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Hypertension. 2005;45:438-444
Published online before print February 7, 2005, doi: 10.1161/01.HYP.0000157169.27818.ae
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(Hypertension. 2005;45:438.)
© 2005 American Heart Association, Inc.


Original Articles

Mitochondria-Derived Reactive Oxygen Species and Vascular MAP Kinases

Comparison of Angiotensin II and Diazoxide

Shoji Kimura; Guo-Xing Zhang; Akira Nishiyama; Takatomi Shokoji; Li Yao; Yu-Yan Fan; Matlubur Rahman; Youichi Abe

From the Department of Pharmacology, Kagawa University Medical School, Kagawa, Japan.

Correspondence to Shoji Kimura, MD, PhD, Department of Pharmacology, Kagawa University Medical School, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan. E-mail kimura{at}kms.ac.jp

Abstract

Reactive oxygen species (ROS) are key mediators in signal transduction of angiotensin II (Ang II). However, roles of vascular mitochondria, a major intracellular ROS source, in response to Ang II stimuli have not been elucidated. This study aimed to examine the involvement of mitochondria-derived ROS in the signaling pathway and the vasoconstrictor mechanism of Ang II. Using 5-hydroxydecanoate (5-HD; a specific inhibitor of mitochondrial ATP-sensitive potassium [mitoKATP] channels) and tempol (a superoxide dismutase mimetic), the effects of Ang II and diazoxide (a mitoKATP channel opener) were compared on redox-sensitive mitogen-activated protein (MAP) kinase activation in rat vascular smooth muscle cells (RVSMCs) in vitro and in rat aorta in vivo. Stimulation of RVSMCs by Ang II or diazoxide increased phosphorylated MAP kinases (ERK1/2, p38, and JNK), as well as superoxide production, which were then suppressed by 5-HD pretreatment in a dose-dependent manner, except for ERK1/2 activation by Ang II. The same events were reproduced in rat aorta in vivo. Ang II-like diazoxide depolarized the mitochondrial membrane potential ({Delta}{Psi}M) of RVSMCs determined by JC-1 fluorescence, which was inhibited by 5-HD. 5-HD did not modulate Ang II–induced calcium mobilization in RVSMCs and did not affect on the vasoconstrictor effect in either acute or chronic phases of Ang II–induced hypertension. These results reveal that Ang II stimulates mitochondrial ROS production through the opening of mitoKATP channels in the vasculature-like diazoxide, leading to reduction of {Delta}{Psi}M and redox-sensitive activation of MAP kinase; however, generated ROS from mitochondria do not contribute to Ang II–induced vasoconstriction.


Key Words: angiotensin • oxidative stress

Reactive oxygen species (ROS) are recognized as mediators of vascular signal transduction and are involved in activation of mitogen-activated protein (MAP) kinases.1 Participation of ROS in blood pressure regulation has been shown in Ang II–induced hypertension2–4 and other hypertensive models.5–7 We recently demonstrated time-dependent transition of ROS sensitivity of Ang II hypertension in rats, in which in the early phase of Ang II infusion, high blood pressure does not depend on ROS production, but thereafter it shifts to being ROS-sensitive.8 In this study, it was also found that in the acute phase of Ang II infusion, MAP kinases are stimulated through a ROS sensitive mechanism.

Recent reports have supported the hypothesis that the enzyme NAD(P)H oxidase plays a major role as the most important source of superoxide anions in vascular cells and contributes significantly to the functional and structural alterations present in hypertension or atherosclerosis.9,10 It has been further proposed that NAD(P)H oxidase is essential for production of superoxide in response to Ang II stimuli to vascular tissues. Mice deficient in the p47phox gene showed significantly lower arterial blood pressure elevation during chronic Ang II infusion.11 Moreover, endothelial cells and vascular smooth muscle cells from p47phox-deficient mice had less responsiveness to Ang II stimuli in the production of ROS.12 These findings clearly indicate that superoxide production by Ang II is regulated by the NAD(P)H oxidase-dependent mechanism. However, these results do not take into consideration mitochondria, which provide another major ROS source.

Superoxide is produced in mitochondria by complexes I and III of the electron transport chain,13 and the rate of ROS synthesis can be modulated by mitochondrial inner membrane potential ({Delta}{Psi}M).14 Mitochondrial ATP-sensitive potassium (mitoKATP) channel openers depolarize the {Delta}{Psi}M and stimulate mitochondrial ROS production.15 To examine the implication of mitochondria-derived ROS in Ang II–induced vasoconstriction and the vascular signaling pathway leading to MAP kinase activation,16 we examined the effects of 5-hydroxydecanoate (5-HD; a mitoKATP channel inhibitor) on Ang II–induced vascular MAP (extracellular signal-regulated kinase [ERK]1/2, p38, and JNK) kinase activation, superoxide generation, and the {Delta}{Psi}M as compared with diazoxide (a mitoKATP channel opener). We further examined the effects of 5-HD and 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (tempol; a membrane permeable radical scavenger)17,18 on acutely and chronically Ang II–induced hypertension in in vitro conscious rats.

Methods

Cell Culture
Rat vascular smooth muscle cells (RVSMCs) prepared by the explant method from descending thoracic aortas of 4-week-old male Sprague–Dawley rats (CLEA; Osaka, Japan) were maintained in Dulbecco modified Eagle medium (DMEM) supplemented with 10% of fetal bovine serum. RVSMCs were authenticated using immunohistochemical staining for smooth muscle {alpha}-actin (Sigma). Cultures showing 95% staining for {alpha}-actin between passages 5 and 7 were used. Before the experiments, cells were starved for 48 hours.

Measurements of Superoxide Generation of RVSMCs
Superoxide generation of RVSMCs was measured by the lucigenin chemiluminescence method and also visualized by dihydroethidium (DHE) fluorescence images. Methods are detailed in the online data supplement (available online at http://www.hypertensionaha.org).

Visualization of Changes in {Delta}{Psi}M of RVSMCs
Imaging study for {Delta}{Psi}M of RVSMC by JC-1 fluorescence is detailed in the online data supplement.

Intracellular Calcium Measurements of RVSMCs
Measurement of intracellular calcium of RVSMCs is detailed in the online data supplement.

Measurements of Phosphorylation of ERK1/2, p38, and JNK MAP Kinases
Measurements of phosphorylated levels of MAP kinases (ERK1/2, p38, and JNK) in the aorta and cultured RVSMCs were conducted as previously described.19 As controls for protein loading and transfer to membrane, the total amounts of each MAP kinase in all groups were essentially constant, as determined by direct immunoblotting (data not shown).

Animal Preparation
Ten-week-old male Sprague–Dawley rats were used. Preparation of acutely and chronically Ang II–infused rats was described previously, and all hemodynamic measurements were performed on conscious rats.4,19 In acute experiments, Ang II and diazoxide were given intravenously at a rate of 200 and 10 ng · kg–1 per minute, respectively. Tempol (Sigma) was given at a priming dose of 30 mg · kg–1, followed by infusion at a rate of 0.5 mg · kg–1 per minute. 5-HD (Sigma) was given at a dose of 10 mg · kg–1 5 minutes before the start of Ang II or diazoxide infusion. Arterial blood pressure was monitored continuously, and after 30 minutes rats were euthanized and the aorta taken, quickly frozen in liquid nitrogen (LN2), and then stored at –80°C. The effects of 5-HD and tempol on chronically Ang II–infused rats (for 14 days, 200 ng · kg–1 per minute subcutaneous; by Alzet osmotic mini-pump) were examined similarly to the acute experiments. Measurements of lipid peroxidation levels in plasma were described previously. All the surgical and experimental procedures were performed according to the guidelines for the care and use of animals as established by Kagawa University.

Statistical Analysis
Values are expressed as the mean±SEM. Statistical significance between >2 groups was tested using 2-way ANOVA followed by Newman–Keuls test or unpaired 2-tailed Student t test as appropriate, and values of P<0.05 were considered to indicate statistical significance.

Results

5-HD and Tempol Suppress MAP Kinase Activation by Ang II or Diazoxide in RVSMCs
As shown in Figure 1A,a 30-minute exposure to 100 nmol/L Ang II increased phosphorylation of ERK1/2, p38, and JNK MAP kinases in RVSMCs. Among these, Ang II–induced augmentation of phosphorylated p38 and JNK MAP kinases was suppressed by 5-HD dose dependently. However, 5-HD suppressed that of ERK1/2 with less intensity, and only the highest dose of 5-HD showed significance. Similarly to 5-HD, tempol suppressed Ang II–induced augmentation of phosphorylated p38 and JNK MAP kinases, and that of phosphorylated ERK1/2 kinase less effectively. As shown in Figure 1B,a 30-minute exposure to 200 µmol/L diazoxide augmented phosphorylation of all MAP kinases in RVSMCs, and the magnitude of induction by this dose of diazoxide was similar to 100 nmol/L Ang II. It is of note that both 5-HD and tempol suppressed all MAP kinase phosphorylation augmented by diazoxide more effectively than that of Ang II. Treatment with 5-HD or tempol at the highest dose alone had no effect on basal MAP kinase activities in RVSMCs (data not shown).



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Figure 1. The effect of 5-HD and tempol on Ang II–induced or diazoxide-induced MAP kinase activation in RVSMCs. Different doses of 5-HD or tempol were added 5 minutes before the exposure of (A) Ang II (100 nmol/L) or (B) diazoxide (200 µmol/L) to RVSMCs. Thirty minutes after treatment, cells were harvested and phosphorylated MAP kinases were analyzed. Upper, Representative blots are shown. Lower, Densitometric analysis of the phosphorylated forms of the MAP kinases. The mean value of each phosphorylated protein in untreated RVSMCs is represented as 1. Data are presented as the mean±SEM (n=4). *P<0.05 vs untreated RVSMCs. {dagger}P<0.05 vs Ang II-treated or diazoxide-treated RVSMCs.

5-HD Suppresses Stimulated Superoxide Generation by Ang II or Diazoxide in RVSMCs
To gain insights into the relation between mitochondrial ROS and vascular MAP kinase activation, we studied the effects of 5-HD on superoxide generation using RVSMCs. As shown in Figure 2A, Ang II and diazoxide increased superoxide generation of RVSMCs during the incubation time determined by the lucigenin chemiluminescence method with a lucigenin concentration of 10 µmol/L. The enhanced superoxide generation by Ang II or diazoxide was suppressed by pretreatment with 5-HD in a dose-dependent manner. DHE fluorescent images of RVSMCs also support 5-HD–sensitive superoxide generation by Ang II or diazoxide in RVSMCs (Figure 2B).



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Figure 2. The effects of 5-HD on Ang II– induced or diazoxide-induced superoxide generation in RVSMCs. A, Dose-dependent suppression by 5-HD on Ang II– induced or diazoxide-induced superoxide production in RVSMCs. Superoxide was measured by lucigenin chemiluminescence with 10 µmol/L of lucigenin. Data are represented as the mean±SEM obtained from 4 different measurements. *P<0.05 vs untreated RVSMCs. {dagger}P<0.05 vs Ang II-treated or diazoxide-treated RVSMCs. B, Fluorescent images of DHE-loaded RVSMCs were visualized by confocal microscopy. 5-HD (300 µmol/L) was given 5 minutes before exposure to Ang II (300 nmol/L) or diazoxide (200 µmol/L). Each panel shows a typical example of a DHE fluorescent image obtained 5 minutes after the stimulation. Three independent coverslips were analyzed.

Ang II and Diazoxide Depolarize {Delta}{Psi}M in RVSMCs
To address the possibility that increases of phosphorylated MAP kinase and superoxide generation by Ang II and diazoxide are related to mitochondrial functions, the changes in {Delta}{Psi}M of living RVSMCs by exposure to Ang II or diazoxide were visualized using dual simultaneous detection confocal microscopy (Figure 3). Before stimulation, a single cell included both green (JC-1 monomer) and red (J-aggregate) mitochondria, indicating that they were composed of a wide range of {Delta}{Psi}M for different mitochondria.20 The number of red mitochondria decreased after the exposure to 300 nmol/L Ang II and 200 µmol/L diazoxide. These changes were blunted by pretreatment with 5-HD, indicating that the depolarization of {Delta}{Psi}M by Ang II stimuli was mediated through the opening of mitoKATP channels.



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Figure 3. The effect of 5-HD on Ang II–induced or diazoxide-induced depolarization of {Delta}{Psi}M in RVSMCs. A, Fluorescent images were visualized with confocal microscopy using an argon laser to excite JC-1 at 488 nm. RVSMCs plated on coverslips were incubated with 2 µg/mL JC-1 for 2 minutes. JC-1 enters the mitochondria in proportion to the membrane potential and forms J-aggregates at the higher intramitochondrial concentrations induced by higher {Delta}{Psi}M values (>150 mV). 5-HD (300 µmol/L) was given 5 minutes before exposure to Ang II (300 nmol/L) or diazoxide (200 µmol/L). Each panel shows typical examples of JC-1 monomer, J-aggregate, and combined images. B, Time course changes of 590:527 nm emission ratio (ratio of J-aggregate to JC-1 monomer) after Ang II or diazoxide exposure to RVSMCs. Twenty regions were selected within a single cell for analysis. The value in preincubation is expressed as 100%. Data are presented as the mean±SEM obtained from 10 to 12 cells (3 to 4 different experiments).

Effects of 5-HD on Intracellular Calcium Mobilization by Ang II in RVSMCs
The interaction between mitochondrial and calcium mobilization is an important issue under some pathological circumstance, such as hypoxia.21 We examined the effect of 5-HD on Ang II–induced calcium mobilization in RVSMCs (Figure 4). Cultured RVSMCs revealed 75±8 nmol/L as a baseline of [Ca2+]i; 100 nmol/L Ang II induced a rapid increase of [Ca2+]i to 450±54 nmol/L, which was followed by a slow return toward baseline. Pretreatment with 5-HD (30 and 300 nmol/L), added 5 minutes before Ang II stimuli, had no significant effect on baseline or Ang II–induced rapid increase of [Ca2+]i.



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Figure 4. The effect of 5-HD on Ang II–induced intracellular calcium mobilization in RVSMCs. RVSMCs were incubated in normal Hanks solution (1 mmol/L Ca2+). Different doses of 5-HD were given 5 minutes before exposure to Ang II (100 nmol/L). Closed and open columns indicate before and after Ang II exposure, respectively. Upper, Representative traces of experiments are shown. Data are presented as the mean±SEM obtained from 4 different experiments.

5-HD and Tempol Suppress Vascular MAP Kinase Activation by Ang II and Diazoxide in Conscious Rats
Using catheterized conscious rats, the effects of 5-HD and tempol on aortic MAP kinase activation by acutely administrated Ang II or diazoxide were examined. As shown in the Table, arterial blood pressure was increased by 50 mm Hg soon after intravenous infusion of Ang II (200 ng · kg–1 per minute) and was decreased by 15 mm Hg during diazoxide infusion (10 ng · kg–1 per minute). Pretreatments of 5-HD (10 mg · kg–1) and tempol (30 mg · kg–1) did not modify any hemodynamic changes elicited by Ang II or diazoxide.


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TABLE. Effects of Ang II and Diazoxide on Mean Blood Pressure Under Tempol or 5-HD Treatment

A 30-minute infusion of Ang II or diazoxide increased phosphorylation of aortic ERK1/2, p38, and JNK MAP kinases. As shown in Figure 5, augmentation of p38 and JNK MAP kinase phosphorylation by Ang II in the aorta was significantly suppressed by 5-HD, whereas that of ERK1/2 was not affected by 5-HD treatment. The augmented phosphorylation of these MAP kinases by diazoxide was completely normalized by treatment with 5-HD. Tempol effectively suppressed Ang II–induced and diazoxide-induced aortic MAP kinase activation.



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Figure 5. The effect of 5-HD and tempol on Ang II–induced or diazoxide-induced MAP kinase activation in the aorta of conscious rats. Aortas were taken 30 minutes after the start of infusion of Ang II (200 ng · kg–1 per minute) or diazoxide (10 ng · kg–1 per minute). 5-HD (10 mg · kg–1 intravenous) or tempol (30 mg · kg–1 intravenous) was administered 5 minutes before Ang II or diazoxide infusion. Top, Representative blots are shown. Bottom, Densitometric analysis of the phosphorylated forms of the MAP kinases. The mean value of each phosphorylated protein in control rats is represented as 1. Data are presented as the mean±SEM (n=4 to {approx}6). *P<0.05 vs control rats. {dagger}P<0.05 vs Ang II–infused or diazoxide II–infused rats.

5-HD Does Not Affect Blood Pressure of Chronically Ang II-Induced Hypertension
Previously, we demonstrated that hypertension of chronically Ang II–infused hypertensive rats is ROS dependent and that it can be normalized by tempol administration.8 To assess whether mitochondrial ROS is involved in the maintenance of chronic phase of Ang II hypertension, the effects of 5-HD were tested in chronically Ang II–infused hypertensive rats in which high arterial blood pressure (153±5 mm Hg) and elevated levels of plasma lipid peroxidation developed. As shown in Figure 6, 5-HD had no significant effects on arterial blood pressure and elevated levels of plasma lipid peroxidation in chronically Ang II–infused rats, whereas tempol successfully normalized blood pressure and plasma lipid peroxidation in this model. We also tested the effects of 4,5-dihydroxy-1,3-benzenedisulfonic acid (tiron), a membrane-permeable radical scavenger. The results showed a similar pattern to tempol treatment, as is shown in the online data supplement.



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Figure 6. The effect of 5-HD and tempol on blood pressure and plasma lipid peroxidation in acutely (open columns) and chronically (closed columns) Ang II–infused rats. 5-HD (10 mg · kg–1) or tempol (30 mg · kg–1) was administered intravenously, and blood pressure was continuously measured. A, Mean blood pressure at 30 minutes after the drug administration. B, The levels of plasma lipid peroxidation. The blood was collected 30 minutes after the drug administration for analysis of plasma lipid peroxidation. Data are presented as the mean±SEM (n=4 to {approx}6). *P<0.05 vs control rats or sham-operated rats in acute and chronic experiments, respectively. {dagger}P<0.05 vs acutely Ang II–infused rats or chronic Ang II-infused rats.

Discussion

The significant finding of the present study is that 5-HD, a specific inhibitor of mitoKATP channels, suppressed Ang II–induced redox-sensitive vascular MAP kinase activation, in particular, p38 and JNK MAP kinases in rat aorta in vivo and in cultured RVSMCs in vitro. These observations resemble the results of diazoxide treatment under both in vivo and in vitro conditions, indicating that acutely administered Ang II may activate mitoKATP channels and contribute to superoxide production in the vascular tissue. In support of this finding, we clearly demonstrated that Ang II reduced the {Delta}{Psi}M of RVSMCs through the opening of mitoKATP channels in a similar manner to diazoxide.

We compared 2 stimulants, Ang II and diazoxide, because the latter is a mitochondrial-related compound and has been implicated in redox-sensitive phosphorylation and activation of ERK.22 Although Ang II and diazoxide have opposite actions for vascular tone, ie, as a vasoconstrictor and a vasodilator, both can activate aortic MAP kinases. The action of diazoxide is nonspecific to mitoKATP channels, and it also activates the sarcolemmal KATP channel. In our in vivo experiments, diazoxide decreased arterial blood pressure, which was caused by the opening of sarcolemmal KATP channels. However, the increases of MAP kinase activation by diazoxide may be caused by its action on mitoKATP but not on sarcolemmal KATP channels, because the vasodilator effect of diazoxide was not affected by pretreatment with 5-HD, a specific inhibitor of mitoKATP channels. The opening of mitoKATP channels by diazoxide increases superoxide generation in the heart.23 In this study, we confirmed that diazoxide did increase superoxide generation in RVSMCs, and that 5-HD suppressed the enhancing signals of superoxide by diazoxide, determined by lucigenin chemiluminescence and DHE fluorescence. In a related study, we found that 5-HD did not possess any radical scavenging activity (not shown), nor did it affect on activation of vascular NAD(P)H oxidase, a well-known target of Ang II (see the online data supplement). Thus, it seems likely that vascular mitoKATP channels are responsible for the production of superoxide by diazoxide and Ang II in vasculature, at least during the early phases of their actions. There have been few reports concerning the effects of Ang II on mitochondrial function; however, in this study we found a decrease in {Delta}{Psi}M and augmented superoxide generation in response to Ang II stimuli of RVSMCs in a manner similar to that of diazoxide, supporting the hypothesis that the intracellular signaling of Ang II passes through mitochondrial functions, reaching redox-sensitive MAP kinase activation.1

In regard to the sensitivity of MAP kinase activation to mitochondrial ROS, a difference was seen in the case of ERK1/2 as activated by either Ang II or diazoxide. Previously, we have shown that the increase of phosphorylated MAP kinases in rat aorta by Ang II was eliminated by tempol.19 In this study, diazoxide-induced activation of ERK, p38, and JNK MAP kinases was also tempol-quenchable in the in vivo experiment, indicating a critical role of ROS for the activation of these 3 MAP kinases in vasculature. Furthermore, we found that 5-HD suppressed the increase of all the phosphorylated MAP kinases by diazoxide, and those of p38 and JNK MAP kinases by Ang II, but not that of ERK1/2 by Ang II. Although we used a high dose of tempol to suppress Ang II–induced ERK1/2 activation in this study, the resistance of ERK1/2 to tempol treatment was also observed in the in vivo study.19 Taken together, these results suggest that mitochondrial-derived ROS could be responsible for the Ang II–induced stimuli of all MAP kinases, including ERK1/2. However, another pathway independent of mitochondrial ROS might be involved in the redox-sensitive activation of vascular ERK1/2.

Inappropriate production of ROS in vasculature contributes to the maintenance of hypertension. To assess the possibility that Ang II–induced enhancement of mitochondrial ROS generation contributes to Ang II–mediated vasoconstriction, we examined the effects of 5-HD on blood pressure of acutely and chronically Ang II–infused rats. We previously demonstrated that tempol normalizes blood pressure of chronically Ang II–infused hypertensive rats, but this is not the case for acute vasoconstrictor effect of Ang II.8 However, the data from this study clearly demonstrated that 5-HD does not affect on vasoconstriction in either acutely or chronically administered Ang II, indicating that mitochondrial ROS do not participate in the vasoconstrictor mechanisms of Ang II–induced hypertension. Because a rapid increase of intracellular calcium is a determinant of vasoconstrictor effects of Ang II,24 we also tested the effects of 5-HD on intracellular calcium induction of RVSMCs by Ang II. To support our in vivo observation, we confirmed that the calcium mobilization in RVSMCs by Ang II was not affected by mitoKATP channel inhibition. Torrecillas et al suggested the contribution of H2O2 in vasoconstrictor mechanisms of Ang II by showing that catalase prevented Ang II–induced myosin light chain phosphorylation and intracellular calcium mobilization of RVSMCs, and also inhibited Ang II–induced constriction of rat aortic rings.25 Waypa et al also have shown mitochondria-mediated calcium increases in hypoxia in pulmonary arterial myocytes through ROS generation from the electron transport chain.21 However, our in vivo and in vitro data arising from this study indicated that mitochondria-derived ROS could not influence contractility of vasculature during the chronic phase of Ang II–induced hypertension.

In conclusion, we studied the involvement of mitochondria-derived ROS in intracellular signal transduction and vasoconstriction by Ang II stimuli in vivo and in vitro. Our results reveal that Ang II stimulates mitochondrial ROS generation through the opening of mitoKATP channels in the vasculature, as does diazoxide, leading to the reduction of {Delta}{Psi}M and redox-sensitive activation of MAP kinases, especially p38 and JNK, and that ROS generated from mitochondria do not contribute to Ang II–induced vasoconstriction.

Perspectives
The findings of the current study indicate an important association between Ang II and mitochondrial function in ROS generation of vasculature. Inhibition of the renin-angiotensin system attenuated age-associated changes in mitochondrial function.26 Mitochondria are a major subcellular source of ROS, which would promote oxidative damage to cell structures and functions.27 In this respect, studies using materials such as mitochondrial-deficient ({rho}°) cells or cells separated from aged population should provide further understanding of Ang II physiology and assessments of therapeutic intervention with renin-angiotensin system inhibitors. In this study, we have not examined inhibitors of mitochondrial respiratory chains to identify the site of superoxide generation. It has been shown that rotenone, an inhibitor of complex I, had no effect on Ang II–induced p38 and JNK activation in human vascular smooth muscle cells.28 Further studies will be necessary to clarify the site of superoxide generation for redox-sensitive MAP kinase activation in vasculature.

Acknowledgments

This work was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science, and Culture, Japan.

Received October 13, 2004; first decision October 31, 2004; accepted January 14, 2005.

References

  1. Kyriakis JM, Avruch J. Mammalian mitogen-activated protein kinase signal transduction pathways activated by stress and inflammation. Physiol Rev. 2001; 81: 807–869.[Abstract/Free Full Text]
  2. Wilson SK. Role of oxygen-derived free radicals in acute angiotensin II–induced hypertensive vascular disease in the rat. Circ Res. 1990; 66: 722–734.[Abstract/Free Full Text]
  3. Romero JC, Reckelhoff JF. Role of angiotensin and oxidative stress in essential hypertension. Hypertension. 1999; 34: 943–949.[Abstract/Free Full Text]
  4. Nishiyama A, Fukui T, Fujisawa Y, Rahman M, Tian RX, Kimura S, Abe Y. Systemic and regional hemodynamic responses to tempol in angiotensin II-infused hypertensive rats. Hypertension. 2001; 37: 77–83.[Abstract/Free Full Text]
  5. Schnackenberg CG, Welch WJ, Wilcox CS. Normalization of blood pressure and renal vascular resistance in SHR with a membrane-permeable superoxide dismutase mimetic: role of nitric oxide. Hypertension. 1998; 32: 59–64.[Abstract/Free Full Text]
  6. Zalba G, Beaumont FJ, S. Jose G, Fortuno A, Fortuno MA, Etayo JC, Diez J, Vascular NADH/NADPH oxidase is involved in enhanced superide production in spontaneously hypertensive rats. Hypertension. 2000; 35: 1055–1061.[Abstract/Free Full Text]
  7. Wu R, Millette E, Wu L, de Champlain J. Enhanced superoxide anion formation in vascular tissues from spontaneously hypertensive and desoxycorticosterone acetate-salt hypertensive rats. J Hypertens. 2001; 19: 741–748.[CrossRef][Medline] [Order article via Infotrieve]
  8. Kimura S, Zhang G-X, Nagai Y, Miyata K, Nishiyama A, Shokoji T, Li Y, Fan Y-Y, Rahman M, Fujisawa Y, Miyatake A, Abe Y. Time dependent transition of tempol sensitive reduction of blood pressure in angiotensin II induced hypertension. J Hypertens. 2004; 22: 2161–2168.[CrossRef][Medline] [Order article via Infotrieve]
  9. Griendling KK, Sorescu D, Ushio-Fukai M. NAD(P)H oxidase: role in cardiovascular biology and disease. Circ Res. 2000; 86: 494–501.[Abstract/Free Full Text]
  10. Zalba G, Jose GS, Moreno MU, Fortuno MA, Ana Fortuno A, Beaumont FJ, Diez J. Oxidative stress in arterial hypertension role of NAD(P)H oxidase. Hypertension. 2000; 38: 1395–1399.
  11. Landmesser U, Cai H, Dikalov S, McCann L, Hwang J, Jo H, Holland SM, Harrison DG. Role of p47phox in vascular oxidative stress and hypertension caused by angiotensin II. Hypertension. 2002; 40: 511–515.[Abstract/Free Full Text]
  12. Lavigne MC, Malech HL, Holland SM, Leto TL. Genetic demonstration of p47phox-dependent superoxide anion production in murine vascular smooth muscle cells. Circulation. 2001; 104: 79–84.[Abstract/Free Full Text]
  13. Li Y, Zhu H, Trush MA. Detection of mitochondria-derived reactive oxygen species production by the chemilumigenic probes lucigenin and luminol. Biochim Biophys Acta. 1999; 1428: 1–12.[Medline] [Order article via Infotrieve]
  14. Holmuhamedov EL, Jovanovic S, Dzeja PP, Jovanovic A, Terzic A. Mitochondrial ATP-sensitive K+ channels modulate cardiac mitochondrial function. Am J Physiol Heart Circ Physiol. 1998; 275: H1567–H1576.[Abstract/Free Full Text]
  15. Garlid KD, Dos Santos P, Xie ZJ, Costa AD, Paucek P. Mitochondrial potassium transport: the role of the mitochondrial ATP-sensitive K(+) channel in cardiac function and cardioprotection. Biochim Biophys Acta. 2003; 1606: 1–21.[Medline] [Order article via Infotrieve]
  16. Nishida E, Gotoh Y. The MAP kinase cascade is essential for diverse signal transduction pathways. Trends Biochem Sci. 1993; 18: 128–131.[CrossRef][Medline] [Order article via Infotrieve]
  17. Bonini MG, Mason RP, Augusto O. The Mechanism by which 4-hydroxy-2,2,6,6-tetramethylpiperidene-1-oxyl (tempol) diverts peroxynitrite decomposition from nitrating to nitrosating species. Chem Res Toxicol. 2002; 15: 506–511.[CrossRef][Medline] [Order article via Infotrieve]
  18. Samuni A, Goldstein S, Russo A, Mitchell JB, Krishna MC, Neta P. Kinetics and mechanism of hydroxyl radical and OH-adduct radical reactions with nitroxides and with their hydroxylamines. J Am Chem Soc. 2002; 124: 8719–8724.[CrossRef][Medline] [Order article via Infotrieve]
  19. Zhang G-X, Kimura S, Nishiyama A, Shokoji T, Rahman M, Abe Y. ROS during the acute phase of Ang II hypertension participates in cardiovascular MAPK activation but not vasoconstriction. Hypertension. 2004; 43: 117–124.[Abstract/Free Full Text]
  20. Wadia JS, Chalmes-edman RME, Ju WJH, Carlile GW, Phillips JL, Fraser AD, Tatton WG. Mitochondrial membrane potential and nuclear changes in apoptosis caused by serum and nerve growth factor withdrawal: time course and modification by (-)-depenyl. J Neurosci. 1998; 18: 932–947.[Abstract/Free Full Text]
  21. Waypa GB, Marks JD, Mack MM, Boriboun C, Mungai PT, Schumacker PT. Mitochondrial reactive oxygen species trigger calcium increases during hypoxia in pulmonary arterial myocytes. Circ Res. 2002; 91: 719–726.[Abstract/Free Full Text]
  22. Samavati L, Monick1 MM, Sanlioglu1 S, Buettner GR, Oberley LW, Hunninghake GW. Mitochondrial KATP channel openers activate the ERK kinase by an oxidant-dependent mechanism. Am J Physiol Cell Physiol. 2002; 283: C273–C281.[Abstract/Free Full Text]
  23. Pain T, Yang X-M, Critz SD, Yue Y, Nakano A, Guang S. Liu, Heusch G, Cohen MV, Downey JM. Opening of mitochondrial KATP channels triggers the preconditioned state by generating free radicals. Circ Res. 2000; 87: 460–466.[Abstract/Free Full Text]
  24. Rasmussen H, Barrett PQ. Calcium messenger system: an integrated view. Physiol Rev. 1984; 64: 938–984.[Free Full Text]
  25. Torrecillas G, Boyano-Adánez MdC, Medina J, Parra T, Griera M, López-Ongil S, Arilla E, Rodríguez-Puyol M, Rodríguez-Puyol D. The role of hydrogen peroxide in the contractile response to angiotensin II. Mol Pharmacol. 2001; 59: 104–112.[Abstract/Free Full Text]
  26. De Cavanagh EMV, Piotrkowski B, Basso N, Stella I, Inserra F, Ferder L, Fraga CG. Enalapril and losartan attenuate mitochondrial dysfunction in aged rats. FASEB J. 2003; 17: 1096–1098.[Abstract/Free Full Text]
  27. Chandel NS, Maltepe E, Goldwasser E, Mathies CE, Simon MC, Schumacker PT. Mitochondrial reactive oxygen species trigger hypoxia-induced transcription. Proc Natl Acad Sci U S A. 1998; 95: 11715–11720.[Abstract/Free Full Text]
  28. Touyz RM, Yao G, Viel E, Amiri F, Schiffrin EL. Angiotensin II and endothelin-1 regulate MAP kinases through different redox-dependent mechanisms in human vascular smooth muscle cells. J Hypertens. 2004; 22: 1141–1149.[CrossRef][Medline] [Order article via Infotrieve]



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