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Bryson TD, Pandrangi TS, Khan SZ, Xu J, Pavlov TS, Ortiz PA, Peterson E, Harding P. The deleterious role of the prostaglandin E 2 EP 3 receptor in angiotensin II hypertension. Am J Physiol Heart Circ Physiol 2020; 318:H867-H882. [PMID: 32142358 DOI: 10.1152/ajpheart.00538.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Angiotensin II (ANG II) plays a key role in regulating blood pressure and inflammation. Prostaglandin E2 (PGE2) signals through four different G protein-coupled receptors, eliciting a variety of effects. We reported that activation of the EP3 receptor reduces cardiac contractility. More recently, we have shown that overexpression of the EP4 receptor is protective in a mouse myocardial infarction model. We hypothesize in this study that the relative abundance of EP3 and EP4 receptors is a major determinant of end-organ damage in the diseased heart. Thus EP3 is detrimental to cardiac function and promotes inflammation, whereas antagonism of the EP3 receptor is protective in an ANG II hypertension (HTN) model. To test our hypothesis, male 10- to 12-wk-old C57BL/6 mice were anesthetized with isoflurane and osmotic minipumps containing ANG II were implanted subcutaneously for 2 wk. We found that antagonism of the EP3 receptor using L798,106 significantly attenuated the increase in blood pressure with ANG II infusion. Moreover, antagonism of the EP3 receptor prevented a decline in cardiac function after ANG II treatment. We also found that 10- to 12-wk-old EP3-transgenic mice, which overexpress EP3 in the cardiomyocytes, have worsened cardiac function. In conclusion, activation or overexpression of EP3 exacerbates end-organ damage in ANG II HTN. In contrast, antagonism of the EP3 receptor is beneficial and reduces cardiac dysfunction, inflammation, and HTN.NEW & NOTEWORTHY This study is the first to show that systemic treatment with an EP3 receptor antagonist (L798,106) attenuates the angiotensin II-induced increase in blood pressure in mice. The results from this project could complement existing hypertension therapies by combining blockade of the EP3 receptor with antihypertensive drugs.
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Affiliation(s)
- Timothy D Bryson
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Teja S Pandrangi
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan
| | - Safa Z Khan
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan
| | - Jiang Xu
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan
| | - Tengis S Pavlov
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan
| | - Pablo A Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Edward Peterson
- Department of Public Health Sciences, Henry Ford Health System, Detroit, Michigan
| | - Pamela Harding
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Health System, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Dee RA, Mangum KD, Bai X, Mack CP, Taylor JM. Druggable targets in the Rho pathway and their promise for therapeutic control of blood pressure. Pharmacol Ther 2019; 193:121-134. [PMID: 30189292 PMCID: PMC7235948 DOI: 10.1016/j.pharmthera.2018.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The prevalence of high blood pressure (also known as hypertension) has steadily increased over the last few decades. Known as a silent killer, hypertension increases the risk for cardiovascular disease and can lead to stroke, heart attack, kidney failure and associated sequela. While numerous hypertensive therapies are currently available, it is estimated that only half of medicated patients exhibit blood pressure control. This signifies the need for a better understanding of the underlying cause of disease and for more effective therapies. While blood pressure homeostasis is very complex and involves the integrated control of multiple body systems, smooth muscle contractility and arterial resistance are important contributors. Strong evidence from pre-clinical animal models and genome-wide association studies indicate that smooth muscle contraction and BP homeostasis are governed by the small GTPase RhoA and its downstream target, Rho kinase. In this review, we summarize the signaling pathways and regulators that impart tight spatial-temporal control of RhoA activity in smooth muscle cells and discuss current therapeutic strategies to target these RhoA pathway components. We also discuss known allelic variations in the RhoA pathway and consider how these polymorphisms may affect genetic risk for hypertension and its clinical manifestations.
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Affiliation(s)
- Rachel A Dee
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kevin D Mangum
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Xue Bai
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Christopher P Mack
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Joan M Taylor
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA.
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Xu Q, Huff LP, Fujii M, Griendling KK. Redox regulation of the actin cytoskeleton and its role in the vascular system. Free Radic Biol Med 2017; 109:84-107. [PMID: 28285002 PMCID: PMC5497502 DOI: 10.1016/j.freeradbiomed.2017.03.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/17/2017] [Accepted: 03/06/2017] [Indexed: 12/17/2022]
Abstract
The actin cytoskeleton is critical for form and function of vascular cells, serving mechanical, organizational and signaling roles. Because many cytoskeletal proteins are sensitive to reactive oxygen species, redox regulation has emerged as a pivotal modulator of the actin cytoskeleton and its associated proteins. Here, we summarize work implicating oxidants in altering actin cytoskeletal proteins and focus on how these alterations affect cell migration, proliferation and contraction of vascular cells. Finally, we discuss the role of oxidative modification of the actin cytoskeleton in vivo and highlight its importance for vascular diseases.
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Affiliation(s)
- Qian Xu
- Division of Cardiology, Department of Medicine, Emory University, 101 Woodruff Circle, 308a WMB, Atlanta, GA 30322, United States; Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, China
| | - Lauren P Huff
- Division of Cardiology, Department of Medicine, Emory University, 101 Woodruff Circle, 308a WMB, Atlanta, GA 30322, United States
| | - Masakazu Fujii
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Japan
| | - Kathy K Griendling
- Division of Cardiology, Department of Medicine, Emory University, 101 Woodruff Circle, 308a WMB, Atlanta, GA 30322, United States.
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da Costa RM, Fais RS, Dechandt CRP, Louzada-Junior P, Alberici LC, Lobato NS, Tostes RC. Increased mitochondrial ROS generation mediates the loss of the anti-contractile effects of perivascular adipose tissue in high-fat diet obese mice. Br J Pharmacol 2017; 174:3527-3541. [PMID: 27930804 DOI: 10.1111/bph.13687] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/29/2016] [Accepted: 12/01/2016] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Obesity is associated with structural and functional changes in perivascular adipose tissue (PVAT), favouring release of reactive oxygen species (ROS), vasoconstrictor and proinflammatory factors. The cytokine TNF-α induces vascular dysfunction and is produced by PVAT. We tested the hypothesis that obesity-associated PVAT dysfunction was mediated by augmented mitochondrial ROS (mROS) generation due to increased TNF-α production in this tissue. EXPERIMENTAL APPROACH C57Bl/6J and TNF-α receptor-deficient mice received control or high fat diet (HFD) for 18 weeks. We used pharmacological tools to determine the participation of mROS in PVAT dysfunction. Superoxide anion (O2.- ) and H2 O2 were assayed in PVAT and aortic rings were used to assess vascular function. KEY RESULTS Aortae from HFD-fed obese mice displayed increased contractions to phenylephrine and loss of PVAT anti-contractile effect. Inactivation of O2.- , dismutation of mitochondria-derived H2 O2 , uncoupling of oxidative phosphorylation and Rho kinase inhibition, decreased phenylephrine-induced contractions in aortae with PVAT from HFD-fed mice. O2.- and H2 O2 were increased in PVAT from HFD-fed mice. Mitochondrial respiration analysis revealed decreased O2 consumption rates in PVAT from HFD-fed mice. TNF-α inhibition reduced H2 O2 levels in PVAT from HFD-fed mice. PVAT dysfunction, i.e. increased contraction to phenylephrine in PVAT-intact aortae, was not observed in HFD-obese mice lacking TNF-α receptors. Generation of H2 O2 was prevented in PVAT from TNF-α receptor deficient obese mice. CONCLUSION AND IMPLICATIONS TNF-α-induced mitochondrial oxidative stress is a key and novel mechanism involved in obesity-associated PVAT dysfunction. These findings elucidate molecular mechanisms whereby oxidative stress in PVAT could affect vascular function. LINKED ARTICLES This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.
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Affiliation(s)
- Rafael Menezes da Costa
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Rafael S Fais
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Carlos R P Dechandt
- Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Paulo Louzada-Junior
- Division of Clinical Immunology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Luciane C Alberici
- Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Núbia S Lobato
- Department of Medicine, Federal University of Goias, Jatai, GO, Brazil
| | - Rita C Tostes
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
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Szasz T, Webb RC. Rho-Mancing to Sensitize Calcium Signaling for Contraction in the Vasculature: Role of Rho Kinase. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:303-322. [PMID: 28212799 DOI: 10.1016/bs.apha.2016.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Vascular smooth muscle contraction is an important physiological process contributing to cardiovascular homeostasis. The principal determinant of smooth muscle contraction is the intracellular free Ca2+ concentration, and phosphorylation of myosin light chain (MLC) by activated myosin light chain kinase (MLCK) in response to increased Ca2+ is the main pathway by which vasoconstrictor stimuli induce crossbridge cycling of myosin and actin filaments. A secondary pathway for vascular smooth muscle contraction that is not directly dependent on Ca2+ concentration, but rather mediating Ca2+ sensitization, is the RhoA/Rho kinase pathway. In response to contractile stimuli, the small GTPase RhoA activates its downstream effector Rho kinase which, in turn, promotes contraction via myosin light chain phosphatase (MLCP) inhibition. RhoA/Rho kinase-mediated MLCP inhibition occurs mainly by phosphorylation and inhibition of MYPT1, the regulatory subunit of MLCP, or by CPI-17-mediated inhibition of the catalytic subunit of MLCP. In this review, we describe the molecular mechanisms underlying the pivotal role exerted by Rho kinase on vascular smooth muscle contraction and discuss the main regulatory pathways for its activity.
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Affiliation(s)
- T Szasz
- Augusta University, Augusta, GA, United States.
| | - R C Webb
- Augusta University, Augusta, GA, United States
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c-Src, ERK1/2 and Rho kinase mediate hydrogen peroxide-induced vascular contraction in hypertension: role of TXA2, NAD(P)H oxidase and mitochondria. J Hypertens 2016; 33:77-87. [PMID: 25380156 DOI: 10.1097/hjh.0000000000000383] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AIM : The aim of this study was to analyse the signalling pathways involved in H2O2 vascular responses in hypertension. METHODS Vascular function, thromboxane A2 (TXA2) production, oxidative stress and protein expression were determined in mesenteric resistance arteries (MRAs) from hypertensive (spontaneously hypertensive rats, SHR) and normotensive Wistar Kyoto (WKY) rats. RESULTS H2O2 and the TP agonist U46619 induced greater contractile responses in MRA from SHR than WKY. Moreover, H2O2 increased TXA2 production more in SHR than in WKY. The c-Src inhibitor PP1 reduced H2O2 and U46619-induced contraction and TXA2 release in both strains. The ERK1/2 inhibitor PD98059 reduced H2O2 but not U46619-induced contraction only in SHR arteries. The Rho kinase inhibitor Y26372 reduced H2O2 and U46619-induced contractions only in SHR arteries. Basal c-Src, ERK1/2 and Rho kinase expression were greater in MRA from SHR than WKY. In SHR, the combination of PD98059 with the TP antagonist SQ29548 but not with Y27632 inhibited the H2O2 contraction more than each inhibitor alone. H2O2 and U46619 increased NAD(P)H oxidase activity and O2 production and decreased mitochondrial membrane potential in vessels from SHR. The effects induced by H2O2 were abolished by inhibitors of TXA2 synthase, ERK1/2 and c-Src. The mitochondrial antioxidant mitoTEMPO reduced H2O2-induced contraction and NAD(P)H oxidase activation. CONCLUSION In arteries from WKY, c-Src mediates H2O2 contractile responses by modulating TXA2 release and TXA2 effect. In SHR, H2O2 induces c-Src dependent TXA2 release that provokes vascular contractile responses through Rho kinase, c-Src and O2 from NAD(P)H Oxidase and mitochondria. Moreover, ERK1/2 activation contributes to H2O2 contraction in SHR through effects on mitochondria/NAD(P)H Oxidase.
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Bai X, Dee R, Mangum KD, Mack CP, Taylor JM. RhoA signaling and blood pressure: The consequence of failing to “Tone it Down”. World J Hypertens 2016; 6:18-35. [DOI: 10.5494/wjh.v6.i1.18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/24/2015] [Accepted: 01/22/2016] [Indexed: 02/06/2023] Open
Abstract
Uncontrolled high blood pressure is a major risk factor for heart attack, stroke, and kidney failure and contributes to an estimated 25% of deaths worldwide. Despite numerous treatment options, estimates project that reasonable blood pressure (BP) control is achieved in only about half of hypertensive patients. Improvements in the detection and management of hypertension will undoubtedly be accomplished through a better understanding of the complex etiology of this disease and a more comprehensive inventory of the genes and genetic variants that influence BP regulation. Recent studies (primarily in pre-clinical models) indicate that the small GTPase RhoA and its downstream target, Rho kinase, play an important role in regulating BP homeostasis. Herein, we summarize the underlying mechanisms and highlight signaling pathways and regulators that impart tight spatial-temporal control of RhoA activity. We also discuss known allelic variations in the RhoA pathway and consider how these polymorphisms may affect genetic risk for hypertension and its clinical manifestations. Finally, we summarize the current (albeit limited) clinical data on the efficacy of targeting the RhoA pathway in hypertensive patients.
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Chung S, Kim YH, Joeng JH, Ahn DS. Transient receptor potential c4/5 like channel is involved in stretch-induced spontaneous uterine contraction of pregnant rat. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2014; 18:503-8. [PMID: 25598665 PMCID: PMC4296040 DOI: 10.4196/kjpp.2014.18.6.503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 09/22/2014] [Accepted: 09/23/2014] [Indexed: 12/23/2022]
Abstract
Spontaneous myometrial contraction (SMC) in pregnant uterus is greatly related with gestational age and growing in frequency and amplitude toward the end of gestation to initiate labor. But, an accurate mechanism has not been elucidated. In human and rat uterus, all TRPCs except TRPC2 are expressed in pregnant myometrium and among them, TRPC4 are predominant throughout gestation, suggesting a possible role in regulation of SMC. Therefore, we investigated whether the TRP channel may be involved SMC evoked by mechanical stretch in pregnant myometrial strips of rat using isometric tension measurement and patch-clamp technique. In the present results, hypoosmotic cell swelling activated a potent outward rectifying current in G protein-dependent manner in rat pregnant myocyte. The current was significantly potentiated by 1µM lanthanides (a potent TRPC4/5 stimulator) and suppressed by 10µM 2-APB (TRPC4-7 inhibitor). In addition, in isometric tension experiment, SMC which was evoked by passive stretch was greatly potentiated by lanthanide (1µM) and suppressed by 2-APB (10µM), suggesting a possible involvement of TRPC4/5 channel in regulation of SMC in pregnant myometrium. These results provide a possible cellular mechanism for regulation of SMC during pregnancy and provide basic information for developing a new agent for treatment of premature labor.
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Affiliation(s)
- Seungsoo Chung
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Young-Hwan Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Ji-Hyun Joeng
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Duck-Sun Ahn
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
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Ca2+ sensitization and Ca2+ entry in the control of blood pressure and adrenergic vasoconstriction in conscious Wistar-Kyoto and spontaneously hypertensive rats. J Hypertens 2014; 31:2025-35. [PMID: 24107733 DOI: 10.1097/hjh.0b013e328362adb3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Calcium entry through nifedipine-sensitive L-type voltage-dependent calcium channels (L-VDCC) is augmented in spontaneously hypertensive rats (SHR) characterized by enhanced sympathetic vasoconstriction. However, the changes of calcium sensitization mediated by RhoA/Rho kinase pathway are less understood. METHODS AND RESULTS The participation of calcium entry and calcium sensitization in the control of blood pressure (BP) and vascular contraction was studied in SHR and normotensive Wistar-Kyoto (WKY) rats. The acute administration of fasudil (Rho kinase inhibitor) caused BP decrease which lasted longer in SHR. Fasudil also attenuated adrenergic contraction in femoral or mesenteric arteries of WKY and SHR. BP reduction elicited by fasudil in WKY was more pronounced than that induced by L-VDCC blocker nifedipine (-33±2 vs. -15±3% of baseline BP, P<0.001), whereas both inhibitors were similarly effective in SHR (-36±4 vs. -41±2%). Fasudil pretreatment also attenuated BP elevation elicited by L-VDCC agonist BAY K8644 more in WKY than in SHR (-63±4 vs. -42±5%, P<0.001), indicating reduced calcium sensitization in SHR. Moreover, fasudil pretreatment shifted norepinephrine dose-response curves to the right more in WKY than in SHR. The additional nifedipine pretreatment shifted these curves further to the right but this shift was more pronounced in SHR than in WKY. Thus adrenergic vasoconstriction is more dependent on L-VDCC in SHR and on RhoA/Rho kinase pathway in WKY rats. CONCLUSION Ca sensitization mediated by RhoA/Rho kinase pathway is attenuated in SHR compared with normotensive WKY rats. This might be a part of the compensation for enhanced Ca entry through L-VDCC in genetic hypertension.
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Contribution of Rho kinase to blood pressure elevation and vasoconstrictor responsiveness in type 2 diabetic Goto–Kakizaki rats. J Hypertens 2013; 31:1160-9. [DOI: 10.1097/hjh.0b013e328360383a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Martinsen A, Yerna X, Rath G, Gomez EL, Dessy C, Morel N. Different effect of Rho kinase inhibition on calcium signaling in rat isolated large and small arteries. J Vasc Res 2012; 49:522-33. [PMID: 22948674 DOI: 10.1159/000341230] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 06/10/2012] [Indexed: 11/19/2022] Open
Abstract
In addition to its role in the regulation of artery contraction, Rho kinase (ROCK) was reported to be involved in the cytosolic calcium response to vasoconstrictor agonists in rat aorta and superior mesenteric artery (SMA). However, it remains to be determined whether ROCK also contributes to calcium signaling in resistance arteries, which play a major role in blood pressure regulation. The investigation of the effect of ROCK inhibition on the calcium and contractile responses of rat resistance mesenteric artery (RMA), in comparison with aorta and SMA, indicated that the calcium response to noradrenaline was inhibited by the ROCK inhibitor Y-27632 in aorta and SMA but not in RMA. The effect of Y-27632 on the calcium signal was unaffected by cytochalasin-D. ROCK activation in noradrenaline-stimulated arteries was confirmed by the inhibition of myosin light chain phosphorylation by Y-27632. Moreover, noradrenaline-induced calcium signaling was similarly inhibited by nimodipine in aorta, SMA and RMA, but nimodipine sensitivity of the contraction increased from the aorta to the RMA, suggesting that the contraction was controlled by different sources of calcium. In pressurized RMA, Y-27632 and H-1152 depressed pressure-induced calcium responses and abolished myogenic contraction. These results stress the important differences in calcium signaling between conductance and resistance arteries.
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Affiliation(s)
- Anneloes Martinsen
- Department of Cellular Physiology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
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Abstract
We used isolated superior mesenteric arteries (SMAs) from hemorrhagic-shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs; mimicking the shock state) to observe the effects of platelet-derived growth factor (PDGF; Rac1 stimulator) and NSC23766 (Rac1 antagonist) on vascular reactivity and the relationship with the Rho kinase-myosin light-chain phosphatase (MLCP) and p21-activated kinase (PAK)-myosin light-chain kinase (MLCK) signal pathway. The results indicated that the contractile responses of the SMAs and VSMCs were significantly increased at early shock or after transient hypoxia. NSC23766 (Rac1 antagonist) further increased, whereas PDGF (Rac1 stimulator) decreased the contractile responses of SMAs and VSMCs. In the late period of shock or prolonged hypoxia, the contractile responses of SMAs and VSMCs were significantly decreased; NSC23766 increased (whereas PDGF further decreased) the contractile response of the SMAs and VSMCs. Activation of Rac1 with PDGF significantly increased the activity of PAK and MLCP, and decreased Rho kinase and MLCK activity and 20-kDa myosin light-chain phosphorylation in VSMCs. The PAK inhibitor PAK-18 significantly antagonized the PDGF-induced decrease in MLCK activity, whereas the Rho kinase antagonist Y-27632 further enforced the PDGF-induced increase in MLCP activity. Simple fluid resuscitation did not improve but in combination with NSC23766 significantly improved vascular reactivity and animal survival at 24 hours. This suggested that Rac1 has an inhibitory effect on vasoreactivity after shock. Rac1-mediated regulation of vascular reactivity is mainly through activation of PAK, inhibition of MLCK and inhibition of Rho kinase, unpack the inhibition of Rho kinase to MLCP. Rac1 may be a potential target to treat vascular hyporeactivity in many critical conditions.
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de Godoy MAF, Rattan S. Role of rho kinase in the functional and dysfunctional tonic smooth muscles. Trends Pharmacol Sci 2011; 32:384-93. [PMID: 21497405 DOI: 10.1016/j.tips.2011.03.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 03/05/2011] [Accepted: 03/11/2011] [Indexed: 01/13/2023]
Abstract
Tonic smooth muscles play pivotal roles in the pathophysiology of debilitating diseases of the gastrointestinal and cardiovascular systems. Tonic smooth muscles differ from phasic smooth muscles in the ability to spontaneously develop myogenic tone. This ability has been primarily attributed to the local production of specific neurohumoral substances that can work in conjunction with calcium sensitization via signal transduction events associated with the Ras homolog gene family, member A (RhoA)/Rho-associated, coiled-coil containing protein kinase 2 (ROCK II) pathways. In this article, we discuss the molecular pathways involved in the myogenic properties of tonic smooth muscles, particularly the contribution of protein kinase C vs the RhoA/ROCK II pathway in the genesis of basal tone, pathophysiology and novel therapeutic approaches for certain gastrointestinal and cardiovascular diseases. Emerging evidence suggests that manipulation of RhoA/ROCK II activity through inhibitors or silencing of RNA interface techniques could represent a new therapeutic approach for various gastrointestinal and cardiovascular diseases.
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Affiliation(s)
- Márcio A F de Godoy
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA, USA
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Sevoflurane inhibits angiotensin II-induced Rho kinase-mediated contraction of vascular smooth muscle from spontaneously hypertensive rat. J Anesth 2011; 25:398-404. [DOI: 10.1007/s00540-011-1121-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 02/22/2011] [Indexed: 10/18/2022]
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Snetkov VA, Smirnov SV, Kua J, Aaronson PI, Ward JPT, Knock GA. Superoxide differentially controls pulmonary and systemic vascular tone through multiple signalling pathways. Cardiovasc Res 2010; 89:214-24. [PMID: 20805095 PMCID: PMC3002873 DOI: 10.1093/cvr/cvq275] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Aims The aim of this study was to determine the relative importance of Ca2+ sensitization, ion channels, and intracellular Ca2+ ([Ca2+]i) in the mixed constrictor/relaxation actions of superoxide anion on systemic and pulmonary arteries. Methods and results Pulmonary and mesenteric arteries were obtained from rat. Superoxide was generated in arteries and cells with 6-anilino-5,8-quinolinequinone (LY83583). Following pre-constriction with U46619, 10 μmol/L LY83583 caused constriction in pulmonary and relaxation in mesenteric arteries. Both constrictor and relaxant actions of LY83583 were inhibited by superoxide dismutase and catalase. LY83583 caused Rho-kinase-dependent constriction in α-toxin-permeabilized pulmonary but not mesenteric arteries. Phosphorylation of myosin phosphatase-targeting subunit-1 (MYPT-1; as determined by western blot), was enhanced by LY83583 in pulmonary artery only. However, in both artery types, changes in tension were closely correlated with changes in phosphorylation of the 20 kDa myosin light chain as well as changes in [Ca2+]i (as measured with Fura PE-3), with LY83583 causing increases in pulmonary and decreases in mesenteric arteries. When U46619 was replaced by 30 mmol/L K+, all changes in [Ca2+]i were abolished and LY83583 constricted both artery types. The KV channel inhibitor 4-aminopyridine abolished the LY83583-induced relaxation in mesenteric artery without affecting constriction in pulmonary artery. However, LY83583 caused a similar hyperpolarizing shift in the steady-state activation of KV current in isolated smooth muscle cells of both artery types. Conclusions Superoxide only causes Rho-kinase-dependent Ca2+ sensitization in pulmonary artery, resulting in constriction, and whilst it opens KV channels in both artery types, this only results in relaxation in mesenteric.
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Affiliation(s)
- Vladimir A Snetkov
- Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College London, Room 3.20, Franklin Wilkins Building, Stamford Street, London SE1 9NH, UK
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Alvarez SM, Miner AS, Browne BM, Ratz PH. Failure of Bay K 8644 to induce RhoA kinase-dependent calcium sensitization in rabbit blood vessels. Br J Pharmacol 2010; 160:1326-37. [PMID: 20590624 PMCID: PMC2938805 DOI: 10.1111/j.1476-5381.2010.00751.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 01/18/2010] [Accepted: 01/20/2010] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE RhoA kinase (ROCK) participates in K(+) depolarization (KCl)-induced Ca(2+) sensitization of contraction. Whether constitutive, depolarization- or Ca(2+)-activated ROCK plays the major role in this signalling system remains to be determined. Here, we determined whether Bay K 8644, a dihydropyridine that promotes Ca(2+) channel clusters to operate in a persistent Ca(2+) influx mode, could cause ROCK-dependent Ca(2+) sensitization. EXPERIMENTAL APPROACH Renal and femoral artery rings from New Zealand white rabbits were contracted with Bay K 8644. Tissues were frozen and processed to measure active RhoA and ROCK substrate (myosin phosphatase targeting subunit, MYPT1) and myosin light chain (MLC) phosphorylation, or loaded with fura-2 to measure intracellular free Ca(2+) ([Ca(2+)](i)). Effects of selective inhibitors of contraction were assessed in resting (basal) tissues and those contracted with Bay K 8644. KEY RESULTS Bay K 8644 produced strong increases in [Ca(2+)](i), MLC phosphorylation and tension, but not in MYPT1 phosphorylation. ROCK inhibition by H-1152 abolished basal MYPT1-pT853, diminished basal MLC phosphorylation and inhibited Bay K 8644-induced increases in MLC phosphorylation and tension. MLC kinase inhibition by wortmannin abolished Bay K 8644-induced contraction and increase in MLC phosphorylation but did not inhibit basal MYPT1-pT853. H-1152 and wortmannin had no effect on MYPT1-pT696, but 1 microM staurosporine inhibited basal MYPT1-pT853, MYPT1-pT696 and MLC phosphorylation. CONCLUSIONS AND IMPLICATIONS These data suggest that the constitutive activities of ROCK and a staurosporine-sensitive kinase regulate basal phosphorylation of MYPT1, which participates along with activation of MLC kinase in determining the strength of contraction induced by the Ca(2+) agonist, Bay K 8644.
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Affiliation(s)
- S M Alvarez
- Departments of Biochemistry and Molecular Biology and Pediatrics, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
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Wirth A. Rho kinase and hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1276-84. [PMID: 20460153 DOI: 10.1016/j.bbadis.2010.05.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 04/16/2010] [Accepted: 05/01/2010] [Indexed: 11/26/2022]
Abstract
Arterial hypertension is a multifactorial disease that is characterised by increased peripheral vascular resistance often accompanied by smooth muscle cell hypertrophy and proliferation. Rho kinases (ROCKs) are the most extensively studied effectors of the small G-protein RhoA and abnormalities in RhoA/ROCK signalling have been observed in various cardiovascular disease including hypertension. The RhoA/ROCK-pathway is a key player in different smooth muscle cell functions including contractility, proliferation and migration. Furthermore, there is extensive crosstalk between RhoA/ROCK- and NO-signalling. Therefore, not only ROCK inhibitors but also NO-donators or pleiotropic agents like statins exert their beneficial effects on the cardiovascular system at least in part via Rho/Rho-kinase.
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Affiliation(s)
- Angela Wirth
- Max-Planck-Institute for Heart and Lung Research, Dept. of Pharmacology, Ludwigstraße 43, 61231 Bad Nauheim, Germany.
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Abstract
The pyeloureteral function is to transport urine from the kidneys into the ureter toward the urinary bladder for storage until micturition. A set of mechanisms collaborates to achieve this purpose: the basic process regulating ureteral peristalsis is myogenic, initiated by active pacemaker cells located in the renal pelvis. Great emphasis has been given to hydrodynamic factors, such as urine flow rate in determining the size and pattern of urine boluses which, in turn, affect the mechanical aspects of peristaltic rhythm, rate, amplitude, and baseline pressure. Neurogenic contribution is thought to be limited to play a modulatory role in ureteral peristalsis. The myogenic theory of ureteral peristalsis can be traced back to Engelmann (1) who was able to localize the peristaltic pressure wave's origin in the renal pelvis and suggested that the ureteral contraction impulse passes from one ureteral cell to another, the whole ureter working as a functional syncitium. Recent studies of ureteral biomechanics, smooth muscle cell electrophysiology, membrane ionic currents, cytoskeletal components and pharmacophysiology much improved our understanding of the mechanism of how the urine bolus is propelled, how this process is disturbed in pathological states, and what could be done to improve it.
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Affiliation(s)
- F Osman
- Department of Urology and Clinical Experimental Research Department, Semmelweis University, Budapest, Hungary.
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Shah TJ, Leik CE, Walsh SW. Neutrophil infiltration and systemic vascular inflammation in obese women. Reprod Sci 2009; 17:116-24. [PMID: 19820230 DOI: 10.1177/1933719109348252] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Obesity has become epidemic worldwide and is especially pronounced in women of reproductive age, which is important because obesity is a major risk factor for preeclampsia and chronic hypertension. We hypothesized that vascular inflammation is critical to the pathophysiology of hypertension in obese individuals because obesity and hypertensive disorders share common features related to inflammation. To study this, we collected subcutaneous fat biopsies from normal weight, overweight, and obese women and stained the tissues for CD66b, a neutrophil marker, and for activated nuclear factor-kappaB (NF-kappaB) and cyclooxygenase-2 (COX-2) as markers of inflammation. We found that the number of neutrophils per vessel and the percentage and intensity of vessel staining for CD66b, NF-kappaB and COX-2 were greatest in obese women and least in normal weight women, and that neutrophil infiltration and vascular inflammation significantly correlated with body mass index (BMI) and blood pressure. These data may help explain the relationship between obesity and hypertensive disorders.
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Affiliation(s)
- Tanvi J Shah
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, Virginia 23298, USA
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20
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Freitas MR, Eto M, Kirkbride JA, Schott C, Sassard J, Stoclet JC. Y27632, a Rho-activated kinase inhibitor, normalizes dysregulation in alpha1-adrenergic receptor-induced contraction of Lyon hypertensive rat artery smooth muscle. Fundam Clin Pharmacol 2009; 23:169-78. [PMID: 19298234 DOI: 10.1111/j.1472-8206.2008.00658.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RhoA-activated kinase (ROK) is involved in the disorders of smooth muscle contraction found in hypertension model animals and patients. We examined whether the alpha1-adrenergic receptor agonist-induced ROK signal is perturbed in resistance small mesentery artery (SMA) of Lyon genetically hypertensive (LH) rats, using a ROK antagonist, Y27632. Smooth muscle strips of SMA and aorta were isolated from LH and Lyon normotensive (LN) rats. After Ca(2+)-depletion and pre-treatment with phenylephrine (PE), smooth muscle contraction was induced by serial additions of CaCl(2). In LH SMA Ca(2+) permeated cells to a lesser extent as compared with LN SMA, while CaCl(2)-induced contraction of LH SMA was greater than that of LN SMA, indicating a higher ratio of force to Ca(2+) in LH SMA contraction (Ca(2+) sensitization). No hyper-contraction was observed in LH aorta tissues. Treatment of LH SMA with Y27632 restored both Ca(2+) permeability and Ca(2+)-force relationship to levels seen for LN SMA. In response to PE stimulation, phosphorylation of CPI-17, a phosphorylation-dependent myosin phosphatase inhibitor protein, and MYPT1 at Thr853, the inhibitory phosphorylation site of the myosin phosphatase regulatory subunit, was increased in LN SMA, but remained unchanged in LH SMA. These results suggest that the disorder in ROK-dependent Ca(2+) permeability and Ca(2+)-force relationship is responsible for LH SMA hyper-contraction. Unlike other hypertensive models, the ROK-induced hyper-contractility of LH SMA is independent of MYPT1 and CPI-17 phosphorylation, which suggests that ROK-mediated inhibition of myosin phosphatase does not affect SMA hyper-contractility in LH SMA cells.
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Affiliation(s)
- Maria Regina Freitas
- Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Université Louis Pasteur de Strasbourg, Faculté de Pharmacie, Illkirch-Cedex, France
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Budzyn K, Ravi RM, Miller AA, Sobey CG. Mechanisms of augmented vasoconstriction induced by 5-hydroxytryptamine in aortic rings from spontaneously hypertensive rats. Br J Pharmacol 2008; 155:210-6. [PMID: 18552867 DOI: 10.1038/bjp.2008.247] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE To test whether development of enhanced vasoconstriction to 5-hydroxytryptamine (5-HT; serotonin) in SHR was temporally related to hypertension, elevated vascular superoxide (O(2)(-)) levels, decreased NO bioavailability, or increased contractile effects of cyclooxygenase or rho-kinase and/or PKC. EXPERIMENTAL APPROACH We examined systolic blood pressure (SBP), vascular O(2)(-), and 5-HT-induced contractile responses of aortic segments from 4- and 8-week-old WKY and SHR. KEY RESULTS SBP was 35% higher in SHR than WKY at 4 weeks and 60% higher at 8 weeks. Contractile responses to 5-HT were similar in WKY and SHR at 4 weeks, but were markedly augmented in SHR at 8 weeks. The NO synthase inhibitor, L-NAME, enhanced contractile responses to 5-HT markedly in both strains at 4 weeks and in WKY at 8 weeks, but only very modestly in SHR at 8 weeks. These functional differences were associated with higher O(2)(-) levels in SHR versus WKY at 8 weeks, but not at 4 weeks. The rho-kinase inhibitor, Y-27632, and the PKC inhibitor, Ro 31-8220, each only modestly attenuated contractions in WKY and SHR in each age group, and their effects in each strain were more pronounced at 8 weeks. The cyclooxygenase inhibitor, indomethacin, had no effect on contractile responses. CONCLUSIONS AND IMPLICATIONS Development of augmented vascular contractile responses to 5-HT in SHR is preceded by hypertension. It is associated with increased vascular O(2)(-) levels and reduced modulatory effects of NO, and is unlikely to be due to enhanced activity of rho-kinase, PKC or cyclooxygenase.
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Affiliation(s)
- K Budzyn
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
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Rho-Kinase Inhibitors for Cardiovascular Disease. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2008. [DOI: 10.1016/s0065-7743(08)00006-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Nordquist L, Lai EY, Sjöquist M, Patzak A, Persson AEG. Proinsulin C-peptide constricts glomerular afferent arterioles in diabetic mice. A potential renoprotective mechanism. Am J Physiol Regul Integr Comp Physiol 2007; 294:R836-41. [PMID: 18077505 DOI: 10.1152/ajpregu.00811.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE an increased glomerular filtration rate (GFR) has been postulated as a potential mechanism involved in the progression of diabetic nephropathy. Studies suggest that C-peptide exerts a renoprotective effect on diabetes. The peptide decreases hyperfiltration in patients with type 1 diabetes, as well as in diabetic animal models. In this study, we investigated whether C-peptide causes a change in arteriolar diameter. RESEARCH DESIGN AND METHODS C57-Bl mice were made diabetic by means of a single intravenous injection of alloxan 2 wk prior to the experiment. Age-matched normoglycemic mice served as controls. Afferent arterioles, intact with the glomeruli, were dissected and microperfused. The effect of luminal application of C-peptide, compared with scrambled C-peptide or vehicle, was investigated. The effect of the Rho-kinase inhibitor Y-27632 was also investigated. RESULTS C-peptide constricted afferent arterioles in diabetic mice by -27% compared with the control value. Normoglycemic arterioles administered C-peptide displayed a delayed and minute response (-4%). Scrambled C-peptide or vehicle administration, whether administered to hyperglycemic or normoglycemic mice, did not induce any effect. Addition of Y-27632 abolished the effect of C-peptide. CONCLUSION C-peptide induces constriction of afferent arterioles in diabetic mice. This can reduce enhanced GFR and may be one of the mechanisms in the renoprotective action of C-peptide in diabetes.
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Affiliation(s)
- Lina Nordquist
- Department of Medical Cell Biology, Division of Physiology, University of Uppsala, Uppsala, Sweden
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Allahdadi KJ, Walker BR, Kanagy NL. ROK contribution to endothelin-mediated contraction in aorta and mesenteric arteries following intermittent hypoxia/hypercapnia in rats. Am J Physiol Heart Circ Physiol 2007; 293:H2911-8. [PMID: 17720771 DOI: 10.1152/ajpheart.00217.2007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We reported previously that intermittent hypoxia with CO(2) to maintain eucapnia (IH-C) elevates plasma endothelin-1 (ET-1) and arterial pressure. In small mesenteric arteries (sMA; inner diameter = 150 microm), IH-C augments ET-1 constrictor sensitivity but diminishes ET-1-induced increases in intracellular Ca(2+) concentration, suggesting IH-C exposure increases both ET-1 levels and ET-1-stimulated Ca(2+) sensitization. Because Rho-associated kinase (ROK) can mediate Ca(2+) sensitization, we hypothesized that augmented vasoconstrictor sensitivity to ET-1 in arteries from IH-C-exposed rats is dependent on ROK activation. In thoracic aortic rings, ET-1 contraction was not different between groups, but ROK inhibition (Y-27632, 3 and 10 microM) attenuated ET-1 contraction more in IH-C than in sham arteries (50 +/- 11 and 78 +/- 7% vs. 41 +/- 12 and 48 +/- 9% inhibition, respectively). Therefore, ROK appears to contribute more to ET-1 contraction in IH-C than in sham aorta. In sMA, ROK inhibitors did not affect ET-1-mediated constriction in sham arteries and only modestly inhibited it in IH-C arteries. In ionomycin-permeabilized sMA with intracellular Ca(2+) concentration held at basal levels, Y-27632 did not affect ET-1-mediated constriction in either IH-C or sham sMA and ET-1 did not stimulate ROK translocation. In contrast, inhibition of myosin light-chain kinase (ML-9, 100 microM) prevented ET-1-mediated constriction in sMA from both groups. Therefore, IH-C exposure increases ET-1 vasoconstrictor sensitivity in sMA but not in aorta. Furthermore, ET-1 constriction is myosin light-chain kinase dependent and mediated by Ca(2+) sensitization that is independent of ROK activation in sMA but not aorta. Thus ET-1-mediated signaling in aorta and sMA is altered by IH-C but is dependent on different second messenger systems in small vs. large arteries.
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Affiliation(s)
- Kyan J Allahdadi
- Department of Cell Biology and Physiology, Vascular Physiology Group, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Nishikimi T, Koshikawa S, Ishikawa Y, Akimoto K, Inaba C, Ishimura K, Ono H, Matsuoka H. Inhibition of Rho-kinase attenuates nephrosclerosis and improves survival in salt-loaded spontaneously hypertensive stroke-prone rats. J Hypertens 2007; 25:1053-63. [PMID: 17414670 DOI: 10.1097/hjh.0b013e3280825440] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES We examined whether the Rho/Rho-kinase pathway is involved in the pathogenesis of nephrosclerosis in severely hypertensive rats and assessed the effects of long-term treatment with a Rho-kinase inhibitor, fasudil, on kidney function, histological findings, gene expressions, and survival. We also attempted to elucidate the mechanisms involved. METHODS We studied the following four groups: control Wistar-Kyoto rats (WKY), untreated salt-loaded spontaneously hypertensive stroke-prone rats (SHR-SP), low-dose fasudil (15 mg/kg per day)-treated SHR-SP, and high-dose fasudil (30 mg/kg per day)-treated SHR-SP. After 8 weeks' treatment, the effects of fasudil were examined. RESULTS Untreated SHR-SP were characterized by increased blood pressure without circadian variation, decreased kidney function, abnormal renal morphological findings, and increased messenger RNA expression levels of transforming growth factor beta, collagen I, collagen III, p40phox, p47phox, plasminogen activator inhibitor 1, and intracellular adhesion molecule 1 in the renal cortex, compared with WKY. Long-term high-dose fasudil treatment significantly improved renal function (serum creatinine -32%, creatine clearance +39%), proteinuria (-92%) and histological findings (glomerular injury score -57%, arteriolar injury score -55%, fibrous area -40%, ED-1-positive cells -43%) without changing blood pressure or circadian variation, compared with untreated SHR-SP. In addition, fasudil significantly improved increased mRNA expression levels in the renal cortex. Furthermore, high-dose fasudil significantly prolonged survival time compared with untreated SHR-SP (P < 0.01). Low-dose fasudil treatment improved these variables slightly, but did not affect most significantly. CONCLUSION The Rho/Rho-kinase pathway participates in the pathogenesis of nephrosclerosis in SHR-SP independently of blood pressure-lowering activity, partly by upregulation of the gene expressions of extracellular matrix, oxidative stress, adhesion molecules, and antifibrinolysis.
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Affiliation(s)
- Toshio Nishikimi
- Department of Hypertension and Cardiorenal Medicine, Dokkyo Medical University School of Medicine, Mibu, Tochigi 321-0293, Japan.
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Barman SA. Vasoconstrictor effect of endothelin-1 on hypertensive pulmonary arterial smooth muscle involves Rho-kinase and protein kinase C. Am J Physiol Lung Cell Mol Physiol 2007; 293:L472-9. [PMID: 17468135 DOI: 10.1152/ajplung.00101.2006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although one of the common characteristics of pulmonary hypertension is abnormal sustained vasoconstriction, the signaling pathways that mediate this heightened pulmonary vascular response are still not well defined. Protein kinase C (PKC) and Rho-kinase are regulators of smooth muscle contraction induced by G protein-coupled receptor agonists including endothelin-1 (ET-1), which has been implicated as a signaling pathway in pulmonary hypertension. Toward this end, it was hypothesized that both Rho-kinase and PKC mediate the pulmonary vascular response to ET-1 in hypertensive pulmonary arterial smooth muscle, and therefore, the purpose of this study was to determine the role of PKC and Rho-kinase signaling in ET-1-induced vasoconstriction in both normotensive (Sprague-Dawley) and hypertensive (Fawn-Hooded) rat pulmonary arterial smooth muscle. Results indicate that ET-1 caused greater vasoconstriction in hypertensive pulmonary arteries compared with the normal vessels, and treatment with the PKC antagonists chelerythrine, rottlerin, and Gö 6983 inhibited the vasoconstrictor response to ET-1 in the hypertensive vessels. In addition, the specific Rho-kinase inhibitor Y-27632 significantly attenuated the effect of ET-1 in both normotensive and hypertensive phenotypes, with greater inhibition occurring in the hypertensive arteries. Furthermore, Western blot analysis revealed that ET-1 increased RhoA expression in both normotensive and hypertensive pulmonary arteries, with expression being greater in the hypertensive state. These results suggest that both PKC and Rho/Rho-kinase mediate the heightened pulmonary vascular response to ET-1 in hypertensive pulmonary arterial smooth muscle.
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MESH Headings
- Amides/pharmacology
- Animals
- Blotting, Western
- Carbazoles/pharmacology
- Endothelin-1/metabolism
- Endothelin-1/pharmacology
- Enzyme Inhibitors/pharmacology
- Hypertension, Pulmonary/metabolism
- Hypertension, Pulmonary/pathology
- Hypertrophy, Right Ventricular/metabolism
- Hypertrophy, Right Ventricular/pathology
- Indoles
- Intracellular Signaling Peptides and Proteins/antagonists & inhibitors
- Intracellular Signaling Peptides and Proteins/metabolism
- Male
- Maleimides
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Potassium Chloride/pharmacology
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- Protein Serine-Threonine Kinases/metabolism
- Pulmonary Artery/drug effects
- Pulmonary Artery/enzymology
- Pyridines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Species Specificity
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
- rho-Associated Kinases
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Affiliation(s)
- Scott A Barman
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912, USA.
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Hu E, Lee D. Rho kinase as potential therapeutic target for cardiovascular diseases: opportunities and challenges. Expert Opin Ther Targets 2007; 9:715-36. [PMID: 16083339 DOI: 10.1517/14728222.9.4.715] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Rho kinase (ROCK) belongs to a family of Ser/Thr protein kinases that are activated via interaction with the small GTP-binding protein RhoA. Growing evidence suggests that RhoA and ROCK participate in a variety of important physiological functions in vasculature including smooth muscle contraction, cell proliferation, cell adhesion and migration, and many aspects of inflammatory responses. As these processes mediate the onset and progression of cardiovascular disease, modulation of the Rho/ROCK signalling pathway is a potential strategy for targeting an array of cardiovascular indications. Two widely employed ROCK inhibitors, fasudil and Y-27632, have provided preliminary but compelling evidence supporting the potential cardiovascular benefits of ROCK inhibition in preclinical animal disease models and in the clinic. This review summarises the molecular biology of ROCK and its biological functions in smooth muscle, endothelium and other vascular tissues. In addition, there will be a focus on recent progress demonstrating the benefits of ROCK inhibition in several animal models of cardiovascular diseases. Finally, recent progress in the identification of novel ROCK inhibitors and challenges associated with their development for clinical use will be discussed.
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Affiliation(s)
- Erding Hu
- Center of Excellence for Cardiovascular and Urogenital Drug Discovery, Department of Vascular Biology, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road, King of Prussia, PA 19406, USA.
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Williams J, Bogwu J, Oyekan A. The role of the RhoA/Rho-kinase signaling pathway in renal vascular reactivity in endothelial nitric oxide synthase null mice. J Hypertens 2006; 24:1429-36. [PMID: 16794494 DOI: 10.1097/01.hjh.0000234125.01638.3b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Smooth muscle contraction is regulated by the small GTPase RhoA and its target, Rho-kinase and recent evidence indicates that nitric oxide (NO) causes vasodilation through inhibition of the RhoA/Rho-kinase (ROCK) signaling pathway. AIM This study tested the hypothesis that the enhanced renal vascular tone and systemic hypertension in endothelial nitric oxide synthase (eNOS) null mice is due to disinhibition of the ROCK signaling pathway. METHODS Systolic blood pressure (SBP) was measured by tail-cuff plethysmography and the isolated Krebs-perfused kidney preparation was used to evaluate renal vascular responses in C57BL/6 (wild type, WT) and eNOS knockout (KO) mice treated with Y-27632, a ROCK inhibitor. RESULTS Compared with the WT mice, Rho kinase activity was higher in eNOS KO mice (37 +/- 8%, P < 0.05) as was SBP (33 +/- 4%, P < 0.05), basal renal perfusion pressure (31 +/- 4%, P < 0.05) and renal vascular resistance (35 +/- 4%, P < 0.05). Y-27632 abolished these differences. Vasoconstriction elicited by angiotensin II (Ang II) or phenylephrine (PE), G-protein-coupled receptor (GPCR) agonists, but not that elicited by arachidonic acid or KCl, was greater in eNOS KO mice. Y-27632 eliminated the amplified vasoconstriction elicited by Ang II or phenylephrine but to a greater extent in eNOS KO mice. Similarly, responses elicited by guanosine 5'-gamma-thiotriphosphate (GTPgammaS), a non-hydrolyzable GTP analog, or sodium tetrafluoride (NaF4), an activator of G-proteins, was greater in eNOS KO mice, 53 +/- 14 and 50 +/- 3%, respectively. Y-27632 normalized the difference. Y-27632 also elicited a dose-dependent renal vasodilation that was greater in eNOS KO mice. CONCLUSIONS These results show that the ROCK signaling pathway is amplified in the eNOS KO mouse kidney and that the enhanced renal vascular tone and selective increase in reactivity to GPCR agonists supports a role for ROCK in the hypertension and vascular dysfunction in the eNOS KO mice.
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Affiliation(s)
- Janae Williams
- Center for Cardiovascular Diseases, College of Pharmacy and Health Sciences, Texas Southern University, Houston, Texas 77004, USA
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Futer O, Saadat AR, Doran JD, Raybuck SA, Pazhanisamy S. Phosphoryl transfer is not rate-limiting for the ROCK I-catalyzed kinase reaction. Biochemistry 2006; 45:7913-23. [PMID: 16784244 DOI: 10.1021/bi052468q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rho-associated coiled-coil kinase, ROCK, is implicated in Rho-mediated cell adhesion and smooth muscle contraction. Animal models suggest that the inhibition of ROCK can ameliorate conditions, such as vasospasm, hypertension, and inflammation. As part of our effort to design novel inhibitors of ROCK, we investigated the kinetic mechanism of ROCK I. Steady-state bisubstrate kinetics, inhibition kinetics, isotope partition analysis, viscosity effects, and presteady-state kinetics were used to explore the kinetic mechanism. Plots of reciprocals of initial rates obtained in the presence of nonhydrolyzable ATP analogues and the small molecule inhibitor of ROCK, Y-27632, against the reciprocals of the peptide concentrations yielded parallel lines (uncompetitive pattern). This pattern is indicative of an ordered binding mechanism, with the peptide adding first. The staurosporine analogue K252a, however, gave a noncompetitive pattern. When a pulse of (33)P-gamma-ATP mixed with ROCK was chased with excess unlabeled ATP and peptide, 0.66 enzyme equivalent of (33)P-phosphate was incorporated into the product in the first turnover. The presence of ATPase activity coupled with the isotope partition data is a clear evidence for the existence of a viable [E-ATP] complex in the kinase reaction and implicates a random binding mechanism. The k(cat)/K(m) parameters were fully sensitive to viscosity (viscosity effects of 1.4 +/- 0.2 and 0.9 +/- 0.3 for ATP and peptide 5, respectively), and therefore, the barriers to dissociation of either substrate are higher than the barrier for the phosphoryl transfer step. As a consequence, not all the binding steps are at fast equilibrium. The observation of a burst in presteady-state kinetics (k(b) = 10.2 +/- 2.1 s(-)(1)) and the viscosity effect on k(cat) of 1.3 +/- 0.2 characterize the phosphoryl transfer step to be fast and the release of product and/or the enzyme isomerization step accompanying it as rate-limiting at V(max) conditions. From the multiple kinetic studies, most of the rate constants for the individual steps were either evaluated or estimated.
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Affiliation(s)
- Olga Futer
- Vertex Pharmaceuticals Incorporated, 130 Waverly Street, Cambridge, Massachusetts 02139-4242, USA
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Hung GHY, Jones RL, Lam FFY, Chan KM, Hidaka H, Suzuki M, Sasaki Y. Investigation of the pronounced synergism between prostaglandin E2 and other constrictor agents on rat femoral artery. Prostaglandins Leukot Essent Fatty Acids 2006; 74:401-15. [PMID: 16737803 DOI: 10.1016/j.plefa.2006.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 03/22/2006] [Accepted: 04/11/2006] [Indexed: 11/29/2022]
Abstract
This study investigates the pronounced synergism between the weak contractile action of prostaglandin E(2) (PGE(2)) and strong actions of phenylephrine, U-46619 and K(+) on rat isolated femoral artery. The potency ranking for synergism was SC-46275 (prostanoid receptor agonist selectivity: EP(3)>>EP(1))=sulprostone (EP(3)>EP(1))>17-phenyl PGE(2) (EP(1)>EP(3)). The novel EP(3) antagonist L-798106 (0.2-1microM) blocked the enhanced action of sulprostone (pA(2)=7.35-8.10), while the EP(1) antagonist SC-51322 (1microM) did not (pA(2)<6.0). Matching responses to priming agent and priming agent/sulprostone were similarly suppressed by nifedipine (300nM) and the selective Rho-kinase inhibitors H-1152 (0.1-1microM) and Y-27632 (1-10microM). Our findings implicate an EP(3) receptor in the prostanoid component of contractile synergism. While the synergism predominantly operates through a Ca(2+) influx-Rho-kinase pathway, the EP(3) receptor does not necessarily transduce via Rho-kinase.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Alprostadil/analogs & derivatives
- Alprostadil/pharmacology
- Animals
- Dinoprostone/analogs & derivatives
- Dinoprostone/analysis
- Dinoprostone/pharmacology
- Drug Interactions
- Drug Synergism
- Femoral Artery/drug effects
- In Vitro Techniques
- Intracellular Signaling Peptides and Proteins
- Male
- Nifedipine/pharmacology
- Phenylephrine/pharmacology
- Potassium/pharmacology
- Prostaglandins F, Synthetic/pharmacology
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- Rats
- Rats, Sprague-Dawley
- Receptors, Prostaglandin/agonists
- Receptors, Prostaglandin/metabolism
- Receptors, Prostaglandin E/agonists
- Receptors, Prostaglandin E/antagonists & inhibitors
- Receptors, Prostaglandin E/metabolism
- Receptors, Prostaglandin E, EP1 Subtype
- Receptors, Prostaglandin E, EP3 Subtype
- Sensitivity and Specificity
- Sulfonamides/metabolism
- Vasoconstrictor Agents/pharmacology
- rho-Associated Kinases
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Affiliation(s)
- Gloria H Y Hung
- Department of Pharmacology, Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
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Chen X, Pavlish K, Zhang HY, Benoit JN. Effects of chronic portal hypertension on agonist-induced actin polymerization in small mesenteric arteries. Am J Physiol Heart Circ Physiol 2006; 290:H1915-21. [PMID: 16339838 DOI: 10.1152/ajpheart.00643.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability of arterial smooth muscle to respond to vasoconstrictor stimuli is reduced in chronic portal hypertension (PHT). Additional evidence supports the existence of a postreceptor defect in vascular smooth muscle excitation contraction coupling. However, the nature of this defect is unclear. Recent studies have shown that vasoconstrictor stimuli induce actin polymerization in smooth muscle and that the associated increase in F-actin is necessary for force development. In the present study we have tested the hypothesis that impaired actin polymerization contributes to reduced vasoconstrictor function in small mesenteric arteries derived from rats with chronic prehepatic PHT. In vitro studies were conducted on small mesenteric artery vessel rings isolated from normal and PHT rats. Isometric tension responses to incremental concentrations of phenylephrine were significantly reduced in PHT arteries. The ability to polymerize actin in portal hypertensive mesenteric arteries stimulated by phenylephrine was attenuated compared with control. Inhibition of cAMP-dependent protein kinase (PKA) restored agonist-induced actin polymerization of arteries from PHT rats to normal levels. Depolymerization of actin in arteries from normal rats reduced maximal contractile force but not myosin phosphorylation, suggesting a key role for the dynamic regulation of actin polymerization in the maintenance of vascular smooth muscle contraction. We conclude that reductions in agonist-induced maximal force development of PHT vascular smooth muscle is due, in part, to impaired actin polymerization, and prolonged PKA activation may underlie these changes.
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Affiliation(s)
- Xuesong Chen
- Deparment of Pharmacology, Physiology, and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
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Seasholtz TM, Wessel J, Rao F, Rana BK, Khandrika S, Kennedy BP, Lillie EO, Ziegler MG, Smith DW, Schork NJ, Brown JH, O'Connor DT. Rho kinase polymorphism influences blood pressure and systemic vascular resistance in human twins: role of heredity. Hypertension 2006; 47:937-47. [PMID: 16585408 DOI: 10.1161/01.hyp.0000217364.45622.f0] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Rho/Rho kinase (ROCK) pathway is implicated in experimental hypertension. We, therefore, explored the role of ROCK2 genetic variation in human blood pressure (BP) regulation, exploiting the advantages of a human twin sample to probe heritability. The focus of this work is the common nonsynonymous variant at ROCK2: Thr431Asn. Cardiovascular and autonomic traits displayed substantial heritability (from approximately 33% to 71%; P<0.05). The Asn/Asn genotype (compared with Asn/Thr or Thr/Thr) was associated with greater resting systolic (P<0.001), diastolic (P<0.0001), and mean BP (P<0.0001); allelic variation at ROCK2 accounted for up to approximately 5% of BP variation (P<0.0001). Systemic vascular resistance was higher in Asn/Asn individuals (P=0.049), whereas cardiac output, large artery compliance, and vasoactive hormone secretion were not different. Coupling of the renin-angiotensin system to systemic resistance and BP was diminished in Asn/Asn homozygotes, suggesting genetic pleiotropy of Thr431Asn, confirmed by bivariate genetic analyses. The Asn/Asn genotype also predicted higher BP after environmental (cold) stress. The rise in heart rate after cold was less pronounced in Asn/Asn individuals, consistent with intact baroreceptor function, and baroreceptor slope was not influenced by genotype. Common genetic variation (Thr431Asn) at ROCK2 predicts increased BP, systemic vascular resistance (although not large artery compliance), and resistance in response to the endogenous renin-angiotensin system, indicating a resistance vessel-based effect on elevated BP. The results suggest that common variation in ROCK2 exerts systemic resistance-mediated changes in BP, documenting a novel mechanism for human circulatory control, and suggesting new possibilities for diagnostic profiling and treatment of subjects at risk of developing hypertension.
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Affiliation(s)
- Tammy M Seasholtz
- Department of Pharmacology, University of California, San Diego, CA, USA
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33
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Ryu SK, Ahn DS, Cho YE, Choi SK, Kim YH, Morgan KG, Lee YH. Augmented sphingosylphosphorylcholine-induced Ca2+-sensitization of mesenteric artery contraction in spontaneously hypertensive rat. Naunyn Schmiedebergs Arch Pharmacol 2006; 373:30-6. [PMID: 16521007 DOI: 10.1007/s00210-006-0036-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Accepted: 01/10/2006] [Indexed: 10/24/2022]
Abstract
Sphingosylphosphorylcholine (SPC) is a vasoconstricting lysosphingolipid, and the RhoA/Rho-kinase pathway plays an important role in SPC-induced contraction. Since RhoA/Rho-kinase-mediated signaling is involved in the generation and/or maintenance of hypertension, we compared the effect of SPC on the contractility of endothelium-denuded small mesenteric arteries in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Fura-2 Ca2+ signals, contractile responses, and phosphorylation of 20-kDa myosin light chains (MLC20) were measured. Ten microM SPC induced a gradual and sustained vasoconstriction, which was greater in arteries of the SHR (82.5 +/- 4.3%, n=9) than in those of the WKY (26.7 +/- 4.5%, n=10). In Ca2+-free media, SPC gradually increased vascular tone in the SHR, but caused little vasoconstriction in the WKY. In the SHR and WKY, SPC evoked a greater vasoconstriction than did high K+ depolarization at a given Ca2+ ratio, and the Ca2+ ratio-tension curve induced by SPC was significantly shifted to the left compared with that induced by high K+ depolarization. However, the magnitude of shift to the left was greater in the SHR than in the WKY. The Rho-kinase inhibitor Y-27632 significantly inhibited SPC-induced contractions, but neither the protein kinase C inhibitor calphostin-C nor PD98059, which inhibits activation of some mitogen-activated protein kinases, had any effect on the SHR or the WKY. SPC significantly increased the phosphorylation of MLC20 in both the SHR and the WKY, and Y-27632 inhibited the SPC-induced increase in MLC(20) phosphorylation in the SHR. Our results suggest that SPC induces greater vascular tone in the SHR than in the WKY. Furthermore, our results indicate that activation of the Rho-kinase pathway plays an important role in the SPC-induced Ca2+ sensitization in the SHR.
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Affiliation(s)
- Sung-Kyung Ryu
- Department of Physiology, College of Medicine, Yonsei University, C.P.O. Box 8044, Seoul, 120-752, South Korea
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34
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Budzyn K, Paull M, Marley PD, Sobey CG. Segmental differences in the roles of rho-kinase and protein kinase C in mediating vasoconstriction. J Pharmacol Exp Ther 2006; 317:791-6. [PMID: 16452393 DOI: 10.1124/jpet.105.100040] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Rho-kinase and protein kinase C (PKC) have each been reported to mediate vasoconstriction via calcium sensitization. However, the relative contributions of these two kinases to vascular contraction, and whether their roles vary between large and small arteries, are largely unknown. We therefore assessed the relative roles of rho-kinase and PKC in mediating vasoconstriction in arteries from three segments of the aortic and mesenteric vasculature. We studied contractile responses of rat isolated thoracic aorta (diameter approximately 2 mm), superior mesenteric artery (SMA; approximately 1.5 mm), and second order branches of the superior mesenteric artery (BMA; approximately 300 mum). The roles of rho-kinase and PKC in mediating contractile responses to phenylephrine, 9,11-dideoxy-9,11-methanoepoxy prostaglandin F(2alpha) (U46619), and KCl were assessed by using the rho-kinase inhibitor R-[+]-trans-N-[4-pyridyl]-4-[1-aminoethyl]-cycloheaxanecarboxamide (Y-27632) (1 and 10 muM) and the PKC inhibitor 3-[1-[3-(amidinothio)propyl-1H-indol-3-yl]-3-(1-methyl-1H-indol-3-yl) maleimide (Ro 31-8220) (5 muM). Contractile responses of aorta and SMA were reduced by either 1 or 10 muM Y-27632 (P < 0.05), whereas responses of BMA were reduced by 10 muM (P < 0.05) but not 1 muM Y-27632. In contrast, Ro 31-8220 partly reduced contractile responses in aorta and SMA (P < 0.05), but it abolished responses of BMA (P < 0.05). Cotreatment with Y-27632 and Ro 31-8220 markedly attenuated contractile responses to phenylephrine and KCl in all vessels, but it had only a moderate inhibitory effect on responses to U46619 in aorta and SMA. Thus, contractile responses of the larger arteries can involve both rho-kinase and PKC to varying degrees. Conversely, contractile responses of small mesenteric resistance arteries seem to be mediated exclusively by PKC, with no apparent role for rho-kinase.
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Affiliation(s)
- Klaudia Budzyn
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
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35
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Ozdem SS, Batu O, Tayfun F, Yalcin O, Meiselman HJ, Baskurt OK. The effect of morphine in rat small mesenteric arteries. Vascul Pharmacol 2005; 43:56-61. [PMID: 15939674 DOI: 10.1016/j.vph.2005.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Accepted: 04/11/2005] [Indexed: 11/15/2022]
Abstract
We investigated the effect of morphine in phenylephrine (PE)- or KCl-precontracted rat small mesenteric arteries. Morphine (10(-6)-10(-4) M) administration caused concentration-dependent relaxation responses in small mesenteric arteries precontracted by PE or KCl. Removal of endothelium did not significantly alter the relaxation responses to morphine. The relaxant responses to morphine were partially inhibited by pre-treatment of tissues with naloxone (NAL, 10(-5) M) for 20 min. The inhibitory effect of NAL on relaxant responses to morphine in PE- or KCl-precontracted arteries did not differ significantly between endothelium-intact and endothelium-denuded preparations. Incubation of endothelium-intact or endothelium-denuded arterial segments with NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME, 10(-4) M) or cyclooxygenase (COX) inhibitor indomethacin (10(-5) M) or histamine H(1)-receptor blocker diphenhydramine (10(-6) M), for 20 min did not inhibit the relaxation responses to morphine. Small mesenteric arterial segment contractions induced by stepwise addition of calcium to high KCl solution with no calcium were almost completely inhibited by morphine. These findings suggested that morphine-induced relaxation responses in isolated rat small mesenteric arteries were neither dependent on endothelium nor blocked by NOS or COX inhibition but they rather seem to depend on an interaction of morphine with calcium influx pathways.
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Affiliation(s)
- Sadi S Ozdem
- Department of Pharmacology, Akdeniz University, Medical Faculty, 07070 Antalya, Turkey.
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36
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Naik JS, Xiang L, Hester RL. Enhanced role for RhoA-associated kinase in adrenergic-mediated vasoconstriction in gracilis arteries from obese Zucker rats. Am J Physiol Regul Integr Comp Physiol 2005; 290:R154-61. [PMID: 16141308 DOI: 10.1152/ajpregu.00245.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Obesity, insulin resistance, dyslipidemia, and hypertension are components of the pathophysiological state known as metabolic syndrome. Adrenergic vasoconstriction is mediated through increases in cytosolic Ca2+ and the myofilaments' sensitivity to Ca2+. In many pathophysiological states, there is an enhanced role for Rho kinase (ROK)-mediated increases in Ca2+ sensitivity of the contractile apparatus. Thus we hypothesized that there is a greater role for ROK-mediated increases in Ca2+ sensitivity in alpha1-adrenergic vasoconstriction in arteries from obese Zucker (OZ) rats. Therefore, small gracilis muscle arteries from 11- to 12-wk-old and 16- to 18-wk-old lean and OZ rats were isolated, cannulated, and pressurized to 75 mmHg. For some experiments, vessels were loaded with fura 2-AM. Changes in luminal diameter and vessel wall Ca2+ concentration ([Ca2+]) were measured in response to phenylephrine (PE), the thromboxane mimetic U-46619, and KCl. alpha1-Adrenergic vasoconstriction was similar between 11- to 12-wk-old lean and obese animals and greater in older obese animals compared with controls. PE-induced increases in vascular smooth muscle cell [Ca2+] were blunted in OZ animals compared with lean controls in both age groups of animals. KCl and U-46619 elicited similar vasoconstriction and vascular smooth muscle cell [Ca2+] in both groups. ROK inhibition attenuated PE vasoconstriction to a greater degree in arteries from 11- to 12-wk-old OZ rats compared with lean animals; ROK inhibition in arteries from older rats right shifted both concentration-response curves to the same point. Total RhoA and ROKalpha protein expressions were similar between groups. These results suggest an enhanced role for the ROK pathway in alpha1-adrenergic vasoconstriction in metabolic syndrome.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Adrenergic Agents/pharmacology
- Aging
- Amides/pharmacology
- Animals
- Arteries/drug effects
- Arteries/enzymology
- Arteries/physiology
- Calcium Signaling
- Gene Expression Regulation
- In Vitro Techniques
- Intracellular Signaling Peptides and Proteins
- Male
- Muscle, Skeletal
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Obesity/physiopathology
- Phenylephrine/pharmacology
- Potassium Chloride/pharmacology
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Pyridines/pharmacology
- Rats
- Rats, Zucker
- Thinness
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
- rho-Associated Kinases
- rhoA GTP-Binding Protein/genetics
- rhoA GTP-Binding Protein/metabolism
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Affiliation(s)
- Jay S Naik
- University of Mississippi Medical Center, Deptartment of Physiology and Biophysics, 2500 N. State St., Jackson, MS 39216, USA.
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37
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Ratz PH, Berg KM, Urban NH, Miner AS. Regulation of smooth muscle calcium sensitivity: KCl as a calcium-sensitizing stimulus. Am J Physiol Cell Physiol 2005; 288:C769-83. [PMID: 15761211 DOI: 10.1152/ajpcell.00529.2004] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
KCl has long been used as a convenient stimulus to bypass G protein-coupled receptors (GPCR) and activate smooth muscle by a highly reproducible and relatively “simple” mechanism involving activation of voltage-operated Ca2+channels that leads to increases in cytosolic free Ca2+([Ca2+]i), Ca2+-calmodulin-dependent myosin light chain (MLC) kinase activation, MLC phosphorylation and contraction. This KCl-induced stimulus-response coupling mechanism is a standard tool-set used in comparative studies to explore more complex mechanisms generated by activation of GPCRs. One area where this approach has been especially productive is in studies designed to understand Ca2+sensitization, the relationship between [Ca2+]iand force produced by GPCR agonists. Studies done in the late 1980s demonstrated that a unique relationship between stimulus-induced [Ca2+]iand force does not exist: for a given increase in [Ca2+]i, GPCR activation can produce greater force than KCl, and relaxant agents can produce the opposite effect to cause Ca2+desensitization. Such changes in Ca2+sensitivity are now known to involve multiple cell signaling strategies, including translocation of proteins from cytosol to plasma membrane, and activation of enzymes, including RhoA kinase and protein kinase C. However, recent studies show that KCl can also cause Ca2+sensitization involving translocation and activation of RhoA kinase. Rather than complicating the Ca2+sensitivity story, this surprising finding is already providing novel insights into mechanisms regulating Ca2+sensitivity of smooth muscle contraction. KCl as a “simple” stimulus promises to remain a standard tool for smooth muscle cell physiologists, whose focus is to understand mechanisms regulating Ca2+sensitivity.
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Affiliation(s)
- Paul H Ratz
- Virginia Commonwealth Univ., School of Medicine, Dept. of Biochemistry, 1101 E. Marshall St., PO Box 980614, Richmond, VA 23298-0614, USA.
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Löhn M, Steioff K, Bleich M, Busch AE, Ivashchenko Y. Inhibition of Rho-kinase stimulates nitric oxide-independent vasorelaxation. Eur J Pharmacol 2004; 507:179-86. [PMID: 15659308 DOI: 10.1016/j.ejphar.2004.11.047] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Accepted: 11/23/2004] [Indexed: 01/14/2023]
Abstract
Vasoconstrictor factors, like urotensin, angiotensin and catecholamines, activate Rho-dependent serine-threonine kinase (Rho-kinase) and inhibition of this pathway represents a novel therapy for cardiovascular diseases with hypertensive syndrome. The disbalance of relaxing endothelial nitric oxide (NO)-producing and vasoconstrictive pathways can be especially important in diseases where hypertension is accompanied by endothelial dysfunction that compromises NO generation. However, a recent study reported that the efficacy of the Rho-kinase inhibitor (R)-(+)-trans-N-(4-Pyridyl)-4-(1-aminoethyl)cyclohexanecarboxamide (Y27632) is dramatically attenuated upon removal of endothelium or inhibition of endothelial NO synthase (eNOS). This raises the question whether Rho-kinase inhibition could be an effective treatment in case of hypertension associated with endothelial dysfunction. The purpose of the present study was to determine whether the vasorelaxing effect of Rho-kinase inhibition is mediated through eNOS-dependent mechanisms. We show here that in the models of genetically reduced endothelial NO production (eNOS-/- mice and spontaneous hypertensive rats (SHR)) or in models of pharmacologically reduced endogenous NO production (N(omega)-nitro-L-arginine methyl ester (LNAME) treatment), Rho-kinase inhibition induced a strong vasodilation and reduction of blood pressure indicating independence of Rho-kinase pathway from eNOS. An additional important finding of our study is that Rho-kinase inhibitors induce a strong vasorelaxation and blood pressure reduction upon intravenous injection not only in hypertensive but in normotensive animals, as well. Inhibition of Rho-kinase represents a promising possibility to treat hypertension that is accompanied by endothelial dysfunction.
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Affiliation(s)
- Matthias Löhn
- Aventis Pharma GmbH, Department Cardiovascular Diseases, Industriepark Höchst, 65926 Frankfurt am Main, Germany.
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39
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Andresen BT, Shome K, Jackson EK, Romero GG. AT2 receptors cross talk with AT1 receptors through a nitric oxide- and RhoA-dependent mechanism resulting in decreased phospholipase D activity. Am J Physiol Renal Physiol 2004; 288:F763-70. [PMID: 15572519 DOI: 10.1152/ajprenal.00323.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ANG II activation of phospholipase D (PLD) is required for ERK and NAD(P)H oxidase activation, both of which are involved in hypertension. Previous findings demonstrate that ANG II stimulates PLD activity through AT(1) receptors in a RhoA-dependent mechanism. Additionally, endogenous AT(2) receptors in preglomerular smooth muscle cells attenuate ANG II-mediated PLD activity. In the present study, we examined the signal transduction mechanisms used by endogenous AT(2) receptors to modulate ANG II-induced PLD activity through either PLA(2) generation of lysophosphatidylethanolamine or Galpha(i)-mediated generation of nitric oxide (NO) and interaction with RhoA. Blockade of AT(2) receptors, Galpha(i) and NO synthase, but not PLA(2), enhanced ANG II-mediated PLD activity in cells rich in, but not poor in, AT(2) receptors. Moreover, NO donors, a direct activator of guanylyl cyclase and a cGMP analog, but not lysophosphatidylethanolamine, inhibited ANG II-mediated PLD activity, whereas an inhibitor of guanylyl cyclase augmented ANG II-induced PLD activity. AT(2) receptor- and NO-mediated attenuation of ANG II-induced PLD activity was completely lost in cells transfected with S188A RhoA, which cannot be phosphorylated on serine 188. Therefore, our data indicate that AT(2) receptors activate Galpha(i), subsequently stimulating NO synthase and leading to increased soluble guanylyl cyclase activity, generation of cGMP, and activation of a protein kinase, resulting in phosphorylation of RhoA on serine 188. Furthermore, because AT(2) receptors inhibit AT(1) receptor signaling to PLD via modulating RhoA activity, AT(2) receptor signaling can potentially regulate multiple vasoconstrictive signaling systems through inactivating RhoA.
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Affiliation(s)
- Bradley T Andresen
- Dept. of Pharmacology, W1345 Biomedical Science Tower, Univ. of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA
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40
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Lee DL, Webb RC, Jin L. Hypertension and RhoA/Rho-kinase signaling in the vasculature: highlights from the recent literature. Hypertension 2004; 44:796-9. [PMID: 15520302 DOI: 10.1161/01.hyp.0000148303.98066.ab] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Under normal conditions, contractile activity in vascular smooth muscle is initiated by either receptor activation (norepinephrine, angiotensin II, etc.) or by a stretch-activated mechanism. After this activation, several signaling pathways can initiate a Ca2+-calmodulin interaction to stimulate phosphorylation of the light chain of myosin. Ca2+ sensitization of the contractile proteins is signaled by the RhoA/Rho-kinase pathway to inhibit the dephosphorylation of the light chain by myosin phosphatase thereby maintaining force generation. In opposition to force generation, NO is released from endothelial cells and causes vasodilation through inhibition of the RhoA/Rho-kinase signaling pathway. This brief review will highlight recent studies demonstrating a role for the RhoA/Rho-kinase signaling pathway in the increased vasoconstriction characteristic of hypertension.
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Affiliation(s)
- Dexter L Lee
- Department of Physiology, Medical College of Georgia, Augusta 30912-3000, USA
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41
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Sylvester JT. The tone of pulmonary smooth muscle: ROK and Rho music? Am J Physiol Lung Cell Mol Physiol 2004; 287:L624-30. [PMID: 15355859 DOI: 10.1152/ajplung.00215.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- J T Sylvester
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
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42
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Shabir S, Borisova L, Wray S, Burdyga T. Rho-kinase inhibition and electromechanical coupling in rat and guinea-pig ureter smooth muscle: Ca2+-dependent and -independent mechanisms. J Physiol 2004; 560:839-55. [PMID: 15331677 PMCID: PMC1665275 DOI: 10.1113/jphysiol.2004.070615] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Recent data have shown Ca(2+)-dependent activation of Rho-kinase by sustained depolarization of arterial smooth muscle. Visceral smooth muscles, however, contract phasically in response to action potentials and it is unclear whether Ca(2+)-dependent or -independent Rho-kinase activation occurs. We have therefore investigated this, under physiologically relevant conditions, in intact ureter. Action potentials, ionic currents, Ca(2+) transients, myosin light chain (MLC) phosphorylation and phasic contraction evoked by action potentials in guinea-pig and rat ureter were investigated. In rat, but not guinea-pig ureter, three Rho-kinase inhibitors, Y-27632, HA-1077 and H-1152, significantly decreased phasic contractions and Ca(2+) transients. Voltage- and current-clamp data showed that Rho-kinase inhibition reduced the plateau component of the action potential, inhibited Ca(2+)-channels and, indirectly, Ca(2+)-activated Cl(-) channels. The Ca(2+) channel agonist Bay K8644 could reverse these effects. The K(+) channel blocker TEA could also reverse the inhibitory effect of Y-27632 on the action potential and Ca(2+) transient. Ca(2+) transients and inward current, activated by carbachol-induced sarcoplasmic reticulum Ca(2+)release, were not affected by Rho-kinase inhibition. Rho-kinase inhibition produced a Ca(2+)-independent increase in the relaxation rate of contraction, associated with acceleration of MLC dephosphorylation, which was sensitive to calyculin A. These data show for the first time that: (1) Rho-kinase has major effects on Ca(2+) signalling associated with the action potential, (2) this effect is species dependent and (3) Rho-kinase controls relaxation of phasic contraction of myogenic origin. Thus Rho-kinase can modulate phasic smooth muscle in the absence of agonist, and the mechanisms are both Ca(2+)-dependent, involving ion channels, and Ca(2+)-independent, involving MLC phosphorylation activity.
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Affiliation(s)
- S Shabir
- Department of Physiology, The University of Liverpool, Liverpool L69 3BX, UK
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Wehrwein EA, Northcott CA, Loberg RD, Watts SW. Rho/Rho kinase and phosphoinositide 3-kinase are parallel pathways in the development of spontaneous arterial tone in deoxycorticosterone acetate-salt hypertension. J Pharmacol Exp Ther 2004; 309:1011-9. [PMID: 14982964 DOI: 10.1124/jpet.103.062265] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypertension is characterized by abnormal vascular contractility and function. Arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive rats develop spontaneous tone that is not observed in arteries from normotensive rats. Inhibition of phosphoinositide 3-kinase (PI3-kinase) by 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) reduces spontaneous tone development. The Rho/Rho-kinase pathway has been suggested to play a role in hypertension and may be dependent on PI3-kinase activity. We hypothesized that Rhokinase is involved in spontaneous tone development and that Rho/Rho-kinase is a downstream effector of PI3-kinase. Using endothelium-denuded aortic strips in isolated tissue bath, we demonstrated that (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) (Y27632) (1 microM), a Rho-kinase inhibitor, significantly reduced spontaneous tone in the DOCA aorta but that it did not affect sham aorta basal tone (DOCA 63.5 +/- 15.9 versus sham 1.2 +/- 0.4 total change in percentage of phenylephrine contraction). We examined the interaction between the PI3-kinase and Rho pathways by observing the effects of LY294002 on a Rhokinase effector, myosin phosphatase (MYPT), and Y27632 on a PI3-kinase effector, Akt, using Western blot analysis. Inhibition of PI3-kinase reduced spontaneous tone, but it had no effect on the phosphorylation status of MYPT, indicating that PI3-kinase is not a downstream effector of Rho/Rho-kinase. These data indicate that there is little interaction between the Rho/Rhokinase and PI3-kinase pathways in the DOCA-salt aorta, and the two pathways seem to operate in parallel in supporting spontaneous arterial tone. These data reflect spontaneous tone only and do not rule out the possibility of interaction between these pathways in agonist-stimulated tone.
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Affiliation(s)
- Erica A Wehrwein
- Department of Pharmacology and Toxicology, B445 Life Science Bldg., Michigan State University, East Lansing, MI 48824-1317, USA
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Büyükafşar K, Arikan O, Ark M, Seçilmiş A, Un I, Singirik E. Rho-kinase expression and its contribution to the control of perfusion pressure in the isolated rat mesenteric vascular bed. Eur J Pharmacol 2004; 485:263-8. [PMID: 14757149 DOI: 10.1016/j.ejphar.2003.11.076] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Rho-kinase expression was investigated in the rat mesenteric artery and the effects of its inhibitors, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride monohydrate (Y-27632) and fasudil (HA-1077), were examined on the increase in perfusion pressure induced by two different receptor agonists, namely the alpha-adrenoceptor agonist, phenylephrine and, the endothelin ET(A) and ET(B) receptor agonist, endothelin-1. Y-27632 and fasudil produced a concentration-dependent decrease in perfusion pressure. There was no difference between the concentration-response lines of these two inhibitors. The maximum decrease in the perfusion pressure induced by 10(-5) M Y-27632 was 85.8+/-3.7% when the tone was increased by phenylephrine. However, it was 48.1+/-5.4% (P<0.001) when the perfusion pressure was elevated by endothelin-1. Saponin perfusion (100 mg l(-1), for 10 min), which abolished acetylcholine-induced relaxation, did not significantly modify the Y-27632-elicited relaxation. Western blot analysis revealed that rat mesenteric artery expresses Rho-kinase protein with a molecular weight of approximately 160 kDa. These results show that Rho-kinase enzyme is expressed in rat mesenteric artery and that it contributes to the control of vascular resistance. Moreover, endothelium removal had no marked effect on the vasodilatation induced by Y-27632. In addition, the endothelin-1-induced vasoconstriction was more resistant to the Rho-kinase inhibitors than was that induced by phenylephrine, probably because excitatory endothelin receptors are associated with this signal transduction pathway at a different level from that of alpha-adrenoceptors.
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Affiliation(s)
- Kansu Büyükafşar
- Department of Pharmacology, Medical Faculty Mersin University, Campus Yenişehir 33169, Mersin, Turkey.
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Büyükafşar K, Levent A, Ark M. Expression of Rho-kinase and its functional role in the contractile activity of the mouse vas deferens. Br J Pharmacol 2003; 140:743-9. [PMID: 14504141 PMCID: PMC1574068 DOI: 10.1038/sj.bjp.0705479] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The effects of two Rho-kinase inhibitors, Y-27632 and fasudil, were investigated on the contractions produced by electrical field stimulation (EFS, 40 V, 1 mS, 2, 4, 8 and 16 Hz, for 20 s), KCl (30 - 60 mm), phenylephrine (Phe) (10-5 - 10-4 m), adenosine-3', 5'-triphosphate (ATP) (10-4 - 10-3 m) and alpha,beta-methylene ATP (10-5 m). EFS produced frequency-dependent reproducible contractile activity, which was almost abolished by guanethidine (10-5 m, for 1 h). This contraction consisted of two components (a phasic initial contraction followed by a tonic one), and it was inhibited by Y-27632 and fasudil (both at 10-5 m). However, these inhibitors had no effect on resting tension of the tissue. Contractions elicited by KCl (30 - 60 mm) were insensitive to guanethidine (10-5 m, for 1 h), but suppressed by Y-27632 (10-5 m) and fasudil (10-5 m). In addition, the contractions induced by Phe (an alpha1-adrenoceptor agonist) and ATP (a purinergic agent) were inhibited significantly by Y-27632 (10-5 m). Phasic contractions evoked by the selective P2X purinoceptor agonist alpha,beta-methylene ATP were also suppressed by Y-27632 (10-5 m). Western blot analysis revealed that the mouse vas deferens expresses Rho-kinase (ROKalpha, ROCK-2 isoform) protein with a molecular weight of approximately 160 kDa. As a positive control, the presence of this protein was also shown in homogenates of smooth muscle from the rat mesenteric artery. In conclusion, Rho-kinase protein is expressed in the mouse vas deferens, and it mediates neurogenic contractile activity as well as the contractions induced by KCl, Phe, ATP and alpha,beta-methylene ATP. Owing to the suppressive effects of Rho-kinase inhibitors on the contractile activity of the vas deferens, the possibility that these compounds might impair ejaculation must be taken into account when considering them as potential agents in the treatment of erectile dysfunction.
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Affiliation(s)
- Kansu Büyükafşar
- Department of Pharmacology, Medical Faculty, Mersin University, Campus Yenişehir, Mersin 33169, Turkey.
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