Published online before print January 19, 2004, doi: 10.1161/01.HYP.0000114602.82140.a4
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Hypertension. 2004;43:156.)
© 2004 American Heart Association, Inc.
Rapid Communication |
Rho/Rho-Kinase Pathway in the Brainstem Contributes to Hypertension Caused by Chronic Nitric Oxide Synthase Inhibition
From Department of Cardiovascular Medicine (K.I., Y.H., T.K., Y.K., H.S., A.T.), Kyushu University Graduate School of Medical Sciences, Fukuoka, and the Department of Cell Pharmacology (K.K.), Nagoya University Graduate School of Medicine, Nagoya, Japan.
Correspondence to Dr Yoshitaka Hirooka, Fellow of the Council for HBPR, Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. E-mail hyoshi{at}cardiol.med.kyushu-u.ac.jp
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Central nervous system mechanisms are involved in hypertension caused by chronic inhibition of nitric oxide (NO) synthesis. Chronic inhibition of NO synthesis might also activate the Rho/Rho-kinase pathway in the vasculature. We recently demonstrated that activation of the Rho/Rho-kinase pathway in the nucleus tractus solitarii (NTS) contributes to hypertensive mechanisms in spontaneously hypertensive rats. The aim of the present study was to determine whether activation of this pathway also contributes to neurogenic hypertensive mechanisms caused by chronic NO synthesis inhibition. The NO synthase inhibitor N
-nitro-L-arginine methyl ester (L-NAME) was administered to Wistar-Kyoto rats in their drinking water (1 mg/mL) for 2 weeks. Bilateral microinjection of Y-27632, a specific Rho-kinase inhibitor, into the NTS elicited decreases in arterial pressure, heart rate, and renal sympathetic nerve activity in control rats and L-NAME–treated rats. The magnitude of the decrease, however, was significantly greater in L-NAME–treated than in control rats. In another group of rats, the specific Rho-kinase inhibitor, Y-27632, was administered intracisternally for 2 weeks with a mini-osmotic pump from the beginning of treatment with L-NAME. Y-27632 co-treatment significantly attenuated the increase in arterial pressure. Furthermore, the expression level of membranous RhoA and phosphorylation of the target proteins of Rho-kinase, the ERM (ezrin, radixin, moesin) family members, was significantly greater in L-NAME–treated rats than in control rats. These results indicate that activation of the Rho/Rho-kinase pathway in the NTS contributes to neurogenic hypertension caused by chronic NO synthase inhibition.
Key Words: nitric oxide • blood pressure • sympathetic nervous system • hypertension • brain
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Inhibition of nitric oxide (NO) synthesis produces hypertension in many species.1,2 Although this hypertension was initially attributed to the inhibition of endothelial NO synthesis, numerous studies suggest that inhibition of neuronal NO also plays an important role in blood pressure regulation.3–7 A previous study demonstrated that increased sympathetic nerve activity plays a role in hypertension caused by chronic NO synthesis inhibition, and activation of the renin–angiotensin system in the nucleus tractus solitarii (NTS) of the brainstem via angiotensin II type 1 receptors is involved.8 Chronic inhibition of NO synthesis might activate the Rho/Rho-kinase pathway in the cardiac tissues or vasculature.9,10 The Rho/Rho-kinase pathway regulates the phosphorylation state of myosin light chains and contributes to smooth muscle contraction.11 Y-27632, a specific Rho-kinase inhibitor, dramatically reduces blood pressure in rat models of hypertension.12 In addition, Rho-kinase activity is augmented in hypertensive blood vessels13 and inhibition of Rho-kinase induces preferential forearm vasodilatation in hypertensive patients, but not in normal subjects.14 Thus, the Rho/Rho-kinase pathway plays an important role in peripheral mechanisms of hypertension.11–14
RhoA and Rho-kinase are also distributed in the central nervous system.15,16 Activation of the Rho/Rho-kinase pathway in the NTS contributes to maintain basal blood pressure via the sympathetic nervous system, and this pathway might contribute to hypertensive mechanisms in spontaneously hypertensive rats.17 It is unknown, however, whether activation of the Rho/Rho-kinase pathway also contributes to neurogenic hypertensive mechanisms caused by chronic NO synthesis inhibition. The aim of this study was to elucidate the role of the Rho/Rho-kinase pathway in the brainstem in neurogenic hypertension caused by chronic NO synthesis inhibition.
For this purpose, we microinjected Y-27632 into the NTS of Wistar-Kyoto (WKY) rats treated with the NO synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME) and monitored systolic blood pressure (SBP), heart rate (HR), and renal sympathetic nerve activity (RSNA) under anesthesia. Furthermore, Y-27632 or vehicle was continuously infused intracisternally for 2 weeks with a mini-osmotic pump in WKY rats from the beginning of treatment with L-NAME, and SBP was measured. Finally, we compared RhoA and Rho-kinase activity in the NTS between control rats and L-NAME–treated rats.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
This study was reviewed and approved by the Committee on Ethics of Animal Experiments, Kyushu University Graduate School of Medical Sciences and was conducted according to the guidelines for animal experiments of Kyushu University.
Microinjection Experiments With Rho-Kinase Inhibitors
Male WKY rats (280 to 340 g, 16 to 20 weeks old) obtained from an established colony at the Animal Research Institute of Kyushu University Faculty of Medicine13 were used. The rats were randomly divided into two groups. The first group (control rats) received nontreated drinking water for 2 weeks. The second group received L-NAME (Sigma Chemical Co.) in the drinking water (1 mg/mL) for 2 weeks (L-NAME-treated rats).8 The animals were anesthetized with sodium pentobarbital (50 mg/kg intraperitoneally), and a cannula (PE 50) was inserted into the right femoral artery for measurement of SBP and HR and into the femoral vein for infusion of pentobarbital (10 to 15 mg/kg per hour).18 The anesthetized animals were artificially ventilated and placed in a stereotaxic frame. The dorsal surface of the medulla was exposed, the microinjection sites were defined according to an atlas of the rat brain,19 and the depressor response was evoked by L-glutamate (40 pmol) microinjection. We then microinjected Y-2763212 (0.4, 4, 40 pmol/sitex2 sites/side, bilaterally; injection volume: 80 nL/site).17 In addition, we measured RSNA in another experiment. The left renal nerve was exposed with a left retroperitoneal flank incision. A pair of stainless-steel bipolar electrodes was placed beneath the renal nerve to record multifiber RSNA, as described previously.8 Background noise levels were determined by crushing the nerve at the end of the experiment. The background noise levels were subtracted during a later analysis of RSNA. Y-27632 was microinjected bilaterally into the NTS at only one site per side (40 pmol/site; injection volume: 80 nL/site) in this experiment because of the difficulty in stably recording RSNA without noise.
Repetitive Injection of Rho-Kinase Inhibitor
We performed repetitive injections of Y-27632 into the NTS of control rats (40 pmol/sitex2 sites/side, bilaterally; injection volume: 80 nL/site) to determine whether microinjection of Y-27632 elicited reproducible responses.
Microinjection of Hydralazine Into the NTS
We microinjected another vasodilator, hydralazine (50 pmol/site or 500 pmol/sitex1 site/side, bilaterally; injection volume: 50 nL/site), into the NTS of L-NAME–treated rats as a control for the vasodilator effect of Y-2763220 to determine if the effects of microinjection of Y-27632 into the NTS were caused by an increase in local blood flow. Experimental procedures were the same as described.
Intravenous Infusion of Rho-Kinase Inhibitor
Intravenous Y-27632 (200 pmol or 1000 pmol/0.2 mL injection over a 50-second period with an infusion pump) was infused into L-NAME–treated rats to determine if microinjection or intracisternal infusion of Y-27632 acts on the vasculature.
Continuous Intracisternal Infusion Experiments With Rho-Kinase Inhibitor
The rats were randomly divided into four groups. The first group (L-NAME-VEH) received continuous infusion of vehicle (a-CSF, 0.25 µL/h). The second group (L-NAME-Y-27632) received continuous infusion of Y-27632 (5 mmol/L, 0.25 µL/h) intracisternally for 2 weeks with a mini-osmotic pump (Alzet model 1002; DURECT Corporation) from the beginning of treatment with L-NAME (1 mg/mL). The third group (control-VEH) received continuous infusion of vehicle (a-CSF, 0.25 µL/h), and the fourth group (control-Y-27632) received continuous infusion of Y-27632 (5 mmol/L, 0.25 µL/h) intracisternally for 2 weeks with a mini-osmotic pump while receiving nontreated drinking water. The rats were anesthetized with sodium pentobarbital (50 mg/kg, intraperitoneally). The mini-osmotic pump, filled with vehicle or Y-27632, was implanted subcutaneously in the back and connected to a polyethylene tube (PE 10). A small hole was then made in the atlantooccipital membrane that covers the dorsal surface of the medulla, and the tip of the tube was placed intracisternally and fixed in place with tissue adhesive. After full recovery from anesthesia, the rats were free to move about in their cages. The infusion was calculated to end after 14 days. SBP was measured using the tail-cuff method for 21 days.
Western Blot Analysis for Phosphorylation of the ERM Family
The rats were randomly divided into two groups. The first group (control rats) received nontreated drinking water for 2 weeks. The second group (L-NAME–treated rats) received L-NAME in drinking water (1 mg/mL) for 2 weeks. We then performed Western blot analysis to compare the RhoA or Rho-kinase activity in the NTS of control rats with that in L-NAME–treated rats. The animals were killed with an overdose of sodium pentobarbital, and the NTS tissue was obtained by punching out the NTS from coronal slices (2-mm thickness) of the brainstem with an 18-gauge needle (inside diameter: 950 µm). The tissues were homogenized in a lysing buffer containing 40 mmol/L HEPES, 1% Triton X-100, 10% glycerol, and 1 mmol/L Na3VO4 and 1 mmol/L PMSF. The tissue lysate was centrifuged and the supernatant collected. The protein concentration was determined using a BCA protein assay kit (Pierce Chemical). An aliquot of 15 µg of protein from each sample was separated on 10% SDS-polyacrylamide gel. Proteins were subsequently transferred onto polyvinylidene difluoride membranes (Immobilon-P membrane; Millipore). Membranes were incubated with rabbit anti-phosphorylated ERM family members moesin (Thr558), ezrin (Thr567), and radixin (Thr564), which are the target proteins of Rho-kinase.21 Membranes were then incubated with a horseradish peroxidase-conjugated horse anti-rabbit IgG antibody (1:10000). Immunoreactivity was detected by enhanced chemiluminescence autoradiography (ECL Western blotting detection kit; Amersham Pharmacia Biotechnology), and the film was analyzed with National Institutes of Health image software. Membrane and cytosolic proteins were isolated as described previously.22 Western blot analysis was performed as mentioned using rabbit IgG polyclonal antibody to RhoA (1:1000; Santa Cruz Biotechnology) and horseradish peroxidase-conjugated goat anti-rabbit IgG antibody (1:10000).
Confirmation of Inhibitory Effects of Y-27632 on Rho-Kinase Activity
Ten days after the beginning of treatment with L-NAME and intracisternal infusion of Y-27632, the animals were killed with an overdose of sodium pentobarbital. The tissues of the brainstem were obtained and Western blot analysis for phosphorylation of the ERM family members was performed as described, except that 30 µg of protein was applied to the gel.
Statistical Analysis
All values are expressed as mean±SEM. ANOVA was used to compare SBP between rats co-treated with Y-27632 and vehicle. Any two mean values were compared by application of the Bonferroni procedure. An unpaired t test was used to compare the baseline values and the effects of each intervention between the groups. Differences were considered to be statistically significant when P<0.05.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Effect of Microinjection of Y-27632 Into the NTS
Baseline SBP (175±11 versus 120±11 mm Hg; P<0.01; n=9 for each) was significantly higher in L-NAME–treated rats than in control rats, and HR (278±8 versus 281±3 bpm; n=9 for each) did not differ between the two groups. Baseline RSNA did not differ between the two groups (110±15 versus 86±12 spikes/sec; n=5 for each). Microinjection of Y-27632 into the NTS elicited a dose-dependent decrease in SBP and HR in both groups (Figure 1A). The magnitude of the decrease in SBP and HR was significantly greater in L-NAME–treated rats than in control rats (Figure 1B). Furthermore, in other experiments in which RSNA was recorded, microinjection of Y-27632 into the NTS elicited decreases in SBP, HR, and RSNA in both groups (Figure 2A). The magnitude of the decreases in these variables was also significantly greater in L-NAME–treated rats than in control rats (Figure 2B). Moreover, the percent reduction of SBP (19±3 versus 10±3%; P<0.05; n=5 for each) or HR (15±2 versus 6±2%; P<0.01; n=5 for each) was significantly greater in L-NAME–treated rats than in control rats.
|
|
Effects of Repetitive Injection of Y-27632 Into the NTS
A similar depressor response was observed (40 pmol/sitex2 sites/side, bilaterally; injection volume: 80 nL/site) if there was a 20-minute interval between injections (
SBP: -32±3 versus -30±2 mm Hg; HR: -58±6 versus -56±7 bpm; n=3 for each), although the magnitude of the decrease in SBP was smaller at 10 minutes after the injection than that of the first injection (SBP: -12±4 versus -29±3 mm Hg; HR: -20±3 versus -52±5 bpm; P<0.01; n=3 for each).
Effect of Microinjection of Hydralazine Into the NTS of L-NAME–Treated Rats
There was no significant change in SBP or HR after microinjection of hydralazine (50 pmol/sitex1 site/side; SBP: 179±5 versus 177±4 mm Hg; HR: 280±3 versus 284±2 bpm; n=3 for each; or 500 pmol/sitex1 site/side; SBP: 180±14 versus 177±11 mm Hg; HR: 288±9 versus 284±6 bpm; n=3 for each).
Intravenous Infusion of Rho-Kinase Inhibitor to L-NAME-Treated Rats
Intravenous infusion of Y-27632 (200 pmol or 1000 pmol/0.2 mL injection over 50-second period with infusion pump) elicited no significant changes in SBP or HR (200 pmol; SBP: 175±3 versus 176±5 mm Hg; HR: 278±5 versus 279±5 bpm; n=3 for each; or 1000 pmol; SBP: 177±12 versus 176±16 mm Hg; HR: 276±11 versus 274±6 bpm; n=3 for each).
Blood Pressure Changes After the Beginning of L-NAME Treatment
Figure 3A and 3B show the time course of SBP after treatment with L-NAME and intracisternal infusion of Y-27632. SBP was increased in the L-NAME-VEH and L-NAME-Y-27632 groups. Y-27632, however, significantly attenuated the increase in SBP. After discontinuing treatment with Y-27632, SBP increased to a level similar to that in L-NAME-VEH rats (Figure 3A). There was a small transient decrease in SBP from day 7 to day 11 compared with before treatment (day 0) in the control-Y-27632 group.
|
Inhibitory Effects of Y27632 on Rho-Kinase Activity
To confirm the specific inhibitory effects of Y-27632 on Rho-kinase activity, we examined phosphorylation of the ERM family members, the target proteins of Rho-kinase,21 in the brainstem of rats treated with Y-27632. The expression level of phosphorylation of the ERM family members was significantly reduced in the L-NAME- -Y-27632 rats than in the L-NAME-VEH rats (Figure 3C). Furthermore, the extent of phosphorylation of the ERM family members significantly increased in L-NAME–treated rats compared with control rats (Figure 3C). In control rats, the expression level of phosphorylation of the ERM family members was slightly reduced in the control-Y-27632 rats compared with the control-VEH rats (Figure 3D).
RhoA and Rho-Kinase Activity in the NTS
The expression level of RhoA in membranes, which represents RhoA activity,22 was greater in L-NAME–treated rats than in control rats (Figure 4A). Furthermore, the extent of phosphorylation of the ERM family members, which represents Rho-kinase activity,21 was greater in L-NAME–treated rats than in control rats (Figure 4B).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
The present study provides the first direct evidence that activation of the Rho/Rho-kinase pathway in the brainstem plays an important role in hypertension caused by chronic NO synthase inhibition. We demonstrated that: (1) microinjection of Rho-kinase inhibitor into the NTS significantly decreased SBP, HR, and RSNA in the L-NAME–treated rats than in control rats; (2) chronic intracisternal infusion of Rho-kinase inhibitor suppressed hypertension caused by chronic NO synthase inhibition; and (3) membrane translocation of RhoA and phosphorylation of the ERM family members were increased in the NTS of L-NAME–treated rats.
The results of the present study demonstrate that the membrane expression level of RhoA in the NTS was significantly greater in L-NAME-treated rats than in control rats, and microinjection of Y-27632 elicited a dose-dependent decrease of SBP and HR in L-NAME–treated rats and control rats. The magnitude of the decrease in SBP, HR, and RSNA was greater in L-NAME–treated rats than in control rats. In the microinjection study, we reproduced the responses to injections of Y-27632 into the bilateral NTS by repeating the injection after 20 minutes, although it was expected that enzymatic inhibition of Rho-kinase evoked by Y-27632 could be effective for a much longer period.12,13 Thus, we cannot exclude the possibility that Y-27632, a pyridine derivative, might elicit an action like that of an agonist, or short-lived antagonist, at the specific receptors in the NTS. Furthermore, the extent of the phosphorylation of ERM family members in the NTS was greater in L-NAME–treated rats than in control rats. Previous studies demonstrated that the Rho/Rho-kinase pathway is activated in blood vessels of L-NAME–treated rats.10 Thus, in the peripheral circulation, Rho-kinase is apparently involved in the mechanisms of L-NAME–induced hypertension. There is evidence that L-NAME crosses the blood–brain barrier when administered orally23 and the sympathetic nervous system is involved primarily in the maintenance, rather than initiation, of L-NAME–induced hypertension.24,25 Furthermore, activation of the Rho/Rho-kinase pathway in the NTS plays an important role in the maintenance of the basal arterial blood pressure via the sympathetic nervous system.17 In addition, activation of the pathway might be involved in the central nervous system mechanisms of hypertension in spontaneously hypertensive rats.17 Our results indicate that the Rho/Rho-kinase pathway is activated in the NTS of L-NAME–treated rats and contributes, at least in part, to the central nervous system mechanisms of hypertension caused by chronic NO synthase inhibition.
The Rho/Rho-kinase pathway plays an important role in vascular tone regulation. Because the NTS is rich in blood vessels, it is possible that inhibition of Rho-kinase activity in the NTS changes blood pressure by increasing local blood flow. Therefore, we microinjected another vasodilator, hydralazine, bilaterally into the NTS of L-NAME–treated rats and confirmed that hydralazine did not alter blood pressure. Thus, the effects of the Rho-kinase inhibitor in the NTS on blood pressure regulation were not caused by its local vasodilator effect.20
Our findings suggest that endogenous Rho-kinase in the brainstem plays an important role in L-NAME–induced hypertension. As demonstrated by the chronic experiments, the L-NAME–induced increase in blood pressure was significantly suppressed during intracisternal Y-27632 infusion. Nonspecific effects caused by the surgical procedure are unlikely because continuous intracisternal infusion of vehicle using the same devices did not suppress the SBP elevation, and after discontinuing the Y-27632 infusion, SBP increased to a level similar to that in L-NAME-VEH rats. In addition, phosphorylation of ERM family members in the brainstem was significantly increased in L-NAME-VEH rats and reduced in the L-NAME-Y-27632 rats, which strongly suggests that the Rho/Rho-kinase pathway in the brainstem of L-NAME–treated rats activates Rho-kinase activity in vivo and Y27632 suppresses it.
In the present study, intracisternal infusion of Y-27632 prevented the increase in SBP on the first day of L-NAME treatment, which is not consistent with the reports that the initial increase in SBP with L-NAME is caused by the inhibition of vascular NO.3–7 The latency of the onset of the sympathectomy-sensitive component of intravenous infusion of L-NAME–induced hypertension, however, was 1 to 2 hours.24 The latency of onset of neural component after oral administration of L-NAME might be longer than intravenous infusion; 24 hours is when the neural component of L-NAME–induced blood pressure elevation becomes apparent. Furthermore, the effect of intracisternal infusion of Y-27632 on SBP was expected to begin much faster than that of oral administration of L-NAME. Therefore, intracisternal infusion of Y-27632 might prevent L-NAME–induced blood pressure elevation.
To exclude the possibility of vascular action of intracisternal infusion of Y-27632, we intravenously infused Y-27632 (1000 pmol/0.2 mL injection over 50-second period with an infusion pump) into L-NAME–treated rats. This amount of Y-27632 was the same as that of an 8-hour intracisternal infusion dose with the pump used in the present study and elicited no significant change in SBP or HR. Furthermore, Y-27632 was intracisternally infused into the control rats. In the control rats, Y-27632 induced a small transient decrease in SBP from day 7 to day 11 compared with before treatment (day 0). In addition, the expression level of phosphorylation of the ERM family members in the brainstem was slightly reduced in control-Y-27632 rats compared with control-VEH rats. SBP and the extent of phosphorylation of the ERM family members was significantly decreased in control-Y27632 rats, although the magnitudes were small because of indirect effects of Y-27632 in the NTS and other brain areas. These results suggest that the Rho/Rho-kinase pathway in the brainstem of normotensive rats contributes somewhat to blood pressure regulation.17 This result is also consistent with the results of our previous study, demonstrating transfection of adenovirus encoding dominant-negative Rho-kinase into the NTS in normotensive WKY rats.17
There is a possibility that the greater effect in L-NAME–treated rats was caused by differences in Rho-kinase activity somewhere downstream from the NTS. The rostral ventrolateral medulla (RVLM) neurons are activated in rats with chronic NO synthase inhibition.26 Intracisternal infusion of a drug might affect neurons not only in the NTS but also in the rostral ventrolateral medulla.27 Therefore, intracisternal infusion of Y-27632 might also alter neuronal activity in areas other than the NTS, such as the rostral ventrolateral medulla in L-NAME–treated rats. We demonstrated, however, that a greater depressor effect of Y-27632 on blood pressure and/or RSNA in L-NAME–treated rats than in control rats in microinjection experiments. In addition, RhoA and Rho-kinase activity was enhanced in L-NAME–treated rats compared with control rats. Thus, we believe that the effect of Y-27632 is at least partly mediated by inhibition of Rho-kinase activity in the NTS. Further studies are needed to determine whether other cardiovascular centers of the brainstem are affected by chronic NO synthesis inhibition or intracisternal infusion of Y-27632.
In conclusion, we demonstrated that the Rho/Rho-kinase pathway in the NTS is activated in L-NAME–treated rats as compared with control rats. Activation of the Rho/Rho-kinase pathway plays an important role in L-NAME–induced hypertension.
Perspectives
We do not know the mechanisms by which activation of the Rho/Rho-kinase pathway in the NTS alters arterial blood pressure via the sympathetic nervous system or the cause of the greater activation the Rho/Rho-kinase pathway in L-NAME–treated rats. A recent study demonstrated that activity of the renin-angiotensin system in the NTS is increased by chronic NO synthase inhibition.8 Accumulating evidence suggests that Rho-kinase is substantially involved in the signal transduction initiated by many vasoactive substances, such as angiotensin II.28,29 Indeed, a considerable amount of evidence suggests that angiotensin II in the central nervous system contributes to the neural mechanisms of hypertension.27 Therefore, activation of the Rho/Rho-kinase pathway in the NTS of L-NAME–treated rats might be elicited by activation of the renin–angiotensin system in the NTS. Furthermore, the neuronal Rho/Rho-kinase pathway contributes to dendritic spine formation.30,31 Dendritic spines form postsynaptic sites in excitatory synapses in the central nervous system. Recent studies suggest that morphological changes in dendritic spines occur rapidly32 and are associated with glutamate sensitivity.33 Indeed, there are structural differences of dendritic spines in the NTS between WKY rats and SHR.34 Therefore, the Rho/Rho-kinase pathway affects synaptic transmission in the NTS and might also be involved in baroreflex function. Further studies are needed to clarify the mechanisms responsible for our observations.
|
Acknowledgments |
|---|
We thank the Mitsubishi Pharma Corporation for their generous gift of Y-27632.
This work was supported by grants-in-aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture (A13307024, B12470158, C13670721).
Received June 12, 2003; first decision June 30, 2003; accepted November 25, 2003.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Zatz R, Baylis C. Chronic nitric oxide inhibition model six years on. Hypertension. 1998; 32: 958–964.
2. Riberio MO, Antunes E, De Nucci, Lovisolo SM, Zatz R. Chronic inhibition of nitric oxide synthesis: a new model of arterial hypertension. Hypertension. 1992; 20: 298–303.
3. Ollerstam A, Pittner J, Persson AEG, Thorup C. Increased blood pressure in rats after long-term inhibition of the neuronal isoform of nitric oxide synthesis. J Clin Invest. 1997; 99: 2212–2218.[Medline] [Order article via Infotrieve]
4. El Karib AO, Sheng J, Betz AL, Malvin RL. The central effects of a nitric oxide synthase inhibitor (N-nitro-L-arginine) on blood pressure and plasma rennin. Clin Exp Hypertens. 1993; 15: 819–832.[CrossRef][Medline]
[Order article via Infotrieve]
5. Cabrera CL, Bohr DF. The role of nitric oxide in the central control of blood pressure. Biochem Biophys Res Commun. 1995; 206: 77–81.[CrossRef][Medline] [Order article via Infotrieve]
6. Sakuma I, Togashi H, Yoshioka M, Kobayashi T, Yasuda H, Kitabatake A, Saito H, Gross SS, Levi R. NG-Methyl-L-arginine, an inhibitor of L-arginine-derived nitric oxide synthesis, stimulates renal sympathetic nerve activity in vivo: a role for nitric oxide in the central regulation of sympathetic tone? Circ Res. 1992; 70: 607–611.
7. Togashi H, Sakuma I, Yoshioka M, Kobayashi T, Yasuda H, Kitabatake A, Saito H, Gross SS, Levi R. a central nervous system action of nitric oxide in blood pressure regulation. J Pharmacol Exp Ther. 1992; 262: 343–347.
8. Eshima K, Hirooka Y, Shigematsu H, Matsuo I, Koike G, Sakai K, Takeshita A. Angiotensin in the nucleus tractus solitarii contributes to neurogenic hypertension caused by chronic nitric oxide synthase inhibition. Hypertension. 2000; 36: 259–263.
9. Kataoka C, Egashira K, Inoue S, Takemoto M, Ni W, Koyanagi M, Kitamoto S, Usui M, Kaibuchi K, Shimokawa H, Takeshita A. Important role of Rho-kinase in the pathogenesis of cardiovascular inflammation and remodeling induced by long-term blockade of nitric oxide synthesis in rats. Hypertension. 2002; 39: 245–250.
10. Seasholtz TM, Zhang T, Morissette MR, Howes AL, Yang AH, Brown JH. Increased expression and activity of RhoA are associated with increased DNA synthesis and reduced p27Kip1 expression in the vasculature of hypertensive rats. Circ Res. 2001; 89: 488–495.
11. Kureishi Y, Kobayashi S, Amano M, Kimura K, Kanaide H, Nakano T, Kaibuchi K, Ito M. Rho-associated kinase directly induces smooth muscle contraction through myosin light chain phosphorylation. J Biol Chem. 1997; 272: 12257–12260.
12. Uehata M, Ishizaki T, Satoh H, Ono T, Kawahara T, Morishita T, Tamakawa H, Yamagami K, Inui J, Maekawa M, Narumuiya S. Calcium sensitization of smooth muscle mediated by a Rho-associated protein kinase in hypertension. Nature. 1997; 389: 990–994.[CrossRef][Medline] [Order article via Infotrieve]
13. Mukai Y, Shimokawa H, Matoba T, Kandabashi T, Satoh S, Hiroki J, Kaibuchi K, Takeshita A. Involvement of Rho-kinase in hypertensive vascular disease: a novel therapeutic target in hypertension. FASEB J. 2001; 15: 1062–1064.
14. Masumoto A, Hirooka Y, Shimokawa H, Hironaga K, Setoguchi S, Takeshita A. Possible involvement of Rho-kinase in the pathogenesis of hypertension in humans. Hypertension. 2001; 38: 1307–1310.
15. Hashimoto R, Nakamura Y, Kosako H, Amano M, Kaibuchi K, Inagaki M, Takeda M. Distribution of Rho-kinase in the bovine brain. Biochem Biophys Res Comm. 1999; 263: 575–579.[CrossRef][Medline] [Order article via Infotrieve]
16. Olenik C, Barth H, Just I, Aktories K, Meyer DK. Gene expression of the small GTP-binding proteins RhoA, RhoB, Rac1, and Cdc42 in adult rat brain. Mol Brain Res. 1997; 52: 263–269.[Medline] [Order article via Infotrieve]
17. Ito K, Hirooka Y, Sakai K, Kishi T, Kaibuchi K, Shimokawa H, Takeshita A. Rho/Rho-kinase pathway in brainstem contributes to blood pressure regulation via sympathetic nervous system. Circ Res. 2003; 92: 1337–1343.
18. Sakai k, Hirooka Y, Matsuo I, Eshima K, Shigematsu H, Shimokawa H, Takeshita A. Overexpression of eNOS in NTS causes hypotension and bradycardia in vivo. Hypertension. 2000; 36: 1023–1028.
19. Paxinos G, Watson C. The Rat Brain in Stereotaxic Coordinates. New York: Academic Press; 1998.
20. Zhang K, Mayhan WG, Patel KP. Nitric oxide with in the paraventricular nucleus mediates changes in renal sympathetic nerve activity. Am J Physiol. 1997; 273: R864–R872.[Medline] [Order article via Infotrieve]
21. Matsui T, Maeda M, Doi Y, Yonemura S, Amano M, Kaibuchi K, Tsukita S. Rho-kinase phosphorylate COOH-terminal threonines of Ezrin/Radixin/Moesin (ERM) proteins and regulates their head-to-tail association. J Cell Biol. 1998; 140: 647–657.
22. Liao JK, Homcy CJ. Specific receptor-guanine nucleotide binding protein interaction mediates the release of endothelium-derived relaxing factor. Circ Res. 1992; 70: 1018–1026.
23. Zanchi A, Schaad NC, Osterheld MC, Grouzmann E, Nussberger J, Brunner HR, Waeber B. Effects of chronic NO synthase inhibition in rats on renin-angiotensin system and sympathetic nervous system. Am J Physiol. 1995; 268: H2267–H2273.[Medline] [Order article via Infotrieve]
24. Sander M, Hansen J, Victor RG. Sympathetic nervous system is involved in the maintenance but not initiation of the hypertension induced by N-nitro-L-arginine methyl ester. Hypertension. 1997; 30: 64–70.
25. Sander M, Hansen J, Victor RG. Sympathetic mediated hypertension caused by chronic inhibition of nitric oxide. Hypertension. 1995; 26: 691–695.
26. Bergamaschi CT, Campos RR, Lopes OU. Rostral ventrolateral medulla: a source of sympathetic activation in rats subjected to long-term treatment with L-NAME. Hypertension. 1999; 34: 744–747.
27. Hirooka Y, Head GA, Potts PD, Godwin SJ, Bendle RD, Dampney RAL. Medullary neurons activated by angiotensin II in conscious rabbit. Hypertension. 1996; 27: 287–296.
28. Funakoshi Y, Ichiki T, Shimokawa H, Egashira K, Takeda K. Kaibuchi K, Takeya M, Yoshimura T, Takeshita A. A critical role of Rho-kinase in angiotensin II-induced monocyte chemoattractant protein-1 expression in rat vascular smooth muscle cells. Hypertension. 2001; 38: 100–104.
29. Aoki H, Izumo S, Sadoshima J. Angiotensin II activates RhoA in cardiac myocytes: a critical role of RhoA in angiotensin II-induced premyofibril formation. Cir Res. 1998; 82: 666–676.
30. Nakayama AY, Harms MB, Luo L. Small GTPases Rac and Rho in the maintenance of dendritic spines and branches in hippocampal pyramidal neurons. J Neurosci. 2000; 20: 5329–5338.
31. Nakazawa T, Watabe AM, Tezuka T, Yoshida Y, Yokoyama K, Umemori H, Inoue A, Okabe S, Manabe T, Yamamoto T. p250GAP, a novel brain-enriched GTPase-activating protein for Rho family GTPases, is involved in the N-methyl-D-aspartate receptor signaling. Mol Biol Cell. 2003; 14: 2921–2934.
32. Fischer M, Kaech S, Knutti D, Matus A. Rapid actin-based plasticity in dendritic spines. Neuron. 1998; 20: 847–854.[CrossRef][Medline] [Order article via Infotrieve]
33. Matsuzaki M, Ellis-Davies GC, Nemoto T, Miyashita Y, Iino M, Kasai H. Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons. Nat Neurosci. 2001; 4: 1086–1092.[CrossRef][Medline] [Order article via Infotrieve]
34. Aicher SA, Sharma S, Mitchell JL. Structural changes in AMPA-Receptive neurons in the nucleus of the solitary tract of spontaneously hypertensive rats. Hypertension. 2003; 41: 1246–1252.
This article has been cited by other articles:
 |
|
 |
|
  K. Ito, Y. Hirooka, and K. Sunagawa Acquisition of Brain Na Sensitivity Contributes to Salt-Induced Sympathoexcitation and Cardiac Dysfunction in Mice With Pressure Overload Circ. Res., April 24, 2009; 104(8): 1004 - 1011. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. S. Thompson-Torgerson, L. A. Holowatz, N. A. Flavahan, and W. Larry Kenney Rho kinase-mediated local cold-induced cutaneous vasoconstriction is augmented in aged human skin Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H30 - H36. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. S. Thompson-Torgerson, L. A. Holowatz, N. A. Flavahan, and W. L. Kenney Cold-induced cutaneous vasoconstriction is mediated by Rho kinase in vivo in human skin Am J Physiol Heart Circ Physiol, April 1, 2007; 292(4): H1700 - H1705. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. H. Zucker Novel Mechanisms of Sympathetic Regulation in Chronic Heart Failure Hypertension, December 1, 2006; 48(6): 1005 - 1011. [Full Text] [PDF]
|
|
|
|
|
|
K. Ito, Y. Hirooka, Y. Kimura, Y. Sagara, and K. Sunagawa Ovariectomy Augments Hypertension Through Rho-Kinase Activation in the Brain Stem in Female Spontaneously Hypertensive Rats Hypertension, October 1, 2006; 48(4): 651 - 657. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. M. Seasholtz, J. Wessel, F. Rao, B. K. Rana, S. Khandrika, B. P. Kennedy, E. O. Lillie, M. G. Ziegler, D. W. Smith, N. J. Schork, et al. Rho Kinase Polymorphism Influences Blood Pressure and Systemic Vascular Resistance in Human Twins: Role of Heredity Hypertension, May 1, 2006; 47(5): 937 - 947. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Ito, Y. Hirooka, N. Hori, Y. Kimura, Y. Sagara, H. Shimokawa, A. Takeshita, and K. Sunagawa Inhibition of Rho-Kinase in the Nucleus Tractus Solitarius Enhances Glutamate Sensitivity in Rats Hypertension, August 1, 2005; 46(2): 360 - 365. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kimura, Y. Hirooka, Y. Sagara, K. Ito, T. Kishi, H. Shimokawa, A. Takeshita, and K. Sunagawa Overexpression of Inducible Nitric Oxide Synthase in Rostral Ventrolateral Medulla Causes Hypertension and Sympathoexcitation via an Increase in Oxidative Stress Circ. Res., February 4, 2005; 96(2): 252 - 260. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Lonergan, A. G. Teschemacher, D. Y. Hwang, K.-S. Kim, A. E. Pickering, and S. Kasparov Targeting brain stem centers of cardiovascular control using adenoviral vectors: impact of promoters on transgene expression Physiol Genomics, January 20, 2005; 20(2): 165 - 172. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. L. Lee, R. C. Webb, and L. Jin Hypertension and RhoA/Rho-Kinase Signaling in the Vasculature: Highlights From the Recent Literature Hypertension, December 1, 2004; 44(6): 796 - 799. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Ito, Y. Hirooka, Y. Sagara, Y. Kimura, K. Kaibuchi, H. Shimokawa, A. Takeshita, and K. Sunagawa Inhibition of Rho-Kinase in the Brainstem Augments Baroreflex Control of Heart Rate in Rats Hypertension, October 1, 2004; 44(4): 478 - 483. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||