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Peixoto-Neves D, Jaggar JH. Physiological functions and pathological involvement of ion channel trafficking in the vasculature. J Physiol 2024; 602:3275-3296. [PMID: 37818949 PMCID: PMC11006830 DOI: 10.1113/jp285007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/28/2023] [Indexed: 10/13/2023] Open
Abstract
A variety of ion channels regulate membrane potential and calcium influx in arterial smooth muscle and endothelial cells to modify vascular functions, including contractility. The current (I) generated by a population of ion channels is equally dependent upon their number (N), open probability (Po) and single channel current (i), such that I = N.PO.i. A conventional view had been that ion channels traffic to the plasma membrane in a passive manner, resulting in a static surface population. It was also considered that channels assemble with auxiliary subunits prior to anterograde trafficking of the multimeric complex to the plasma membrane. Recent studies have demonstrated that physiological stimuli can regulate the surface abundance (N) of several different ion channels in arterial smooth muscle and endothelial cells to control arterial contractility. Physiological stimuli can also regulate the number of auxiliary subunits present in the plasma membrane to modify the biophysical properties, regulatory mechanisms and physiological functions of some ion channels. Furthermore, ion channel trafficking becomes dysfunctional in the vasculature during hypertension, which negatively impacts the regulation of contractility. The temporal kinetics of ion channel and auxiliary subunit trafficking can also vary depending on the signalling mechanisms and proteins involved. This review will summarize recent work that has uncovered the mechanisms, functions and pathological modifications of ion channel trafficking in arterial smooth muscle and endothelial cells.
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Affiliation(s)
| | - Jonathan H. Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis TN 38139
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Inderwiedenstraße L, Kienitz MC. Angiotensin receptors and α 1B-adrenergic receptors regulate native IK (ACh) and phosphorylation-deficient GIRK4 (S418A) channels through different PKC isoforms. Pflugers Arch 2024; 476:1041-1064. [PMID: 38658400 DOI: 10.1007/s00424-024-02966-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/03/2024] [Accepted: 04/17/2024] [Indexed: 04/26/2024]
Abstract
Signaling of G protein-activated inwardly rectifying K+ (GIRK) channels is an important mechanism of the parasympathetic regulation of the heart rate and cardiac excitability. GIRK channels are inhibited during stimulation of Gq-coupled receptors (GqPCRs) by depletion of phosphatidyl-4,5-bisphosphate (PIP2) and/or channel phosphorylation by protein kinase C (PKC). The GqPCR-dependent modulation of GIRK currents in terms of specific PKC isoform activation was analyzed in voltage-clamp experiments in rat atrial myocytes and in CHO or HEK 293 cells. By using specific PKC inhibitors, we identified the receptor-activated PKC isoforms that contribute to phenylephrine- and angiotensin-induced GIRK channel inhibition. We demonstrate that the cPKC isoform PKCα significantly contributes to GIRK inhibition during stimulation of wildtype α1B-adrenergic receptors (α1B-ARs). Deletion of the α1B-AR serine residues S396 and S400 results in a preferential regulation of GIRK activity by PKCβ. As a novel finding, we report that the AT1-receptor-induced GIRK inhibition depends on the activation of the nPKC isoform PKCε whereas PKCα and PKCβ do not mainly participate in the angiotensin-mediated GIRK reduction. Expression of the dominant negative (DN) PKCε prolonged the onset of GIRK inhibition and significantly reduced AT1-R desensitization, indicating that PKCε regulates both GIRK channel activity and the strength of the receptor signal via a negative feedback mechanism. The serine residue S418 represents an important phosphorylation site for PKCε in the GIRK4 subunit. To analyze the functional impact of this PKC phosphorylation site for receptor-specific GIRK channel modulation, we monitored the activity of a phosphorylation-deficient (GIRK4 (S418A)) GIRK4 channel mutant during stimulation of α1B-ARs or AT1-receptors. Mutation of S418 did not impede α1B-AR-mediated GIRK inhibition, suggesting that S418 within the GIRK4 subunit is not subject to PKCα-induced phosphorylation. Furthermore, activation of angiotensin receptors induced pronounced GIRK4 (S418A) channel inhibition, excluding that this phosphorylation site contributes to the AT1-R-induced GIRK reduction. Instead, phosphorylation of S418 has a facilitative effect on GIRK activity that was abolished in the GIRK4 (S418A) mutant. To summarize, the present study shows that the receptor-dependent regulation of atrial GIRK channels is attributed to the GqPCR-specific activation of different PKC isoforms. Receptor-specific activated PKC isoforms target distinct phosphorylation sites within the GIRK4 subunit, resulting in differential regulation of GIRK channel activity with either facilitative or inhibitory effects on GIRK currents.
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Affiliation(s)
- Leonie Inderwiedenstraße
- Department for Cellular and Translational Physiology, Institute of Physiology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Marie-Cécile Kienitz
- Department for Cellular and Translational Physiology, Institute of Physiology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
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Li G, Xu K, Xing W, Yang H, Li Y, Wang X, Zhou J, An J, Dong L, Zhang X, Wang L, Li J, Gao F. Swimming Exercise Alleviates Endothelial Mitochondrial Fragmentation via Inhibiting Dynamin-Related Protein-1 to Improve Vascular Function in Hypertension. Hypertension 2022; 79:e116-e128. [PMID: 35950516 DOI: 10.1161/hypertensionaha.122.19126] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Regular exercise has been recommended clinically for all individuals to protect against hypertension but the underlying mechanisms are not fully elucidated. We recently found a significant mitochondrial fragmentation in the vascular endothelium of hypertensive human subjects. In this study, we investigated whether exercise could restore endothelial mitochondrial dynamics and thus improve vascular function in hypertension. METHODS Vascular endothelial mitochondrial morphological alterations were examined in patients with hypertension and hypertensive animal models. Furthermore, swimming exercise-induced endothelial mitochondrial dynamics and vascular function changes were investigated in spontaneously hypertensive rats (SHRs). RESULTS Mitochondrial fragmentation with an elevated mitochondrial fission mediator Drp1 (dynamin-related protein-1) was observed in the mesenteric artery endothelium from hypertensive patients. A similar mitochondrial fragmentation with increased Drp1 expression were exhibited in the aortic endothelium of angiotensin II-induced hypertensive mice and SHRs. Interestingly, swimming exercise significantly reduced vascular Drp1 expression and alleviated endothelial mitochondrial fragmentation, thus improving blood pressure in SHRs. In cultured endothelial cells, angiotensin II exposure induced Drp1 upregulation, mitochondrial fragmentation and dysfunction, and reduced nitric oxide production, which was blunted by Drp1 genetic reduction or its inhibitor Mdivi-1. Mdivi-1 administration also ameliorated endothelial mitochondrial fragmentation, vascular dysfunction and blood pressure elevation in SHRs while swimming exercise plus Mdivi-1 treatment provided no additional benefits, suggesting that Drp1 inhibition may partially contribute to swimming exercise-conferred anti-hypertensive effects. CONCLUSIONS These findings suggest that swimming exercise alleviates endothelial mitochondrial fragmentation via inhibiting Drp1, which may contribute to exercise-induced improvement of vascular function and blood pressure in hypertension.
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Affiliation(s)
- Guohua Li
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Ke Xu
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Wenjuan Xing
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Hongyan Yang
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Youyou Li
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Xinpei Wang
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Jiaheng Zhou
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Jiong An
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Ling Dong
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Xing Zhang
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Li Wang
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Jia Li
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Feng Gao
- Key Laboratory of Aerospace Medicine of the Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
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Brennan S, Esposito S, Abdelaziz MIM, Martin CA, Makwana S, Sims MW, Squire IB, Sharma P, Chadwick AE, Rainbow RD. Selective protein kinase C inhibition switches time-dependent glucose cardiotoxicity to cardioprotection. Front Cardiovasc Med 2022; 9:997013. [PMID: 36158799 PMCID: PMC9489859 DOI: 10.3389/fcvm.2022.997013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/15/2022] [Indexed: 12/03/2022] Open
Abstract
Hyperglycaemia at the time of myocardial infarction has an adverse effect on prognosis irrespective of a prior diagnosis of diabetes, suggesting glucose is the damaging factor. In ex vivo models of ischaemia, we demonstrated that deleterious effects of acutely elevated glucose are PKCα/β-dependent, and providing PKCα/β are inhibited, elevated glucose confers cardioprotection. Short pre-treatments with high glucose were used to investigate time-dependent glucose cardiotoxicity, with PKCα/β inhibition investigated as a potential mechanism to reverse the toxicity. Freshly isolated non-diabetic rat cardiomyocytes were exposed to elevated glucose to investigate the time-dependence toxic effects. High glucose challenge for >7.5 min was cardiotoxic, proarrhythmic and lead to contractile failure, whilst cardiomyocytes exposed to metabolic inhibition following 5-min high glucose, displayed a time-dependent protection lasting ∼15 min. This protection was further enhanced with PKCα/β inhibition. Cardioprotection was measured as a delay in contractile failure and KATP channel activation, improved contractile and Ca2+ transient recovery and increased cell survival. Finally, the effects of pre-ischaemic treatment with high glucose in a whole-heart coronary ligation protocol, where protection was evident with PKCα/β inhibition. Selective PKCα/β inhibition enhances protection suggesting glycaemic control with PKC inhibition as a potential cardioprotective therapeutics in myocardial infarction and elective cardiac surgery.
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Affiliation(s)
- Sean Brennan
- Department of Cardiovascular, Metabolic Medicine and Liverpool Centre for Cardiovascular Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
- *Correspondence: Sean Brennan,
| | - Simona Esposito
- Department of Cardiovascular, Metabolic Medicine and Liverpool Centre for Cardiovascular Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom
| | - Muhammad I. M. Abdelaziz
- Department of Cardiovascular, Metabolic Medicine and Liverpool Centre for Cardiovascular Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Christopher A. Martin
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom
| | - Samir Makwana
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom
| | - Mark W. Sims
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom
| | - Iain B. Squire
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom
- Leicester NIHR Biomedical Research Centre, Glenfield General Hospital, Leicester, United Kingdom
| | - Parveen Sharma
- Department of Cardiovascular, Metabolic Medicine and Liverpool Centre for Cardiovascular Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Amy E. Chadwick
- Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, Liverpool, United Kingdom
| | - Richard D. Rainbow
- Department of Cardiovascular, Metabolic Medicine and Liverpool Centre for Cardiovascular Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
- Richard D. Rainbow,
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The Vasoactive Effect of Perivascular Adipose Tissue and Hydrogen Sulfide in Thoracic Aortas of Normotensive and Spontaneously Hypertensive Rats. Biomolecules 2022; 12:biom12030457. [PMID: 35327649 PMCID: PMC8946625 DOI: 10.3390/biom12030457] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/28/2022] [Accepted: 03/09/2022] [Indexed: 02/05/2023] Open
Abstract
The objective of this study was to investigate the vasoregulatory role of perivascular adipose tissue (PVAT) and its mutual interaction with endogenous and exogenous H2S in the thoracic aorta (TA) of adult normotensive Wistar rats and spontaneously hypertensive rats (SHRs). In SHRs, hypertension was associated with cardiac hypertrophy and increased contractility. Regardless of the strain, PVAT revealed an anticontractile effect; however, PVAT worsened endothelial-dependent vasorelaxation. Since H2S produced by both the vascular wall and PVAT had a pro-contractile effect in SHRs, H2S decreased the sensitivity of adrenergic receptors to noradrenaline in Wistar rats. While H2S had no contribution to endothelium-dependent relaxation in Wistar rats, in SHRs, H2S produced by the vascular wall had a pro-relaxant effect. We observed a larger vasorelaxation induced by exogenous H2S donor in SHRs than in Wistar rats. Additionally, in the presence of PVAT, this effect was potentiated. We demonstrated that PVAT of the TA aggravated endothelial function in SHRs. However, H2S produced by the TA vascular wall had a pro-relaxation effect, and PVAT revealed anti-contractile activity mediated by the release of an unknown factor and potentiated the vasorelaxation induced by exogenous H2S. All these actions could represent a form of compensatory mechanism to balance impaired vascular tone regulation.
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Angiotensin-II Modulates GABAergic Neurotransmission in the Mouse Substantia Nigra. eNeuro 2021; 8:ENEURO.0090-21.2021. [PMID: 33771900 PMCID: PMC8174047 DOI: 10.1523/eneuro.0090-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 03/22/2021] [Indexed: 11/26/2022] Open
Abstract
GABAergic projections neurons of the substantia nigra reticulata (SNr), through an extensive network of dendritic arbors and axon collaterals, provide robust inhibitory input to neighboring dopaminergic neurons in the substantia nigra compacta (SNc). Angiotensin-II (Ang-II) receptor signaling increases SNc dopaminergic neuronal sensitivity to insult, thus rendering these cells susceptible to dysfunction and destruction. However, the mechanisms by which Ang-II regulates SNc dopaminergic neuronal activity are unclear. Given the complex relationship between SN dopaminergic and GABAergic neurons, we hypothesized that Ang-II could regulate SNc dopaminergic neuronal activity directly and indirectly by modulating SNr GABAergic neurotransmission. Here, using transgenic mice, slice electrophysiology, and optogenetics, we provide evidence of an AT1 receptor-mediated signaling mechanism in SNr GABAergic neurons where Ang-II suppresses electrically-evoked neuronal output by facilitating postsynaptic GABAA receptors (GABAARs) and prolonging the action potential (AP) duration. Unexpectedly, Ang-II had no discernable effects on the electrical properties of SNc dopaminergic neurons. Also, and indicating a nonlinear relationship between electrical activity and neuronal output, following phasic photoactivation of SNr GABAergic neurons, Ang-II paradoxically enhanced the feedforward inhibitory input to SNc dopaminergic neurons. In sum, our observations describe an increasingly complex and heterogeneous response of the SN to Ang-II by revealing cell-specific responses and nonlinear effects on intranigral GABAergic neurotransmission. Our data further implicate the renin-angiotensin-system (RAS) as a functionally relevant neuromodulator in the substantia nigra, thus underscoring a need for additional inquiry.
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Xu T, Fan X, Zhao M, Wu M, Li H, Ji B, Zhu X, Li L, Ding H, Sun M, Xu Z, Gao Q. DNA Methylation-Reprogrammed Ang II (Angiotensin II) Type 1 Receptor-Early Growth Response Gene 1-Protein Kinase C ε Axis Underlies Vascular Hypercontractility in Antenatal Hypoxic Offspring. Hypertension 2020; 77:491-506. [PMID: 33342239 DOI: 10.1161/hypertensionaha.120.16247] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
As the most common clinical stress during mid and late pregnancy, antenatal hypoxia has profound adverse effects on individual's vascular health later in life, but the underlying mechanisms are still not understood. The purpose of this study was to reveal the mechanisms of the acquired vascular dysfunction in offspring imposed by antenatal hypoxia. Pregnant rats were housed in a normoxic or hypoxic (10.5% oxygen) chamber from gestation day 10 to 21. Male offspring were euthanized at gestational day 21 (fetus) or postnatal 16 weeks old (adult offspring). Mesenteric arteries were collected for examining Ang II (angiotensin II)-mediated vascular contractility, gene expression, and promoter methylation. Antenatal hypoxia increased vascular sensitivity to Ang II, which was resulted by an upregulated AT1R (angiotensin II type 1 receptor). The increased AT1R was correlated with a hypomethylation-mediated activated transcription of Agtr1a (alpha subtype of AT1R). In addition, we presented evidences that there was an AT1R-Egr1 (early growth response gene 1)-PKCε (ε isoform of protein kinase C) axis in vasculature; AT1R could modulate PKCε expression via upregulating Egr1; Egr1 mediated transcription activation of PKCε via Egr1 binding sites in PKCε gene promoter. Overall, antenatal hypoxia activated AT1R-Egr1-PKCε axis in vasculature, eventually predisposed offspring to vascular hypercontractility. This is the first description that antenatal hypoxia resulted in vascular adverse outcomes in postnatal offspring, was strongly associated with reprogrammed gene expression via a DNA methylation-mediated epigenetic mechanism, advancing understanding toward the influence of adverse antenatal factors in early life on long-term vascular health.
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Affiliation(s)
- Ting Xu
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Xiaorong Fan
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (X.F.)
| | - Meng Zhao
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Meng Wu
- Institutes of Biological and Medical Sciences, Soochow University Medical School, Suzhou, China (M.W.)
| | - Huan Li
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Bingyu Ji
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Xiaolin Zhu
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Lingjun Li
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Hongmei Ding
- Department of Obstetrics and Gynecology (H.D.), First Hospital of Soochow University, Suzhou, China
| | - Miao Sun
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Zhice Xu
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
| | - Qinqin Gao
- From the Institute for Fetology (T.X., M.Z., H.L., B.J., X.Z., L.L., M.S., Z.X., Q.G.), First Hospital of Soochow University, Suzhou, China
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Ahmad T, Shah AJ, Khan T, Roberts R. Mechanism underlying the vasodilation induced by diosmetin in porcine coronary artery. Eur J Pharmacol 2020; 884:173400. [PMID: 32730832 DOI: 10.1016/j.ejphar.2020.173400] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 11/25/2022]
Abstract
Diosmetin is a flavonoid present naturally in citrus fruit. Plants containing diosmetin have been reported to have anti-hypertensive and vasorelaxant effects. Therefore, experiments were carried out to study the effects of diosmetin in segments of the porcine coronary artery (PCA). PCA rings were mounted for isometric tension recording in isolated tissue baths and pre-contracted with the thromboxane A2 mimetic U46619 or KCl. Cumulative concentration response curves to diosmetin were then carried out in the presence or absence of inhibitors or activators of different signaling pathways. The effect on calcium channels was determined by investigating the effect of a single concentration of diosmetin (30 μM) on calcium-induced contractions or contractions to BAY K8644. Diosmetin caused a concentration-dependent relaxation after pre-contraction with U46619 or KCl, which was unaffected by removal of the endothelium. Tetraethylammonium (TEA), and 4-aminopyridine (4-AP), but not barium chloride, caused significant inhibition of the diosmetin-mediated vasorelaxation, indicating a role for potassium channels. Diosmetin inhibited calcium-induced contractions and contractions to the L-type calcium channel opener BAY K8644. Furthermore, diosmetin inhibited the contractions in response to caffeine, cyclopiazonic acid and ionomycin, indicating a general effect on calcium-induced contractions. Contractions in response to the protein kinase C (PKC) activator Phorbol 12-myristate 13-acetate (PMA) were also inhibited by diosmetin, suggesting that it may inhibit a calcium-activated PKC isoform. In summary, diosmetin produced significant vasodilatory effects. The data indicate a role for potassium channels as well as an effect on calcium-induced contractile pathways, possible through inhibition of PKC.
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Affiliation(s)
- Taseer Ahmad
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, University Road, Abbottabad, KPK, 22060, Pakistan; Department of Pharmacology, College of Pharmacy, University of Sargodha, University Road, Sargodha, Punjab, 40100, Pakistan; School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, NG7 2UH, England, UK
| | - Abdul Jabbar Shah
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, University Road, Abbottabad, KPK, 22060, Pakistan
| | - Taous Khan
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, University Road, Abbottabad, KPK, 22060, Pakistan
| | - Richard Roberts
- School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, NG7 2UH, England, UK.
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Heaps CL, Bray JF, Parker JL. Enhanced KCl-mediated contractility and Ca 2+ sensitization in porcine collateral-dependent coronary arteries persist after exercise training. Am J Physiol Heart Circ Physiol 2020; 319:H915-H926. [PMID: 32857599 DOI: 10.1152/ajpheart.00384.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have previously reported enhanced Ca2+ sensitivity of coronary arteries that is dependent upon collateral circulation for their blood supply. For the current study, we hypothesized that small collateral-dependent arteries would exhibit an enhanced KCl-mediated contractile response attributable to Ca2+ sensitization and increased Ca2+ channel current. Ameroid constrictors were surgically placed around the left circumflex (LCX) artery of female Yucatan miniature swine. Eight weeks postoperatively, pigs were randomized into sedentary or exercise-trained (treadmill run; 5 days/wk; 14 wk) groups. Small coronary arteries (150-300 μm luminal diameter) were isolated from myocardial regions distal to the collateral-dependent LCX and the nonoccluded left anterior descending arteries. Contractile tension and simultaneous measures of both tension and intracellular free Ca2+ levels (fura-2) were measured in response to increasing concentrations of KCl. In addition, whole cell Ca2+ currents were also obtained. Chronic occlusion enhanced contractile responses to KCl and increased Ca2+ sensitization in collateral-dependent compared with nonoccluded arteries of both sedentary and exercise-trained pigs. In contrast, smooth muscle cell Ca2+ channel current was not altered by occlusion or exercise training. Ca2+/calmodulin-dependent protein kinase II (CaMKII; inhibited by KN-93, 0.3-1 μM) contributed to the enhanced contractile response in collateral-dependent arteries of sedentary pigs, whereas both CaMKII and Rho-kinase (inhibited by hydroxyfasudil, 30 μM or Y27632, 10 μM) contributed to increased contraction in exercise-trained animals. Taken together, these data suggest that chronic occlusion leads to enhanced contractile responses to KCl in collateral-dependent coronary arteries via increased Ca2+ sensitization, a response that is further augmented with exercise training.NEW & NOTEWORTHY Small coronary arteries distal to chronic occlusion displayed enhanced contractile responses, which were further augmented after exercise training and attributable to enhanced calcium sensitization without alterations in calcium channel current. The calcium sensitization mediators Rho-kinase and CaMKII significantly contributed to enhanced contraction in collateral-dependent arteries of exercise-trained, but not sedentary, pigs. Exercise-enhanced contractile responses may increase resting arterial tone, creating an enhanced coronary flow reserve that is accessible during periods of increased metabolic demand.
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Affiliation(s)
- Cristine L Heaps
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas.,Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Jeff F Bray
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Janet L Parker
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas.,Department of Medical Physiology, Texas A&M Health Science Center, Texas A&M University, College Station, Texas
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Brennan S, Chen S, Makwana S, Martin CA, Sims MW, Alonazi ASA, Willets JM, Squire IB, Rainbow RD. A novel form of glycolytic metabolism-dependent cardioprotection revealed by PKCα and β inhibition. J Physiol 2019; 597:4481-4501. [PMID: 31241168 DOI: 10.1113/jp278332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 06/24/2019] [Indexed: 01/21/2023] Open
Abstract
KEY POINTS Acute hyperglycaemia at the time of a heart attack worsens the outcome for the patient. Acute hyperglycaemia is not limited to diabetic patients and can be due to a stress response in non-diabetics. This study suggests that the damaging cardiac effects of hyperglycaemia can be reversed by selective PKC inhibition. If PKCα/β isoforms are inhibited, then high glucose itself becomes protective against ischaemic damage. Selective PKC inhibition may therefore be a useful therapeutic tool to limit the damage that can occur during a heart attack by stress-induced hyperglycaemia. ABSTRACT Hyperglycaemia has a powerful association with adverse prognosis for patients with acute coronary syndromes (ACS). Previous work shows that high glucose prevents ischaemic preconditioning and causes electrical and mechanical disruption via protein kinase C α/β (PKCα/β) activation. The present study aimed to: (i) determine whether the adverse clinical association of hyperglycaemia in ACS can be replicated in preclinical cellular models of ACS and (ii) determine the importance of PKCα/β activation to the deleterious effect of glucose. Freshly isolated rat, guinea pig or rabbit cardiomyocytes were exposed to simulated ischaemia after incubation in the presence of normal (5 mm) or high (20 mm) glucose in the absence or presence of small molecule or tat-peptide-linked PKCαβ inhibitors. In each of the four conditions, the following hallmarks of cardioprotection were recorded using electrophysiology or fluorescence imaging: cardiomyocyte contraction and survival, action potential stability and time to failure, intracellular calcium and ATP, mitochondrial depolarization, ischaemia-sensitive leak current, and time to Kir 6.2 opening. High glucose alone resulted in decreased cardiomyocyte contraction and survival; however, it also imparted cardioprotection in the presence of PKCα/β inhibitors. This cardioprotective phenotype displayed improvements in all of the measured parameters and decreased myocardium damage during whole heart coronary ligation experiments. High glucose is deleterious to cellular and whole-heart models of simulated ischaemia, in keeping with the clinical association of hyperglycaemia with an adverse outcome in ACS. PKCαβ inhibition revealed high glucose to show a cardioprotective phenotype in this setting. The results of the present study suggest the potential for the therapeutic application of PKCαβ inhibition in ACS associated with hyperglycaemia.
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Affiliation(s)
- Sean Brennan
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Shen Chen
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Samir Makwana
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Christopher A Martin
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Mark W Sims
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Asma S A Alonazi
- Department of Molecular and Cellular Biology, University of Leicester, Leicester, UK
- Department of Pharmacology and Toxicology, Pharmacy College, King Saud University, Riyadh, Saudi Arabia
| | - Jonathan M Willets
- Department of Molecular and Cellular Biology, University of Leicester, Leicester, UK
| | - Iain B Squire
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
- Leicester NIHR Biomedical Research Centre, Glenfield General Hospital, Leicester, UK
| | - Richard D Rainbow
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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11
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Hasan R, Jaggar JH. K V channel trafficking and control of vascular tone. Microcirculation 2018; 25. [PMID: 28963858 DOI: 10.1111/micc.12418] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/25/2017] [Indexed: 12/21/2022]
Abstract
Membrane potential is a principal regulator of arterial contractility. Arterial smooth muscle cells express several different types of ion channel that control membrane potential, including KV channels. KV channel activation leads to membrane hyperpolarization, resulting in inhibition of voltage-dependent Ca2+ channels, a reduction in [Ca2+ ]i , and vasodilation. In contrast, KV channel inhibition leads to membrane depolarization and vasoconstriction. The ability of KV channels to regulate arterial contractility is dependent upon the number of plasma membrane-resident channels and their open probability. Here, we will discuss mechanisms that alter the surface abundance of KV channel proteins in arterial smooth muscle cells and the functional consequences of such regulation. Cellular processes that will be described include those that modulate KV channel transcription, retrograde and anterograde trafficking, and protein degradation.
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Affiliation(s)
- Raquibul Hasan
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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12
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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13
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Zhai X, Leo MD, Jaggar JH. Endothelin-1 Stimulates Vasoconstriction Through Rab11A Serine 177 Phosphorylation. Circ Res 2017; 121:650-661. [PMID: 28696251 DOI: 10.1161/circresaha.117.311102] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 01/18/2023]
Abstract
RATIONALE Large-conductance calcium-activated potassium channels (BK) are composed of pore-forming BKα and auxiliary β1 subunits in arterial smooth muscle cells (myocytes). Vasoconstrictors, including endothelin-1 (ET-1), inhibit myocyte BK channels, leading to contraction, but mechanisms involved are unclear. Recent evidence indicates that BKα is primarily plasma membrane localized, whereas the cellular location of β1 can be rapidly altered by Rab11A-positive recycling endosomes. Whether vasoconstrictors regulate the multisubunit composition of surface BK channels to stimulate contraction is unclear. OBJECTIVE Test the hypothesis that ET-1 inhibits BK channels by altering BKα and β1 surface trafficking in myocytes, identify mechanisms involved, and determine functional significance in myocytes of small cerebral arteries. METHODS AND RESULTS ET-1, through activation of PKC (protein kinase C), reduced surface β1 abundance and the proximity of β1 to surface BKα in myocytes. In contrast, ET-1 did not alter surface BKα, total β1, or total BKα proteins. ET-1 stimulated Rab11A phosphorylation, which reduced Rab11A activity. Rab11A serine 177 was identified as a high-probability PKC phosphorylation site. Expression of a phosphorylation-incapable Rab11A construct (Rab11A S177A) blocked the ET-1-induced Rab11A phosphorylation, reduction in Rab11A activity, and decrease in surface β1 protein. ET-1 inhibited single BK channels and transient BK currents in myocytes and stimulated vasoconstriction via a PKC-dependent mechanism that required Rab11A S177. In contrast, NO-induced Rab11A activation, surface trafficking of β1 subunits, BK channel and transient BK current activation, and vasodilation did not involve Rab11A S177. CONCLUSIONS ET-1 stimulates PKC-mediated phosphorylation of Rab11A at serine 177, which inhibits Rab11A and Rab11A-dependent surface trafficking of β1 subunits. The decrease in surface β1 subunits leads to a reduction in BK channel calcium-sensitivity, inhibition of transient BK currents, and vasoconstriction. We describe a unique mechanism by which a vasoconstrictor inhibits BK channels and identify Rab11A serine 177 as a modulator of arterial contractility.
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Affiliation(s)
- Xue Zhai
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - M Dennis Leo
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - Jonathan H Jaggar
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis.
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14
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Kidd MW, Bulley S, Jaggar JH. Angiotensin II reduces the surface abundance of K V 1.5 channels in arterial myocytes to stimulate vasoconstriction. J Physiol 2017; 595:1607-1618. [PMID: 27958660 DOI: 10.1113/jp272893] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/30/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Several different voltage-dependent K+ (KV ) channel isoforms are expressed in arterial smooth muscle cells (myocytes). Vasoconstrictors inhibit KV currents, but the isoform selectivity and mechanisms involved are unclear. We show that angiotensin II (Ang II), a vasoconstrictor, stimulates degradation of KV 1.5, but not KV 2.1, channels through a protein kinase C- and lysosome-dependent mechanism, reducing abundance at the surface of mesenteric artery myocytes. The Ang II-induced decrease in cell surface KV 1.5 channels reduces whole-cell KV 1.5 currents and attenuates KV 1.5 function in pressurized arteries. We describe a mechanism by which Ang II stimulates protein kinase C-dependent KV 1.5 channel degradation, reducing the abundance of functional channels at the myocyte surface. ABSTRACT Smooth muscle cells (myocytes) of resistance-size arteries express several different voltage-dependent K+ (KV ) channels, including KV 1.5 and KV 2.1, which regulate contractility. Myocyte KV currents are inhibited by vasoconstrictors, including angiotensin II (Ang II), but the mechanisms involved are unclear. Here, we tested the hypothesis that Ang II inhibits KV currents by reducing the plasma membrane abundance of KV channels in myocytes. Angiotensin II (applied for 2 h) reduced surface and total KV 1.5 protein in rat mesenteric arteries. In contrast, Ang II did not alter total or surface KV 2.1, or KV 1.5 or KV 2.1 cellular distribution, measured as the percentage of total protein at the surface. Bisindolylmaleimide (BIM; a protein kinase C blocker), a protein kinase C inhibitory peptide or bafilomycin A (a lysosomal degradation inhibitor) each blocked the Ang II-induced decrease in total and surface KV 1.5. Immunofluorescence also suggested that Ang II reduced surface KV 1.5 protein in isolated myocytes; an effect inhibited by BIM. Arteries were exposed to Ang II or Ang II plus BIM (for 2 h), after which these agents were removed and contractility measurements performed or myocytes isolated for patch-clamp electrophysiology. Angiotensin II reduced both whole-cell KV currents and currents inhibited by Psora-4, a KV 1.5 channel blocker. Angiotensin II also reduced vasoconstriction stimulated by Psora-4 or 4-aminopyridine, another KV channel inhibitor. These data indicate that Ang II activates protein kinase C, which stimulates KV 1.5 channel degradation, leading to a decrease in surface KV 1.5, a reduction in whole-cell KV 1.5 currents and a loss of functional KV 1.5 channels in myocytes of pressurized arteries.
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Affiliation(s)
- Michael W Kidd
- University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Simon Bulley
- University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Jonathan H Jaggar
- University of Tennessee Health Science Center, Memphis, TN, 38163, USA
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15
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Ringvold HC, Khalil RA. Protein Kinase C as Regulator of Vascular Smooth Muscle Function and Potential Target in Vascular Disorders. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:203-301. [PMID: 28212798 PMCID: PMC5319769 DOI: 10.1016/bs.apha.2016.06.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Vascular smooth muscle (VSM) plays an important role in maintaining vascular tone. In addition to Ca2+-dependent myosin light chain (MLC) phosphorylation, protein kinase C (PKC) is a major regulator of VSM function. PKC is a family of conventional Ca2+-dependent α, β, and γ, novel Ca2+-independent δ, ɛ, θ, and η, and atypical ξ, and ι/λ isoforms. Inactive PKC is mainly cytosolic, and upon activation it undergoes phosphorylation, maturation, and translocation to the surface membrane, the nucleus, endoplasmic reticulum, and other cell organelles; a process facilitated by scaffold proteins such as RACKs. Activated PKC phosphorylates different substrates including ion channels, pumps, and nuclear proteins. PKC also phosphorylates CPI-17 leading to inhibition of MLC phosphatase, increased MLC phosphorylation, and enhanced VSM contraction. PKC could also initiate a cascade of protein kinases leading to phosphorylation of the actin-binding proteins calponin and caldesmon, increased actin-myosin interaction, and VSM contraction. Increased PKC activity has been associated with vascular disorders including ischemia-reperfusion injury, coronary artery disease, hypertension, and diabetic vasculopathy. PKC inhibitors could test the role of PKC in different systems and could reduce PKC hyperactivity in vascular disorders. First-generation PKC inhibitors such as staurosporine and chelerythrine are not very specific. Isoform-specific PKC inhibitors such as ruboxistaurin have been tested in clinical trials. Target delivery of PKC pseudosubstrate inhibitory peptides and PKC siRNA may be useful in localized vascular disease. Further studies of PKC and its role in VSM should help design isoform-specific PKC modulators that are experimentally potent and clinically safe to target PKC in vascular disease.
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Affiliation(s)
- H C Ringvold
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - R A Khalil
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
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16
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Panhwar F, Rainbow RD, Jackson R, Davies NW. Ca2+ dependent but PKC independent signalling mediates UTP induced contraction of rat mesenteric arteries. J Smooth Muscle Res 2016; 51:58-69. [PMID: 26447104 PMCID: PMC5137259 DOI: 10.1540/jsmr.51.58] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Uridine triphosphate (UTP) can be released from damaged cells to cause vasoconstriction.
Although UTP is known to act through P2Y receptors and PLC activation in vascular smooth
muscle, the role of PKC in generating the response is somewhat unclear. Here we have used
Tat-linked membrane permeable peptide inhibitors of PKC to assess the general role of PKC
and also of specific isoforms of PKC in the UTP induced contraction of rat mesenteric
artery. We examined the effect of PKC inhibition on UTP induced contraction, increased
cytoplasmic Ca2+ and reduction of K+ currents and found that PKC
inhibition caused a relatively small attenuation of contraction but had little effect on
changes in cytoplasmic Ca2+. UTP attenuation of both voltage-gated
(Kv) and ATP-dependent (KATP) K+ currents was abolished
when intracellular Ca2+ was decreased from 100 to 20 nM. PKC inhibition reduced
slightly the ability of UTP to attenuate Kv currents but had no effect on
KATP current inhibition. In conclusion, both UTP induced contraction of
mesenteric artery and the inhibition of Kv and KATP currents of
mesenteric artery smooth muscle cells by UTP are relatively independent of PKC activation;
furthermore, the inhibition of both Kv and KATP currents requires
intracellular Ca2+.
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Affiliation(s)
- Fouzia Panhwar
- Departments of Cell Physiology & Pharmacology, University of Leicester, Leicester, UK
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17
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Tabeling C, Noe E, Naujoks J, Doehn JM, Hippenstiel S, Opitz B, Suttorp N, Klopfleisch R, Witzenrath M. PKCα Deficiency in Mice Is Associated with Pulmonary Vascular Hyperresponsiveness to Thromboxane A2 and Increased Thromboxane Receptor Expression. J Vasc Res 2016; 52:279-88. [PMID: 26890419 DOI: 10.1159/000443402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/14/2015] [Indexed: 11/19/2022] Open
Abstract
Pulmonary vascular hyperresponsiveness is a main characteristic of pulmonary arterial hypertension (PAH). In PAH patients, elevated levels of the vasoconstrictors thromboxane A2 (TXA2), endothelin (ET)-1 and serotonin further contribute to pulmonary hypertension. Protein kinase C (PKC) isozyme alpha (PKCα) is a known modulator of smooth muscle cell contraction. However, the effects of PKCα deficiency on pulmonary vasoconstriction have not yet been investigated. Thus, the role of PKCα in pulmonary vascular responsiveness to the TXA2 analog U46619, ET-1, serotonin and acute hypoxia was investigated in isolated lungs of PKCα-/- mice and corresponding wild-type mice, with or without prior administration of the PKC inhibitor bisindolylmaleimide I or Gö6976. mRNA was quantified from microdissected intrapulmonary arteries. We found that broad-spectrum PKC inhibition reduced pulmonary vascular responsiveness to ET-1 and acute hypoxia and, by trend, to U46619. Analogously, selective inhibition of conventional PKC isozymes or PKCα deficiency reduced ET-1-evoked pulmonary vasoconstriction. The pulmonary vasopressor response to serotonin was unaffected by either broad PKC inhibition or PKCα deficiency. Surprisingly, PKCα-/- mice showed pulmonary vascular hyperresponsiveness to U46619 and increased TXA2 receptor (TP receptor) expression in the intrapulmonary arteries. To conclude, PKCα regulates ET-1-induced pulmonary vasoconstriction. However, PKCα deficiency leads to pulmonary vascular hyperresponsiveness to TXA2, possibly via increased pulmonary arterial TP receptor expression.
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Affiliation(s)
- Christoph Tabeling
- Department of Infectious Diseases and Pulmonary Medicine, Charitx00E9; - Universitx00E4;tsmedizin Berlin, Berlin, Germany
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18
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Jackson R, Brennan S, Fielding P, Sims MW, Challiss RAJ, Adlam D, Squire IB, Rainbow RD. Distinct and complementary roles for α and β isoenzymes of PKC in mediating vasoconstrictor responses to acutely elevated glucose. Br J Pharmacol 2016; 173:870-87. [PMID: 26660275 DOI: 10.1111/bph.13399] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/23/2015] [Accepted: 11/30/2015] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE We investigated the hypothesis that elevated glucose increases contractile responses in vascular smooth muscle and that this enhanced constriction occurs due to the glucose-induced PKC-dependent inhibition of voltage-gated potassium channels. EXPERIMENTAL APPROACH Patch-clamp electrophysiology in rat isolated mesenteric arterial myocytes was performed to investigate the glucose-induced inhibition of voltage-gated potassium (Kv ) current. To determine the effects of glucose in whole vessel, wire myography was performed in rat mesenteric, porcine coronary and human internal mammary arteries. KEY RESULTS Glucose-induced inhibition of Kv was PKC-dependent and could be pharmacologically dissected using PKC isoenzyme-specific inhibitors to reveal a PKCβ-dependent component of Kv inhibition dominating between 0 and 10 mM glucose with an additional PKCα-dependent component becoming evident at concentrations greater than 10 mM. These findings were supported using wire myography in all artery types used, where contractile responses to vessel depolarization and vasoconstrictors were enhanced by increasing bathing glucose concentration, again with evidence for distinct and complementary PKCα/PKCβ-mediated components. CONCLUSIONS AND IMPLICATIONS Our results provide compelling evidence that glucose-induced PKCα/PKCβ-mediated inhibition of Kv current in vascular smooth muscle causes an enhanced constrictor response. Inhibition of Kv current causes a significant depolarization of vascular myocytes leading to marked vasoconstriction. The PKC dependence of this enhanced constrictor response may present a potential therapeutic target for improving microvascular perfusion following percutaneous coronary intervention after myocardial infarction in hyperglycaemic patients.
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Affiliation(s)
- Robert Jackson
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Sean Brennan
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Peter Fielding
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Mark W Sims
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - R A John Challiss
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - David Adlam
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Iain B Squire
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
| | - Richard D Rainbow
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK
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Modulation of CaV1.2 calcium channel by neuropeptide W regulates vascular myogenic tone via G protein-coupled receptor 7. J Hypertens 2015; 33:2431-42. [DOI: 10.1097/hjh.0000000000000723] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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20
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Labrousse-Arias D, Castillo-González R, Rogers NM, Torres-Capelli M, Barreira B, Aragonés J, Cogolludo Á, Isenberg JS, Calzada MJ. HIF-2α-mediated induction of pulmonary thrombospondin-1 contributes to hypoxia-driven vascular remodelling and vasoconstriction. Cardiovasc Res 2015; 109:115-30. [PMID: 26503986 PMCID: PMC4692290 DOI: 10.1093/cvr/cvv243] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 10/11/2015] [Indexed: 11/12/2022] Open
Abstract
Aims Hypoxic conditions stimulate pulmonary vasoconstriction and vascular remodelling, both pathognomonic changes in pulmonary arterial hypertension (PAH). The secreted protein thrombospondin-1 (TSP1) is involved in the maintenance of lung homeostasis. New work identified a role for TSP1 in promoting PAH. Nonetheless, it is largely unknown how hypoxia regulates TSP1 in the lung and whether this contributes to pathological events during PAH. Methods and results In cell and animal experiments, we found that hypoxia induces TSP1 in lungs, pulmonary artery smooth muscle cells and endothelial cells, and pulmonary fibroblasts. Using a murine model of constitutive hypoxia, gene silencing, and luciferase reporter experiments, we found that hypoxia-mediated induction of pulmonary TSP1 is a hypoxia-inducible factor (HIF)-2α-dependent process. Additionally, hypoxic tsp1−/− pulmonary fibroblasts and pulmonary artery smooth muscle cell displayed decreased migration compared with wild-type (WT) cells. Furthermore, hypoxia-mediated induction of TSP1 destabilized endothelial cell–cell interactions. This provides genetic evidence that TSP1 contributes to vascular remodelling during PAH. Expanding cell data to whole tissues, we found that, under hypoxia, pulmonary arteries (PAs) from WT mice had significantly decreased sensitivity to acetylcholine (Ach)-stimulated endothelial-dependent vasodilation. In contrast, hypoxic tsp1−/− PAs retained sensitivity to Ach, mediated in part by TSP1 regulation of pulmonary Kv channels. Translating these preclinical studies, we find in the lungs from individuals with end-stage PAH, both TSP1 and HIF-2α protein expression increased in the pulmonary vasculature compared with non-PAH controls. Conclusions These findings demonstrate that HIF-2α is clearly implicated in the TSP1 pulmonary regulation and provide new insights on its contribution to PAH-driven vascular remodelling and vasoconstriction.
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Affiliation(s)
- David Labrousse-Arias
- Instituto de Investigacion Sanitaria Princesa (IIS-IP), Department of Medicine, School of Medicine, Universidad Autonoma of Madrid, Diego de Leon 62, Madrid 28006, Spain
| | - Raquel Castillo-González
- Instituto de Investigacion Sanitaria Princesa (IIS-IP), Department of Medicine, School of Medicine, Universidad Autonoma of Madrid, Diego de Leon 62, Madrid 28006, Spain
| | - Natasha M Rogers
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
| | - Mar Torres-Capelli
- Instituto de Investigacion Sanitaria Princesa (IIS-IP), Department of Medicine, School of Medicine, Universidad Autonoma of Madrid, Diego de Leon 62, Madrid 28006, Spain
| | - Bianca Barreira
- Department of Pharmacology, Faculty of Medicine, Universidad Complutense of Madrid, Madrid, Spain
| | - Julián Aragonés
- Instituto de Investigacion Sanitaria Princesa (IIS-IP), Department of Medicine, School of Medicine, Universidad Autonoma of Madrid, Diego de Leon 62, Madrid 28006, Spain
| | - Ángel Cogolludo
- Department of Pharmacology, Faculty of Medicine, Universidad Complutense of Madrid, Madrid, Spain Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERES), Spain
| | - Jeffrey S Isenberg
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh School of Medicine Pittsburgh, PA, USA Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh School of Medicine, E1258, BST, 200 Lothrop Street, Pittsburgh, PA 15261, USA
| | - María J Calzada
- Instituto de Investigacion Sanitaria Princesa (IIS-IP), Department of Medicine, School of Medicine, Universidad Autonoma of Madrid, Diego de Leon 62, Madrid 28006, Spain
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21
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Benyahia C, Ozen G, Orie N, Ledwozyw A, Louedec L, Li F, Senbel AM, Silverstein A, Danel C, Longrois D, Clapp LH, Norel X, Topal G. Ex vivo relaxations of pulmonary arteries induced by prostacyclin mimetics are highly dependent of the precontractile agents. Prostaglandins Other Lipid Mediat 2015; 121:46-52. [PMID: 26362969 DOI: 10.1016/j.prostaglandins.2015.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 08/18/2015] [Accepted: 09/04/2015] [Indexed: 01/08/2023]
Abstract
Prostacyclin (PGI2) mimetics (iloprost, treprostinil) are potent vasodilators (primarily via IP-receptor activation) and major therapeutic interventions for pulmonary hypertension (PH). Increased plasma levels of endothelin (ET-1), thromboxane (TxA2) and catecholamines have been demonstrated from patients with PH. In this study, we aimed to compare relaxant effects of iloprost and treprostinil on human (HPA) and rat pulmonary arteries precontracted with either ET-1, thromboxane (U46619) or an α-adrenergic receptor agonist (Norepinephrine, NE or phenylephrine, PE). Treprostinil and iloprost induced vasorelaxation of HPA precontracted with NE, ET-1 or U46619. We obtained greater relaxation response and sensitivity to treprostinil when ET-1 or U46619 were used to induce the precontraction in comparison to NE. In contrast, iloprost showed less relaxation response and sensitivity in HPA precontracted with U46619 versus NE. In the rat, treprostinil and iloprost induced vasorelaxation of pulmonary arteries precontracted with PE and U46619 but minimally with ET-1. However, in rat pulmonary arteries, PE-induced precontractions were comparatively low amplitude. Our study showed that the ex vivo relaxation or sensitivity of pulmonary arteries induced by PGI2 mimetics is highly dependent on both the pre-contraction agent and the species. To best extrapolate to effects on human tissue, our results suggest that U46619 is the appropriate contractile agent for assessing the relaxant effect of PGI2 mimetics in rat pulmonary arteries. Finally we suggest that in PH patients with high plasma concentration of TxA2, treprostinil (not iloprost) would be a preferential treatment. On the other hand, if the ET-1 plasmatic level is high, either treprostinil or iloprost will be effective.
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Affiliation(s)
- Chabha Benyahia
- INSERM U1148, CHU X. Bichat, 46 rue H. Huchard, F-75018 Paris, France; Paris Nord University, Sorbonne Paris Cité, UMR-S1148, Paris F-75018, France
| | - Gulsev Ozen
- INSERM U1148, CHU X. Bichat, 46 rue H. Huchard, F-75018 Paris, France; Istanbul University, Faculty of Pharmacy, Department of Pharmacology, Beyazit, 34116 Istanbul, Turkey
| | | | - Agatha Ledwozyw
- Department of Medicine, University College London, London WC1E 6JF, UK
| | - Liliane Louedec
- INSERM U1148, CHU X. Bichat, 46 rue H. Huchard, F-75018 Paris, France
| | - Fangfang Li
- INSERM U1148, CHU X. Bichat, 46 rue H. Huchard, F-75018 Paris, France; Paris Descartes University, Sorbonne Paris Cité, UMR-S1148, Paris F-75018, France
| | - Amira M Senbel
- Alexandria University, Faculty of Pharmacy, Department of Pharmacology and Toxicology, Alexandria, Egypt
| | | | - Claire Danel
- CHU X. Bichat, Assistance Publique-Hôpitaux de Paris, Paris Diderot University, Sorbonne Paris Cité, UMR-1148, Paris F-75018, France
| | - Dan Longrois
- INSERM U1148, CHU X. Bichat, 46 rue H. Huchard, F-75018 Paris, France; Paris Nord University, Sorbonne Paris Cité, UMR-S1148, Paris F-75018, France; CHU X. Bichat, Assistance Publique-Hôpitaux de Paris, Paris Diderot University, Sorbonne Paris Cité, UMR-1148, Paris F-75018, France
| | - Lucie H Clapp
- Department of Medicine, University College London, London WC1E 6JF, UK
| | - Xavier Norel
- INSERM U1148, CHU X. Bichat, 46 rue H. Huchard, F-75018 Paris, France; Paris Nord University, Sorbonne Paris Cité, UMR-S1148, Paris F-75018, France.
| | - Gökçe Topal
- Istanbul University, Faculty of Pharmacy, Department of Pharmacology, Beyazit, 34116 Istanbul, Turkey
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22
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Grześk E, Malinowski B, Wiciński M, Szadujkis-Szadurska K, Sinjab TA, Manysiak S, Tejza B, Słupski M, Odrowąż-Sypniewska G, Grześk G. Cyclosporine-A, but not tacrolimus significantly increases reactivity of vascular smooth muscle cells. Pharmacol Rep 2015; 68:201-5. [PMID: 26721374 DOI: 10.1016/j.pharep.2015.08.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/09/2015] [Accepted: 08/19/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Application of cyclosporine-A (CsA) or tacrolimus is associated with numerous side effects. One of the main reasons for restricting usage of CsA is hypertension. In tacrolimus treated subjects the frequency of these phenomena is significantly lower. The known molecular mechanism of action of tacrolimus and cyclosporine-A seems to be the same, thus we decided to compare modulatory effect of drugs on vascular smooth muscle contractility. METHODS Experiments were performed on isolated and perfused tail artery of Wistar rats. Contraction force was measured by increased degree of perfusion pressure with a constant flow rate. RESULTS Concentration-response curves for agonist in the presence CsA were significantly shifted to the left with increase in maximal responses. This effect was due to increased calcium influx from extracellular calcium stores whereas there were no significant changes in calcium influx in the presence of tacrolimus; concentration-response curve was comparable to controls. CONCLUSION Our results strongly support the idea that main difference between effects on smooth muscle contractility of calcineurin-dependent immunosuppressants: CsA and tacrolimus is related to the different level of extracellular calcium influx to the cytoplasm. The elucidation of these mechanisms may permit the identification of new therapeutic strategies against CsA-induced hypertension.
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Affiliation(s)
- Elżbieta Grześk
- Department of Pediatrics, Hematology and Oncology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland.
| | - Bartosz Malinowski
- Department of Pharmacology and Therapeutics, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Michał Wiciński
- Department of Pharmacology and Therapeutics, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | | | - Thabit A Sinjab
- Department of Pharmacology and Therapeutics, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Sławomir Manysiak
- Department of Laboratory Medicine, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Barbara Tejza
- Department of Pediatrics, Hematology and Oncology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Maciej Słupski
- Department of Liver and General Surgery, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | | | - Grzegorz Grześk
- Department of Pharmacology and Therapeutics, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
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23
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Steady-state modulation of voltage-gated K+ channels in rat arterial smooth muscle by cyclic AMP-dependent protein kinase and protein phosphatase 2B. PLoS One 2015; 10:e0121285. [PMID: 25793374 PMCID: PMC4368632 DOI: 10.1371/journal.pone.0121285] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 01/29/2015] [Indexed: 01/17/2023] Open
Abstract
Voltage-gated potassium channels (Kv) are important regulators of membrane potential in vascular smooth muscle cells, which is integral to controlling intracellular Ca2+ concentration and regulating vascular tone. Previous work indicates that Kv channels can be modulated by receptor-driven alterations of cyclic AMP-dependent protein kinase (PKA) activity. Here, we demonstrate that Kv channel activity is maintained by tonic activity of PKA. Whole-cell recording was used to assess the effect of manipulating PKA signalling on Kv and ATP-dependent K+ channels of rat mesenteric artery smooth muscle cells. Application of PKA inhibitors, KT5720 or H89, caused a significant inhibition of Kv currents. Tonic PKA-mediated activation of Kv appears maximal as application of isoprenaline (a β-adrenoceptor agonist) or dibutyryl-cAMP failed to enhance Kv currents. We also show that this modulation of Kv by PKA can be reversed by protein phosphatase 2B/calcineurin (PP2B). PKA-dependent inhibition of Kv by KT5720 can be abrogated by pre-treatment with the PP2B inhibitor cyclosporin A, or inclusion of a PP2B auto-inhibitory peptide in the pipette solution. Finally, we demonstrate that tonic PKA-mediated modulation of Kv requires intact caveolae. Pre-treatment of the cells with methyl-β-cyclodextrin to deplete cellular cholesterol, or adding caveolin-scaffolding domain peptide to the pipette solution to disrupt caveolae-dependent signalling each attenuated PKA-mediated modulation of the Kv current. These findings highlight a novel, caveolae-dependent, tonic modulatory role of PKA on Kv channels providing new insight into mechanisms and the potential for pharmacological manipulation of vascular tone.
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Yu J, Ok SH, Kim WH, Cho H, Park J, Shin IW, Lee HK, Chung YK, Choi MJ, Kwon SC, Sohn JT. Dexmedetomidine-Induced Contraction in the Isolated Endothelium-Denuded Rat Aorta Involves PKC-δ-mediated JNK Phosphorylation. Int J Med Sci 2015; 12:727-36. [PMID: 26392810 PMCID: PMC4571550 DOI: 10.7150/ijms.11952] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 08/17/2015] [Indexed: 12/18/2022] Open
Abstract
Vasoconstriction mediated by the highly selective alpha-2 adrenoceptor agonist dexmedetomidine leads to transiently increased blood pressure and severe hypertension. The dexmedetomidine-induced contraction involves the protein kinase C (PKC)-mediated pathway. However, the main PKC isoform involved in the dexmedetomidine-induced contraction remains unknown. The goal of this in vitro study was to examine the specific PKC isoform that contributes to the dexmedetomidine-induced contraction in the isolated rat aorta. The endothelium-denuded rat aorta was suspended for isometric tension recording. Dexmedetomidine dose-response curves were generated in the presence or absence of the following inhibitors: the pan-PKC inhibitor, chelerythrine; the PKC-α and -β inhibitor, Go6976; the PKC-α inhibitor, safingol; the PKC-β inhibitor, ruboxistaurin; the PKC-δ inhibitor, rottlerin; the c-Jun NH2-terminal kinase (JNK) inhibitor, SP600125; and the myosin light chain kinase inhibitor, ML-7 hydrochloride. Western blot analysis was used to examine the effect of rottlerin on dexmedetomidine-induced PKC-δ expression and JNK phosphorylation in rat aortic vascular smooth muscle cells (VSMCs) and to investigate the effect of dexmedetomidine on PKC-δ expression in VSMCs transfected with PKC-δ small interfering RNA (siRNA) or control siRNA. Chelerythrine as well as SP600125 and ML-7 hydrochloride attenuated the dexmedetomidine-induced contraction. Go6976, safingol, and ruboxistaurin had no effect on the dexmedetomidine-induced contraction, whereas rottlerin inhibited the dexmedetomidine-induced contraction. Dexmedetomidine induced PKC-δ expression, whereas rottlerin and PKC-δ siRNA transfection inhibited dexmedetomidine-induced PKC-δ expression. Dexmedetomidine also induced JNK phosphorylation, which was inhibited by rottlerin. Taken together, these results suggest that the dexmedetomidine-induced contraction involves PKC-δ-dependent JNK phosphorylation in the isolated rat aorta.
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Affiliation(s)
- Jongsun Yu
- 1. Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Seong-Ho Ok
- 1. Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Won Ho Kim
- 2. Department of Anesthesiology and Pain Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Hyunhoo Cho
- 3. Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, Jinju, Republic of Korea
| | - Jungchul Park
- 3. Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, Jinju, Republic of Korea
| | - Il-Woo Shin
- 1. Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Heon Keun Lee
- 1. Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Young-Kyun Chung
- 1. Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Mun-Jeoung Choi
- 4. Department of Oral and Maxillofacial Surgery, Gyeongsang National University Hospital, Jinju, Republic of Korea
| | - Seong-Chun Kwon
- 5. Department of Physiology, Institute for Clinical and Translational Research, Catholic Kwandong University College of Medicine, Gangneung, 25601, Korea
| | - Ju-Tae Sohn
- 1. Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea ; 6. Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
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25
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Sims MW, Winter J, Brennan S, Norman RI, André Ng G, Squire IB, Rainbow RD. PKC-mediated toxicity of elevated glucose concentration on cardiomyocyte function. Am J Physiol Heart Circ Physiol 2014; 307:H587-97. [DOI: 10.1152/ajpheart.00894.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
While it is well established that mortality risk after myocardial infarction (MI) increases in proportion to blood glucose concentration at the time of admission, it is unclear whether there is a direct, causal relationship. We investigated potential mechanisms by which increased blood glucose may exert cardiotoxicity. Using a Wistar rat or guinea-pig isolated cardiomyocyte model, we investigated the effects on cardiomyocyte function and electrical stability of alterations in extracellular glucose concentration. Contractile function studies using electric field stimulation (EFS), patch-clamp recording, and Ca2+ imaging were used to determine the effects of increased extracellular glucose concentration on cardiomyocyte function. Increasing glucose from 5 to 20 mM caused prolongation of the action potential and increased both basal Ca2+ and variability of the Ca2+ transient amplitude. Elevated extracellular glucose concentration also attenuated the protection afforded by ischemic preconditioning (IPC), as assessed using a simulated ischemia and reperfusion model. Inhibition of PKCα and β, using Gö6976 or specific inhibitor peptides, attenuated the detrimental effects of glucose and restored the cardioprotected phenotype to IPC cells. Increased glucose concentration did not attenuate the cardioprotective role of PKCε, but rather activation of PKCα and β masked its beneficial effect. Elevated extracellular glucose concentration exerts acute cardiotoxicity mediated via PKCα and β. Inhibition of these PKC isoenzymes abolishes the cardiotoxic effects and restores IPC-mediated cardioprotection. These data support a direct link between hyperglycemia and adverse outcome after MI. Cardiac-specific PKCα and β inhibition may be of clinical benefit in this setting.
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Affiliation(s)
- Mark W. Sims
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - James Winter
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Sean Brennan
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Robert I. Norman
- Department of Medical and Social Care Education, University of Leicester, Leicester, United Kingdom
| | - G. André Ng
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Iain B. Squire
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Richard D. Rainbow
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
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26
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Schleifenbaum J, Kassmann M, Szijártó IA, Hercule HC, Tano JY, Weinert S, Heidenreich M, Pathan AR, Anistan YM, Alenina N, Rusch NJ, Bader M, Jentsch TJ, Gollasch M. Stretch-activation of angiotensin II type 1a receptors contributes to the myogenic response of mouse mesenteric and renal arteries. Circ Res 2014; 115:263-72. [PMID: 24838176 DOI: 10.1161/circresaha.115.302882] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Vascular wall stretch is the major stimulus for the myogenic response of small arteries to pressure. The molecular mechanisms are elusive, but recent findings suggest that G protein-coupled receptors can elicit a stretch response. OBJECTIVE To determine whether angiotensin II type 1 receptors (AT1R) in vascular smooth muscle cells exert mechanosensitivity and identify the downstream ion channel mediators of myogenic vasoconstriction. METHODS AND RESULTS We used mice deficient in AT1R signaling molecules and putative ion channel targets, namely AT1R, angiotensinogen, transient receptor potential channel 6 (TRPC6) channels, or several subtypes of the voltage-gated K+ (Kv7) gene family (KCNQ3, 4, or 5). We identified a mechanosensing mechanism in isolated mesenteric arteries and in the renal circulation that relies on coupling of the AT1R subtype a to a Gq/11 protein as a critical event to accomplish the myogenic response. Arterial mechanoactivation occurs after pharmacological block of AT1R and in the absence of angiotensinogen or TRPC6 channels. Activation of AT1R subtype a by osmotically induced membrane stretch suppresses an XE991-sensitive Kv channel current in patch-clamped vascular smooth muscle cells, and similar concentrations of XE991 enhance mesenteric and renal myogenic tone. Although XE991-sensitive KCNQ3, 4, and 5 channels are expressed in vascular smooth muscle cells, XE991-sensitive K+ current and myogenic contractions persist in arteries deficient in these channels. CONCLUSIONS Our results provide definitive evidence that myogenic responses of mouse mesenteric and renal arteries rely on ligand-independent, mechanoactivation of AT1R subtype a. The AT1R subtype a signal relies on an ion channel distinct from TRPC6 or KCNQ3, 4, or 5 to enact vascular smooth muscle cell activation and elevated vascular resistance.
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Affiliation(s)
- Johanna Schleifenbaum
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Mario Kassmann
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - István András Szijártó
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Hantz C Hercule
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Jean-Yves Tano
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Stefanie Weinert
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Matthias Heidenreich
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Asif R Pathan
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Yoland-Marie Anistan
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Natalia Alenina
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Nancy J Rusch
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Michael Bader
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Thomas J Jentsch
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.)
| | - Maik Gollasch
- From the Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC), Berlin, Germany (J.S., M.K., I.A.S., H.C.H., J.-Y.T., Y.-M.A., M.G.); Max Delbrück Center for Molecular Medicine, Berlin, Germany (S.W., M.H., N.A., M.B., T.J.J.); Department Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany (S.W., M.H., T.J.J.); Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock (A.R.P., N.J.R.); and Broad Institute of MIT and Harvard, Cambridge, MA (M.H.).
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27
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Vascular endothelial cells mediate mechanical stimulation-induced enhancement of endothelin hyperalgesia via activation of P2X2/3 receptors on nociceptors. J Neurosci 2013; 33:2849-59. [PMID: 23407944 DOI: 10.1523/jneurosci.3229-12.2013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Endothelin-1 (ET-1) is unique among a broad range of hyperalgesic agents in that it induces hyperalgesia in rats that is markedly enhanced by repeated mechanical stimulation at the site of administration. Antagonists to the ET-1 receptors, ET(A) and ET(B), attenuated both initial as well as stimulation-induced enhancement of hyperalgesia (SIEH) by endothelin. However, administering antisense oligodeoxynucleotide to attenuate ET(A) receptor expression on nociceptors attenuated ET-1 hyperalgesia but had no effect on SIEH, suggesting that this is mediated via a non-neuronal cell. Because vascular endothelial cells are both stretch sensitive and express ET(A) and ET(B) receptors, we tested the hypothesis that SIEH is dependent on endothelial cells by impairing vascular endothelial function with octoxynol-9 administration; this procedure eliminated SIEH without attenuating ET-1 hyperalgesia. A role for protein kinase Cε (PKCε), a second messenger implicated in the induction and maintenance of chronic pain, was explored. Intrathecal antisense for PKCε did not inhibit either ET-1 hyperalgesia or SIEH, suggesting no role for neuronal PKCε; however, administration of a PKCε inhibitor at the site of testing selectively attenuated SIEH. Compatible with endothelial cells releasing ATP in response to mechanical stimulation, P2X(2/3) receptor antagonists eliminated SIEH. The endothelium also appears to contribute to hyperalgesia in two ergonomic pain models (eccentric exercise and hindlimb vibration) and in a model of endometriosis. We propose that SIEH is produced by an effect of ET-1 on vascular endothelial cells, sensitizing its release of ATP in response to mechanical stimulation; ATP in turn acts at the nociceptor P2X(2/3) receptor.
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28
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Aziz Q, Thomas AM, Khambra T, Tinker A. Regulation of the ATP-sensitive potassium channel subunit, Kir6.2, by a Ca2+-dependent protein kinase C. J Biol Chem 2011; 287:6196-207. [PMID: 22207763 DOI: 10.1074/jbc.m111.243923] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of ATP-sensitive potassium (K(ATP)) channels is governed by the concentration of intracellular ATP and ADP and is thus responsive to the metabolic status of the cell. Phosphorylation of K(ATP) channels by protein kinase A (PKA) or protein kinase C (PKC) results in the modulation of channel activity and is particularly important in regulating smooth muscle tone. At the molecular level the smooth muscle channel is composed of a sulfonylurea subunit (SUR2B) and a pore-forming subunit Kir6.1 and/or Kir6.2. Previously, Kir6.1/SUR2B channels have been shown to be inhibited by PKC, and Kir6.2/SUR2B channels have been shown to be activated or have no response to PKC. In this study we have examined the modulation of channel complexes formed of the inward rectifier subunit, Kir6.2, and the sulfonylurea subunit, SUR2B. Using a combination of biochemical and electrophysiological techniques we show that this complex can be inhibited by protein kinase C in a Ca(2+)-dependent manner and that this inhibition is likely to be as a result of internalization. We identify a residue in the distal C terminus of Kir6.2 (Ser-372) whose phosphorylation leads to down-regulation of the channel complex. This inhibitory effect is distinct from activation which is seen with low levels of channel activity.
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Affiliation(s)
- Qadeer Aziz
- William Harvey Heart Centre, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, United Kingdom
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29
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Hald BO, Jacobsen JCB, Braunstein TH, Inoue R, Ito Y, Sørensen PG, Holstein-Rathlou NH, Jensen LJ. BKCa and KV channels limit conducted vasomotor responses in rat mesenteric terminal arterioles. Pflugers Arch 2011; 463:279-95. [PMID: 22052159 DOI: 10.1007/s00424-011-1049-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 09/15/2011] [Accepted: 10/16/2011] [Indexed: 11/28/2022]
Abstract
Intracellular Ca(2+) signals underlying conducted vasoconstriction to local application of a brief depolarizing KCl stimulus was investigated in rat mesenteric terminal arterioles (<40 μm). Using a computer model of an arteriole segment comprised of coupled endothelial cells (EC) and vascular smooth muscle cells (VSMC) simulations of both membrane potential and intracellular [Ca(2+)] were performed. The "characteristic" length constant, λ, was approximated using a modified cable equation in both experiments and simulations. We hypothesized that K(+) conductance in the arteriolar wall limit the electrotonic spread of a local depolarization along arterioles by current dissipation across the VSMC plasma membrane. Thus, we anticipated an increased λ by inhibition of voltage-activated K(+) channels. Application of the BK(Ca) channel blocker iberiotoxin (100 nM) onto mesenteric arterioles in vitro and inhibition of BK(Ca) channel current in silico increased λ by 34% and 32%, respectively. Similarly, inhibition of K(V) channels in vitro (4-aminopyridine, 1 mM) or in silico increased λ by 41% and 21%, respectively. Immunofluorescence microscopy demonstrated expression of BK(Ca), Kv1.5, Kv2.1, but not Kv1.2, in VSMCs of rat mesenteric terminal arterioles. Our results demonstrate that inhibition of voltage-activated K(+) channels enhance vascular-conducted responses to local depolarization in terminal arterioles by increasing the membrane resistance of VSMCs. These data contribute to our understanding of how differential expression patterns of voltage-activated K(+) channels may influence conducted vasoconstriction in small arteriolar networks. This finding is potentially relevant to understanding the compromised microcirculatory blood flow in systemic vascular diseases such as diabetes mellitus and hypertension.
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Affiliation(s)
- Bjørn Olav Hald
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Lee YC, Chang HH, Chiang CL, Liu CH, Yeh JI, Chen MF, Chen PY, Kuo JS, Lee TJF. Role of perivascular adipose tissue-derived methyl palmitate in vascular tone regulation and pathogenesis of hypertension. Circulation 2011; 124:1160-71. [PMID: 21844078 DOI: 10.1161/circulationaha.111.027375] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Perivascular adipose tissue (PVAT)-derived relaxing factor (PVATRF) significantly regulates vascular tone. Its chemical nature remains unknown. We determined whether palmitic acid methyl ester (PAME) was the PVATRF and whether its release and/or vasorelaxing activity decreased in hypertension. METHODS AND RESULTS Using superfusion bioassay cascade technique, tissue bath myography, and gas chromatography/mass spectrometry, we determined PVATRF and PAME release from aortic PVAT preparations of Wistar Kyoto rats and spontaneously hypertensive rats. The PVAT of Wistar Kyoto rats spontaneously and calcium dependently released PVATRF and PAME. Both induced aortic vasorelaxations, which were inhibited by 4-aminopyridine (2 mmol/L) and tetraethylammonium 5 and 10 mmol/L but were not affected by tetraethylammonium 1 or 3 mmol/L, glibenclamide (3 μmol/L), or iberiotoxin (100 nmol/L). Aortic vasorelaxations induced by PVATRF- and PAME-containing Krebs solutions were not affected after heating at 70°C but were equally attenuated after hexane extractions. Culture mediums of differentiated adipocytes, but not those of fibroblasts, contained significant PAME and caused aortic vasorelaxation. The PVAT of spontaneously hypertensive rats released significantly less PVATRF and PAME with an increased release of angiotensin II. In addition, PAME-induced relaxation of spontaneously hypertensive rats aortic smooth muscle diminished drastically, which was ameliorated significantly by losartan. CONCLUSIONS We found that PAME is the PVATRF, causing vasorelaxation by opening voltage-dependent K+ channels on smooth muscle cells. Diminished PAME release and its vasorelaxing activity and increased release of angiotensin II in the PVAT suggest a noble role of PVAT in pathogenesis of hypertension. The antihypertensive effect of losartan is attributed partly to its reversing diminished PAME-induced vasorelaxation.
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Affiliation(s)
- Yuan-Chieh Lee
- Department of Ophthalmology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
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Berwick ZC, Dick GM, Moberly SP, Kohr MC, Sturek M, Tune JD. Contribution of voltage-dependent K⁺ channels to metabolic control of coronary blood flow. J Mol Cell Cardiol 2011; 52:912-9. [PMID: 21771599 DOI: 10.1016/j.yjmcc.2011.07.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 06/27/2011] [Accepted: 07/02/2011] [Indexed: 01/12/2023]
Abstract
The purpose of this investigation was to test the hypothesis that K(V) channels contribute to metabolic control of coronary blood flow and that decreases in K(V) channel function and/or expression significantly attenuate myocardial oxygen supply-demand balance in the metabolic syndrome (MetS). Experiments were conducted in conscious, chronically instrumented Ossabaw swine fed either a normal maintenance diet or an excess calorie atherogenic diet that produces the clinical phenotype of early MetS. Data were obtained under resting conditions and during graded treadmill exercise before and after inhibition of K(V) channels with 4-aminopyridine (4-AP, 0.3mg/kg, iv). In lean-control swine, 4-AP reduced coronary blood flow ~15% at rest and ~20% during exercise. Inhibition of K(V) channels also increased aortic pressure (P<0.01) while reducing coronary venous PO(2) (P<0.01) at a given level of myocardial oxygen consumption (MVO(2)). Administration of 4-AP had no effect on coronary blood flow, aortic pressure, or coronary venous PO(2) in swine with MetS. The lack of response to 4-AP in MetS swine was associated with a ~20% reduction in coronary K(V) current (P<0.01) and decreased expression of K(V)1.5 channels in coronary arteries (P<0.01). Together, these data demonstrate that K(V) channels play an important role in balancing myocardial oxygen delivery with metabolism at rest and during exercise-induced increases in MVO(2). Our findings also indicate that decreases in K(V) channel current and expression contribute to impaired control of coronary blood flow in the MetS. This article is part of a Special Issue entitled "Coronary Blood Flow".
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Affiliation(s)
- Zachary C Berwick
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Moral-Sanz J, Gonzalez T, Menendez C, David M, Moreno L, Macias A, Cortijo J, Valenzuela C, Perez-Vizcaino F, Cogolludo A. Ceramide inhibits Kv currents and contributes to TP-receptor-induced vasoconstriction in rat and human pulmonary arteries. Am J Physiol Cell Physiol 2011; 301:C186-94. [DOI: 10.1152/ajpcell.00243.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neutral sphingomyelinase (nSMase)-derived ceramide has been proposed as a mediator of hypoxic pulmonary vasoconstriction (HPV), a specific response of the pulmonary circulation. Voltage-gated K+ (Kv) channels are modulated by numerous vasoactive factors, including hypoxia, and their inhibition has been involved in HPV. Herein, we have analyzed the effects of ceramide on Kv currents and contractility in rat pulmonary arteries (PA) and in mesenteric arteries (MA). The ceramide analog C6-ceramide inhibited Kv currents in PA smooth muscle cells (PASMC). Similar effects were obtained after the addition of bacterial sphingomyelinase (SMase), indicating a role for endogenous ceramide in Kv channel regulation. Kv current was reduced by stromatoxin and diphenylphosphine oxide-1 (DPO-1), selective inhibitors of Kv2.1 and Kv1.5 channels, respectively. The inhibitory effect of ceramide was still present in the presence of stromatoxin or DPO-1, suggesting that this sphingolipid inhibited both components of the native Kv current. Accordingly, ceramide inhibited Kv1.5 and Kv2.1 channels expressed in Ltk− cells. Ceramide-induced effects were reduced in human embryonic kidney 293 cells expressing Kv1.5 channels but not the regulatory subunit Kvβ2.1. The nSMase inhibitor GW4869 reduced the thromboxane-endoperoxide receptor agonist U46619-induced, but not endothelin-1-induced pulmonary vasoconstriction that was partly restored after addition of exogenous ceramide. The PKC-ζ pseudosubstrate inhibitor (PKCζ-PI) inhibited the Kv inhibitory and contractile effects of ceramide. In MA ceramide had no effect on Kv currents and GW4869 did not affect U46619-induced contraction. The effects of SMase were also observed in human PA. These results suggest that ceramide represents a crucial signaling mediator in the pulmonary vasculature.
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Affiliation(s)
- Javier Moral-Sanz
- Department of Pharmacology, School of Medicine, Universidad Complutense Madrid
- Centro de Investigaciones Biomedicas en Red de Enfermedades Respiratorias (CIBERES)
| | - Teresa Gonzalez
- Instituto de Investigaciones Biomédicas “Alberto Sols” Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid; and
| | - Carmen Menendez
- Department of Pharmacology, School of Medicine, Universidad Complutense Madrid
- Centro de Investigaciones Biomedicas en Red de Enfermedades Respiratorias (CIBERES)
| | - Miren David
- Instituto de Investigaciones Biomédicas “Alberto Sols” Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid; and
| | - Laura Moreno
- Department of Pharmacology, School of Medicine, Universidad Complutense Madrid
- Centro de Investigaciones Biomedicas en Red de Enfermedades Respiratorias (CIBERES)
| | - Alvaro Macias
- Instituto de Investigaciones Biomédicas “Alberto Sols” Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid; and
| | - Julio Cortijo
- Centro de Investigaciones Biomedicas en Red de Enfermedades Respiratorias (CIBERES)
- Department of Pharmacology, Faculty of Medicine, University of Valencia. Fundación Investigación, Hospital General Universitario de Valencia,Valencia, Spain
| | - Carmen Valenzuela
- Instituto de Investigaciones Biomédicas “Alberto Sols” Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid; and
| | - Francisco Perez-Vizcaino
- Department of Pharmacology, School of Medicine, Universidad Complutense Madrid
- Centro de Investigaciones Biomedicas en Red de Enfermedades Respiratorias (CIBERES)
| | - Angel Cogolludo
- Department of Pharmacology, School of Medicine, Universidad Complutense Madrid
- Centro de Investigaciones Biomedicas en Red de Enfermedades Respiratorias (CIBERES)
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Rainbow RD, Parker AM, Davies NW. Protein kinase C-independent inhibition of arterial smooth muscle K(+) channels by a diacylglycerol analogue. Br J Pharmacol 2011; 163:845-56. [PMID: 21323899 PMCID: PMC3111686 DOI: 10.1111/j.1476-5381.2011.01268.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Analogues of the endogenous diacylglycerols have been used extensively as pharmacological activators of protein kinase C (PKC). Several reports show that some of these compounds have additional effects that are independent of PKC activation, including direct block of K(+) and Ca(2+) channels. We investigated whether dioctanoyl-sn-glycerol (DiC8), a commonly used diacylglycerol analogue, blocks K(+) currents of rat mesenteric arterial smooth muscle in a PKC-independent manner. EXPERIMENTAL APPROACH Conventional whole-cell and inside-out patch clamp was used to measure the inhibition of K(+) currents of rat isolated mesenteric smooth muscle cells by DiC8 in the absence and presence of PKC inhibitor peptide. KEY RESULTS Mesenteric artery smooth muscle K(v) currents inactivated very slowly with a time constant of about 2 s following pulses from -65 to +40 mV. Application of 1 µM DiC8 produced an approximate 40-fold increase in the apparent rate of inactivation. Pretreatment of the cells with PKC inhibitor peptide had a minimal effect on the action of DiC8, and substantial inactivation still occurred, indicating that this effect was mainly independent of PKC. We also found that DiC8 blocked BK and K(ATP) currents, and again a significant proportion of these blocks occurred independently of PKC activation. CONCLUSIONS AND IMPLICATIONS These results show that DiC8 has a direct effect on arterial smooth muscle K(+) channels, and this precludes its use as a PKC activator when investigating PKC-mediated effects on vascular K(+) channels.
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Affiliation(s)
- RD Rainbow
- Department of Cardiovascular Sciences, University of LeicesterLeicester, UK
| | - AM Parker
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, UK
| | - NW Davies
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, UK
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Differential dephosphorylation of the protein kinase C-zeta (PKCζ) in an integrin αIIbβ3-dependent manner in platelets. Biochem Pharmacol 2011; 82:505-13. [PMID: 21645497 DOI: 10.1016/j.bcp.2011.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 05/19/2011] [Accepted: 05/20/2011] [Indexed: 12/19/2022]
Abstract
Protein kinase C-zeta (PKCζ), an atypical isoform of the PKC family of protein serine/threonine kinases, is expressed in human platelets. However, the mechanisms of its activation and the regulation of its activity in platelets are not known. We have found that under basal resting conditions, PKCζ has a high phosphorylation status at the activation loop threonine 410 (T410) and the turn motif (autophosphorylation site) threonine 560 (T560), both of which have been shown to be important for its catalytic activity. After stimulation with agonist under stirring conditions, the T410 residue was dephosphorylated in a time- and concentration-dependent manner, while the T560 phosphorylation remained unaffected. The T410 dephosphorylation could be significantly prevented by blocking the binding of fibrinogen to integrin αIIbβ3 with an antagonist, SC-57101; or by okadaic acid used at concentrations that inhibits protein serine/threonine phosphatases PP1 and PP2A in vitro. The dephosphorylation of T410 residue on PKCζ was also observed in PP1cγ null murine platelets after agonist stimulation, suggesting that other isoforms of PP1c or another phosphatase could be responsible for this dephosphorylation event. We conclude that human platelets express PKCζ, and it may be constitutively phosphorylated at the activation loop threonine 410 and the turn motif threonine 560 under basal resting conditions, which are differentially dephosphorylated by outside-in signaling. This differential dephosphorylation of PKCζ might be an important regulatory mechanism for platelet functional responses.
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Lima VV, Giachini FR, Hardy DM, Webb RC, Tostes RC. O-GlcNAcylation: a novel pathway contributing to the effects of endothelin in the vasculature. Am J Physiol Regul Integr Comp Physiol 2010; 300:R236-50. [PMID: 21068200 DOI: 10.1152/ajpregu.00230.2010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Glycosylation with O-linked β-N-acetylglucosamine (O-GlcNAc) or O-GlcNAcylation on serine and threonine residues of nuclear and cytoplasmic proteins is a posttranslational modification that alters the function of numerous proteins important in vascular function, including kinases, phosphatases, transcription factors, and cytoskeletal proteins. O-GlcNAcylation is an innovative way to think about vascular signaling events both in physiological conditions and in disease states. This posttranslational modification interferes with vascular processes, mainly vascular reactivity, in conditions where endothelin-1 (ET-1) levels are augmented (e.g. salt-sensitive hypertension, ischemia/reperfusion, and stroke). ET-1 plays a crucial role in the vascular function of most organ systems, both in physiological and pathophysiological conditions. Recognition of ET-1 by the ET(A) and ET(B) receptors activates intracellular signaling pathways and cascades that result in rapid and long-term alterations in vascular activity and function. Components of these ET-1-activated signaling pathways (e.g., mitogen-activated protein kinases, protein kinase C, RhoA/Rho kinase) are also targets for O-GlcNAcylation. Recent experimental evidence suggests that ET-1 directly activates O-GlcNAcylation, and this posttranslational modification mediates important vascular effects of the peptide. This review focuses on ET-1-activated signaling pathways that can be modified by O-GlcNAcylation. A brief description of the O-GlcNAcylation biology is presented, and its role on vascular function is addressed. ET-1-induced O-GlcNAcylation and its implications for vascular function are then discussed. Finally, the interplay between O-GlcNAcylation and O-phosphorylation is addressed.
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Affiliation(s)
- Victor V Lima
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
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Park WS, Firth AL, Han J, Ko EA. Patho-, physiological roles of voltage-dependent K+ channels in pulmonary arterial smooth muscle cells. J Smooth Muscle Res 2010; 46:89-105. [PMID: 20551590 DOI: 10.1540/jsmr.46.89] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In this review, we demonstrate the basic properties, modulation of, and pathological changes in voltage-dependent K+ (Kv) channels that are expressed in pulmonary arterial smooth muscle cells (PASMCs). Pulmonary Kv channels are thought to play a crucial role in the maintenance of resting membrane potentials, and therefore the vascular tone of the pulmonary arteries. Although the molecular identity of pulmonary Kv channels is not clear, Kv1.1, Kv1.2, Kv1.5, Kv2.1, Kv9.3, and Kv3.1 subtypes are expressed in PASMCs. In addition, resistant PASMCs contain greater amount of Kv channels as compared to conduit PASMCs. This heterogenetic expression of Kv channels is consistent with regional differences in the contractile response to hypoxia. Similar to other K+ channels, pulmonary Kv channels can also be modulated by several vasoconstrictors concomitant with the activation of protein kinase C (PKC). Alterations in Kv channel function have several additional and interrelated consequences, including the regulation of cell proliferation and apoptosis, which ultimately lead to pulmonary vascular remodeling. Increased pulmonary vasoconstriction in pulmonary arterial hypertension is attributable to decreased expression and activity of Kv channels in smooth muscle cells. Kv channels play a central role in the maintenance of cellular homeostasis and ion channels, and consequential signaling cascades. Therefore, Kv channels are potential therapeutic targets for the treatment of pulmonary vascular disease.
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Affiliation(s)
- Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Korea
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Amberg GC, Earley S, Glapa SA. Local regulation of arterial L-type calcium channels by reactive oxygen species. Circ Res 2010; 107:1002-10. [PMID: 20798361 DOI: 10.1161/circresaha.110.217018] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
RATIONALE Reactive oxygen species (ROS) are implicated in the development of cardiovascular disease, and oxidants are important signaling molecules in many cell types. Recent evidence suggests that localized subcellular compartmentalization of ROS generation is an important feature of ROS signaling. However, mechanisms that transduce localized subcellular changes in redox status to functionally relevant changes in cellular processes such as Ca(2+) influx are poorly understood. OBJECTIVE To test the hypothesis that ROS regulate L-type Ca(2+) channel activity in cerebral arterial smooth muscle. METHODS AND RESULTS Using a total internal reflection fluorescence imaging-based approach, we found that highly localized subplasmalemmal generation of endogenous ROS preceded and colocalized with sites of enhanced L-type Ca(2+) channel sparklet activity in isolated cerebral arterial smooth muscle cells. Consistent with this observation and our hypothesis, exogenous ROS increased localized L-type Ca(2+) channel sparklet activity in isolated arterial myocytes via activation of protein kinase Cα and when applied to intact cerebral arterial segments, exogenous ROS increased arterial tone in an L-type Ca(2+) channel-dependent fashion. Furthermore, angiotensin II-dependent stimulation of local L-type Ca(2+) channel sparklet activity in isolated cells and contraction of intact arteries was abolished following inhibition of NADPH oxidase. CONCLUSIONS Our data support a novel model of local oxidative regulation of Ca(2+) influx where vasoconstrictors coupled to NAPDH oxidase (eg, angiotensin II) induce discrete sites of ROS generation resulting in oxidative activation of adjacent protein kinase Cα molecules that in turn promote local sites of enhanced L-type Ca(2+) channel activity, resulting in increased Ca(2+) influx and contraction.
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Affiliation(s)
- Gregory C Amberg
- Colorado State University, Department of Biomedical Sciences, 1617 Campus Delivery, Fort Collins, CO 80523, USA.
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Perez-Vizcaino F, Cogolludo A, Moreno L. Reactive oxygen species signaling in pulmonary vascular smooth muscle. Respir Physiol Neurobiol 2010; 174:212-20. [PMID: 20797450 DOI: 10.1016/j.resp.2010.08.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 08/16/2010] [Accepted: 08/17/2010] [Indexed: 02/07/2023]
Abstract
In recent years, it has become evident that reactive oxygen species (ROS) play a critical role in the regulation of several physiological and pathophysiological processes. Herein we review the main sources, targets and pathophysiological roles of ROS in pulmonary vascular smooth muscle. Mitochondria and NADPH oxidases represent the major sources of ROS in vascular cells. In addition, ROS can be produced by different pathways of arachidonic acid metabolism, endothelial NO synthase (eNOS) and xantine oxidase. There is increasing evidence for the role of ROS, specially hydrogen peroxide, as signaling moieties to induce increase in intracellular calcium concentration ([Ca2+]i) and contraction in pulmonary artery smooth muscle cells (PASMC) through the modulation of a variety of targets, such as Rho kinases (ROCK), protein kinase C (PKC), voltage-gated potassium K+ (Kv) channels and ryanodine receptors (RyR). Thus, an increase in ROS has been reported to contribute to the responses induced by different vasoconstrictor stimuli, including hypoxia. Finally, results from recent studies highlighting the involvement of ROS in the development of pulmonary hypertension are discussed in the present paper.
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Affiliation(s)
- Francisco Perez-Vizcaino
- Department of Pharmacology, School of Medicine, University Complutense of Madrid and Ciber Enfermedades Respiratorias (Ciberes), 28040 Madrid, Spain.
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Abstract
Neuronal activity is communicated to the cerebral vasculature so that adequate perfusion of brain tissue is maintained at all levels of neuronal metabolism. An increase in neuronal activity is accompanied by vasodilation and an increase in local cerebral blood flow. This process, known as neurovascular coupling (NVC) or functional hyperemia, is essential for cerebral homeostasis and survival. Neuronal activity is encoded in astrocytic Ca(2+) signals that travel to astrocytic processes (;endfeet') encasing parenchymal arterioles within the brain. Astrocytic Ca(2+) signals cause the release of vasoactive substances to cause relaxation, and in some circumstances contraction, of the smooth muscle cells (SMCs) of parenchymal arterioles to modulate local cerebral blood flow. Activation of potassium channels in the SMCs has been proposed to mediate NVC. Here, the current state of knowledge of NVC and potassium channels in parenchymal arterioles is reviewed.
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Affiliation(s)
- Kathryn M Dunn
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Increased sensitivity of serotonin on the voltage-dependent K+ channels in mesenteric arterial smooth muscle cells of OLETF rats. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:88-94. [PMID: 20219524 DOI: 10.1016/j.pbiomolbio.2010.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 02/18/2010] [Indexed: 11/21/2022]
Abstract
This study examined the mechanisms of hypertension in diabetes. We investigated the effects of serotonin (5-HT) on voltage-dependent K(+) (Kv) channel activity, vasoconstriction, 5-HT receptor expression levels, and the involvement of protein kinase C (PKC) in mesenteric arteries of Otsuka Long-Evans Tokushima fatty (OLETF) rats compared with Long-Evans Tokushima Otsuka (LETO) rats. Blood pressure, body weight, blood glucose level, and mesenteric arterial wall thickness were greater in OLETF rats. The 5-HT-induced vasoconstriction of mesenteric arteries was greater in OLETF rats than in LETO rats and inhibited by the 5-HT(2A) inhibitor inhibitor, ketanserin. The Kv currents in mesenteric arterial smooth muscle cells (MASMCs), determined using a perforated patch clamp technique, was inhibited by 1 mM 4-AP (42.5 +/- 4.1% vs. 63.5 +/- 2.3% in LETO vs. OLETF rats at +40 mV), but was insensitive to 1 mM TEA and 100 nM iberiotoxin. The inhibition of Kv current by 1 microM 5-HT in MASMCs was greater in OLETF rats than in LETO rats (17.1 +/- 2.2% vs. 33.2 +/- 2.7% in LETO vs. OLETF rats at +40 mV), and the inhibition was prevented by treatment with the PKCalpha- and beta- selective inhibitor, Gö6976. The expression level of 5-HT(2A), but not 5-HT(2B), receptor and the expression levels of total PKC, PKCbeta, and PKCepsilon, but not PKCalpha, were higher in the mesenteric arteries of OLETF rats compared with LETO rats. The enhanced expression of 5-HT(2A) receptor together with PKCbeta may promote mesenteric vasoconstriction and increase vascular resistance in OLETF rats.
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Hajjar I, Sorond F, Hsu YH, Galica A, Cupples LA, Lipsitz LA. Renin angiotensin system gene polymorphisms and cerebral blood flow regulation: the MOBILIZE Boston study. Stroke 2010; 41:635-40. [PMID: 20185782 DOI: 10.1161/strokeaha.109.572669] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Our objective was to investigate the associations between polymorphisms in representative genes of the renin angiotensin system with measures of cerebral blood flow regulation in older adults. METHODS Participants in this analysis were white subjects (n=335) in the MOBILIZE Boston study (Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly of Boston), an observational study of community-dwelling elders who underwent transcranial Doppler while sitting and standing and during hypercapnea and hypocapnea. Autoregulation phenotype was the change in cerebrovascular resistance from sit to stand. Vasoreactivity phenotype was the slope of the change in cerebrovascular conductance versus change in end-tidal CO2. A total of 33 tagged single nucleotide polymorphisms were selected in the angiotensinogen gene, the angiotensin converting enzyme gene, and the angiotensin receptor gene. Regression analyses adjusted for age, gender, body mass index, mean arterial blood pressure, stroke, and use of antihypertensives were conducted for each single nucleotide polymorphism and outcome. Bonferroni corrections were used to adjust P values for multiple testing. RESULTS In the angiotensinogen gene, only the rs699 single nucleotide polymorphism was associated with vasoreactivity after Bonferroni correction (P=0.00028). Homozygous carriers of the CC genotype of this single nucleotide polymorphism had lower vasoreactivity compared with the CT or TT genotypes. There were no significant associations with autoregulation measures. None of the single nucleotide polymorphisms in the other genes were associated with our phenotypes. CONCLUSION This analysis suggests that the angiotensinogen gene may be involved in vasoreactivity independent of blood pressure. Larger studies are needed to confirm the role of this gene in cerebrovascular health and aging.
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Affiliation(s)
- Ihab Hajjar
- Harvard Medical School, Institute for Aging Research/Hebrew SeniorLife/Beth Israel Deaconess Medical Center, Division of Gerontology, Boston, MA 02130, USA.
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Xia M, Li G, Ma J, Ling W. Phosphoinositide 3-kinase mediates CD40 ligand-induced oxidative stress and endothelial dysfunction via Rac1 and NADPH oxidase 2. J Thromb Haemost 2010; 8:397-406. [PMID: 19895673 DOI: 10.1111/j.1538-7836.2009.03683.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES CD40 ligand (CD40L) has been implicated as an inducer of reactive oxygen species (ROS) generation in endothelial cells, but definitive evidence for this and the in vivo relevance haves not been demonstrated fully. We thus investigated whether phosphoinositide 3-kinase (PI3K) was linked to ROS generation and endothelial reactivity in response to CD40L. METHODS AND RESULTS CD40L treatment activated PI3K activity by regulating the association between PI3K p85 and the CD40 receptor. CD40L exposure also stimulated the GTPase Rac1, which is known to activate NADPH oxidases, and enhanced ROS formation, whereas PI3K inhibition or depletion by small interfering RNA (siRNA) prevented these responses. Subsequently, PI3K overexpression activated Rac1 and increased ROS generation. These responses were not observed in the presence of inactive Rac1 or siRNA against the NADPH oxidase subunit NOX2. Protein kinase Czeta mediates PI3K-regulated NADPH oxidase activation by promoting cellular p47phox translocation. Importantly, PI3K inhibition prevented CD40L-mediated ROS generation and endothelial dysfunction in a mouse model. In summary, PI3K mediates CD40L-induced ROS production and subsequent endothelial dysfunction. CONCLUSIONS Targeting PI3K may provide a new therapeutic approach in diseases associated with oxidative stress and endothelial dysfunction.
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Affiliation(s)
- M Xia
- Department of Nutrition, School of Public Health, Sun Yat-Sen University, Guangzhou, China.
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