoptosis in HL60 cells. J Cell Biochem. 2001; 82: 271–276.[CrossRef][Medline] [Order article via Infotrieve]
27. Gariboldi MB, Rimoldi V, Supino R, Favini E, Monti E. The nitroxide tempol induces oxidative stress, p21(WAF1/CIP1), and cell death in HL60 cells. Free Radic Biol Med. 2000; 29: 633–641.[CrossRef][Medline] [Order article via Infotrieve]
28. Suy S, Mitchell JB, Ehleiter D, Haimovitz-Friedman A, Kasid U. Nitroxides tempol and tempo induce divergent signal transduction pathways in MDA-MB 231 breast cancer cells. J Biol Chem. 1998; 273: 17871–17878.
29. Lefebvre RA. Influence of superoxide dismutase inhibition on the discrimination between NO and the nitrergic neurotransmitter in the rat gastric fundus. Br J Pharmacol. 1996; 118: 2171–2177.[Medline] [Order article via Infotrieve]
30. Mohazzab H, Kaminski PM, Fayngersh RP, Wolin MS. Oxygen-elicited responses in calf coronary arteries: role of H2O2 production via NADH-derived superoxide. Am J Physiol. 1996; 270: H1044–H1053.[Medline] [Order article via Infotrieve]
31. Tolias CM, McNeil CJ, Kazlauskaite J, Hillhouse EW. Superoxide generation from constitutive nitric oxide synthase in astrocytes in vitro regulates extracellular nitric oxide availability. Free Radic Biol Med. 1999; 26: 99–106.[CrossRef][Medline] [Order article via Infotrieve]
32. Welch WJ, Tojo A, Wilcox CS. Roles of NO and oxygen radicals in tubuloglomerular feedback in SHR. Am J Physiol. 2000; 278: F769–F776.
33. Plato CF, Shesely EG, Garvin JL. eNOS mediates L-arginine-induced inhibition of thick ascending limb chloride flux. Hypertension. 2000; 35: 319–323.
34. Garcia-Cardena G, Oh P, Liu J, Schnitzer JE, Sessa WC. Targeting of nitric oxide synthase to endothelial cell caveolae via palmitoylation: implications for nitric oxide signaling. Proc Natl Acad Sci U. S A. 1996; 93: 6448–6453.
35. Fridovich I. Overview: biological sources of O2. Methods Enzymol. 1984; 105: 59–61.[Medline] [Order article via Infotrieve]
36. Geiszt M, Kopp JB, Varnai P, Leto TL. Identification of renox, an NAD(P)H oxidase in kidney. Proc Natl Acad Sci U S A. 2000; 97: 8010–8014.
37. Baer PG, Navar LG, Guyton AC. Renal autoregulation, filtration rate, and electrolyte excretion during vasodilatation. Am J Physiol. 1970; 219: 619–625.
38. Yun JC, Oriji G, Gill JR Jr, Coleman BR, Peters J, Keiser H. carinic receptors in renal response to acetylcholine. Am J Physiol. 1993; 265: F46–F52.[Medline] [Order article via Infotrieve]
39. Lahera V, Salom MG, Fiksen-Olsen MJ, Raij L, Romero JC. Effects of NG-monomethyl-L-arginine and L-arginine on acetylcholine renal response. Hypertension. 1990; 15: 659–663.
40. Lahera V, Navarro J, Biondi ML, Ruilope LM, Romero JC. Exogenous cGMP prevents decrease in diuresis and natriuresis induced by inhibition of NO synthesis. Am J Physiol. 1993; 264: F344–F347.[Medline] [Order article via Infotrieve]
41. Mattson DL, Wu F. Control of arterial blood pressure and renal sodium excretion by nitric oxide synthase in the renal medulla. Acta Physiol Scand. 2000; 168: 149–154.[CrossRef][Medline] [Order article via Infotrieve]
42. Lu M, Wang WH. Reaction of nitric oxide with superoxide inhibits basolateral K+ channels in the rat CCD. Am J Physiol. 1998; 275: C309–C316.[Medline] [Order article via Infotrieve]
43. Zou AP, Li N, Cowley AW Jr. Production and actions of superoxide in the renal medulla. Hypertension. 2001; 37: 547–553.
44. Mattson DL, Lu S, Nakanishi K, Papanek PE, Cowley AW Jr. Effect of chronic renal medullary nitric oxide inhibition on blood pressure. Am J Physiol. 1994; 266: H1918–H1926.[Medline] [Order article via Infotrieve]
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 C. S. Wilcox and A. Pearlman Chemistry and Antihypertensive Effects of Tempol and Other Nitroxides Pharmacol. Rev., December 1, 2008; 60(4): 418 - 469. [Abstract] [Full Text] [PDF]
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A. W. Cowley Jr Renal Medullary Oxidative Stress, Pressure-Natriuresis, and Hypertension Hypertension, November 1, 2008; 52(5): 777 - 786. [Full Text] [PDF]
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G. R. Ares, P. Caceres, F. J. Alvarez-Leefmans, and P. A. Ortiz cGMP decreases surface NKCC2 levels in the thick ascending limb: role of phosphodiesterase 2 (PDE2) Am J Physiol Renal Physiol, October 1, 2008; 295(4): F877 - F887. [Abstract] [Full Text] [PDF]
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S. Kelsen, B. J. Patel, L. B. Parker, T. Vera, J. M. Rimoldi, R. S. V. Gadepalli, H. A. Drummond, and D. E. Stec Heme oxygenase attenuates angiotensin II-mediated superoxide production in cultured mouse thick ascending loop of Henle cells Am J Physiol Renal Physiol, October 1, 2008; 295(4): F1158 - F1165. [Abstract] [Full Text] [PDF]
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T. Vera, S. Kelsen, and D. E. Stec Kidney-Specific Induction of Heme Oxygenase-1 Prevents Angiotensin II Hypertension Hypertension, October 1, 2008; 52(4): 660 - 665. [Abstract] [Full Text] [PDF]
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J. M. Moreno, I. Rodriguez Gomez, R. Wangensteen, M. Alvarez-Guerra, J. d. D. Luna, J. Garcia-Estan, and F. Vargas Tempol improves renal hemodynamics and pressure natriuresis in hyperthyroid rats Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2008; 294(3): R867 - R873. [Abstract] [Full Text] [PDF]
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D. E. Stec, H. A. Drummond, and T. Vera Role of Carbon Monoxide in Blood Pressure Regulation Hypertension, March 1, 2008; 51(3): 597 - 604. [Full Text] [PDF]
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S. Soodvilai, Z. Jia, and T. Yang Hydrogen peroxide stimulates chloride secretion in primary inner medullary collecting duct cells via mPGES-1-derived PGE2 Am J Physiol Renal Physiol, November 1, 2007; 293(5): F1571 - F1576. [Abstract] [Full Text] [PDF]
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T. Mori, P. M. O'Connor, M. Abe, and A. W. Cowley Jr Enhanced Superoxide Production in Renal Outer Medulla of Dahl Salt-Sensitive Rats Reduces Nitric Oxide Tubular-Vascular Cross-Talk Hypertension, June 1, 2007; 49(6): 1336 - 1341. [Abstract] [Full Text] [PDF]
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G. B. Silva, P. A. Ortiz, N. J. Hong, and J. L. Garvin Superoxide Stimulates NaCl Absorption in the Thick Ascending Limb Via Activation of Protein Kinase C Hypertension, September 1, 2006; 48(3): 467 - 472. [Abstract] [Full Text] [PDF]
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M. Abe, P. O'Connor, M. Kaldunski, M. Liang, R. J. Roman, and A. W. Cowley Jr. Effect of sodium delivery on superoxide and nitric oxide in the medullary thick ascending limb Am J Physiol Renal Physiol, August 1, 2006; 291(2): F350 - F357. [Abstract] [Full Text] [PDF]
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R. Juncos, N. J. Hong, and J. L. Garvin Differential effects of superoxide on luminal and basolateral Na+/H+ exchange in the thick ascending limb Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R79 - R83. [Abstract] [Full Text] [PDF]
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K. Patel, Y. Chen, K. Dennehy, J. Blau, S. Connors, M. Mendonca, M. Tarpey, M. Krishna, J. B. Mitchell, W. J. Welch, et al. Acute antihypertensive action of nitroxides in the spontaneously hypertensive rat Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R37 - R43. [Abstract] [Full Text] [PDF]
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Y. E. Lau, J. J. Galligan, D. L. Kreulen, and G. D. Fink Activation of ETB receptors increases superoxide levels in sympathetic ganglia in vivo Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R90 - R95. [Abstract] [Full Text] [PDF]
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C. S. Wilcox Oxidative stress and nitric oxide deficiency in the kidney: a critical link to hypertension? Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2005; 289(4): R913 - R935. [Abstract] [Full Text] [PDF]
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M. Herrera and J. L. Garvin Recent Advances in the Regulation of Nitric Oxide in the Kidney Hypertension, June 1, 2005; 45(6): 1062 - 1067. [Abstract] [Full Text] [PDF]
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R. Juncos and J. L. Garvin Superoxide enhances Na-K-2Cl cotransporter activity in the thick ascending limb Am J Physiol Renal Physiol, May 1, 2005; 288(5): F982 - F987. [Abstract] [Full Text] [PDF]
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 L. G. Bongartz, M. J. Cramer, P. A. Doevendans, J. A. Joles, and B. Braam The severe cardiorenal syndrome: 'Guyton revisited' Eur. Heart J., January 1, 2005; 26(1): 11 - 17. [Abstract] [Full Text] [PDF]
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P. A. Ortiz, N. J. Hong, and J. L. Garvin Luminal flow induces eNOS activation and translocation in the rat thick ascending limb Am J Physiol Renal Physiol, August 1, 2004; 287(2): F274 - F280. [Abstract] [Full Text] [PDF]
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P. A. Ortiz, N. J. Hong, and J. L. Garvin Luminal flow induces eNOS activation and translocation in the rat thick ascending limb. II. Role of PI3-kinase and Hsp90 Am J Physiol Renal Physiol, August 1, 2004; 287(2): F281 - F288. [Abstract] [Full Text] [PDF]
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D. H. Evans, R. E. Rose, J. M. Roeser, and J. D. Stidham NaCl transport across the opercular epithelium of Fundulus heteroclitus is inhibited by an endothelin to NO, superoxide, and prostanoid signaling axis Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2004; 286(3): R560 - R568. [Abstract] [Full Text] [PDF]
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T. Mori and A. W. Cowley Jr. Renal Oxidative Stress in Medullary Thick Ascending Limbs Produced by Elevated NaCl and Glucose Hypertension, February 1, 2004; 43(2): 341 - 346. [Abstract] [Full Text] [PDF]
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A. D. Dobrian, S. D. Schriver, A. A. Khraibi, and R. L. Prewitt Pioglitazone Prevents Hypertension and Reduces Oxidative Stress in Diet-Induced Obesity Hypertension, January 1, 2004; 43(1): 48 - 56. [Abstract] [Full Text] [PDF]
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M. W. Brands, T. D. Bell, and B. Gibson Nitric Oxide May Prevent Hypertension Early in Diabetes by Counteracting Renal Actions of Superoxide Hypertension, January 1, 2004; 43(1): 57 - 63. [Abstract] [Full Text] [PDF]
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J. Zimpelmann, N. Li, and K. D. Burns Nitric oxide inhibits superoxide-stimulated urea permeability in the rat inner medullary collecting duct Am J Physiol Renal Physiol, December 1, 2003; 285(6): F1160 - F1167. [Abstract] [Full Text]
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B. Lopez, M. G. Salom, B. Arregui, F. Valero, and F. J. Fenoy Role of Superoxide in Modulating the Renal Effects of Angiotensin II Hypertension, December 1, 2003; 42(6): 1150 - 1156. [Abstract] [Full Text] [PDF]
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A. D. Dobrian, S. D. Schriver, T. Lynch, and R. L. Prewitt Effect of salt on hypertension and oxidative stress in a rat model of diet-induced obesity Am J Physiol Renal Physiol, October 1, 2003; 285(4): F619 - F628. [Abstract] [Full Text] [PDF]
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T. Mori and A. W. Cowley Jr Angiotensin II-NAD(P)H Oxidase-Stimulated Superoxide Modifies Tubulovascular Nitric Oxide Cross-Talk in Renal Outer Medulla Hypertension, October 1, 2003; 42(4): 588 - 593. [Abstract] [Full Text] [PDF]
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P. A. Ortiz and J. L. Garvin Cardiovascular and renal control in NOS-deficient mouse models Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2003; 284(3): R628 - R638. [Abstract] [Full Text] [PDF]
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P. Ortiz, B. A. Stoos, N. J. Hong, D. M. Boesch, C. F. Plato, and J. L. Garvin High-Salt Diet Increases Sensitivity to NO and eNOS Expression But Not NO Production in THALs Hypertension, March 1, 2003; 41(3): 682 - 687. [Abstract] [Full Text] [PDF]
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T. L. Pallone, Z. Zhang, and K. Rhinehart Physiology of the renal medullary microcirculation Am J Physiol Renal Physiol, February 1, 2003; 284(2): F253 - F266. [Abstract] [Full Text] [PDF]
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P. A. Ortiz and J. L. Garvin Superoxide stimulates NaCl absorption by the thick ascending limb Am J Physiol Renal Physiol, November 1, 2002; 283(5): F957 - F962. [Abstract] [Full Text] [PDF]
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M. Szentivanyi Jr., A.-P. Zou, D. L. Mattson, P. Soares, C. Moreno, R. J. Roman, and A. W. Cowley Jr. Renal medullary nitric oxide deficit of Dahl S rats enhances hypertensive actions of angiotensin II Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2002; 283(1): R266 - R272. [Abstract] [Full Text] [PDF]
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