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Xing H, Sabe SA, Shi G, Harris DD, Liu Y, Sellke FW, Feng J. Role of Protein Kinase C in Metabolic Regulation of Coronary Endothelial Small Conductance Calcium-Activated Potassium Channels. J Am Heart Assoc 2024; 13:e031028. [PMID: 38293916 PMCID: PMC11056132 DOI: 10.1161/jaha.123.031028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 11/02/2023] [Indexed: 02/01/2024]
Abstract
BACKGROUND Small conductance calcium-activated potassium (SK) channels are largely responsible for endothelium-dependent coronary arteriolar relaxation. Endothelial SK channels are downregulated by the reduced form of nicotinamide adenine dinucleotide (NADH), which is increased in the setting of diabetes, yet the mechanisms of these changes are unclear. PKC (protein kinase C) is an important mediator of diabetes-induced coronary endothelial dysfunction. Thus, we aimed to determine whether NADH signaling downregulates endothelial SK channel function via PKC. METHODS AND RESULTS SK channel currents of human coronary artery endothelial cells were measured by whole cell patch clamp method in the presence/absence of NADH, PKC activator phorbol 12-myristate 13-acetate, PKC inhibitors, or endothelial PKCα/PKCβ knockdown by using small interfering RNA. Human coronary arteriolar reactivity in response to the selective SK activator NS309 was measured by vessel myography in the presence of NADH and PKCβ inhibitor LY333531. NADH (30-300 μmol/L) or PKC activator phorbol 12-myristate 13-acetate (30-300 nmol/L) reduced endothelial SK current density, whereas the selective PKCᵦ inhibitor LY333531 significantly reversed the NADH-induced SK channel inhibition. PKCβ small interfering RNA, but not PKCα small interfering RNA, significantly prevented the NADH- and phorbol 12-myristate 13-acetate-induced SK inhibition. Incubation of human coronary artery endothelial cells with NADH significantly increased endothelial PKC activity and PKCβ expression and activation. Treating vessels with NADH decreased coronary arteriolar relaxation in response to the selective SK activator NS309, and this inhibitive effect was blocked by coadministration with PKCβ inhibitor LY333531. CONCLUSIONS NADH-induced inhibition of endothelial SK channel function is mediated via PKCβ. These findings may provide insight into novel therapeutic strategies to preserve coronary microvascular function in patients with metabolic syndrome and coronary disease.
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Affiliation(s)
- Hang Xing
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
| | - Sharif A. Sabe
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
| | - Guangbin Shi
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
| | - Dwight D. Harris
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
| | - Yuhong Liu
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
| | - Frank W. Sellke
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
| | - Jun Feng
- Division of Cardiothoracic Surgery, Rhode Island HospitalAlpert Medical School of Brown UniversityProvidenceRI
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Matsumoto T, Kudo M, Taguchi K, Kobayashi T. Effect of Nonsteroidal Mineralocorticoid Receptor Blocker Esaxerenone on Vasoreactivity to an Endothelial Stimulator in Superior Mesenteric Arteries of Type 2 Diabetic Goto-Kakizaki Rat. Biol Pharm Bull 2022; 45:1825-1831. [DOI: 10.1248/bpb.b22-00616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Miyo Kudo
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Kumiko Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
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3
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Sonobe T, Tsuchimochi H, Maeda H, Pearson JT. Increased contribution of KCa channels to muscle contraction induced vascular and blood flow responses in sedentary and exercise trained ZFDM rats. J Physiol 2022; 600:2919-2938. [PMID: 35551673 DOI: 10.1113/jp282981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/04/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Microvascular dysfunction in type 2 diabetes impairs blood flow redistribution during exercise and limits the performance of skeletal muscle and may cause early fatigability. Endothelium-dependent hyperpolarization (EDH), which mediates vasodilation in resistance arteries is known to be depressed in animals with diabetes. Here we report that low-intensity exercise training in ZFDM rats increased KCa channel-derived component in the vasodilator responses to muscle contraction than in sedentary rats, partly due to the increase in KCNN3 expression. These results suggest that low-intensity exercise training improves blood flow redistribution in contracting skeletal muscle in metabolic disease with diabetes via upregulation of EDH. ABSTRACT In resistance arteries, endothelium-dependent hyperpolarization (EDH) mediated vasodilation is depressed in diabetes. We hypothesized that downregulation of KCa channel derived EDH reduces exercise-induced vasodilation and blood flow redistribution in diabetes. To test this hypothesis, we evaluated vascular function in response to hindlimb muscle contraction, and the contribution of KCa channels in anaesthetised ZFDM, metabolic disease rats with type 2 diabetes. We also tested whether exercise training ameliorated the vascular response. Using in vivo microangiography, the hindlimb vasculature was visualized before and after rhythmic muscle contraction (0.5 s tetanus every 3 sec, 20 times) evoked by sciatic nerve stimulation (40 Hz). Femoral blood flow of the contracting hindlimb was simultaneously measured by an ultrasonic flowmeter. The contribution of KCa channels was investigated in the presence and absence of apamin and charybdotoxin. We found that vascular and blood flow responses to muscle contraction were significantly impaired at the level of small artery segments in ZFDM fa/fa rats compared to its lean control fa/+ rats. The contribution of KCa channels was also smaller in fa/fa than in fa/+ rats. Low-intensity exercise training for 12 weeks in fa/fa rats demonstrated minor changes in the vascular and blood flow response to muscle contraction. However, KCa-derived component in the response to muscle contraction was much greater in exercise trained than in sedentary fa/fa rats. These data suggest that exercise training increases the contribution of KCa channels among endothelium-dependent vasodilatory mechanisms to maintain vascular and blood flow responses to muscle contraction in this metabolic disease rat model. Abstract figure legend Low-intensity exercise training in ZFDM, metabolic disease rats with type 2 diabetes increases KCa channel-derived component of endothelium-dependent hyperpolarization in the vascular and blood flow responses to skeletal muscle contraction than the responses in sedentary rats, partly due to upregulation of KCNN3 protein expression. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Takashi Sonobe
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - Hirotsugu Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - Hisashi Maeda
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - James T Pearson
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan.,Victoria Heart Institute and Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Australia
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4
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Metabolic regulation and dysregulation of endothelial small conductance calcium activated potassium channels. Eur J Cell Biol 2022; 101:151208. [DOI: 10.1016/j.ejcb.2022.151208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 12/13/2022] Open
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Xing H, Zhang Z, Shi G, He Y, Song Y, Liu Y, Harrington EO, Sellke FW, Feng J. Chronic Inhibition of mROS Protects Against Coronary Endothelial Dysfunction in Mice With Diabetes. Front Cell Dev Biol 2021; 9:643810. [PMID: 33681229 PMCID: PMC7930489 DOI: 10.3389/fcell.2021.643810] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/29/2021] [Indexed: 11/13/2022] Open
Abstract
Diabetes is associated with coronary endothelial dysfunction. Persistent oxidative stress during diabetes contributes to coronary endothelial dysfunction. The mitochondria are main sources of reactive oxygen species (ROS) in diabetes, and mitochondria-targeted antioxidant mito-Tempo can prevent mitochondrial reactive oxygen species (mROS) generation in a variety of disorders. Inhibition/inactivation of small-conductance Ca2+-activated K+ (SK) channels contribute to diabetic downregulation of coronary endothelial function/relaxation. However, few investigated the role of mROS on endothelial dysfunction/vasodilation and endothelial SK channel downregulation in diabetes. The aim of present study was to investigate the chronic administration of mito-Tempo, on coronary vasodilation, and endothelial SK channel activity of mice with or without diabetes. Mito-Tempo (1 mg/kg/day) was applied to the mice with or without diabetes (n = 10/group) for 4 weeks. In vitro relaxation response of pre-contracted arteries was examined in the presence or absence of the vasodilatory agents. SK channel currents of the isolated mouse heart endothelial cells were measured using whole-cell patch clamp methods. At baseline, coronary endothelium-dependent relaxation responses to ADP and the selective SK channel activator NS309 and endothelial SK channel currents were decreased in diabetic mice compared with that in non-diabetic (ND) mice (p < 0.05). After a 4-week treatment with mito-Tempo, coronary endothelium-dependent relaxation response to ADP or NS309 and endothelial SK channel currents in the diabetic mice was significantly improved when compared with that in untreated diabetic mice (p < 0.05). Interestingly, coronary relaxation responses to ADP and NS309 and endothelial SK channel currents were not significantly changed in ND mice after mito-Tempo treatment, as compared to that of untreated control group. Chronic inhibition of endothelial mROS appears to improve coronary endothelial function/dilation and SK channel activity in diabetes, and mROS inhibitors may be a novel strategy to treat vascular complications in diabetes.
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Affiliation(s)
- Hang Xing
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Zhiqi Zhang
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Guangbin Shi
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yixin He
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yi Song
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yuhong Liu
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Elizabeth O Harrington
- Vascular Research Laboratory, Providence VA Medical Center, Department of Medicine, Alpert Medical School of Brown University, Providence, RI, United States
| | - Frank W Sellke
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Jun Feng
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
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Mishra RC, Kyle BD, Kendrick DJ, Svystonyuk D, Kieser TM, Fedak PWM, Wulff H, Braun AP. KCa channel activation normalizes endothelial function in Type 2 Diabetic resistance arteries by improving intracellular Ca 2+ mobilization. Metabolism 2021; 114:154390. [PMID: 33039407 PMCID: PMC7736096 DOI: 10.1016/j.metabol.2020.154390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Endothelial dysfunction is an early pathogenic event in the progression of cardiovascular disease in patients with Type 2 Diabetes (T2D). Endothelial KCa2.3 and KCa3.1 K+ channels are important regulators of arterial diameter, and we thus hypothesized that SKA-31, a small molecule activator of KCa2.3 and KCa3.1, would positively influence agonist-evoked dilation in myogenically active resistance arteries in T2D. METHODOLOGY Arterial pressure myography was utilized to investigate endothelium-dependent vasodilation in isolated cremaster skeletal muscle resistance arteries from 22 to 24 week old T2D Goto-Kakizaki rats, age-matched Wistar controls, and small human intra-thoracic resistance arteries from T2D subjects. Agonist stimulated changes in cytosolic free Ca2+ in acutely isolated, single endothelial cells from Wistar and T2D Goto-Kakizaki cremaster and cerebral arteries were examined using Fura-2 fluorescence imaging. MAIN FINDINGS Endothelium-dependent vasodilation in response to acetylcholine (ACh) or bradykinin (BK) was significantly impaired in isolated cremaster arteries from T2D Goto-Kakizaki rats compared with Wistar controls, and similar results were observed in human intra-thoracic arteries. In contrast, inhibition of myogenic tone by sodium nitroprusside, a direct smooth muscle relaxant, was unaltered in both rat and human T2D arteries. Treatment with a threshold concentration of SKA-31 (0.3 μM) significantly enhanced vasodilatory responses to ACh and BK in arteries from T2D Goto-Kakizaki rats and human subjects, whereas only modest effects were observed in non-diabetic arteries of both species. Mechanistically, SKA-31 enhancement of evoked dilation was independent of vascular NO synthase and COX activities. Remarkably, SKA-31 treatment improved agonist-stimulated Ca2+ elevation in acutely isolated endothelial cells from T2D Goto-Kakizaki cremaster and cerebral arteries, but not from Wistar control vessels. In contrast, SKA-31 treatment did not affect intracellular Ca2+ release by the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor cyclopiazonic acid. CONCLUSIONS Collectively, our data demonstrate that KCa channel modulation can acutely restore endothelium-dependent vasodilatory responses in T2D resistance arteries from rats and humans, which appears to involve improved endothelial Ca2+ mobilization.
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Affiliation(s)
- Ramesh C Mishra
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Barry D Kyle
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Dylan J Kendrick
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Daniyil Svystonyuk
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Teresa M Kieser
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Paul W M Fedak
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Heike Wulff
- Dept of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Andrew P Braun
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
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7
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Pang ZD, Wang Y, Song Z, She G, Ma XZ, Sun X, Wu W, Lai BC, Zhang J, Zhang Y, Du XJ, Shyy JYJ, Deng XL. AMPK upregulates K Ca2.3 channels and ameliorates endothelial dysfunction in diet-induced obese mice. Biochem Pharmacol 2020; 183:114337. [PMID: 33186592 DOI: 10.1016/j.bcp.2020.114337] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/21/2020] [Accepted: 11/06/2020] [Indexed: 01/01/2023]
Abstract
The opening of endothelial small-conductance calcium-activated potassium channels (KCa2.3) is essential for endothelium-dependent hyperpolarization (EDH), which predominantly occurs in small resistance arteries. Adenosine monophosphate-activated protein kinase (AMPK), an important metabolic regulator, has been implicated in regulating endothelial nitric oxide synthase activity. However, it was unclear whether AMPK regulated endothelial KCa2.3-mediated EDH-type vasodilation. Using bioinformatics analysis and myograph system, we investigated the regulation by AMPK of KCa2.3 in human umbilical vein endothelial cells (HUVECs) or mouse second-order mesenteric resistance arteries. In HUVECs, AMPK activation either by activators (AICAR, A769662 and MK-8722) or expression of the constitutively active form of AMPK significantly upregulated KCa2.3 expression. Such effects were abolished by AMPK inhibitor (compound C) or AMPK α1-/α2-siRNA, extracellular-signal-regulated-kinase 5 (ERK5) inhibitor (ERK5-IN-1), and specific siRNA to myocyte-enhancer factor 2 (MEF2) or krüppel-like factor 2/4 (KLF2/4). KCa2.3 expression was significantly reduced in mesenteric resistance arteries in AMPKα2 knockout mice when compared with littermate control mice. Furthermore, in high-fat diet fed mice, 2-week treatment with AICAR restored endothelial KCa2.3 expression in mesenteric resistance arteries with improved endothelial dysfunction. Our results demonstrate that activation of AMPK upregulates KCa2.3 channel expression through the ERK5-MEF2-KLF2/4 signaling pathway in vascular endothelium, which contributes to benefits through KCa2.3-mediated EDH-type vasodilation in mesenteric resistance arteries.
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Affiliation(s)
- Zheng-Da Pang
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Yan Wang
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Zheng Song
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Gang She
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Xiao-Zhen Ma
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Xia Sun
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Wei Wu
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Bao-Chang Lai
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Jiao Zhang
- Division of Cardiology, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla CA 92093-0613, CA, United States
| | - Yi Zhang
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - Xiao-Jun Du
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China
| | - John Y J Shyy
- Division of Cardiology, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla CA 92093-0613, CA, United States.
| | - Xiu-Ling Deng
- Department of Physiology and Pathophysiology, Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an 710061, Shaanxi, China.
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8
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Mesenteric arterial dysfunction in the UC Davis Type 2 Diabetes Mellitus rat model is dependent on pre-diabetic versus diabetic status and is sexually dimorphic. Eur J Pharmacol 2020; 879:173089. [PMID: 32320701 DOI: 10.1016/j.ejphar.2020.173089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 03/21/2020] [Accepted: 03/25/2020] [Indexed: 01/27/2023]
Abstract
Previous reports suggest that diabetes may differentially affect the vascular beds of females and males. However, there is insufficient evidence to establish the timeline of the vascular dysfunction in diabetes, specifically in relation to sex. Here, we determined whether mesenteric arterial function is altered in UC Davis Type-2 Diabetes Mellitus (UCD-T2DM) rats and if this occurs as early as the pre-diabetic stage of the disease. Specifically, we investigated whether vascular dysfunction differs between pre-diabetic or diabetic status and if this varies by sex. We measured the responses to endothelium-dependent and -independent vasorelaxant as well as vasoconstrictor agents and explored the potential mechanisms involved in sex-specific development of arterial dysfunction in UCD-T2DM rats. In addition, indices of insulin sensitivity were assessed. We report the reduced insulin sensitivity in pre-diabetic males and diabetic females. Vascular relaxation to acetylcholine was impaired to a greater extent in mesenteric artery from males in the pre-diabetic stage than in their female counterparts. In contrast, the arteries from females with diabetes exhibited a greater impairment to acetylcholine compared with diabetic males. Additionally, the sensitivity of mesenteric artery to contractile agents in females, but not in males, after the onset of diabetes was increased. Our data suggest that the reduced insulin sensitivity through AKT may predispose vessels to injury in the pre-diabetic stage in males. On the other hand, reduced insulin sensitivity as well as enhanced responsiveness to contractile agents may predispose arteries to injury in the diabetic stage in females.
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Zhang Z, Shi G, Liu Y, Xing H, Kabakov AY, Zhao AS, Agbortoko V, Kim J, Singh AK, Koren G, Harrington EO, Sellke FW, Feng J. Coronary endothelial dysfunction prevented by small-conductance calcium-activated potassium channel activator in mice and patients with diabetes. J Thorac Cardiovasc Surg 2020; 160:e263-e280. [PMID: 32199659 PMCID: PMC7439127 DOI: 10.1016/j.jtcvs.2020.01.078] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 12/30/2019] [Accepted: 01/31/2020] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To investigate coronary endothelial protection of a small-conductance calcium-activated potassium (SK) channel activator against a period of cardioplegic-hypoxia and reoxygenation (CP-H/R) injury in mice and patients with diabetes (DM) and those without diabetes (nondiabetic [ND]). METHODS Mouse small coronary arteries/heart endothelial cells (MHECs) and human coronary arterial endothelial cells (HCAECs) were dissected from the harvested hearts of mice (n = 16/group) and from discarded right atrial tissue samples of patients with DM and without DM (n = 8/group). The SK current density of MHECs was measured. The in vitro small arteries/arterioles, MHECs, and HCAECs were subjected to 60 minutes of CP hypoxia, followed by 60 minutes of oxygenation. Vessels were treated with or without the selective SK activator NS309 for 5 minutes before and during CP hypoxia. RESULTS DM and/or CP-H/R significantly inhibited the total SK currents of MHECs and HCAECs and significantly diminished the mouse coronary relaxation response to NS309. Administration of NS309 immediately before and during CP hypoxia significantly improved the recovery of coronary endothelial function, as demonstrated by increased relaxation responses to adenosine 5'-diphosphate and substance P compared with those seen in controls (P < .05). This protective effect was more pronounced in vessels from ND mice and patients compared with DM mice and patients (P < .05). Cell surface membrane SK3 expression was significantly reduced after hypoxia, whereas cytosolic SK3 expression was greater than that of the sham control group (P < .05). CONCLUSIONS Application of NS309 immediately before and during CP hypoxia protects mouse and human coronary microvasculature against CP-H/R injury, but this effect is diminished in the diabetic coronary microvasculature. SK inhibition/inactivation and/or internalization/redistribution may contribute to CP-H/R-induced coronary endothelial and vascular relaxation dysfunction.
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Affiliation(s)
- Zhiqi Zhang
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Guangbin Shi
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Yuhong Liu
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Hang Xing
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Anatoli Y Kabakov
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI
| | - Amy S Zhao
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Vahid Agbortoko
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Justin Kim
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Arun K Singh
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI
| | | | - Frank W Sellke
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Jun Feng
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI.
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Oxidative stress induced by palmitic acid modulates K Ca2.3 channels in vascular endothelium. Exp Cell Res 2019; 383:111552. [PMID: 31415760 DOI: 10.1016/j.yexcr.2019.111552] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 07/27/2019] [Accepted: 08/10/2019] [Indexed: 02/08/2023]
Abstract
Elevated plasma free fatty acids level has been implicated in the development of insulin resistance, inflammation, and endothelial dysfunction in diabetic and nondiabetic individuals. However, the underlying mechanisms still remain to be defined. Herein, we investigated the effect of palmitic acid (PA), the most abundant saturated fatty acid in the human body, on small-conductance Ca2+-activated potassium channels (KCa2.3)-mediated relaxation in rodent resistance arteries and the underlying molecular mechanism. The effect of PA on KCa2.3 in endothelium was evaluated using real-time PCR, Western blotting, whole-cell patch voltage-clamp, wire and pressure myograph system, and reactive oxygen species (ROS) were measured by using dihydroethidium and 2', 7'-dichlorofluorescein diacetate. KCa2.3-mediated vasodilatation responses to acetylcholine and NS309 (agonist of KCa2.3 and KCa3.1) were impaired by incubation of normal mesenteric arteries with 100 μM PA for 24 h. In cultured human umbilical vein endothelial cells (HUVECs), PA decreased KCa2.3 current and expression at mRNA and protein levels. Incubation with the NADPH oxidase (Nox) inhibitor dibenziodolium (DPI) partly inhibited the PA-induced ROS production and restored KCa2.3 expression. Inhibition of either p38-MAPK or NF-κB using specific inhibitors (SB203580, SB202190 or Bay11-7082, pyrrolidinedithiocarbamate) attenuated PA-induced downregulation of KCa2.3 and inhibition of p38-MAPK also attenuated PA-induced phosphorylation of NF-κB p65. Furthermore, DPI reversed the increment of phospho-p38-MAPK by PA. These results demonstrated that PA downregulated KCa2.3 expressions via Nox/ROS/p38-MAPK/NF-κB signaling leading to endothelial vasodilatory dysfunction.
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11
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Endothelium-Dependent Hyperpolarization (EDH) in Diabetes: Mechanistic Insights and Therapeutic Implications. Int J Mol Sci 2019; 20:ijms20153737. [PMID: 31370156 PMCID: PMC6695796 DOI: 10.3390/ijms20153737] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/25/2019] [Accepted: 07/30/2019] [Indexed: 02/07/2023] Open
Abstract
Diabetes mellitus is one of the major risk factors for cardiovascular disease and is an important health issue worldwide. Long-term diabetes causes endothelial dysfunction, which in turn leads to diabetic vascular complications. Endothelium-derived nitric oxide is a major vasodilator in large-size vessels, and the hyperpolarization of vascular smooth muscle cells mediated by the endothelium plays a central role in agonist-mediated and flow-mediated vasodilation in resistance-size vessels. Although the mechanisms underlying diabetic vascular complications are multifactorial and complex, impairment of endothelium-dependent hyperpolarization (EDH) of vascular smooth muscle cells would contribute at least partly to the initiation and progression of microvascular complications of diabetes. In this review, we present the current knowledge about the pathophysiology and underlying mechanisms of impaired EDH in diabetes in animals and humans. We also discuss potential therapeutic approaches aimed at the prevention and restoration of EDH in diabetes.
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Guo Y, Yang X, He J, Liu J, Yang S, Dong H. Important roles of the Ca 2+-sensing receptor in vascular health and disease. Life Sci 2018; 209:217-227. [PMID: 30098342 DOI: 10.1016/j.lfs.2018.08.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 07/30/2018] [Accepted: 08/06/2018] [Indexed: 02/07/2023]
Abstract
Ca2+-sensing receptor (CaSR), a member of G protein-coupled receptor family, is widely expressed in the vascular system, including perivascular neurons, vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs). When stimulated, CaSR can further increase the cytosolic Ca2+ concentration ([Ca2+]cyt) in two ways: intracellular Ca2+ release from endo/sarcoplasmic reticulum (ER/SR) and extracellular Ca2+ entry through Ca2+-permeable cation channels. In endothelium, increased Ca2+ subsequently activate nitric oxide synthase (NOS) and intermediate conductance Ca2+-activated K+ channels (IKCa), resulting in vasodilation through NOS-mediated NO release or membrane hyperpolarization. In VSMCs, CaSR-induced intracellular Ca2+ increase causes blood vessel constriction. CaSR activation predominantly induces vasorelaxation of whole vascular tissues through VECs-dependent mechanisms; however, CaSR-induced Ca2+ signaling in VSMCs may play a braking role in CaSR-mediated vasorelaxation. Emerging evidence reveals the importance of CaSR in the regulation of vascular tone and blood pressure. Here, we summarized recent advances in CaSR-mediated vascular reaction and the underlying mechanisms in different species, including humans. In addition, several studies have demonstrated that CaSR dysfunction may be associated with some fatal vascular diseases, such as pulmonary arterial hypertension, primary hypertension, diabetes, acute myocardial infarction and vascular calcification. With the advance of studies on CaSR in vascular health and disease, it is expected positive modulators or negative modulators of CaSR used for the treatment of specific diseases may be promising therapeutic options for the prevention and/or treatment of vascular diseases.
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Affiliation(s)
- Yanjun Guo
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Xin Yang
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Jialin He
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Jingjing Liu
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Shiming Yang
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China.
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Lemmey HAL, Ye X, Ding HC, Triggle CR, Garland CJ, Dora KA. Hyperglycaemia disrupts conducted vasodilation in the resistance vasculature of db/db mice. Vascul Pharmacol 2018; 103-105:29-35. [PMID: 29339138 PMCID: PMC5906692 DOI: 10.1016/j.vph.2018.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 11/27/2017] [Accepted: 01/10/2018] [Indexed: 11/17/2022]
Abstract
Vascular dysfunction in small resistance arteries is observed during chronic elevations in blood glucose. Hyperglycaemia-associated effects on endothelium-dependent vasodilation have been well characterized, but effects on conducted vasodilation in the resistance vasculature are not known. Small mesenteric arteries were isolated from healthy and diabetic db/db mice, which were used as a model of chronic hyperglycaemia. Endothelium-dependent vasodilation via the Gq/11-coupled proteinase activated receptor 2 (PAR2) was stimulated with the selective agonist SLIGRL. The Ca2+-sensitive fluorescent indicator fluo-8 reported changes in endothelial cell (EC) [Ca2+]i, and triple cannulated bifurcating mesenteric arteries were used to study conducted vasodilation. Chronic hyperglycaemia did not affect either EC Ca2+ or local vasodilation to SLIGRL. However, both acute and chronic exposure to high glucose or the mannitol osmotic control attenuated conducted vasodilation to 10μM SLIGRL. This investigation demonstrates for the first time that a hypertonic solution containing glucose or mannitol can interfere with the spread of a hyperpolarizing current along the endothelium in a physiological setting. Our findings reiterate the importance of studying the effects of hyperglycaemia in the vasculature, and provide the basis for further studies regarding the modulation of junctional proteins involved in cell to cell communication by diseases such as diabetes.
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Affiliation(s)
- Hamish A L Lemmey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Xi Ye
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Hong C Ding
- Department of Pharmacology, Weill Cornell Medicine in Qatar, P.O. Box 24144, Education City, Doha, Qatar.
| | - Christopher R Triggle
- Department of Pharmacology, Weill Cornell Medicine in Qatar, P.O. Box 24144, Education City, Doha, Qatar.
| | - Christopher J Garland
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Kim A Dora
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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Decreased coronary arteriolar response to K Ca channel opener after cardioplegic arrest in diabetic patients. Mol Cell Biochem 2018; 445:187-194. [PMID: 29305679 PMCID: PMC6033646 DOI: 10.1007/s11010-017-3264-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/23/2017] [Indexed: 01/16/2023]
Abstract
We have recently found that diabetes is associated with the inactivation of the calcium-activated potassium channels (KCa) in endothelial cells, which may contribute to endothelial dysfunction in diabetic patients at baseline. In the current study, we further investigated the effects of diabetes on coronary arteriolar responses to the small (SK) and intermediate (IK) KCa opener NS309 in diabetic and non-diabetic patients and correlated that data with the changes in the SK/IK protein expression/distribution in the setting of cardioplegic ischemia and reperfusion (CP) and cardiopulmonary bypass (CPB). Coronary arterioles from the harvested right atrial tissue samples from diabetic and non-diabetic patients (n = 8/group) undergoing cardiac surgery were dissected pre- and post-CP/CPB. The in vitro relaxation response of pre-contracted arterioles was examined in the presence of the selective SK/IK opener NS309 (10−9–10−5 M). The protein expression/localization of KCa channels in the harvested atrial tissue samples, coronary microvessels, and primary cultured human coronary endothelial cells were assayed by Western blotting and immunohistochemistry. The relaxation response to NS309 post-CP/CPB was significantly decreased in diabetic and non-diabetic groups compared to their pre-CP/CPB responses, respectively (P < 0.05). Furthermore, this decrease was greater in the diabetic group than that of the non-diabetic group (P < 0.05). There were no significant differences in the total protein expression/distribution of SK/IK in the human myocardium, coronary microvessels or coronary endothelial cells between diabetic and non-diabetic groups or between pre- and post-CP/CPB (P > 0.05). Our results suggest that diabetes further inactivates SK/IK channels of coronary microvasculature early after CP/CPB and cardiac surgery. The lack of diabetic changes in SK/IK protein abundances in the setting of CP/CPB suggests that the effect is post-translational. This alteration may contribute to post-operative endothelial dysfunction in the diabetic patients early after CP/CPB and cardiac surgery.
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Coleman HA, Tare M, Parkington HC. Nonlinear effects of potassium channel blockers on endothelium-dependent hyperpolarization. Acta Physiol (Oxf) 2017; 219:324-334. [PMID: 27639255 DOI: 10.1111/apha.12805] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/12/2016] [Accepted: 09/13/2016] [Indexed: 12/17/2022]
Abstract
In a number of published studies on endothelium-dependent hyperpolarization and relaxation, the results of the effects of K+ blockers have been difficult to interpret. When the effects of two blockers have been studied, often either blocker by itself had little effect, whereas the two blockers combined tended to abolish the responses. Explanations suggested in the literature include an unusual pharmacology of the K+ channels, and possible blocker binding interactions. In contrast, when we applied the same blockers to segments of small blood vessels under voltage clamp, the blockers reduced the endothelium-dependent K+ current in a linearly additive manner. Resolution of these contrasting results is important as endothelium-derived hyperpolarization (EDH) makes its greatest contribution to vasorelaxation in arterioles and small resistance arteries, where it can exert a significant role in tissue perfusion and blood pressure regulation. Furthermore, EDH is impaired in various diseases. Here, we consider why the voltage-clamp results differ from earlier free-running membrane potential and contractility studies. We fitted voltage-clamp-derived current-voltage relationships with mathematical functions and considered theoretically the effects of partial and total block of endothelium-derived K+ -currents on the membrane potential of small blood vessels. When the K+ -conductance was partially reduced, equivalent to applying a single blocker, the effect on EDH was small. Total block of the endothelium-dependent K+ conductance abolished the hyperpolarization, in agreement with various published studies. We conclude that nonlinear summation of the hyperpolarizing response evoked by endothelial stimulation can explain the variable effectiveness of individual K+ channel blockers on endothelium-dependent hyperpolarization and resulting relaxation.
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Affiliation(s)
- H. A. Coleman
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - M. Tare
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - H. C. Parkington
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
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Dal S, Sigrist S. The Protective Effect of Antioxidants Consumption on Diabetes and Vascular Complications. Diseases 2016; 4:E24. [PMID: 28933404 PMCID: PMC5456287 DOI: 10.3390/diseases4030024] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/20/2016] [Accepted: 06/23/2016] [Indexed: 12/14/2022] Open
Abstract
Obesity and diabetes is generally accompanied by a chronic state of oxidative stress, disequilibrium in the redox balance, implicated in the development and progression of complications such as micro- and macro-angiopathies. Disorders in the inner layer of blood vessels, the endothelium, play an early and critical role in the development of these complications. Blunted endothelium-dependent relaxation and/or contractions are quietly associated to oxidative stress. Thus, preserving endothelial function and oxidative stress seems to be an optimization strategy in the prevention of vascular complications associated with diabetes. Diet is a major lifestyle factor that can greatly influence the incidence and the progression of type 2 diabetes and cardiovascular complications. The notion that foods not only provide basic nutrition but can also prevent diseases and ensure good health and longevity is now attained greater prominence. Some dietary and lifestyle modifications associated to antioxidative supply could be an effective prophylactic means to fight against oxidative stress in diabesity and complications. A significant benefit of phytochemicals (polyphenols in wine, grape, teas), vitamins (ascorbate, tocopherol), minerals (selenium, magnesium), and fruits and vegetables in foods is thought to be capable of scavenging free radicals, lowering the incidence of chronic diseases. In this review, we discuss the role of oxidative stress in diabetes and complications, highlight the endothelial dysfunction, and examine the impact of antioxidant foods, plants, fruits, and vegetables, currently used medication with antioxidant properties, in relation to the development and progression of diabetes and cardiovascular complications.
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Affiliation(s)
- Stéphanie Dal
- DIATHEC EA 7294 UMR Centre Européen d'Etude du Diabète (CeeD), Université de Strasbourg (UdS), boulevard René Leriche, Strasbourg 67200, France.
| | - Séverine Sigrist
- DIATHEC EA 7294 UMR Centre Européen d'Etude du Diabète (CeeD), Université de Strasbourg (UdS), boulevard René Leriche, Strasbourg 67200, France.
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Mokhtar SS, Vanhoutte PM, Leung SWS, Suppian R, Yusof MI, Rasool AHG. Reduced nitric oxide-mediated relaxation and endothelial nitric oxide synthase expression in the tail arteries of streptozotocin-induced diabetic rats. Eur J Pharmacol 2016; 773:78-84. [PMID: 26825543 DOI: 10.1016/j.ejphar.2016.01.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 01/03/2016] [Accepted: 01/26/2016] [Indexed: 10/22/2022]
Abstract
Diabetes is associated with endothelial dysfunction, which is characterized by impaired endothelium-dependent relaxations. The present study aimed to examine the role of nitric oxide (NO), prostacyclin and endothelium-dependent hyperpolarization (EDH), in the relaxation of ventral tail arteries of rats under diabetic conditions. Relaxations of tail arteries of control and diabetic rats were studied in wire myograph. Western blotting and immunostaining were used to determine the presence of proteins. Acetylcholine-induced relaxations were significantly smaller in arteries of diabetic compared to control rats (Rmax; 70.81 ± 2.48% versus 85.05 ± 3.15%). Incubation with the combination of non-selective cyclooxygenase (COX) inhibitor, indomethacin and potassium channel blockers, TRAM 34 and UCL 1684, demonstrated that NO-mediated relaxation was attenuated significantly in diabetic compared to control rats (Rmax; 48.47 ± 5.84% versus 68.39 ± 6.34%). EDH-type (in the presence of indomethacin and NO synthase inhibitor, LNAME) and prostacyclin-mediated (in the presence of LNAME plus TRAM 34 and UCL 1684) relaxations were not significantly reduced in arteries of diabetic compared to control rats [Rmax: (EDH; 17.81 ± 6.74% versus 34.16 ± 4.59%) (prostacyclin; 15.85 ± 3.27% versus 17.23 ± 3.75%)]. Endothelium-independent relaxations to sodium nitroprusside, salbutamol and prostacyclin were comparable in the two types of preparations. Western blotting and immunostaining indicated that diabetes diminished the expression of endothelial NO synthase (eNOS), while increasing those of COX-1 and COX-2. Thus, since acetylcholine-induced NO-mediated relaxation was impaired in diabetes because of reduced eNOS protein expression, pharmacological intervention improving NO bioavailability could be useful in the management of diabetic endothelial dysfunction.
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Affiliation(s)
- Siti Safiah Mokhtar
- Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia
| | - Paul M Vanhoutte
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Susan Wai Sum Leung
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Rapeah Suppian
- School of Health Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia
| | - Mohd Imran Yusof
- Department of Orthopaedic, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia
| | - Aida Hanum Ghulam Rasool
- Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia.
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Salheen SM, Panchapakesan U, Pollock CA, Woodman OL. The Dipeptidyl Peptidase-4 Inhibitor Linagliptin Preserves Endothelial Function in Mesenteric Arteries from Type 1 Diabetic Rats without Decreasing Plasma Glucose. PLoS One 2015; 10:e0143941. [PMID: 26618855 PMCID: PMC4664283 DOI: 10.1371/journal.pone.0143941] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/11/2015] [Indexed: 12/15/2022] Open
Abstract
The aim of the study was to investigate the effect of the DPP-4 inhibitor linagliptin on the mechanism(s) of endothelium-dependent relaxation in mesenteric arteries from STZ-induced diabetic rats. Both normal and diabetic animals received linagliptin (2 mg/kg) daily by oral gavage for a period of 4 weeks. To measure superoxide generation in mesenteric arteries, lucigenin-enhanced chemiluminescence was used. ACh-induced relaxation of mesenteric arteries was assessed using organ bath techniques and Western blotting was used to investigate protein expression. Pharmacological tools (1μM TRAM-34, 1μM apamin, 100 nM Ibtx, 100 μM L-NNA, 10 μM ODQ) were used to distinguish between NO and EDH-mediated relaxation. Linagliptin did not affect plasma glucose, but did decrease vascular superoxide levels. Diabetes reduced responses to ACh but did not affect endothelium-independent responses to SNP. Linagliptin improved endothelial function indicated by a significant increase in responses to ACh. Diabetes impaired the contribution of both nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) to endothelium-dependent relaxation and linagliptin treatment significantly enhanced the contribution of both relaxing factors. Western blotting demonstrated that diabetes also increased expression of Nox2 and decreased expression and dimerization of endothelial NO synthase, effects that were reversed by linagliptin. These findings demonstrate treatment of type 1 diabetic rats with linagliptin significantly reduced vascular superoxide levels and preserved both NO and EDH-mediated relaxation indicating that linagliptin can improve endothelial function in diabetes independently of any glucose lowering activity.
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Affiliation(s)
- Salheen M Salheen
- School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Usha Panchapakesan
- Kolling Institute of Medical Research, Royal North Shore Hospital, University of Sydney, St Leonards, New South Wales, Australia
| | - Carol A Pollock
- Kolling Institute of Medical Research, Royal North Shore Hospital, University of Sydney, St Leonards, New South Wales, Australia
| | - Owen L Woodman
- School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia
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Liu Y, Xie A, Singh AK, Ehsan A, Choudhary G, Dudley S, Sellke FW, Feng J. Inactivation of Endothelial Small/Intermediate Conductance of Calcium-Activated Potassium Channels Contributes to Coronary Arteriolar Dysfunction in Diabetic Patients. J Am Heart Assoc 2015; 4:e002062. [PMID: 26304940 PMCID: PMC4599465 DOI: 10.1161/jaha.115.002062] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Background Diabetes is associated with coronary arteriolar endothelial dysfunction. We investigated the role of the small/intermediate (SKCa/IKCa) conductance of calcium-activated potassium channels in diabetes-related endothelial dysfunction. Methods and Results Coronary arterioles (80 to 150 μm in diameter) were dissected from discarded right atrial tissues of diabetic (glycosylated hemoglobin = 9.6±0.25) and nondiabetic patients (glycosylated hemoglobin 5.4±0.12) during coronary artery bypass graft surgery (n=8/group). In-vitro relaxation response of precontracted arterioles was examined in the presence of the selective SKCa/IKCa activator NS309 and other vasodilatory agents. The channel density and membrane potential of diabetic and nondiabetic endothelial cells was measured by using the whole cell patch-clamp technique. The protein expression and distribution of the SKCa/IKCa in the human myocardium and coronary arterioles was examined by Western blotting and immunohistochemistry. Our results indicate that diabetes significantly reduced the coronary arteriolar response to the SKCa/IKCa activator NS309 compared to the respective responses of nondiabetic vessels (P<0.05 versus nondiabetes). The relaxation response of diabetic arterioles to NS309 was prevented by denudation of endothelium (P=0.001 versus endothelium-intact). Diabetes significantly decreased endothelial SKCa/IKCa currents and hyperpolarization induced by the SKCa/IKCa activator NS309 as compared with that of nondiabetics. There were no significant differences in the expression and distribution of SKCa/IKCa proteins in the coronary microvessels. Conclusions Diabetes is associated with inactivation of endothelial SKCa/IKCa channels, which may contribute to endothelial dysfunction in diabetic patients.
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Affiliation(s)
- Yuhong Liu
- Division of Cardiothoracic Surgery, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (Y.L., A.K.S., A.E., F.W.S., J.F.)
| | - An Xie
- Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (A.X., S.D.)
| | - Arun K Singh
- Division of Cardiothoracic Surgery, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (Y.L., A.K.S., A.E., F.W.S., J.F.)
| | - Afshin Ehsan
- Division of Cardiothoracic Surgery, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (Y.L., A.K.S., A.E., F.W.S., J.F.)
| | - Gaurav Choudhary
- Department of Medicine, Providence VA Medical Center, Alpert Medical School of Brown University, Providence, RI (G.C.)
| | - Samuel Dudley
- Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (A.X., S.D.)
| | - Frank W Sellke
- Division of Cardiothoracic Surgery, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (Y.L., A.K.S., A.E., F.W.S., J.F.)
| | - Jun Feng
- Division of Cardiothoracic Surgery, Cardiovascular Research Center, Rhode Island Hospital, Providence, RI (Y.L., A.K.S., A.E., F.W.S., J.F.)
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Gokina NI, Bonev AD, Phillips J, Gokin AP, Veilleux K, Oppenheimer K, Goloman G. Impairment of IKCa channels contributes to uteroplacental endothelial dysfunction in rat diabetic pregnancy. Am J Physiol Heart Circ Physiol 2015; 309:H592-604. [PMID: 26092991 DOI: 10.1152/ajpheart.00901.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/19/2015] [Indexed: 12/18/2022]
Abstract
Diabetes in rat pregnancy is associated with impaired vasodilation of the maternal uteroplacental vasculature. In the present study, we explored the role of endothelial cell (EC) Ca(2+)-activated K(+) channels of small conductance (SKCa channels) and intermediate conductance (IKCa channels) in diabetes-induced uterine vascular dysfunction. Diabetes was induced by injection of streptozotocin to second-day pregnant rats and confirmed by the development of maternal hyperglycemia. Control rats were injected with citrate buffer. Changes in smooth muscle cell intracellular Ca(2+) concentration, membrane potential, and vasodilation induced by SKCa/IKCa channel activators were studied in uteroplacental arteries of control and diabetic rats. The impact of diabetes on SKCa- and IKCa-mediated currents was explored in freshly dissociated ECs. NS309 evoked a potent vasodilation that was effectively inhibited by TRAM-34 but not by apamin. NS309-induced smooth muscle cell intracellular Ca(2+) concentration, membrane potential, and dilator responses were significantly diminished by diabetes; N-cyclohexyl-N-2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine (CyPPA)-evoked responses were not affected. Ca(2+)-activated ion currents in ECs were insensitive to paxilline, markedly inhibited by charybdotoxin (ChTX), and diminished by apamin. NS309-induced EC currents were generated mostly due to activation of ChTX-sensitive channels. Maternal diabetes resulted in a significant reduction in ChTX-sensitive currents with no effect on apamin-sensitive or CyPPA-induced currents. We concluded that IKCa channels play a prevalent role over SKCa channels in the generation of endothelial K(+) currents and vasodilation of uteroplacental arteries. Impaired function of IKCa channels importantly contributes to diabetes-induced uterine endothelial dysfunction. Therapeutic restoration of IKCa channel function may be a novel strategy for improvement of maternal uteroplacental blood flow in pregnancies complicated by diabetes.
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Affiliation(s)
- Natalia I Gokina
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Adrian D Bonev
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont
| | - Julie Phillips
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Alexander P Gokin
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Kelsey Veilleux
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Karen Oppenheimer
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Gabriela Goloman
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
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MOKHTAR SS, RASOOL AHG. Role of endothelium-dependent hyperpolarisation and prostacyclin in diabetes. Malays J Med Sci 2015; 22:8-17. [PMID: 26023290 PMCID: PMC4438087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 11/11/2014] [Indexed: 06/04/2023] Open
Abstract
The endothelium plays a crucial role in maintaining vascular homeostasis by producing several vasodilating factors, including nitric oxide (NO), prostacyclin (PGI2), and endothelium-dependent hyperpolarisation (EDH); however, the balance between endothelial relaxing and contracting factors is disrupted in disease states such as diabetes mellitus and hypertension. Most reported studies of endothelial dysfunction in diabetes focused on the actions of NO; however, there is accumulating evidence demonstrating that in addition to NO, PGI2 and EDH are likely to contribute to the vasodilatation of blood vessels. EDH plays an important role as a regulator of vascular tone and reactivity in resistance and conduit arteries of animal models and humans. PGI2 only plays a minimal role in endothelium-dependent vasodilatation but may serve as an important compensatory mechanism in conditions in which NO and EDH activities are decreased. Further studies are needed to determine the exact roles of EDH and PGI2 in the development of endothelial dysfunction and clinical vasculopathy in humans with type 1 and type 2 diabetes.
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Affiliation(s)
- Siti Safiah MOKHTAR
- Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Malaysia
| | - Aida Hanum Ghulam RASOOL
- Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Malaysia
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Schach C, Resch M, Schmid PM, Riegger GA, Endemann DH. Type 2 diabetes: increased expression and contribution of IKCa channels to vasodilation in small mesenteric arteries of ZDF rats. Am J Physiol Heart Circ Physiol 2014; 307:H1093-102. [DOI: 10.1152/ajpheart.00240.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Impaired endothelial function, which is dysregulated in diabetes, also precedes hypertension. We hypothesized that in Type 2 diabetes, the impaired endothelium-dependent relaxation is due to a loss of endothelium-derived hyperpolarization (EDH) that is regulated by impaired ion channel function. Zucker diabetic fatty (ZDF), Zucker heterozygote, and homozygote lean control rats were used as the experimental models in our study. Third-order mesenteric arteries were dissected and mounted on a pressure myograph; mRNA was quantified by RT-PCR and channel proteins by Western blotting. Under nitric oxide (NO) synthase and cyclooxygenase inhibition, endothelial stimulation with ACh fully relaxes control but not diabetic arteries. In contrast, when small-conductance calcium-activated potassium (KCa) channels and intermediate- and large-conductance KCa (I/BKCa) are inhibited with apamin and charybdotoxin, NO is able to compensate for ACh-induced relaxation in control but not in diabetic vessels. After replacement of charybdotoxin with 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34; IKCa inhibitor), ACh-induced relaxation in diabetic animals is attenuated. Specific inhibition with TRAM-34 or charybdotoxin attenuates ACh relaxation in diabetes. Stimulation with 1-ethyl-2-benzimidazolinone (IKCa activator) shows a reduced relaxation in diabetes. Activation of BKCa with 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one NS619 leads to similar relaxations of control and diabetic arteries. RT-PCR and Western blot analysis demonstrate elevated mRNA and protein expression levels of IKCa in diabetes. Our results suggest that the compensatory effect of NO and EDH-associated, endothelium-dependent relaxation is reduced in ZDF rats. Specific blockade of IKCa with TRAM-34 reduces NO and EDH-type relaxation in diabetic rats, indicating an elevated contribution of IKCa in diabetic small mesenteric artery relaxation. This finding correlates with increased IKCa mRNA and protein expression in this vessel.
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Affiliation(s)
- Christian Schach
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Markus Resch
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Peter M. Schmid
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Guenter A. Riegger
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Dierk H. Endemann
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
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Climent B, Moreno L, Martínez P, Contreras C, Sánchez A, Pérez-Vizcaíno F, García-Sacristán A, Rivera L, Prieto D. Upregulation of SK3 and IK1 channels contributes to the enhanced endothelial calcium signaling and the preserved coronary relaxation in obese Zucker rats. PLoS One 2014; 9:e109432. [PMID: 25302606 PMCID: PMC4193814 DOI: 10.1371/journal.pone.0109432] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/01/2014] [Indexed: 12/19/2022] Open
Abstract
Background and Aims Endothelial small- and intermediate-conductance KCa channels, SK3 and IK1, are key mediators in the endothelium-derived hyperpolarization and relaxation of vascular smooth muscle and also in the modulation of endothelial Ca2+ signaling and nitric oxide (NO) release. Obesity is associated with endothelial dysfunction and impaired relaxation, although how obesity influences endothelial SK3/IK1 function is unclear. Therefore we assessed whether the role of these channels in the coronary circulation is altered in obese animals. Methods and Results In coronary arteries mounted in microvascular myographs, selective blockade of SK3/IK1 channels unmasked an increased contribution of these channels to the ACh- and to the exogenous NO- induced relaxations in arteries of Obese Zucker Rats (OZR) compared to Lean Zucker Rats (LZR). Relaxant responses induced by the SK3/IK1 channel activator NS309 were enhanced in OZR and NO- endothelium-dependent in LZR, whereas an additional endothelium-independent relaxant component was found in OZR. Fura2-AM fluorescence revealed a larger ACh-induced intracellular Ca2+ mobilization in the endothelium of coronary arteries from OZR, which was inhibited by blockade of SK3/IK1 channels in both LZR and OZR. Western blot analysis showed an increased expression of SK3/IK1 channels in coronary arteries of OZR and immunohistochemistry suggested that it takes place predominantly in the endothelial layer. Conclusions Obesity may induce activation of adaptive vascular mechanisms to preserve the dilator function in coronary arteries. Increased function and expression of SK3/IK1 channels by influencing endothelial Ca2+ dynamics might contribute to the unaltered endothelium-dependent coronary relaxation in the early stages of obesity.
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Affiliation(s)
- Belén Climent
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
- * E-mail: (BC); (DP)
| | - Laura Moreno
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain
| | - Pilar Martínez
- Departamento de Anatomía y Anatomía Patológica Comparadas, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | - Cristina Contreras
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - Ana Sánchez
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | | | | | - Luis Rivera
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - Dolores Prieto
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
- * E-mail: (BC); (DP)
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Zhao LM, Wang Y, Yang Y, Guo R, Wang NP, Deng XL. Metformin Restores Intermediate-Conductance Calcium-Activated K+ Channel– and Small-Conductance Calcium-Activated K+ Channel–Mediated Vasodilatation Impaired by Advanced Glycation End Products in Rat Mesenteric Artery. Mol Pharmacol 2014; 86:580-91. [DOI: 10.1124/mol.114.092874] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Endothelial arginine resynthesis contributes to the maintenance of vasomotor function in male diabetic mice. PLoS One 2014; 9:e102264. [PMID: 25033204 PMCID: PMC4102520 DOI: 10.1371/journal.pone.0102264] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 06/16/2014] [Indexed: 02/06/2023] Open
Abstract
Aim Argininosuccinate synthetase (ASS) is essential for recycling L-citrulline, the by-product of NO synthase (NOS), to the NOS substrate L-arginine. Here, we assessed whether disturbed arginine resynthesis modulates endothelium-dependent vasodilatation in normal and diabetic male mice. Methods and Results Endothelium-selective Ass-deficient mice (Assfl/fl/Tie2Cretg/− = Ass-KOTie2) were generated by crossing Assfl/fl mice ( = control) with Tie2Cre mice. Gene ablation in endothelial cells was confirmed by immunohistochemistry. Blood pressure (MAP) was recorded in 34-week-old male mice. Vasomotor responses were studied in isolated saphenous arteries of 12- and 34-week-old Ass-KOTie2 and control animals. At the age of 10 weeks, diabetes was induced in control and Ass-KOTie2 mice by streptozotocin injections. Vasomotor responses of diabetic animals were studied 10 weeks later. MAP was similar in control and Ass-KOTie2 mice. Depletion of circulating L-arginine by arginase 1 infusion or inhibition of NOS activity with L-NAME resulted in an increased MAP (10 and 30 mmHg, respectively) in control and Ass-KOTie2 mice. Optimal arterial diameter, contractile responses to phenylephrine, and relaxing responses to acetylcholine and sodium nitroprusside were similar in healthy control and Ass-KOTie2 mice. However, in diabetic Ass-KOTie2 mice, relaxation responses to acetylcholine and endothelium-derived NO (EDNO) were significantly reduced when compared to diabetic control mice. Conclusions Absence of endothelial citrulline recycling to arginine did not affect blood pressure and systemic arterial vasomotor responses in healthy mice. EDNO-mediated vasodilatation was significantly more impaired in diabetic Ass-KOTie2 than in control mice demonstrating that endothelial arginine recycling becomes a limiting endothelial function in diabetes.
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Waeckel L, Bertin F, Clavreul N, Damery T, Köhler R, Paysant J, Sansilvestri-Morel P, Simonet S, Vayssettes-Courchay C, Wulff H, Verbeuren TJ, Félétou M. Preserved regulation of renal perfusion pressure by small and intermediate conductance KCa channels in hypertensive mice with or without renal failure. Pflugers Arch 2014; 467:817-31. [DOI: 10.1007/s00424-014-1542-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/19/2014] [Accepted: 05/19/2014] [Indexed: 11/29/2022]
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Justo ML, Claro C, Vila E, Herrera MD, Rodriguez-Rodriguez R. Microvascular disorders in obese Zucker rats are restored by a rice bran diet. Nutr Metab Cardiovasc Dis 2014; 24:524-531. [PMID: 24361072 DOI: 10.1016/j.numecd.2013.10.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 01/19/2023]
Abstract
BACKGROUND AND AIM Nutritional-based approaches aimed to prevent microvascular dysfunction associated to obesity present potential advantages over pharmacological strategies. Our aim was to test whether a rice bran enzymatic extract (RBEE)-supplemented diet could attenuate microvascular alterations in obese rats. METHODS AND RESULTS Lean and obese Zucker rats were fed standard diet supplemented or not with 1% and 5% RBEE for 20 weeks. Functional studies were performed in small mesenteric arteries in isometric myograph. Immunoblotting and fluorescence studies were made in arterial homogenates and arterial sections, respectively. RBEE-supplementation restored microvascular function in obese rats through a marked increase in NO and endothelial-derived hyperpolarizing factor contribution by up-regulation of eNOS and calcium-activated potassium channels expression, respectively, in association to a substantial reduction of microvascular inflammation and superoxide anion formation. These data agrees with the beneficial actions of RBEE on dyslipidemia, hyperinsulinemia and hypertension in obesity. CONCLUSION The multi-factorial properties of RBEE-diet, especially for restoring the function of small resistance arteries shows this dietary-based approach to be a promising candidate for prevention of microvascular alterations in obesity, which are crucial in cardiovascular events in obese subjects.
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Affiliation(s)
- M L Justo
- Department of Pharmacology, School of Pharmacy, University of Seville, Seville, Spain
| | - C Claro
- Department of Pharmacology, School of Pharmacy, University of Seville, Seville, Spain
| | - E Vila
- Departament de Farmacologia, Terapèutica i Toxicologia, Facultat de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - M D Herrera
- Department of Pharmacology, School of Pharmacy, University of Seville, Seville, Spain
| | - R Rodriguez-Rodriguez
- Department of Pharmacology, School of Pharmacy, University of Seville, Seville, Spain.
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Zhao LM, Wang Y, Ma XZ, Wang NP, Deng XL. Advanced glycation end products impair K(Ca)3.1- and K(Ca)2.3-mediated vasodilatation via oxidative stress in rat mesenteric arteries. Pflugers Arch 2013; 466:307-17. [PMID: 23873353 DOI: 10.1007/s00424-013-1324-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/18/2013] [Accepted: 06/27/2013] [Indexed: 12/16/2022]
Abstract
The present study was designed to investigate the role of advanced glycation end products (AGEs) in intermediate-conductance and small-conductance Ca(2+)-activated potassium channels (KCa3.1 and KCa2.3)-mediated relaxation in rat resistance arteries and the underlying mechanism. The endothelial function of mesenteric arteries was assessed with the use of wire myography. Expression levels of KCa3.1 and KCa2.3 were measured by using Western blot. Reactive oxygen species (ROS) were measured by using dihydroethidium and 2', 7'-dichlorofluorescein diacetate. KCa3.1 and KCa2.3-mediated vasodilatation responses to acetylcholine and NS309 (opener of KCa3.1 and KCa2.3) were impaired by incubation of the third-order mesenteric arteries from normal rats with AGEs (200 μg ml(-1) for 3 h). In cultured human umbilical vein endothelial cells (HUVECs), AGEs increased ROS level and decreased the protein expression of KCa3.1 and KCa2.3. Antioxidant alpha lipoic acid restored the impairment in both vasodilatation function and expression of KCa3.1 and KCa2.3. H2O2 could mimic the effect of AGEs on the protein expression of KCa3.1 and KCa2.3 in cultured HUVECs. These results demonstrate for the first time that AGEs impaired KCa3.1 and KCa2.3-mediated vasodilatation in rat mesenteric arteries via downregulation of both KCa3.1 and KCa2.3, in which the enhanced oxidative stress was involved.
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Affiliation(s)
- Li-Mei Zhao
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, Shaanxi, China
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Simonet S, Isabelle M, Bousquenaud M, Clavreul N, Félétou M, Vayssettes-Courchay C, Verbeuren TJ. KCa 3.1 channels maintain endothelium-dependent vasodilatation in isolated perfused kidneys of spontaneously hypertensive rats after chronic inhibition of NOS. Br J Pharmacol 2013; 167:854-67. [PMID: 22646737 DOI: 10.1111/j.1476-5381.2012.02062.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The purpose of the study was to investigate renal endothelium-dependent vasodilatation in a model of severe hypertension associated with kidney injury. EXPERIMENTAL APPROACH Changes in perfusion pressure were measured in isolated, perfused kidneys taken from 18-week-old Wistar-Kyoto rat (WKY), spontaneously hypertensive rats (SHR) and SHR treated for 2 weeks with N(ω) -nitro-L-arginine methyl ester in the drinking water (L-NAME-treated SHR, 6 mg·kg(-1) ·day(-1) ). KEY RESULTS Acetylcholine caused similar dose-dependent renal dilatation in the three groups. In vitro administration of indomethacin did not alter the vasodilatation, while the addition of N(w) -nitro-L-arginine (L-NA) produced a differential inhibition of the vasodilatation, (inhibition in WKY > SHR > L-NAME-treated SHR). Further addition of ODQ, an inhibitor of soluble guanylyl cyclase, abolished the responses to sodium nitroprusside but did not affect the vasodilatation to acetylcholine. However, the addition of TRAM-34 (or charybdotoxin) inhibitors of Ca(2+) -activated K(+) channels of intermediate conductance (K(Ca) 3.1), blocked the vasodilatation to acetylcholine, while apamin, an inhibitor of Ca(2+) -activated K(+) channels of small conductance (K(Ca) 2.3), was ineffective. Dilatation induced by an opener of K(Ca) 3.1/K(Ca) 2.3 channels, NS-309, was also blocked by TRAM-34, but not by apamin. The magnitude and duration of NS-309-induced vasodilatation and the renal expression of mRNA for K(Ca) 3.1, but not K(Ca) 2.3, channels followed the same ranking order (WKY < SHR < L-NAME-treated SHR). CONCLUSIONS AND IMPLICATIONS In SHR kidneys, an EDHF-mediated response, involving activation of K(Ca) 3.1 channels, contributed to the mechanism of endothelium-dependent vasodilatation. In kidneys from L-NAME-treated SHR, up-regulation of this pathway fully compensated for the decrease in NO availability.
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Ritchie RH, Leo CH, Qin C, Stephenson EJ, Bowden MA, Buxton KD, Lessard SJ, Rivas DA, Koch LG, Britton SL, Hawley JA, Woodman OL. Low intrinsic exercise capacity in rats predisposes to age-dependent cardiac remodeling independent of macrovascular function. Am J Physiol Heart Circ Physiol 2012; 304:H729-39. [PMID: 23262135 DOI: 10.1152/ajpheart.00638.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rats selectively bred for low (LCR) or high (HCR) intrinsic running capacity simultaneously present with contrasting risk factors for cardiovascular and metabolic disease. However, the impact of these phenotypes on left ventricular (LV) morphology and microvascular function, and their progression with aging, remains unresolved. We tested the hypothesis that the LCR phenotype induces progressive age-dependent LV remodeling and impairments in microvascular function, glucose utilization, and β-adrenergic responsiveness, compared with HCR. Hearts and vessels isolated from female LCR (n = 22) or HCR (n = 26) were studied at 12 and 35 wk. Nonselected N:NIH founder rats (11 wk) were also investigated (n = 12). LCR had impaired glucose tolerance and elevated plasma insulin (but not glucose) and body-mass at 12 wk compared with HCR, with early LV remodeling. By 35 wk, LV prohypertrophic and glucose transporter GLUT4 gene expression were up- and downregulated, respectively. No differences in LV β-adrenoceptor expression or cAMP content between phenotypes were observed. Macrovascular endothelial function was predominantly nitric oxide (NO)-mediated in both phenotypes and remained intact in LCR for both age-groups. In contrast, mesenteric arteries microvascular endothelial function, which was impaired in LCR rats regardless of age. At 35 wk, endothelial-derived hyperpolarizing factor-mediated relaxation was impaired whereas the NO contribution to relaxation is intact. Furthermore, there was reduced β2-adrenoceptor responsiveness in both aorta and mesenteric LCR arteries. In conclusion, diminished intrinsic exercise capacity impairs systemic glucose tolerance and is accompanied by progressive development of LV remodeling. Impaired microvascular perfusion is a likely contributing factor to the cardiac phenotype.
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Oniki H, Goto K, Fujii K, Kansui Y, Murakami N, Ohtsubo T, Matsumura K, Kitazono T. Effects of the superoxide dismutase mimetic tempol on impaired endothelium-dependent and endothelium-independent relaxations in type II diabetic rats. Clin Exp Hypertens 2012; 35:112-9. [PMID: 22783963 DOI: 10.3109/10641963.2012.702829] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Endothelium-derived hyperpolarizing factor (EDHF)-mediated hyperpolarization and relaxation, and endothelium-independent relaxations to the nitric oxide donor sodium nitroprusside and the adenosine 5'-triphosphate (ATP)-sensitive K(+)-channel opener levcromakalim were both impaired in mesenteric arteries of type II diabetic Goto-Kakizaki rats. The treatment with the superoxide dismutase mimetic tempol or its combination with the angiotensin II type 1 receptor blocker candesartan failed to improve EDHF-mediated responses, although both treatments partially improved endothelium-independent relaxations. These findings suggest that increased oxidative stress may in part account for the impaired endothelium-independent relaxations in diabetes, while it does not play a major role in the impaired EDHF-mediated responses.
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Affiliation(s)
- Hideyuki Oniki
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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KERR PAULM, TAM RAYMOND, ONDRUSOVA KATARINA, MITTAL ROHAN, NARANG DEEPAK, TRAN CAMHAT, WELSH DONALDG, PLANE FRANCES. Endothelial Feedback and the Myoendothelial Projection. Microcirculation 2012; 19:416-22. [DOI: 10.1111/j.1549-8719.2012.00187.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Schjørring O, Kun A, Flyvbjerg A, Kirkeby HJ, Jensen JB, Simonsen U. Flow‐Evoked Vasodilation Is Blunted in Penile Arteries from Zucker Diabetic Fatty Rats. J Sex Med 2012; 9:1789-800. [DOI: 10.1111/j.1743-6109.2012.02743.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Howitt L, Grayson TH, Morris MJ, Sandow SL, Murphy TV. Dietary obesity increases NO and inhibits BKCa-mediated, endothelium-dependent dilation in rat cremaster muscle artery: association with caveolins and caveolae. Am J Physiol Heart Circ Physiol 2012; 302:H2464-76. [DOI: 10.1152/ajpheart.00965.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is a risk factor for hypertension and other vascular disease. The aim of this study was to examine the effect of diet-induced obesity on endothelium-dependent dilation of rat cremaster muscle arterioles. Male Sprague-Dawley rats (213 ± 1 g) were fed a cafeteria-style high-fat or control diet for 16–20 wk. Control rats weighed 558 ± 7 g compared with obese rats 762 ± 12 g ( n = 52–56; P < 0.05). Diet-induced obesity had no effect on acetylcholine (ACh)-induced dilation of isolated, pressurized (70 mmHg) arterioles, but sodium nitroprusside (SNP)-induced vasodilation was enhanced. ACh-induced dilation of arterioles from control rats was abolished by a combination of the KCa blockers apamin, 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), and iberiotoxin (IBTX; all 0.1 μmol/l), with no apparent role for nitric oxide (NO). In arterioles from obese rats, however, IBTX had no effect on responses to ACh while the NO synthase (NOS)/guanylate cyclase inhibitors Nω-nitro-l-arginine methyl ester (l-NAME; 100 μmol/l)/1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μmol/l) partially inhibited ACh-induced dilation. Furthermore, NOS activity (but not endothelial NOS expression) was increased in arteries from obese rats. l-NAME/ODQ alone or removal of the endothelium constricted arterioles from obese but not control rats. Expression of caveolin-1 and -2 oligomers (but not monomers or caveolin-3) was increased in arterioles from obese rats. The number of caveolae was reduced in the endothelium of arteries, and caveolae density was increased at the ends of smooth muscle cells from obese rats. Diet-induced obesity abolished the contribution of large-conductance Ca2+-activated K+ channel to ACh-mediated endothelium-dependent dilation of rat cremaster muscle arterioles, while increasing NOS activity and inducing an NO-dependent component.
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Affiliation(s)
- Lauren Howitt
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
| | - T. Hilton Grayson
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Margaret J. Morris
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Shaun L. Sandow
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Timothy V. Murphy
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
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Kerr PM, Tam R, Narang D, Potts K, McMillan D, McMillan K, Plane F. Endothelial calcium-activated potassium channels as therapeutic targets to enhance availability of nitric oxide. Can J Physiol Pharmacol 2012; 90:739-52. [PMID: 22626011 DOI: 10.1139/y2012-075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vascular endothelium plays a critical role in vascular health by controlling arterial diameter, regulating local cell growth, and protecting blood vessels from the deleterious consequences of platelet aggregation and activation of inflammatory responses. Circulating chemical mediators and physical forces act directly on the endothelium to release diffusible relaxing factors, such as nitric oxide (NO), and to elicit hyperpolarization of the endothelial cell membrane potential, which can spread to the surrounding smooth muscle cells via gap junctions. Endothelial hyperpolarization, mediated by activation of calcium-activated potassium (K(Ca)) channels, has generally been regarded as a distinct pathway for smooth muscle relaxation. However, recent evidence supports a role for endothelial K(Ca) channels in production of endothelium-derived NO, and indicates that pharmacological activation of these channels can enhance NO-mediated responses. In this review we summarize the current data on the functional role of endothelial K(Ca) channels in regulating NO-mediated changes in arterial diameter and NO production, and explore the tempting possibility that these channels may represent a novel avenue for therapeutic intervention in conditions associated with reduced NO availability such as hypertension, hypercholesterolemia, smoking, and diabetes mellitus.
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Affiliation(s)
- Paul M Kerr
- Department of Pharmacology, 9-62 Medical Sciences Building, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Félétou M. The Endothelium, Part I: Multiple Functions of the Endothelial Cells -- Focus on Endothelium-Derived Vasoactive Mediators. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00031ed1v01y201105isp019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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3',4'-Dihydroxyflavonol reduces superoxide and improves nitric oxide function in diabetic rat mesenteric arteries. PLoS One 2011; 6:e20813. [PMID: 21673968 PMCID: PMC3108977 DOI: 10.1371/journal.pone.0020813] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 05/10/2011] [Indexed: 12/20/2022] Open
Abstract
Background 3',4'-Dihydroxyflavonol (DiOHF) is an effective antioxidant that acutely preserves nitric oxide (NO) activity in the presence of elevated reactive oxygen species (ROS). We hypothesized that DiOHF treatment (7 days, 1 mg/kg per day s.c.) would improve relaxation in mesenteric arteries from diabetic rats where endothelial dysfunction is associated with elevated oxidant stress. Methodology/Principal Findings In mesenteric arteries from diabetic rats there was an increase in ROS, measured by L-012 and 2',7'-dichlorodihydrofluorescein diacetate fluorescence. NADPH oxidase-derived superoxide levels, assayed by lucigenin chemiluminescence, were also significantly increased in diabetic mesenteric arteries (diabetes, 4892±946 counts/mg versus normal 2486±344 counts/mg, n = 7–10, p<0.01) associated with an increase in Nox2 expression but DiOHF (2094±300 counts/mg, n = 10, p<0.001) reversed that effect. Acetylcholine (ACh)-induced relaxation of mesenteric arteries was assessed using wire myography (pEC50 = 7.94±0.13 n = 12). Diabetes significantly reduced the sensitivity to ACh and treatment with DiOHF prevented endothelial dysfunction (pEC50, diabetic 6.86±0.12 versus diabetic+DiOHF, 7.49±0.13, n = 11, p<0.01). The contribution of NO versus endothelium-derived hyperpolarizing factor (EDHF) to ACh-induced relaxation was assessed by evaluating responses in the presence of TRAM-34+apamin+iberiotoxin or N-nitro-L-arginine+ODQ respectively. Diabetes impaired the contribution of both NO (maximum relaxation, Rmax diabetic 24±7 versus normal, 68±10, n = 9–10, p<0.01) and EDHF (pEC50, diabetic 6.63±0.15 versus normal, 7.14±0.12, n = 10–11, p<0.01) to endothelium-dependent relaxation. DiOHF treatment did not significantly affect the EDHF contribution but enhanced NO-mediated relaxation (Rmax 69±6, n = 11, p<0.01). Western blotting demonstrated that diabetes also decreased expression and increased uncoupling of endothelial NO synthase (eNOS). Treatment of the diabetic rats with DiOHF significantly reduced vascular ROS and restored NO-mediated endothelium-dependent relaxation. Treatment of the diabetic rats with DiOHF also increased eNOS expression, both in total and as a dimer. Conclusions/Significance DiOHF improves NO activity in diabetes by reducing Nox2-dependent superoxide production and preventing eNOS uncoupling to improve endothelial function.
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Haddock RE, Grayson TH, Morris MJ, Howitt L, Chadha PS, Sandow SL. Diet-induced obesity impairs endothelium-derived hyperpolarization via altered potassium channel signaling mechanisms. PLoS One 2011; 6:e16423. [PMID: 21283658 PMCID: PMC3025034 DOI: 10.1371/journal.pone.0016423] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 12/15/2010] [Indexed: 11/20/2022] Open
Abstract
Background The vascular endothelium plays a critical role in the control of blood flow. Altered endothelium-mediated vasodilator and vasoconstrictor mechanisms underlie key aspects of cardiovascular disease, including those in obesity. Whilst the mechanism of nitric oxide (NO)-mediated vasodilation has been extensively studied in obesity, little is known about the impact of obesity on vasodilation to the endothelium-derived hyperpolarization (EDH) mechanism; which predominates in smaller resistance vessels and is characterized in this study. Methodology/Principal Findings Membrane potential, vessel diameter and luminal pressure were recorded in 4th order mesenteric arteries with pressure-induced myogenic tone, in control and diet-induced obese rats. Obesity, reflecting that of human dietary etiology, was induced with a cafeteria-style diet (∼30 kJ, fat) over 16–20 weeks. Age and sexed matched controls received standard chow (∼12 kJ, fat). Channel protein distribution, expression and vessel morphology were determined using immunohistochemistry, Western blotting and ultrastructural techniques. In control and obese rat vessels, acetylcholine-mediated EDH was abolished by small and intermediate conductance calcium-activated potassium channel (SKCa/IKCa) inhibition; with such activity being impaired in obesity. SKCa-IKCa activation with cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) and 1-ethyl-2-benzimidazolinone (1-EBIO), respectively, hyperpolarized and relaxed vessels from control and obese rats. IKCa-mediated EDH contribution was increased in obesity, and associated with altered IKCa distribution and elevated expression. In contrast, the SKCa-dependent-EDH component was reduced in obesity. Inward-rectifying potassium channel (Kir) and Na+/K+-ATPase inhibition by barium/ouabain, respectively, attenuated and abolished EDH in arteries from control and obese rats, respectively; reflecting differential Kir expression and distribution. Although changes in medial properties occurred, obesity had no effect on myoendothelial gap junction density. Conclusion/Significance In obese rats, vasodilation to EDH is impaired due to changes in the underlying potassium channel signaling mechanisms. Whilst myoendothelial gap junction density is unchanged in arteries of obese compared to control, increased IKCa and Na+/K+-ATPase, and decreased Kir underlie changes in the EDH mechanism.
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Affiliation(s)
- Rebecca E. Haddock
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- Department of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (REH); (SLS)
| | - T. Hilton Grayson
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Margaret J. Morris
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Lauren Howitt
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Preet S. Chadha
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Shaun L. Sandow
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail: (REH); (SLS)
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Witcher D, Sakai N, Williams B, Rahimian R, Anderson L. Gender differences in the effects of streptozotocin-induced diabetes on parasympathetic vasodilatation in the rat submandibular gland. Arch Oral Biol 2010; 55:745-53. [PMID: 20667523 DOI: 10.1016/j.archoralbio.2010.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 06/03/2010] [Accepted: 06/25/2010] [Indexed: 12/27/2022]
Abstract
OBJECTIVES Submandibular vasodilatory responses are impaired in male streptozotocin-diabetic rats. However, the effects of diabetes on submandibular vascular reactivity in female rats have not been examined. The purpose of this study was to determine whether there are gender differences in the effects of diabetes on parasympathetic vasodilatation in the rat submandibular gland. METHODS Diabetes was induced using streptozotocin, and vascular responses (calculated as the % increase in submandibular vascular conductance) to parasympathetic stimulation (1-10 Hz) were measured using laser-Doppler flowmetry. To estimate the relative contributions of nitric oxide (NO), prostacyclin (PGI2) and endothelium-derived hyperpolarizing factor (EDHF), vascular conductance was measured before and after inhibition of cyclooxygenase (COX) and NO synthase (NOS). RESULTS Frequency-dependent increases in blood flow were observed in both male and female rats, but the contribution of EDHF was greater in females than in males. Further, PGI2 appeared to play a role only in males. Vasodilatory responses were diminished in all diabetic animals, and when compared with their respective controls the degree of impairment was similar in males and females. However, in diabetic males inhibition of COX and NOS had little or no effect, whereas inhibition of NO, but not COX, resulted in a further significant decrease in vascular responses in diabetic females. CONCLUSIONS Parasympathetic vasodilatation in the rat submandibular gland is diminished equally in diabetic males and females. However, in males diabetes predominantly impairs PGI2- and NO-dependent vasodilatation, whereas in females the contribution of EDHF-mediated pathways are affected and NO-dependent vasodilatation is preferentially maintained.
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Affiliation(s)
- Daniel Witcher
- Department of Physiological Sciences, University of the Pacific, Arthur A. Dugoni School of Dentistry, 2155 Webster Street, San Francisco, CA 94115, United States
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Fatehi-Hassanabad Z, Chan CB, Furman BL. Reactive oxygen species and endothelial function in diabetes. Eur J Pharmacol 2010; 636:8-17. [DOI: 10.1016/j.ejphar.2010.03.048] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 02/27/2010] [Accepted: 03/22/2010] [Indexed: 02/07/2023]
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Ding H, Triggle CR. Endothelial dysfunction in diabetes: multiple targets for treatment. Pflugers Arch 2010; 459:977-94. [PMID: 20238124 DOI: 10.1007/s00424-010-0807-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 02/13/2010] [Accepted: 02/16/2010] [Indexed: 12/20/2022]
Abstract
Robert Furchgott's discovery of the obligatory role that the endothelium plays in the regulation of vascular tone has proved to be a major advance in terms of our understanding of the cellular basis of diabetic vascular disease. Endothelial dysfunction, as defined by a reduction in the vasodilatation response to an endothelium-dependent vasodilator (such as acetylcholine) or to flow-mediated vasodilatation, is an early indicator for the development of the micro- and macroangipathy that is associated with diabetes. In diabetes, hyperglycaemia plays a key role in the initiation and development of endothelial dysfunction; however, the cellular mechanisms involved as well as the importance of dyslipidaemia and co-morbidities such as hypertension and obesity remain incompletely understood. In this review, we discuss the mechanisms whereby hyperglycaemia, oxidative stress and dyslipidaemia can alter endothelial function and highlight their effects on endothelial nitric oxide synthase (eNOS), the endothelium-dependent hyperpolarising factor (EDHF) pathway(s), as well as on the role of endothelium-derived contracting factors (EDCFs) and adipocyte-derived vasoactive factors such as adipose-derived relaxing factor (ADRF).
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Affiliation(s)
- Hong Ding
- Department of Pharmacology & Medical Education, Weill Cornell Medical College in Qatar, P.O. Box 24144, Education City, Doha, Qatar
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de Wit C, Griffith TM. Connexins and gap junctions in the EDHF phenomenon and conducted vasomotor responses. Pflugers Arch 2010; 459:897-914. [PMID: 20379740 DOI: 10.1007/s00424-010-0830-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 03/16/2010] [Indexed: 12/21/2022]
Abstract
It is becoming increasingly evident that electrical signaling via gap junctions plays a central role in the physiological control of vascular tone via two related mechanisms (1) the endothelium-derived hyperpolarizing factor (EDHF) phenomenon, in which radial transmission of hyperpolarization from the endothelium to subjacent smooth muscle promotes relaxation, and (2) responses that propagate longitudinally, in which electrical signaling within the intimal and medial layers of the arteriolar wall orchestrates mechanical behavior over biologically large distances. In the EDHF phenomenon, the transmitted endothelial hyperpolarization is initiated by the activation of Ca(2+)-activated K(+) channels channels by InsP(3)-induced Ca(2+) release from the endoplasmic reticulum and/or store-operated Ca(2+) entry triggered by the depletion of such stores. Pharmacological inhibitors of direct cell-cell coupling may thus attenuate EDHF-type smooth muscle hyperpolarizations and relaxations, confirming the participation of electrotonic signaling via myoendothelial and homocellular smooth muscle gap junctions. In contrast to isolated vessels, surprisingly little experimental evidence argues in favor of myoendothelial coupling acting as the EDHF mechanism in arterioles in vivo. However, it now seems established that the endothelium plays the leading role in the spatial propagation of arteriolar responses and that these involve poorly understood regenerative mechanisms. The present review will focus on the complex interactions between the diverse cellular signaling mechanisms that contribute to these phenomena.
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Affiliation(s)
- Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany.
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Matsumoto T, Ishida K, Nakayama N, Taguchi K, Kobayashi T, Kamata K. Mechanisms underlying the losartan treatment-induced improvement in the endothelial dysfunction seen in mesenteric arteries from type 2 diabetic rats. Pharmacol Res 2010; 62:271-81. [PMID: 20304070 DOI: 10.1016/j.phrs.2010.03.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 03/12/2010] [Accepted: 03/12/2010] [Indexed: 11/24/2022]
Abstract
It is well known that type 2 diabetes mellitus is frequently associated with vascular dysfunction and an elevated systemic blood pressure, yet the underlying mechanisms are not completely understood. We previously reported that in mesenteric arteries from established type 2 diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats, which exhibit endothelial dysfunction, there is an imbalance between endothelium-derived vasodilators [namely, nitric oxide (NO) and hyperpolarizing factor (EDHF)] and vasoconstrictors [contracting factors (EDCFs) such as cyclooxygenase (COX)-derived prostanoids]. Here, we investigated whether the angiotensin II receptor antagonist losartan might improve endothelial dysfunction in OLETF rats at the established stage of diabetes. In mesenteric arteries isolated from OLETF rats [vs. those from age-matched control Long-Evans Tokushima Otsuka (LETO) rats]: (1) the acetylcholine (ACh)-induced relaxation was impaired, (2) the NO- and EDHF-mediated relaxations were reduced, (3) the ACh-induced EDCF-mediated contraction and the production of prostanoids were increased, and (4) superoxide generation was increased. After such OLETF rats had received losartan (25 mg/kg/day p.o. for 4 weeks), their isolated mesenteric arteries exhibited: (1) improvements in ACh-induced NO- and EDHF-mediated relaxations, (2) reduced EDCF- and arachidonic acid-induced contractions, (3) suppressed production of prostanoids, (4) reduced PGE(2)-mediated contraction, and (5) reduced superoxide generation. Within the timescale studied here, losartan did not change the protein expressions of endothelial NO synthase, COX1, or COX2 in mesenteric arteries from either OLETF or LETO rats. Losartan thus normalizes vascular dysfunction in this type 2 diabetic model, and the above effects may contribute to the reduction of adverse cardiovascular events seen in diabetic patients treated with angiotensin II receptor blockers.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
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Feher A, Rutkai I, Beleznai T, Ungvari Z, Csiszar A, Edes I, Bagi Z. Caveolin-1 limits the contribution of BK(Ca) channel to EDHF-mediated arteriolar dilation: implications in diet-induced obesity. Cardiovasc Res 2010; 87:732-9. [PMID: 20299334 DOI: 10.1093/cvr/cvq088] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
AIMS Caveolin-1 (Cav-1) interacts with large conductance Ca(2+)-activated potassium channels (BKCa) and likely exerts a negative regulatory effect on the channel activity. We investigated the role of Cav-1 in modulating BK(Ca) channel-mediated, endothelium-derived hyperpolarizing factor (EDHF)-dependent arteriolar dilation in normal condition and in an experimental model of obesity. METHODS AND RESULTS In isolated, pressurized (80 mmHg) gracilis muscle arterioles (approximately 100 microm) of Cav-1 knockout mice, acetylcholine (ACh)-induced, EDHF-mediated dilations were enhanced and were significantly reduced by the BK(Ca) channel inhibitor, iberiotoxin (IBTX), whereas IBTX had no effect on EDHF-mediated dilations in the wild-type mice. Dilations to the selective BK(Ca) channel opener, NS-1619 were augmented in the Cav-1 knockout mice. In high-fat diet-treated, obese rats ACh-induced coronary arteriolar dilations were preserved, whereas IBTX-sensitive, ACh-induced and also NS-1619-evoked vasodilations were augmented when compared with lean animals. In coronary arterioles of obese rats a reduced protein expression of Cav-1 was detected by western immunoblotting and immunohistochemistry. Moreover, in coronary arterioles of lean rats, disruption of caveolae with methyl-beta-cyclodextrin augmented IBTX-sensitive, ACh-induced, and also NS-1619-evoked dilations. CONCLUSION Thus, under normal conditions, Cav-1 limits the contribution of the BK(Ca) channel to EDHF-mediated arteriolar dilation. In obesity, a reduced expression of Cav-1 leads to greater contribution of the BK(Ca) channel to EDHF-mediated response, which seems essential for maintained coronary dilation.
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Affiliation(s)
- Attila Feher
- Department of Physiology, New York Medical College, Valhalla, NY 10595, USA
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Köhler R, Kaistha BP, Wulff H. Vascular KCa-channels as therapeutic targets in hypertension and restenosis disease. Expert Opin Ther Targets 2010; 14:143-55. [PMID: 20055714 DOI: 10.1517/14728220903540257] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
IMPORTANCE OF THE FIELD Cardiovascular disease is a leading cause of death in modern societies. Hyperpolarizing Ca(2+)-activated K(+) channels (K(Ca)) are important membrane proteins in the control of arterial tone and pathological vascular remodelling and thus could serve as new drug targets. AREAS COVERED IN THIS REVIEW We summarize recent advances in the field of vascular K(Ca) and their roles in cardiovascular pathologies such as hypertension and restenosis disease and draw attention to novel small-molecule channel modulators and their possible therapeutic utility. This review focuses on literature from the last four to five years. WHAT THE READER WILL GAIN Pharmacological opening of endothelial KCa3.1/KCa2.3 channels stimulates endothelium-derived-hyperpolarizing-factor-mediated arteriolar dilation and lowers blood pressure. Inhibition of smooth muscle KCa3.1 channels has beneficial effects in restenosis disease and atherosclerosis. We consider the therapeutic potential of KCa3.1/KCa2.3 openers as novel endothelium-specific antihypertensive drugs as well as of KCa3.1-blockers for the treatment of pathological vascular remodelling and discuss advantages and disadvantages of the pharmacotherapeutic approaches. TAKE HOME MESSAGE Pharmacological manipulation of vascular K(Ca) channels by novel small-molecule modulators offers new venues for alternative treatments of hypertension, restenosis and atherosclerosis. Additional efforts are required to optimize these compounds and to validate them as cardiovascular-protective drugs.
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Affiliation(s)
- Ralf Köhler
- Institute of Medical Biology, Depatrment of Physiology, SDU, J.B. Winsløwsvej 21 3., 5000 Odense C, Denmark.
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Matsumoto T, Ishida K, Taguchi K, Kobayashi T, Kamata K. Losartan normalizes endothelium-derived hyperpolarizing factor-mediated relaxation by activating Ca2+-activated K+ channels in mesenteric artery from type 2 diabetic GK rat. J Pharmacol Sci 2010; 112:299-309. [PMID: 20168046 DOI: 10.1254/jphs.09308fp] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Ca(2+)-activated K(+) (K(Ca)) channels are important for endothelium-derived hyperpolarizing factor (EDHF) signaling. Since treatment with angiotensin II receptor blockers (ARBs) improves vasculopathies in type 2 diabetic patients, we asked whether the EDHF-type relaxation and its associated K(Ca) channels [small (SK(Ca))-, intermediate (IK(Ca))-, and large (BK(Ca))-conductance channels] are abnormal in mesenteric arteries isolated from Goto-Kakizaki (GK) rats at the chronic stage of type 2 diabetes (34 - 38 weeks) and whether an ARBs (losartan, 25 mg . kg(-1) . day(-1) for 2 weeks) might correct these abnormalities. Although the acetylcholine chloride-induced EDHF-type relaxation in mesenteric arteries from GK rats was reduced versus the Wistar controls, it was significantly restored by losartan treatment. The SK(Ca)-blocker apamin or the IK(Ca)-blocker 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34) inhibited such relaxations in the losartan-treated or -untreated Wistar groups and in the losartan-treated GK group, but not in the losartan-untreated GK group. The BK(Ca)-blocker iberiotoxin had a significant inhibitory effect in only one of these groups, the losartan-treated GK. The relaxations induced by the SK(Ca)/IK(Ca) activator NS309 and the BK(Ca) activator NS1619, which were impaired in GK rats, were normalized by losartan treatment. We conclude that losartan improves EDHF-type relaxation in GK rats at least partly by normalizing SK(Ca)/IK(Ca) activities and increasing BK(Ca) activity.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
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Brøndum E, Kold-Petersen H, Simonsen U, Aalkjaer C. NS309 restores EDHF-type relaxation in mesenteric small arteries from type 2 diabetic ZDF rats. Br J Pharmacol 2010; 159:154-65. [PMID: 20015296 PMCID: PMC2823361 DOI: 10.1111/j.1476-5381.2009.00525.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 06/19/2009] [Accepted: 09/03/2009] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The endothelium-derived hyperpolarizing factor (EDHF)-type relaxation in mesenteric small arteries from 21 week old Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats was investigated using (6,7-dichloro-1H-indole-2,3-dione 3-oxime) (NS309), a potent activator of small-conductance, calcium-activated potassium channel (SK(Ca)) and intermediate-conductance, calcium-activated potassium channel (IK(Ca)). EXPERIMENTAL APPROACH In the presence of inhibitors of cyclooxygenase and nitric oxide synthase [indomethacin and N(omega)-nitro-L-arginine methyl ester (l-NAME), respectively], acetylcholine (ACh)-induced hyperpolarization and EDHF-type relaxation were investigated under isometric conditions in the wire myograph using 0.5 and 1 microM NS309 and/or selective blockers of SK(Ca) and IK(Ca) channels. Membrane potential was recorded with glass microelectrodes, and changes in the intracellular calcium concentration of endothelial cells were visualized by confocal microscopy. SK(Ca) expression was assessed by Western blotting. KEY RESULTS In arteries from ZDF rats, ACh-induced relaxation and membrane hyperpolarization were attenuated and, compared with arteries from ZL rats, NS309 was less potent at causing relaxation. Incubation with 0.5 microM NS309 did not increase ACh-induced relaxation in arteries from ZDF rats significantly. However, 1 microM NS309 restored it (both in the absence and in the presence of indomethacin and l-NAME) without changing endothelial intracellular calcium concentration. The restored EDHF-type relaxation was more sensitive to TRAM-34 (1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole) (1 microM) than to apamin. Expression of the SK(Ca) channel was unaltered. CONCLUSIONS AND IMPLICATIONS The attenuated EDHF-type relaxation in mesenteric small arteries from ZDF rats can be restored by NS309 without changes in the intracellular calcium concentration of endothelial cells. These results may have clinical implications for the treatment of endothelial dysfunction in overweight type 2 diabetic patients.
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Affiliation(s)
- E Brøndum
- The Water and Salt Research Center, Institute of Physiology and Biophysics, Aarhus University, DK-8000 Aarhus C, Denmark
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