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Bertagna F, Ahmad S, Lewis R, Silva SRP, McFadden J, Huang CLH, Matthews HR, Jeevaratnam K. Loose-patch clamp analysis applied to voltage-gated ionic currents following pharmacological ryanodine receptor modulation in murine hippocampal cornu ammonis-1 pyramidal neurons. Front Physiol 2024; 15:1359560. [PMID: 38720787 PMCID: PMC11076846 DOI: 10.3389/fphys.2024.1359560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 04/04/2024] [Indexed: 05/12/2024] Open
Abstract
Introduction The loose-patch clamp technique was first developed and used in native amphibian skeletal muscle (SkM), offering useful features complementing conventional sharp micro-electrode, gap, or conventional patch voltage clamping. It demonstrated the feedback effects of pharmacological modification of ryanodine receptor (RyR)-mediated Ca2+ release on the Na+ channel (Nav1.4) currents, initiating excitation-contraction coupling in native murine SkM. The effects of the further RyR and Ca2+-ATPase (SERCA) antagonists, dantrolene and cyclopiazonic acid (CPA), additionally implicated background tubular-sarcoplasmic Ca2+ domains in these actions. Materials and methods We extend the loose-patch clamp approach to ion current measurements in murine hippocampal brain slice cornu ammonis-1 (CA1) pyramidal neurons. We explored the effects on Na+ currents of pharmacologically manipulating RyR and SERCA-mediated intracellular store Ca2+ release and reuptake. We adopted protocols previously applied to native skeletal muscle. These demonstrated Ca2+-mediated feedback effects on the Na+ channel function. Results Experiments applying depolarizing 15 ms duration loose-patch clamp steps to test voltages ranging from -40 to 120 mV positive to the resting membrane potential demonstrated that 0.5 mM caffeine decreased inward current amplitudes, agreeing with the previous SkM findings. It also decreased transient but not prolonged outward current amplitudes. However, 2 mM caffeine affected neither inward nor transient outward but increased prolonged outward currents, in contrast to its increasing inward currents in SkM. Furthermore, similarly and in contrast to previous SkM findings, both dantrolene (10 μM) and CPA (1 μM) pre-administration left both inward and outward currents unchanged. Nevertheless, dantrolene pretreatment still abrogated the effects of subsequent 0.5- and 2-mM caffeine challenges on both inward and outward currents. Finally, CPA abrogated the effects of 0.5 mM caffeine on both inward and outward currents, but with 2 mM caffeine, inward and transient outward currents were unchanged, but sustained outward currents increased. Conclusion We, thus, extend loose-patch clamping to establish pharmacological properties of murine CA1 pyramidal neurons and their similarities and contrasts with SkM. Here, evoked though not background Ca2+-store release influenced Nav and Kv excitation, consistent with smaller contributions of background store Ca2+ release to resting [Ca2+]. This potential non-canonical mechanism could modulate neuronal membrane excitability or cellular firing rates.
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Affiliation(s)
- Federico Bertagna
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Shiraz Ahmad
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - S. Ravi P. Silva
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- Advanced Technology Institute, University of Surrey, Guildford, United Kingdom
| | - Johnjoe McFadden
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Christopher L.-H. Huang
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Hugh R. Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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Afroz M, Bhuia MS, Rahman MA, Hasan R, Islam T, Islam MR, Chowdhury R, Khan MA, Antas E Silva D, Melo Coutinho HD, Islam MT. Anti-diarrheal effect of piperine possibly through the interaction with inflammation inducing enzymes: In vivo and in silico studies. Eur J Pharmacol 2024; 965:176289. [PMID: 38158111 DOI: 10.1016/j.ejphar.2023.176289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/02/2023] [Accepted: 12/14/2023] [Indexed: 01/03/2024]
Abstract
Piperine is a natural alkaloid that possesses a variety of therapeutic properties, including anti-inflammatory, antioxidant, antibacterial, and anticarcinogenic activities. The present study aims to assess the medicinal benefits of piperine as an anti-diarrheal agent in a chick model by utilizing in vivo and in silico techniques. For this, castor oil was administered orally to 2-day-old chicks to cause diarrhea. Bismuth subsalicylate (10 mg/kg), loperamide (3 mg/kg), and nifedipine (2.5 mg/kg) were used as positive controls, while the vehicle was utilized as a negative control. Two different doses (25 and 50 mg/kg b.w.) of the test sample (piperine) were administered orally, and the highest dose was tested with standards to investigate the synergistic activity of the test sample. In our findings, piperine prolonged the latent period while reducing the number of diarrheal feces in the experimental chicks during the monitoring period (4 h). At higher doses, piperine appears to reduce diarrheal secretion while increasing latency in chicks. Throughout the combined pharmacotherapy, piperine outperformed bismuth subsalicylate and nifedipine in terms of anti-diarrheal effects with loperamide. In molecular docking, piperine exhibited higher binding affinities towards different inflammatory enzymes such as cyclooxygenase 1 (-7.9 kcal/mol), cyclooxygenase 2 (-8.4 kcal/mol), nitric oxide synthases (-8.9 kcal/mol), and L-type calcium channel (-8.8 kcal/mol), indicating better interaction of PP with these proteins. In conclusion, piperine showed a potent anti-diarrheal effect in castor oil-induced diarrheal chicks by suppressing the inflammation and calcium ion influx induced by castor oil.
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Affiliation(s)
- Meher Afroz
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | - Md Shimul Bhuia
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | - Md Anisur Rahman
- Department of Pharmacy, Islamic University, Kushtia, 7003, Bangladesh.
| | - Rubel Hasan
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | - Tawhida Islam
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | - Md Rakibul Islam
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | - Raihan Chowdhury
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | - Md Ali Khan
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
| | | | | | - Muhammad Torequl Islam
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
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Bird GS, Lin YP, Tucker CJ, Mueller G, Shi M, Padmanabhan S, Parekh AB. Scrutinizing science to save lives: uncovering flaws in the data linking L-type calcium channels blockers to CRAC channels and heart failure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.06.579229. [PMID: 38370647 PMCID: PMC10871304 DOI: 10.1101/2024.02.06.579229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Hypertension is estimated to affect almost 1 billion people globally and significantly increases risk of myocardial infarction, heart failure, stroke, retinopathy and kidney disease. One major front line therapy that has been used for over 50 years involves L-type Ca 2+ channel blockers (LCCBs). One class of LCCBs is the dihydropyridine family, with amlodipine being widely prescribed regardless of gender, race, ethnicity or age. In 2020, Johnson et al. 7 reported that all LCCBs significantly increased the risk of heart failure, and attributed this effect to non-canonical activation of store-operated Ca 2+ entry. A major approach on which they based many of their arguments was to measure cytosolic Ca 2+ using the fluorescent Ca 2+ indicator dye fura-2. We recently demonstrated that amlodipine is highly fluorescent within cells and overwhelms the fura-2 signal, precluding the use of the indicator dye with amlodipine 24 . Our meta-analyses and prospective real world study showed that dihydropyridines were not associated with an increase in heart failure, likely explained by the lack of consideration by Johnson et al. 7 of well-known confounding factors such as age, race, obesity, prior anti-hypertensive treatment or diabetes 24 . Trebak and colleagues have responded to our paper with a forthright and unwavering defence of their work 27 . In this paper, we carry out a forensic dissection of Johnson et al., 7 and conduct new experiments that address directly points raised by Trebak et al. 27 . We show that there are major flaws in the design and interpretation of their key experiments, that fura-2 cannot be used with amlodipine, that there are fundamental mathematical misunderstandings and mistakes throughout their study leading to critical calculations on heart failure that are demonstrably wrong, and several of their own results are inconsistent with their interpretation. We therefore believe the study by Johnson et al. 7 is flawed at many levels and we stand by our conclusions.
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El-Lakany MA, Haghbin N, Arora N, Hashad AM, Mironova GY, Sancho M, Gros R, Welsh DG. Ca V3.1 channels facilitate calcium wave generation and myogenic tone development in mouse mesenteric arteries. Sci Rep 2023; 13:20407. [PMID: 37989780 PMCID: PMC10663617 DOI: 10.1038/s41598-023-47715-3] [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: 06/19/2023] [Accepted: 11/17/2023] [Indexed: 11/23/2023] Open
Abstract
The arterial myogenic response to intraluminal pressure elicits constriction to maintain tissue perfusion. Smooth muscle [Ca2+] is a key determinant of constriction, tied to L-type (CaV1.2) Ca2+ channels. While important, other Ca2+ channels, particularly T-type could contribute to pressure regulation within defined voltage ranges. This study examined the role of one T-type Ca2+ channel (CaV3.1) using C57BL/6 wild type and CaV3.1-/- mice. Patch-clamp electrophysiology, pressure myography, blood pressure and Ca2+ imaging defined the CaV3.1-/- phenotype relative to C57BL/6. CaV3.1-/- mice had absent CaV3.1 expression and whole-cell current, coinciding with lower blood pressure and reduced mesenteric artery myogenic tone, particularly at lower pressures (20-60 mmHg) where membrane potential is hyperpolarized. This reduction coincided with diminished Ca2+ wave generation, asynchronous events of Ca2+ release from the sarcoplasmic reticulum, insensitive to L-type Ca2+ channel blockade (Nifedipine, 0.3 µM). Proximity ligation assay (PLA) confirmed IP3R1/CaV3.1 close physical association. IP3R blockade (2-APB, 50 µM or xestospongin C, 3 µM) in nifedipine-treated C57BL/6 arteries rendered a CaV3.1-/- contractile phenotype. Findings indicate that Ca2+ influx through CaV3.1 contributes to myogenic tone at hyperpolarized voltages through Ca2+-induced Ca2+ release tied to the sarcoplasmic reticulum. This study helps establish CaV3.1 as a potential therapeutic target to control blood pressure.
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Affiliation(s)
- Mohammed A El-Lakany
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada.
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt.
| | - Nadia Haghbin
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada
| | - Naman Arora
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada
| | - Ahmed M Hashad
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Galina Yu Mironova
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada
| | - Maria Sancho
- Department of Physiology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain
| | - Robert Gros
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada
| | - Donald G Welsh
- Department of Physiology & Pharmacology, Schulich School of Medicine, Robarts Research Institute, University of Western Ontario, 1151 Richmond Road N, London, ON, N6A 5B7, Canada.
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5
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Cottrell J, Cummings K, Jude D, Chaffin D. The effect of impedance cardiography directed antihypertensive therapy on fetal growth restriction rates and perinatal mortality in women with chronic hypertension. Pregnancy Hypertens 2022; 28:123-127. [PMID: 35339775 DOI: 10.1016/j.preghy.2022.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 02/21/2022] [Accepted: 03/14/2022] [Indexed: 11/21/2022]
Abstract
OBJECTIVES We sought to determine the effect of impedance cardiography directed medical antihypertensive therapy on fetal growth restriction and perinatal mortality in women with chronic hypertension. STUDY DESIGN A retrospective study was conducted on 958 women referred to the Maternal Hypertension Center at Cabell Huntington Hospital between 2005 and 2014 for the indication of chronic hypertension. MAIN OUTCOME MEASURES Serial assessments of maternal hemodynamics were obtained using non-invasive impedance cardiography. Vasodilators were initiated for increased systemic vascular resistance. Elevated cardiac output was treated with beta blockade. RESULTS Blood pressure at initial visit was used to stratify patients into five groups. Initial blood pressure of <130 systolic or <80 diastolic had 24 cases of growth restriction (6.8%) and 6 perinatal deaths (1.7%), 130-139 systolic or 80-89 diastolic resulted in 29 cases of growth restriction (9.3%) and 9 perinatal deaths (2.9%), 140-149 systolic or 90-99 diastolic 14 cases of growth restriction (6.5%) and 3 perinatal deaths (1.4%), 150-159 systolic or 100-109 diastolic had 5 cases of growth restriction (8.6%) and 4 perinatal deaths (6.89%), and >160 systolic or >110 diastolic 3 cases of growth restriction (13%) with no perinatal deaths. There were no differences in growth restriction (p = .59) or perinatal death (p = .15) between the groups. CONCLUSION The rates of IUGR and perinatal mortality did not increase even with increasing severity of maternal hypertension. This low cost and non-invasive test should be considered for optimizing rates of growth restriction and perinatal mortality in pregnancies complicated by chronic hypertension.
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Affiliation(s)
- Jesse Cottrell
- Marshall University, Joan C. Edwards School of Medicine, Department of Obstetrics and Gynecology, 1600 Medical Center Drive, Huntington, WV 25701, USA
| | - Kelly Cummings
- Marshall University, Joan C. Edwards School of Medicine, Department of Obstetrics and Gynecology, 1600 Medical Center Drive, Huntington, WV 25701, USA
| | - David Jude
- Marshall University, Joan C. Edwards School of Medicine, Department of Obstetrics and Gynecology, 1600 Medical Center Drive, Huntington, WV 25701, USA
| | - David Chaffin
- Marshall University, Joan C. Edwards School of Medicine, Department of Obstetrics and Gynecology, 1600 Medical Center Drive, Huntington, WV 25701, USA
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Huang ZX, Qiu ZE, Chen L, Hou XC, Zhu YX, Zhou WL, Zhang YL. Cellular mechanism underlying the facilitation of contractile response induced by IL-25 in mouse tracheal smooth muscle. Am J Physiol Lung Cell Mol Physiol 2022; 323:L27-L36. [PMID: 35537103 DOI: 10.1152/ajplung.00468.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Asthma is a common heterogeneous respiratory disease characterized by airway inflammation and airway hyperresponsiveness (AHR) which is associated with abnormality in smooth muscle contractility. The epithelial cell-derived cytokine IL-25 is implicated in type 2 immune pathology including asthma, whereas the underlying mechanisms have not been fully elucidated. This study aims to investigate the effects of IL-25 on mouse tracheal smooth muscle contractility and elucidate the cellular mechanisms. Incubation with IL-25 augmented the contraction of mouse tracheal smooth muscles, which could be suppressed by the L-type voltage-dependent Ca2+ channel (L-VDCC) blocker nifedipine. Furthermore, IL-25 enhanced the cytosolic Ca2+ signals and triggered up-regulation of α1C L-VDCC (CaV1.2) in primary cultured mouse tracheal smooth muscle cells. Knocking down IL-17RA/IL-17RB receptors or inhibiting the transforming growth factor-β-activated kinase 1 (TAK1)-tumor progression locus 2 (TPL2)-MAPK kinase 1/2 (MEK1/2)-ERK1/2-activating protein-1 (AP-1) signaling pathways suppressed the IL-25-elicited up-regulation of CaV1.2 and hyperreactivity in tracheal smooth muscles. Moreover, inhibition of TPL2, ERK1/2 or L-VDCC alleviated the AHR symptom induced by IL-25 in a murine model. This study revealed that IL-25 potentiated the contraction of tracheal smooth muscle and evoked AHR via activation of TPL2-ERK1/2-CaV1.2 signaling, providing novel targets for the treatment of asthma with a high-IL-25 phenotype.
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Affiliation(s)
- Ze-Xin Huang
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhuo-Er Qiu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Lei Chen
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiao-Chun Hou
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yun-Xin Zhu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wen-Liang Zhou
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yi-Lin Zhang
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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7
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Bertagna F, Lewis R, Silva SRP, McFadden J, Jeevaratnam K. Thapsigargin blocks electromagnetic field-elicited intracellular Ca 2+ increase in HEK 293 cells. Physiol Rep 2022; 10:e15189. [PMID: 35510320 PMCID: PMC9069166 DOI: 10.14814/phy2.15189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 11/24/2022] Open
Abstract
Biological effects of electromagnetic fields (EMFs) have previously been identified for cellular proliferation and changes in expression and conduction of diverse types of ion channels. The major effect elicited by EMFs seems to be directed toward Ca2+ homeostasis. This is particularly remarkable since Ca2+ acts as a central modulator in various signaling pathways, including, but not limited to, cell differentiation and survival. Despite this, the mechanisms underlying this modulation have yet to be unraveled. Here, we assessed the effect of EMFs on intracellular [Ca2+], by exposing HEK 293 cells to both radio‐frequency electromagnetic fields (RF‐EMFs) and static magnetic fields (SMFs). We detected a constant and significant increase in [Ca2+] subsequent to exposure to both types of fields. Strikingly, the increase was nulled by administration of 10 μM Thapsigargin, a blocker of sarco/endoplasmic reticulum Ca2+‐ATPases (SERCAs), indicating the involvement of the endoplasmic reticulum (ER) in EMF‐related modulation of Ca2+ homeostasis.
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Affiliation(s)
- Federico Bertagna
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - S Ravi P Silva
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,Advanced Technology Institute, University of Surrey, Guildford, Surrey, UK
| | - Johnjoe McFadden
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - Kamalan Jeevaratnam
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
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8
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Gawri R, Bielecki R, Salter EW, Zelinka A, Shiba T, Collingridge G, Nagy A, Kandel RA. The anabolic effect of inorganic polyphosphate on chondrocytes is mediated by calcium signalling. J Orthop Res 2022; 40:310-322. [PMID: 33719091 DOI: 10.1002/jor.25032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/08/2021] [Accepted: 03/10/2021] [Indexed: 02/04/2023]
Abstract
Inorganic polyphosphates (polyP) are polymers composed of phosphate residues linked by energy-rich phosphoanhydride bonds. As polyP can bind calcium, the hypothesis of this study is that polyP enters chondrocytes and exerts its anabolic effect by calcium influx through calcium channels. PolyP treatment of cartilage tissue formed in 3D culture by bovine chondrocytes showed an increase in proteoglycan accumulation but only when calcium was also present at a concentration of 1.5 mM. This anabolic effect could be prevented by treatment with either ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid or the calcium channel inhibitors gadolinium and nifedipine. Calcium and polyP cotreatment of chondrocytes in monolayer culture resulted in calcium oscillations that were polyP chain length specific and were inhibited by gadolinium and nifedipine. The calcium influx resulted in increased gene expression of sox9, collagen type II, and aggrecan which was prevented by treatment with either calphostin, an inhibitor of protein kinase C, and W7, an inhibitor of calmodulin; suggesting activation of the protein kinase C-calmodulin pathway. Tracing studies using 4',6-diamidino-2-phenylindole, Mitotracker Red, and/or Fura-AM staining showed that polyP was detected in the nucleus, mitochondria, and intracellular vacuoles suggesting that polyP may also enter the cell. PolyP colocalizes with calcium in mitochondria. This study demonstrates that polyP requires the influx of calcium to regulate chondrocyte matrix production, likely via activating calcium signaling. These findings identify the mechanism regulating the anabolic effect of polyP in chondrocytes which will help in its clinical translation into a therapeutic agent for cartilage repair.
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Affiliation(s)
- Rahul Gawri
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.,Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Ryszard Bielecki
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Eric W Salter
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Alena Zelinka
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.,Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Toshikazu Shiba
- Regenetiss Inc., Kunitachi, Japan.,Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Graham Collingridge
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Andras Nagy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Rita A Kandel
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.,Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada.,Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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9
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Chen IS, Liang WZ, Wang JL, Kuo CC, Hao LJ, Chou CT, Jan CR. Exploration of thioridazine-induced Ca 2+ signaling and non-Ca 2+-triggered cell death in HepG2 human hepatocellular carcinoma cells. CHINESE J PHYSIOL 2020; 63:187-194. [PMID: 32859886 DOI: 10.4103/cjp.cjp_45_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Thioridazine, belonging to first-generation antipsychotic drugs, is a prescription used to treat schizophrenia. However, the effect of thioridazine on intracellular Ca2+ concentration ([Ca2+]i) and viability in human liver cancer cells is unclear. This study examined whether thioridazine altered Ca2+ signaling and viability in HepG2 human hepatocellular carcinoma cells. Ca2+ concentrations in suspended cells were measured using the fluorescent Ca2+-sensitive dye fura-2. Cell viability was examined by WST-1 assay. Thioridazine at concentrations of 25-100 μM induced [Ca2+]i rises. Ca2+ removal reduced the signal by 20%. Thioridazine (100 μM) induced Mn2+ influx suggesting of Ca2+ entry. Thioridazine-induced Ca2+ entry was inhibited by 20% by protein kinase C (PKC) activator (phorbol 12-myristate 13 acetate) and inhibitor (GF109203X) and by three inhibitors of store-operated Ca2+ channels: nifedipine, econazole, and SKF96365. In Ca2+-free medium, treatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin (TG) abolished thioridazine-evoked [Ca2+]i rises. On the other hand, thioridazine preincubation completely inhibited the [Ca2+]i rises induced by TG. Furthermore, U73122 totally suppressed the [Ca2+]i rises induced by thioridazine via inhibition of phospholipase C (PLC). Regarding cytotoxicity, at 30-80 μM, thioridazine reduced cell viability in a concentration-dependent fashion. This cytotoxicity was not prevented by preincubation with 1,2-bis (2-aminophenoxy) ethane-N, N, N', N'-tetraacetic acid-acetoxymethyl ester (BAPTA/AM) (a Ca2+ chelator). To conclude, thioridazine caused concentration-dependent [Ca2+]i rises in HepG2 human hepatoma cells by inducing Ca2+ release from the endoplasmic reticulum via PLC-associated pathways and Ca2+ influx from extracellular medium through PKC-sensitive store-operated Ca2+ entry. In addition, thioridazine induced cytotoxicity in a Ca2+-independent manner.
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Affiliation(s)
- I-Shu Chen
- Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Wei-Zhe Liang
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung; Department of Pharmacy, Tajen University, Pingtung, Taiwan
| | - Jue-Long Wang
- Department of Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Chun-Chi Kuo
- Department of Nursing, Tzu Hui Institute of Technology, Pingtung, Taiwan
| | - Lyh-Jyh Hao
- Department of Endocrinology and Metabolism, Kaohsiung Veteran General Hospital Tainan Branch; Chung Hwa University of Medical and Technology, Tainan, Taiwan
| | - Chiang-Ting Chou
- Department of Nursing, Division of Basic Medical Sciences, Chang Gung University of Science and Technology, Chiayi Campus; Division of Pulmonary and Critical Care Medicine, Chang Gung Memorial Hospital Chiayi Branch, Puzi City, Chiayi County, Taiwan
| | - Chung-Ren Jan
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
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Thomas CM, Timson DJ. The Mechanism of Action of Praziquantel: Can New Drugs Exploit Similar Mechanisms? Curr Med Chem 2020; 27:676-696. [DOI: 10.2174/0929867325666180926145537] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 04/06/2018] [Accepted: 08/20/2018] [Indexed: 11/22/2022]
Abstract
Praziquantel (PZQ) is the drug of choice for treating infection with worms from the
genus Schistosoma. The drug is effective, cheap and has few side effects. However, despite its
use in millions of patients for over 40 years its molecular mechanism of action remains elusive.
Early studies demonstrated that PZQ disrupts calcium ion homeostasis in the worm and
the current consensus is that it antagonises voltage-gated calcium channels. It is hypothesised
that disruption of these channels results in uncontrolled calcium ion influx leading to uncontrolled
muscle contraction and paralysis. However, other experimental studies have suggested
a role for myosin regulatory light chains and adenosine uptake in the drug’s mechanism of
action. Assuming voltage-gated calcium channels do represent the main molecular target of
PZQ, the precise binding site for the drug remains to be identified. Unlike other commonly
used anti-parasitic drugs, there are few definitive reports of resistance to PZQ in the literature.
The lack of knowledge about PZQ’s molecular mechanism(s) undermines our ability to predict
how resistance might arise and also hinder our attempts to develop alternative antischistosomal
drugs which exploit the same target(s). Some PZQ derivatives have been identified
which also kill or paralyse schistosomes in culture. However, none of these are in widespread
clinical use. There is a pressing need for fundamental research into the molecular mechanism(
s) of action of PZQ. Such research would enable new avenues for antischsistosomal
drug discovery.
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Affiliation(s)
- Charlotte M. Thomas
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom
| | - David J. Timson
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom
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11
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NS8593 inhibits Ca 2+ permeant channels reversing mouse airway smooth muscle contraction. Life Sci 2019; 238:116953. [PMID: 31626793 DOI: 10.1016/j.lfs.2019.116953] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/09/2019] [Accepted: 10/09/2019] [Indexed: 01/24/2023]
Abstract
AIMS This study focused on investigating whether NS8593 reverses airway smooth muscle (ASM) contraction and the underlying mechanism. MAIN METHODS ASM contraction in mouse tracheal rings and lung slices was measured. Currents mediated by voltage dependent Ca2+ channels (VDCCs) and ACH-activated channels were measured using the whole-cell patch-clamp technique in single tracheal smooth muscle cells (TSMCs). Intracellular Ca2+ level and cell length were measured using an LSM 700 laser confocal microscope and a Zen 2010 software. Mouse respiratory system resistance (Rrs) was assessed using a FlexiVent FX system. KEY FINDINGS High K+ (80 mM K+) and ACH induced ASM contraction in mouse tracheal rings and lung slices, which was partially relaxed by nifedipine (blocker of L-type VDCCs, LVDCCs), YM-58483 (blocker of store-operated Ca2+ entry (SOCE), transient receptor potential C3 (TRPC3) and TRPC5 channels), respectively. However, the contraction was completely reversed by NS8593, whereas, slightly relaxed by formoterol. ACH activated inward currents, which displayed linear and reversed around 0 mV, indicating the currents were mediated by non-selective cation channels (NSCCs). Moreover, these currents were blocked by YM-58483. In addition, such currents were abolished by NS8593, implicating that NS8593 inhibits the same channels. Besides, NS8593 inhibited increases of intracellular Ca2+ and the associated cell shortening. Finally, NS8593 inhibited ACH-induced increases of mouse respirator system resistance (Rrs). SIGNIFICANCE Our results indicate that NS8593 inhibits LVDCCs and NSCCs, resulting in decreases of intracellular Ca2+ and then leading to ASM relaxation. These data suggest that NS8593 might be a new bronchodilator.
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12
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Qureshi AI, Asif A, Waqas MA, Aytac E, Gurkas E, Saleem MA, Wallery SS. Assessment of Cerebral Vasodilatory Capacity as Part of Catheter-Based Cerebral Angiography. J Neuroimaging 2019; 30:90-96. [PMID: 31565831 DOI: 10.1111/jon.12665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/01/2019] [Accepted: 09/11/2019] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Cerebral vasodilatory capacity assessment for risk stratification in patients with extracranial arterial stenosis or occlusion may be useful. We describe a new method that assesses cerebral vasodilatory capacity as part of catheter-based cerebral angiography. METHODS We prospectively assessed regional cerebral blood volume (rCBV) in the arterial distribution of interest using a controlled contrast injection in the common carotid or the subclavian arteries. rCBV maps were created using a predefined algorithm based on contrast distribution in the venous phase (voxel size: .466 mm3 ). rCBV maps were acquired again after selective administration of intra-arterial nicardipine (2.0 mg) distal to the stenosis. Two independent observers graded the change in rCBV in 10 predefined anatomical regions within the tributaries of the artery of interest (0 = reduction, 1 = no change, 2 = increase) and total rCBV change scores were summated. RESULTS Twenty-five patients with internal carotid artery stenosis (n = 18; 0-90% in severity) or extracranial vertebral artery stenosis (n = 7; 0-100% in severity) were assessed. There was an increase in rCBV in a tributary of the artery of interest in 18 of 25 after intra-arterial nicardipine (mean score: 11.98; range 0-19.5). There was no change or decrease in rCBV in 7 of 25 patients. The mean rCBV change score was similar in patients with an assessment of internal carotid artery or vertebral artery distributions (12.2 ± 5.3; 11.4 ± 2.5; P = .68). CONCLUSION Selective vasodilatory response to intra-arterial nicardipine in the affected arterial distribution during catheter-based cerebral angiography may provide new data for risk stratification.
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Affiliation(s)
- Adnan I Qureshi
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL.,Department of Neurology, University of Missouri, Columbia, MO
| | - Ahmer Asif
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL
| | - Muhammad A Waqas
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL
| | - Emrah Aytac
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL.,Zeenat Qureshi Stroke Institute, Department of Neurology, Firat University, Elazig, Turkey
| | - Erdem Gurkas
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL.,Department of Neurology, SBU Gulhane Training and Research Hospital, Ankara, Turkey
| | - Muhammad A Saleem
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL
| | - Shawn S Wallery
- Zeenat Qureshi Stroke Institute, St. Cloud, MN and Mercyhealth Rockford Hospital, Rockford, IL
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13
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Biocatalysis as Useful Tool in Asymmetric Synthesis: An Assessment of Recently Granted Patents (2014–2019). Catalysts 2019. [DOI: 10.3390/catal9100802] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The broad interdisciplinary nature of biocatalysis fosters innovation, as different technical fields are interconnected and synergized. A way to depict that innovation is by conducting a survey on patent activities. This paper analyses the intellectual property activities of the last five years (2014–2019) with a specific focus on biocatalysis applied to asymmetric synthesis. Furthermore, to reflect the inventive and innovative steps, only patents that were granted during that period are considered. Patent searches using several keywords (e.g., enzyme names) have been conducted by using several patent engine servers (e.g., Espacenet, SciFinder, Google Patents), with focus on granted patents during the period 2014–2019. Around 200 granted patents have been identified, covering all enzyme types. The inventive pattern focuses on the protection of novel protein sequences, as well as on new substrates. In some other cases, combined processes, multi-step enzymatic reactions, as well as process conditions are the innovative basis. Both industries and academic groups are active in patenting. As a conclusion of this survey, we can assert that biocatalysis is increasingly recognized as a useful tool for asymmetric synthesis and being considered as an innovative option to build IP and protect synthetic routes.
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14
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Brueggeman L, Sturgeon ML, Martin RM, Grossbach AJ, Nagahama Y, Zhang A, Howard MA, Kawasaki H, Wu S, Cornell RA, Michaelson JJ, Bassuk AG. Drug repositioning in epilepsy reveals novel antiseizure candidates. Ann Clin Transl Neurol 2019; 6:295-309. [PMID: 30847362 PMCID: PMC6389756 DOI: 10.1002/acn3.703] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/24/2018] [Accepted: 10/26/2018] [Indexed: 01/22/2023] Open
Abstract
Objective Epilepsy treatment falls short in ~30% of cases. A better understanding of epilepsy pathophysiology can guide rational drug development in this difficult to treat condition. We tested a low-cost, drug-repositioning strategy to identify candidate epilepsy drugs that are already FDA-approved and might be immediately tested in epilepsy patients who require new therapies. Methods Biopsies of spiking and nonspiking hippocampal brain tissue from six patients with unilateral mesial temporal lobe epilepsy were analyzed by RNA-Seq. These profiles were correlated with transcriptomes from cell lines treated with FDA-approved drugs, identifying compounds which were tested for therapeutic efficacy in a zebrafish seizure assay. Results In spiking versus nonspiking biopsies, RNA-Seq identified 689 differentially expressed genes, 148 of which were previously cited in articles mentioning seizures or epilepsy. Differentially expressed genes were highly enriched for protein-protein interactions and formed three clusters with associated GO-terms including myelination, protein ubiquitination, and neuronal migration. Among the 184 compounds, a zebrafish seizure model tested the therapeutic efficacy of doxycycline, metformin, nifedipine, and pyrantel tartrate, with metformin, nifedipine, and pyrantel tartrate all showing efficacy. Interpretation This proof-of-principle analysis suggests our powerful, rapid, cost-effective approach can likely be applied to other hard-to-treat diseases.
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Affiliation(s)
- Leo Brueggeman
- Department of PsychiatryCarver College of MedicineUniversity of IowaIowa CityIowa
| | - Morgan L. Sturgeon
- The Interdisciplinary Graduate Program in Molecular MedicineCarver College of MedicineUniversity of IowaIowa CityIowa
| | | | | | | | - Angela Zhang
- Department of BiostatisticsUniversity of WashingtonSeattleWashington
| | | | | | - Shu Wu
- Department of PediatricsUniversity of IowaIowa CityIowa
| | - Robert A. Cornell
- Department of Anatomy and Cell BiologyUniversity of IowaIowa CityIowa
| | - Jacob J. Michaelson
- Department of PsychiatryCarver College of MedicineUniversity of IowaIowa CityIowa
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15
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Tabata Y, Imaizumi Y, Sugawara M, Andoh-Noda T, Banno S, Chai M, Sone T, Yamazaki K, Ito M, Tsukahara K, Saya H, Hattori N, Kohyama J, Okano H. T-type Calcium Channels Determine the Vulnerability of Dopaminergic Neurons to Mitochondrial Stress in Familial Parkinson Disease. Stem Cell Reports 2018; 11:1171-1184. [PMID: 30344006 PMCID: PMC6234903 DOI: 10.1016/j.stemcr.2018.09.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 12/11/2022] Open
Abstract
Parkinson disease (PD) is a progressive neurological disease caused by selective degeneration of dopaminergic (DA) neurons in the substantia nigra. Although most cases of PD are sporadic cases, familial PD provides a versatile research model for basic mechanistic insights into the pathogenesis of PD. In this study, we generated DA neurons from PARK2 patient-specific, isogenic PARK2 null and PARK6 patient-specific induced pluripotent stem cells and found that these neurons exhibited more apoptosis and greater susceptibility to rotenone-induced mitochondrial stress. From phenotypic screening with an FDA-approved drug library, one voltage-gated calcium channel antagonist, benidipine, was found to suppress rotenone-induced apoptosis. Furthermore, we demonstrated the dysregulation of calcium homeostasis and increased susceptibility to rotenone-induced stress in PD, which is prevented by T-type calcium channel knockdown or antagonists. These findings suggest that calcium homeostasis in DA neurons might be a useful target for developing new drugs for PD patients. Patient-derived DA neurons recapitulate several PD-related disease phenotypes Establishment of a system for drug screening against PD using patient-derived cells Calcium channel antagonists suppress rotenone-induced apoptosis in PARK2 DA neurons The involvement of dysregulated T-type calcium channels in the progression of PD
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Affiliation(s)
- Yoshikuni Tabata
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan; Tsukuba Research Laboratories, Eisai Co., Ltd, 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Yoichi Imaizumi
- Tsukuba Research Laboratories, Eisai Co., Ltd, 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Michiko Sugawara
- Tsukuba Research Laboratories, Eisai Co., Ltd, 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Tomoko Andoh-Noda
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Satoe Banno
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - MuhChyi Chai
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Takefumi Sone
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Kazuto Yamazaki
- Tsukuba Research Laboratories, Eisai Co., Ltd, 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Masashi Ito
- Tsukuba Research Laboratories, Eisai Co., Ltd, 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Kappei Tsukahara
- Tsukuba Research Laboratories, Eisai Co., Ltd, 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Hideyuki Saya
- Division of Gene Regulation, Institute for Advanced Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Jun Kohyama
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
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16
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Curtis TM, McLaughlin D, O'Hare M, Kur J, Barabas P, Revolta G, Scholfield CN, McGeown JG, McGahon MK. Isolation of Retinal Arterioles for Ex Vivo Cell Physiology Studies. J Vis Exp 2018. [PMID: 30059036 PMCID: PMC6126467 DOI: 10.3791/57944] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The retina is a highly metabolically active tissue that requires a substantial blood supply. The retinal circulation supports the inner retina, while the choroidal vessels supply the photoreceptors. Alterations in retinal perfusion contribute to numerous sight-threatening disorders, including diabetic retinopathy, glaucoma and retinal branch vein occlusions. Understanding the molecular mechanisms involved in the control of blood flow through the retina and how these are altered during ocular disease could lead to the identification of new targets for the treatment of these conditions. Retinal arterioles are the main resistance vessels of the retina, and consequently, play a key role in regulating retinal hemodynamics through changes in luminal diameter. In recent years, we have developed methods for isolating arterioles from the rat retina which are suitable for a wide range of applications including cell physiology studies. This preparation has already begun to yield new insights into how blood flow is controlled in the retina and has allowed us to identify some of the key changes that occur during ocular disease. In this article, we describe methods for the isolation of rat retinal arterioles and include protocols for their use in patch-clamp electrophysiology, calcium imaging and pressure myography studies. These vessels are also amenable for use in PCR-, western blotting- and immunohistochemistry-based studies.
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Affiliation(s)
- Tim M Curtis
- Centre for Experimental Medicine, Queen's University of Belfast
| | - Declan McLaughlin
- Centre for Biomedical Sciences (Education), Queen's University of Belfast
| | - Michael O'Hare
- Centre for Experimental Medicine, Queen's University of Belfast
| | - Joanna Kur
- Centre for Experimental Medicine, Queen's University of Belfast
| | - Peter Barabas
- Centre for Experimental Medicine, Queen's University of Belfast
| | - Gordon Revolta
- Centre for Experimental Medicine, Queen's University of Belfast
| | - C Norman Scholfield
- Department of Pharmaceutical Chemistry and Pharmacognosy, Naresuan University
| | - J Graham McGeown
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University of Belfast
| | - Mary K McGahon
- Centre for Biomedical Sciences (Education), Queen's University of Belfast;
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17
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Jackson WF, Boerman EM. Voltage-gated Ca 2+ channel activity modulates smooth muscle cell calcium waves in hamster cremaster arterioles. Am J Physiol Heart Circ Physiol 2018; 315:H871-H878. [PMID: 29957015 DOI: 10.1152/ajpheart.00292.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cremaster muscle arteriolar smooth muscle cells (SMCs) display inositol 1,4,5-trisphosphate receptor-dependent Ca2+ waves that contribute to global myoplasmic Ca2+ concentration and myogenic tone. However, the contribution made by voltage-gated Ca2+ channels (VGCCs) to arteriolar SMC Ca2+ waves is unknown. We tested the hypothesis that VGCC activity modulates SMC Ca2+ waves in pressurized (80 cmH2O/59 mmHg, 34°C) hamster cremaster muscle arterioles loaded with Fluo-4 and imaged by confocal microscopy. Removal of extracellular Ca2+ dilated arterioles (32 ± 3 to 45 ± 3 μm, n = 15, P < 0.05) and inhibited the occurrence, amplitude, and frequency of Ca2+ waves ( n = 15, P < 0.05), indicating dependence of Ca2+ waves on Ca2+ influx. Blockade of VGCCs with nifedipine (1 μM) or diltiazem (10 μM) or deactivation of VGCCs by hyperpolarization of smooth muscle with the K+ channel agonist cromakalim (10 μM) produced similar inhibition of Ca2+ waves ( P < 0.05). Conversely, depolarization of SMCs with the K+ channel blocker tetraethylammonium (1 mM) constricted arterioles from 26 ± 3 to 14 ± 2 μm ( n = 11, P < 0.05) and increased wave occurrence (9 ± 3 to 16 ± 3 waves/SMC), amplitude (1.6 ± 0.07 to 1.9 ± 0.1), and frequency (0.5 ± 0.1 to 0.9 ± 0.2 Hz, n = 10, P < 0.05), effects that were blocked by nifedipine (1 μM, P < 0.05). Similarly, the VGCC agonist Bay K8644 (5 nM) constricted arterioles from 14 ± 1 to 8 ± 1 μm and increased wave occurrence (3 ± 1 to 10 ± 1 waves/SMC) and frequency (0.2 ± 0.1 to 0.6 ± 0.1 Hz, n = 6, P < 0.05), effects that were unaltered by ryanodine (50 μM, n = 6, P > 0.05). These data support the hypothesis that Ca2+ waves in arteriolar SMCs depend, in part, on the activity of VGCCs. NEW & NOTEWORTHY Arterioles that control blood flow to and within skeletal muscle depend on Ca2+ influx through voltage-gated Ca2+ channels and release of Ca2+ from internal stores through inositol 1,4,5-trisphosphate receptors in the form of Ca2+ waves to maintain pressure-induced smooth muscle tone.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - Erika M Boerman
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
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18
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Jonas KC, Chen S, Virta M, Mora J, Franks S, Huhtaniemi I, Hanyaloglu AC. Temporal reprogramming of calcium signalling via crosstalk of gonadotrophin receptors that associate as functionally asymmetric heteromers. Sci Rep 2018; 8:2239. [PMID: 29396488 PMCID: PMC5797151 DOI: 10.1038/s41598-018-20722-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 01/19/2018] [Indexed: 02/08/2023] Open
Abstract
Signal crosstalk between distinct G protein-coupled receptors (GPCRs) is one mechanism that underlies pleiotropic signalling. Such crosstalk is also pertinent for GPCRs activated by gonadotrophic hormones; follicle-stimulating hormone (FSH) and luteinising hormone (LH), with specific relevance to female reproduction. Here, we demonstrate that gonadotrophin receptor crosstalk alters LH-induced Gαq/11-calcium profiles. LH-induced calcium signals in both heterologous and primary human granulosa cells were prolonged by FSHR coexpression via influx of extracellular calcium in a receptor specific manner. LHR/FSHR crosstalk involves Gαq/11 activation as a Gαq/11 inhibitor abolished calcium responses. Interestingly, the enhanced LH-mediated calcium signalling induced by FSHR co-expression was dependent on intracellular calcium store release and involved Gβγ. Biophysical analysis of receptor and Gαq interactions indicated that ligand-dependent association between LHR and Gαq was rearranged in the presence of FSHR, enabling FSHR to closely associate with Gαq following LHR activation. This suggests that crosstalk may occur via close associations as heteromers. Super-resolution imaging revealed that LHR and FSHR formed constitutive heteromers at the plasma membrane. Intriguingly, the ratio of LHR:FSHR in heterotetramers was specifically altered following LH treatment. We propose that functionally significant FSHR/LHR crosstalk reprograms LH-mediated calcium signalling at the interface of receptor-G protein via formation of asymmetric complexes.
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Affiliation(s)
- K C Jonas
- Centre for Medical and Biomedical Education, St George's, University of London, London, UK.,Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK
| | - S Chen
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK.,Roche Pharma Research and Early Development, Roche Innovation Center Zürich, Zürich, Switzerland
| | - M Virta
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK
| | - J Mora
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK
| | - S Franks
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK
| | - I Huhtaniemi
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK.
| | - A C Hanyaloglu
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, London, UK.
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19
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Wang L, Liu Y, Lu R, Dong G, Chen X, Yun W, Zhou X. The role of S-nitrosylation of kainate-type of ionotropic glutamate receptor 2 in epilepsy induced by kainic acid. J Neurochem 2018; 144:255-270. [PMID: 29193067 DOI: 10.1111/jnc.14266] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/21/2017] [Accepted: 11/22/2017] [Indexed: 11/29/2022]
Abstract
Epilepsy is a chronic brain disease affecting millions of individuals. Kainate receptors, especially kainate-type of ionotropic glutamate receptor 2 (GluK2), play an important role in epileptogenesis. Recent data showed that GluK2 could undergo post-translational modifications in terms of S-nitrosylation (SNO), and affect the signaling pathway of cell death in cerebral ischemia-reperfusion. However, it is unclear whether S-nitrosylation of GluK2 (SNO-GluK2) contributes to cell death induced by epilepsy. Here, we report that kainic acid-induced SNO-GluK2 is mediated by GluK2 itself, regulated by neuronal nitric oxide synthase (nNOS) and the level of cytoplasmic calcium in vivo and in vitro hippocampus neurons. The whole-cell patch clamp recordings showed the influence of SNO-GluK2 on ion channel characterization of GluK2-Kainate receptors. Moreover, immunohistochemistry staining results showed that inhibition of SNO-GluK2 by blocking nNOS or GluK2 or by reducing the level of cytoplasmic calcium-protected hippocampal neurons from kainic acid-induced injury. Finally, immunoprecipitation and western blotting data revealed the involvement of assembly of a GluK2-PSD95-nNOS signaling complex in epilepsy. Taken together, our results showed that the SNO-GluK2 plays an important role in neuronal injury of epileptic rats by forming GluK2-PSD95-nNOS signaling module in a cytoplasmic calcium-dependent way, suggesting a potential therapeutic target site for epilepsy.
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Affiliation(s)
- Linxiao Wang
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Yanyan Liu
- Department of Neurology, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Rulan Lu
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Guoying Dong
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Xia Chen
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Wenwei Yun
- Department of Neurology, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Xianju Zhou
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
- Department of Neurology, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
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20
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Parate D, Franco-Obregón A, Fröhlich J, Beyer C, Abbas AA, Kamarul T, Hui JHP, Yang Z. Enhancement of mesenchymal stem cell chondrogenesis with short-term low intensity pulsed electromagnetic fields. Sci Rep 2017; 7:9421. [PMID: 28842627 PMCID: PMC5572790 DOI: 10.1038/s41598-017-09892-w] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/28/2017] [Indexed: 12/22/2022] Open
Abstract
Pulse electromagnetic fields (PEMFs) have been shown to recruit calcium-signaling cascades common to chondrogenesis. Here we document the effects of specified PEMF parameters over mesenchymal stem cells (MSC) chondrogenic differentiation. MSCs undergoing chondrogenesis are preferentially responsive to an electromagnetic efficacy window defined by field amplitude, duration and frequency of exposure. Contrary to conventional practice of administering prolonged and repetitive exposures to PEMFs, optimal chondrogenic outcome is achieved in response to brief (10 minutes), low intensity (2 mT) exposure to 6 ms bursts of magnetic pulses, at 15 Hz, administered only once at the onset of chondrogenic induction. By contrast, repeated exposures diminished chondrogenic outcome and could be attributed to calcium entry after the initial induction. Transient receptor potential (TRP) channels appear to mediate these aspects of PEMF stimulation, serving as a conduit for extracellular calcium. Preventing calcium entry during the repeated PEMF exposure with the co-administration of EGTA or TRP channel antagonists precluded the inhibition of differentiation. This study highlights the intricacies of calcium homeostasis during early chondrogenesis and the constraints that are placed on PEMF-based therapeutic strategies aimed at promoting MSC chondrogenesis. The demonstrated efficacy of our optimized PEMF regimens has clear clinical implications for future regenerative strategies for cartilage.
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Affiliation(s)
- Dinesh Parate
- Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, NUHS Tower Block, Level 11, 1E Kent Ridge Road, Singapore, 119288, Singapore
| | - Alfredo Franco-Obregón
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, NUHS Tower Block, Level 8, IE Kent Ridge Road, Singapore, 119228, Singapore. .,BioIonic Currents Electromagnetic Pulsing Systems Laboratory, BICEPS, National University of Singapore, MD6, 14 medical Drive, #14-01, Singapore, 117599, Singapore.
| | - Jürg Fröhlich
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, NUHS Tower Block, Level 8, IE Kent Ridge Road, Singapore, 119228, Singapore.,Institute for Electromagnetic Fields, Swiss Federal Institute of Technology (ETH), Rämistrasse 101, 8092, Zurich, Switzerland
| | - Christian Beyer
- Institute for Electromagnetic Fields, Swiss Federal Institute of Technology (ETH), Rämistrasse 101, 8092, Zurich, Switzerland
| | - Azlina A Abbas
- Tissue Engineering Group (TEG), National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, Pantai Valley, Kuala Lumpur, 50603, Malaysia
| | - Tunku Kamarul
- Tissue Engineering Group (TEG), National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, Pantai Valley, Kuala Lumpur, 50603, Malaysia
| | - James H P Hui
- Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, NUHS Tower Block, Level 11, 1E Kent Ridge Road, Singapore, 119288, Singapore. .,Tissue Engineering Program, Life Sciences Institute, National University of Singapore, DSO (Kent Ridge) Building, #04-01, 27 Medical Drive, Singapore, 117510, Singapore.
| | - Zheng Yang
- Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, NUHS Tower Block, Level 11, 1E Kent Ridge Road, Singapore, 119288, Singapore. .,Tissue Engineering Program, Life Sciences Institute, National University of Singapore, DSO (Kent Ridge) Building, #04-01, 27 Medical Drive, Singapore, 117510, Singapore.
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21
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Crombie DE, Curl CL, Raaijmakers AJA, Sivakumaran P, Kulkarni T, Wong RCB, Minami I, Evans-Galea MV, Lim SY, Delbridge L, Corben LA, Dottori M, Nakatsuji N, Trounce IA, Hewitt AW, Delatycki MB, Pera MF, Pébay A. Friedreich's ataxia induced pluripotent stem cell-derived cardiomyocytes display electrophysiological abnormalities and calcium handling deficiency. Aging (Albany NY) 2017; 9:1440-1452. [PMID: 28562313 PMCID: PMC5472743 DOI: 10.18632/aging.101247] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 05/27/2017] [Indexed: 01/12/2023]
Abstract
We sought to identify the impacts of Friedreich's ataxia (FRDA) on cardiomyocytes. FRDA is an autosomal recessive degenerative condition with neuronal and non-neuronal manifestations, the latter including progressive cardiomyopathy of the left ventricle, the leading cause of death in FRDA. Little is known about the cellular pathogenesis of FRDA in cardiomyocytes. Induced pluripotent stem cells (iPSCs) were derived from three FRDA individuals with characterized GAA repeats. The cells were differentiated into cardiomyocytes to assess phenotypes. FRDA iPSC- cardiomyocytes retained low levels of FRATAXIN (FXN) mRNA and protein. Electrophysiology revealed an increased variation of FRDA- cardiomyocyte beating rates which was prevented by addition of nifedipine, suggestive of a calcium handling deficiency. Finally, calcium imaging was performed and we identified small amplitude, diastolic and systolic calcium transients confirming a deficiency in calcium handling. We defined a robust FRDA cardiac-specific electrophysiological profile in patient-derived iPSCs which could be used for high throughput compound screening. This cell-specific signature will contribute to the identification and screening of novel treatments for this life-threatening disease.
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Affiliation(s)
- Duncan E. Crombie
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
| | - Claire L. Curl
- Department of Physiology, the University of Melbourne, Melbourne, Australia
| | | | | | - Tejal Kulkarni
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
- Centre for Neural Engineering & Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, Australia
| | - Raymond CB Wong
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
| | - Itsunari Minami
- Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
| | - Marguerite V. Evans-Galea
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, and Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - Shiang Y. Lim
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
- O'Brien Institute Department, St Vincent Institute of Medical Research, Fitzroy, Australia
| | - Lea Delbridge
- O'Brien Institute Department, St Vincent Institute of Medical Research, Fitzroy, Australia
| | - Louise A. Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, and Department of Paediatrics, The University of Melbourne, Melbourne, Australia
- School of Psychological Sciences, Monash University, Frankston, Australia
| | - Mirella Dottori
- Centre for Neural Engineering & Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, Australia
| | - Norio Nakatsuji
- Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
| | - Ian A. Trounce
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
| | - Alex W. Hewitt
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
- Menzies Institute for Medical Research, School of Medicine, University of Tasmania, Hobart, Australia
| | - Martin B. Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, and Department of Paediatrics, The University of Melbourne, Melbourne, Australia
- School of Psychological Sciences, Monash University, Frankston, Australia
- Victorian Clinical Genetics Services, Parkville, Australia
| | - Martin F. Pera
- Department of Anatomy and Neurosciences, the University of Melbourne, Florey Neuroscience & Mental Health Institute, Walter and Eliza Hall Institute of Medical Research, Australia
| | - Alice Pébay
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Australia
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22
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Winters CJ, Koval O, Murthy S, Allamargot C, Sebag SC, Paschke JD, Jaffer OA, Carter AB, Grumbach IM. CaMKII inhibition in type II pneumocytes protects from bleomycin-induced pulmonary fibrosis by preventing Ca2+-dependent apoptosis. Am J Physiol Lung Cell Mol Physiol 2015; 310:L86-94. [PMID: 26545899 DOI: 10.1152/ajplung.00132.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 10/22/2015] [Indexed: 01/25/2023] Open
Abstract
The calcium and calmodulin-dependent kinase II (CaMKII) translates increases in intracellular Ca(2+) into downstream signaling events. Its function in pulmonary pathologies remains largely unknown. CaMKII is a well-known mediator of apoptosis and regulator of endoplasmic reticulum (ER) Ca(2+). ER stress and apoptosis of type II pneumocytes lead to aberrant tissue repair and progressive collagen deposition in pulmonary fibrosis. Thus we hypothesized that CaMKII inhibition alleviates fibrosis in response to bleomycin by attenuating apoptosis and ER stress of type II pneumocytes. We first established that CaMKII was strongly expressed in the distal respiratory epithelium, in particular in surfactant protein-C-positive type II pneumocytes, and activated after bleomycin instillation. We generated a novel transgenic model of inducible expression of the CaMKII inhibitor peptide AC3-I limited to type II pneumocytes (Tg SPC-AC3-I). Tg SPC-AC3-I mice were protected from development of pulmonary fibrosis after bleomycin exposure compared with wild-type mice. CaMKII inhibition also provided protection from apoptosis in type II pneumocytes in vitro and in vivo. Moreover, intracellular Ca(2+) levels and ER stress were increased by bleomycin and significantly blunted with CaMKII inhibition in vitro. These data demonstrate that CaMKII inhibition prevents type II pneumocyte apoptosis and development of pulmonary fibrosis in response to bleomycin. CaMKII inhibition may therefore be a promising approach to prevent or ameliorate the progression of pulmonary fibrosis.
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Affiliation(s)
| | - Olha Koval
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Shubha Murthy
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Chantal Allamargot
- Central Microscopy Research Facility, University of Iowa, Iowa City, Iowa
| | - Sara C Sebag
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - John D Paschke
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Omar A Jaffer
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - A Brent Carter
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Free Radical and Radiation Biology Graduate Program, University of Iowa, Iowa City, Iowa; Iowa City Veterans Affairs Healthcare System, Iowa City, Iowa; and Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Isabella M Grumbach
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Iowa City Veterans Affairs Healthcare System, Iowa City, Iowa; and
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23
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Participation of the TRP channel in the cardiovascular effects induced by carvacrol in normotensive rat. Vascul Pharmacol 2015; 67-69:48-58. [PMID: 25869504 DOI: 10.1016/j.vph.2015.02.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 02/12/2015] [Accepted: 02/16/2015] [Indexed: 11/21/2022]
Abstract
Carvacrol has been described as an agonist/antagonist of different transient receptor potential (TRP) channels and voltage-dependent calcium channels (Cavs). The aim of this study was to evaluate the role of Cav and TRP channels following carvacrol stimulation. Initially, in mesenteric artery rings carvacrol relaxed phenylephrine-induced contractions. Furthermore, carvacrol inhibited contraction elicited by CaCl2 in depolarizing nominally without Ca2+ medium and antagonized the contractions induced by S(-)-Bay K 8644 and inhibited Ca2+ currents indicating the inhibition of Ca2+ influx through L-type Cav. Additionally, carvacrol antagonized the contractions induced by CaCl2 in the presence of nifedipine/Cyclopiazonic acid/phenylephrine or nifedipine/Cyclopiazonic acid/KCl 60, suggesting a possible inhibition of calcium influx by store operated channels (SOCs), receptor operated channels (ROCs) and/or TRP channels. Interestingly, among the TRP channel blockers used, the effect induced by carvacrol was attenuated by Mg2+ and potentiated by La3+ and Gd3+, suggesting that TRP channels are involved in relaxation induced by carvacrol. Monoterpene also induced hypotension and bradycardia in non-anesthetized normotensive rats and negative inotropic and chronotropic effects. In conclusion, these results suggest that the hypotensive effect of carvacrol is probably due to bradycardia and a peripheral vasodilatation that involves, at least, the inhibition of the Ca2+ influx through Cav and TRP channels.
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24
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Fransen P, Van Hove CE, Leloup AJA, Martinet W, De Meyer GRY, Lemmens K, Bult H, Schrijvers DM. Dissecting out the complex Ca2+-mediated phenylephrine-induced contractions of mouse aortic segments. PLoS One 2015; 10:e0121634. [PMID: 25803863 PMCID: PMC4372603 DOI: 10.1371/journal.pone.0121634] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 02/12/2015] [Indexed: 01/04/2023] Open
Abstract
L-type Ca2+ channel (VGCC) mediated Ca2+ influx in vascular smooth muscle cells (VSMC) contributes to the functional properties of large arteries in arterial stiffening and central blood pressure regulation. How this influx relates to steady-state contractions elicited by α1-adrenoreceptor stimulation and how it is modulated by small variations in resting membrane potential (Vm) of VSMC is not clear yet. Here, we show that α1-adrenoreceptor stimulation of aortic segments of C57Bl6 mice with phenylephrine (PE) causes phasic and tonic contractions. By studying the relationship between Ca2+ mobilisation and isometric tension, it was found that the phasic contraction was due to intracellular Ca2+ release and the tonic contraction determined by Ca2+ influx. The latter component involves both Ca2+ influx via VGCC and via non-selective cation channels (NSCC). Influx via VGCC occurs only within the window voltage range of the channel. Modulation of this window Ca2+ influx by small variations of the VSMC Vm causes substantial effects on the contractile performance of aortic segments. The relative contribution of VGCC and NSCC to the contraction by α1-adrenoceptor stimulation could be manipulated by increasing intracellular Ca2+ release from non-contractile sarcoplasmic reticulum Ca2+ stores. Results of this study point to a complex interactions between α1-adrenoceptor-mediated VSMC contractile performance and Ca2+ release form contractile or non-contractile Ca2+ stores with concomitant Ca2+ influx. Given the importance of VGCC and their blockers in arterial stiffening and hypertension, they further point toward an additional role of NSCC (and NSCC blockers) herein.
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Affiliation(s)
- Paul Fransen
- Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
- * E-mail:
| | - Cor E. Van Hove
- Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Arthur J. A. Leloup
- Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Wim Martinet
- Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | | | - Katrien Lemmens
- Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Hidde Bult
- Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
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25
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Karpinsky-Semper D, Volmar CH, Brothers SP, Slepak VZ. Differential effects of the Gβ5-RGS7 complex on muscarinic M3 receptor-induced Ca2+ influx and release. Mol Pharmacol 2014; 85:758-68. [PMID: 24586057 DOI: 10.1124/mol.114.091843] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The G protein β subunit Gβ5 uniquely forms heterodimers with R7 family regulators of G protein signaling (RGS) proteins (RGS6, RGS7, RGS9, and RGS11) instead of Gγ. Although the Gβ5-RGS7 complex attenuates Ca(2+) signaling mediated by the muscarinic M3 receptor (M3R), the route of Ca(2+) entry (i.e., release from intracellular stores and/or influx across the plasma membrane) is unknown. Here, we show that, in addition to suppressing carbachol-stimulated Ca(2+) release, Gβ5-RGS7 enhanced Ca(2+) influx. This novel effect of Gβ5-RGS7 was blocked by nifedipine and 2-aminoethoxydiphenyl borate. Experiments with pertussis toxin, an RGS domain-deficient mutant of RGS7, and UBO-QIC {L-threonine,(3R)-N-acetyl-3-hydroxy-L-leucyl-(aR)-a-hydroxybenzenepropanoyl-2,3-idehydro-N-methylalanyl-L-alanyl-N-methyl-L-alanyl-(3R)-3-[[(2S,3R)-3-hydroxy-4- methyl-1-oxo-2-[(1-oxopropyl)amino]pentyl]oxy]-L-leucyl-N,O-dimethyl-,(7→1)-lactone (9CI)}, a novel inhibitor of Gq, showed that Gβ5-RGS7 modulated a Gq-mediated pathway. These studies indicate that Gβ5-RGS7, independent of RGS7 GTPase-accelerating protein activity, couples M3R to a nifedipine-sensitive Ca(2+) channel. We also compared the action of Gβ5-RGS7 on M3R-induced Ca(2+) influx and release elicited by different muscarinic agonists. Responses to Oxo-M [oxotremorine methiodide N,N,N,-trimethyl-4-(2-oxo-1-pyrrolidinyl)-2-butyn-1-ammonium iodide] were insensitive to Gβ5-RGS7. Pilocarpine responses consisted of a large release and modest influx components, of which the former was strongly inhibited whereas the latter was insensitive to Gβ5-RGS7. McN-A-343 [(4-hydroxy-2-butynyl)-1-trimethylammonium-3-chlorocarbanilate chloride] was the only compound whose total Ca(2+) response was enhanced by Gβ5-RGS7, attributed to, in part, by the relatively small Ca(2+) release this partial agonist stimulated. Together, these results show that distinct agonists not only have differential M3R functional selectivity, but also confer specific sensitivity to the Gβ5-RGS7 complex.
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Affiliation(s)
- Darla Karpinsky-Semper
- Department of Molecular and Cellular Pharmacology (D.K.-S., V.Z.S.) and Center for Therapeutic Innovation, Department of Psychiatry and Behavioral Sciences (C.-H.V., S.P.B.), University of Miami Miller School of Medicine, Miami, Florida
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26
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Perivascular mural cells of the mouse choroid demonstrate morphological diversity that is correlated to vasoregulatory function. PLoS One 2013; 8:e53386. [PMID: 23308209 PMCID: PMC3537675 DOI: 10.1371/journal.pone.0053386] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 11/27/2012] [Indexed: 01/17/2023] Open
Abstract
Objective Perivascular mural cells of the choroid have been implicated in physiological functioning as well as in retinal disease pathogenesis. However details regarding their form and function are not well understood. We aim to characterize choroidal mural cells in the adult mouse choroid in terms of their distribution and morphology, and correlate these to their contractile behavior. Methods Sclerochoroidal flat-mounted explants were prepared from albino transgenic mice in which the α-smooth muscle actin (α-SMA) promoter drives the expression of green fluorescent protein (GFP). α-SMA-expressing smooth muscle cells and pericytes in the living choroid were thereby rendered fluorescent and imaged with confocal microscopy and live-cell imaging in situ. Results Choroidal perivascular mural cells demonstrate significant diversity in terms of their distribution and morphology at different levels of the vasculature. They range from densely-packed circumferentially-oriented cells that provide complete vascular coverage in primary arteries to widely-spaced stellate-shaped cells that are distributed sparsely over terminal arterioles. Mural cells at each level are immunopositive for contractile proteins α-SMA and desmin and demonstrate vasoconstrictory contractile movements in response to endothelin-1 and the calcium ionophore, A23187, and vasodilation in response to the calcium chelator, BAPTA. The prominence of vasoregulatory contractile responses varies with mural cell morphology and density, and is greater in vessels with dense coverage of mural cells with circumferential cellular morphologies. In the choriocapillaris, pericytes demonstrate a sparse, horizontal distribution and are selectively distributed only to the scleral surface of the choriocapillaris. Conclusions Diversity and regional specialization of perivascular mural cells may subserve varying requirements for vasoregulation in the choroid. The model of the α-SMA-GFP transgenic albino mouse provides a useful and intact system for the morphological and functional study of choroidal mural cells.
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27
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MCGAHON MARYK, MCKEE JONATHAN, DASH DURGAP, BROWN EOIN, SIMPSON DAVIDA, CURTIS TIMOTHYM, McGEOWN JAMESG, SCHOLFIELD CHARLESN. Pharmacological Profiling of Store-Operated Ca2+Entry in Retinal Arteriolar Smooth Muscle. Microcirculation 2012; 19:586-97. [DOI: 10.1111/j.1549-8719.2012.00192.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Fransen P, Van Hove CE, van Langen J, Schrijvers DM, Martinet W, De Meyer GRY, Bult H. Contribution of transient and sustained calcium influx, and sensitization to depolarization-induced contractions of the intact mouse aorta. BMC PHYSIOLOGY 2012; 12:9. [PMID: 22943445 PMCID: PMC3499395 DOI: 10.1186/1472-6793-12-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 08/28/2012] [Indexed: 01/31/2023]
Abstract
Background Electrophysiological studies of L-type Ca2+ channels in isolated vascular smooth muscle cells revealed that depolarization of these cells evoked a transient and a time-independent Ca2+ current. The sustained, non-inactivating current occurred at voltages where voltage-dependent activation and inactivation overlapped (voltage window) and its contribution to basal tone or active tension in larger multicellular blood vessel preparations is unknown at present. This study investigated whether window Ca2+ influx affects isometric contraction of multicellular C57Bl6 mouse aortic segments. Results Intracellular Ca2+ (Cai2+, Fura-2), membrane potential and isometric force were measured in aortic segments, which were clamped at fixed membrane potentials by increasing extracellular K+ concentrations. K+ above 20 mM evoked biphasic contractions, which were not affected by inhibition of IP3- or Ca2+ induced Ca2+ release with 2-aminoethoxydiphenyl borate or ryanodine, respectively, ruling out the contribution of intracellular Ca2+ release. The fast force component paralleled Cai2+ increase, but the slow contraction coincided with Cai2+ decrease. In the absence of extracellular Ca2+, basal tension and Cai2+ declined, and depolarization failed to evoke Cai2+ signals or contraction. Subsequent re-introduction of external Ca2+ elicited only slow contractions, which were now matched by Cai2+ increase. After Cai2+ attained steady-state, isometric force kept increasing due to Ca2+- sensitization of the contractile elements. The slow force responses displayed a bell-shaped voltage-dependence, were suppressed by hyperpolarization with levcromakalim, and enhanced by an agonist of L-type Ca2+ channels (BAY K8644). Conclusion The isometric response of mouse aortic segments to depolarization consists of a fast, transient contraction paralleled by a transient Ca2+ influx via Ca2+ channels which completely inactivate. Ca2+ channels, which did not completely inactivate during the depolarization, initiated a second, sustained phase of contraction, which was matched by a sustained non-inactivating window Ca2+ influx. Together with sensitization, this window L-type Ca2+ influx is a major determinant of basal and active tension of mouse aortic smooth muscle.
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Affiliation(s)
- Paul Fransen
- Laboratory of Physiopharmacology, University of Antwerp, Universiteitsplein 1 Building T, 2.18, Wilrijk B-2610, Belgium.
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29
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Lin KL, Chi CC, Lu T, Tseng LL, Wang JL, Lu YC, Jan CR. Effect of sertraline on [Ca2+](i) and viability of human MG63 osteosarcoma cells. Drug Chem Toxicol 2012; 36:231-40. [PMID: 22931138 DOI: 10.3109/01480545.2012.710625] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The antidepressant, sertraline, has been shown to have diverse in vitro effects. This study examined whether sertraline altered [Ca(2+)](i) in MG63 human osteosarcoma cells by using fura-2 as a Ca(2+)-sensitive fluorescent dye. At 50-200 µM, sertraline induced a [Ca(2+)](i) rise in a concentration-dependent manner. Ca(2+) response was decreased by removing extracellular Ca(2+), suggesting that Ca(2+) entry and release contributed to the [Ca(2+)](i) signal. Sertraline-induced Ca(2+) entry was inhibited by nifedipine, La(3+), Gd(3+), and SK&F96365. When extracellular Ca(2+) was removed, pretreatment with the endoplasmic reticulum (ER) Ca(2+) pump inhibitor, thapsigargin, or 2,5-di-tert-butylhydroquinone (BHQ) abolished the sertraline-evoked [Ca(2+)](i) rise. Incubation with sertraline also abolished the thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C (PLC) with U73122 abolished the sertraline-induced [Ca(2+)](i) rise. At 20-30 µM, overnight treatment with sertraline killed cells in a concentration-dependent manner. The cytotoxic effect of sertraline was not reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Annexin V/propidium iodide staining data demonstrate that sertraline (30 µM) evoked apoptosis. Sertraline (20 and 30 µM) also increased levels of reactive oxygen species. Together, in human osteosarcoma cells, sertraline evoked a [Ca(2+)](i) rise by inducing PLC-dependent Ca(2+) release from the ER and Ca(2+) entry by L-type Ca(2+) channels and store-operated Ca(2+) channels. Sertraline induced cell death that may involve apoptosis by mitochondrial pathways.
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Affiliation(s)
- Ko-Long Lin
- Department of Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
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30
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Endothelin and endothelin receptors in the renal and cardiovascular systems. Life Sci 2012; 91:490-500. [PMID: 22480517 DOI: 10.1016/j.lfs.2012.03.026] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 03/12/2012] [Accepted: 03/16/2012] [Indexed: 01/08/2023]
Abstract
Endothelin-1 (ET-1) is a multifunctional hormone which regulates the physiology of the cardiovascular and renal systems. ET-1 modulates cardiac contractility, systemic and renal vascular resistance, salt and water renal reabsorption, and glomerular function. ET-1 is responsible for a variety of cellular events: contraction, proliferation, apoptosis, etc. These effects take place after the activation of the two endothelin receptors ET(A) and ET(B), which are present - among others - on cardiomyocytes, fibroblasts, smooth muscle and endothelial cells, glomerular and tubular cells of the kidney. The complex and numerous intracellular pathways, which can be contradictory in term of functional response depending on the receptor type, cell type and physiological situation, are described in this review. Many diseases share an enhanced ET-1 expression as part of the pathophysiology. However, the use of endothelin blockers is currently restricted to pulmonary arterial hypertension, and more recently to digital ulcer. The complexity of the endothelin system does not facilitate the translation of the molecular knowledge to clinical applications. Endothelin antagonists can prevent disease development but secondary undesirable effects limit their usage. Nevertheless, the increasing understanding of the effects of ET-1 on the cardiac and renal physiology maintains the endothelin system as a promising therapeutic target.
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31
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Mufti RE, Brett SE, Tran CHT, Abd El-Rahman R, Anfinogenova Y, El-Yazbi A, Cole WC, Jones PP, Chen SRW, Welsh DG. Intravascular pressure augments cerebral arterial constriction by inducing voltage-insensitive Ca2+ waves. J Physiol 2010; 588:3983-4005. [PMID: 20736418 DOI: 10.1113/jphysiol.2010.193300] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This study examined whether elevated intravascular pressure stimulates asynchronous Ca(2+) waves in cerebral arterial smooth muscle cells and if their generation contributes to myogenic tone development. The endothelium was removed from rat cerebral arteries, which were then mounted in an arteriograph, pressurized (20-100 mmHg) and examined under a variety of experimental conditions. Diameter and membrane potential (V(M)) were monitored using conventional techniques; Ca(2+) wave generation and myosin light chain (MLC(20))/MYPT1 (myosin phosphatase targeting subunit) phosphorylation were assessed by confocal microscopy and Western blot analysis, respectively. Elevating intravascular pressure increased the proportion of smooth muscle cells firing asynchronous Ca(2+) waves as well as event frequency. Ca(2+) wave augmentation occurred primarily at lower intravascular pressures (<60 mmHg) and ryanodine, a plant alkaloid that depletes the sarcoplasmic reticulum (SR) of Ca(2+), eliminated these events. Ca(2+) wave generation was voltage insensitive as Ca(2+) channel blockade and perturbations in extracellular [K(+)] had little effect on measured parameters. Ryanodine-induced inhibition of Ca(2+) waves attenuated myogenic tone and MLC(20) phosphorylation without altering arterial V(M). Thapsigargin, an SR Ca(2+)-ATPase inhibitor also attenuated Ca(2+) waves, pressure-induced constriction and MLC(20) phosphorylation. The SR-driven component of the myogenic response was proportionally greater at lower intravascular pressures and subsequent MYPT1 phosphorylation measures revealed that SR Ca(2+) waves facilitated pressure-induced MLC(20) phosphorylation through mechanisms that include myosin light chain phosphatase inhibition. Cumulatively, our findings show that mechanical stimuli augment Ca(2+) wave generation in arterial smooth muscle and that these transient events facilitate tone development particularly at lower intravascular pressures by providing a proportion of the Ca(2+) required to directly control MLC(20) phosphorylation.
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Affiliation(s)
- Rania E Mufti
- Hotchkiss Brain Institute, Libin Cardiovascular Institute, Department of Physiology & Pharmacology, University of Calgary, Alberta, Canada
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Matsushita K, Fukumoto M, Kobayashi T, Kobayashi M, Ishizaki E, Minami M, Katsumura K, Liao SD, Wu DM, Zhang T, Puro DG. Diabetes-induced inhibition of voltage-dependent calcium channels in the retinal microvasculature: role of spermine. Invest Ophthalmol Vis Sci 2010; 51:5979-90. [PMID: 20484578 DOI: 10.1167/iovs.10-5377] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Although decentralized control of blood flow is particularly important in the retina, knowledge of the functional organization of the retinal microvasculature is limited. Here, the authors characterized the distribution and regulation of L-type voltage-dependent calcium channels (VDCCs) within the most decentralized operational complex of the retinal vasculature--the feeder vessel/capillary unit--which consists of a capillary network plus the vessel linking it with a myocyte-encircled arteriole. METHODS Perforated-patch recordings, calcium-imaging, and time-lapse photography were used to assess VDCC-dependent changes in ionic currents, intracellular calcium, abluminal cell contractility, and lumen diameter, in microvascular complexes freshly isolated from the rat retina. RESULTS Topographical heterogeneity was found in the distribution of functional VDCCs; VDCC activity was markedly greater in feeder vessels than in capillaries. Experiments showed that this topographical distribution occurs, in large part, because of the inhibition of capillary VDCCs by a mechanism dependent on the endogenous polyamine spermine. An operational consequence of functional VDCCs predominantly located in the feeder vessels is that voltage-driven vasomotor responses are generated chiefly in this portion of the feeder vessel/capillary unit. However, early in the course of diabetes, this ability to generate voltage-driven vasomotor responses becomes profoundly impaired because of the inhibition of feeder vessel VDCCs by a spermine-dependent mechanism. CONCLUSIONS The regulation of VDCCs by endogenous spermine not only plays a critical role in establishing the physiological organization of the feeder vessel/capillary unit, but also may contribute to dysfunction of this decentralized operational unit in the diabetic retina.
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Affiliation(s)
- Kenji Matsushita
- Department of Ophthalmology and Visual Sciences, Fudan University, Shanghai, China
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Jeffries O, McGahon MK, Bankhead P, Lozano MM, Scholfield CN, Curtis TM, McGeown JG. cAMP/PKA-dependent increases in Ca Sparks, oscillations and SR Ca stores in retinal arteriolar myocytes after exposure to vasopressin. Invest Ophthalmol Vis Sci 2009; 51:1591-8. [PMID: 19959643 DOI: 10.1167/iovs.09-4401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the effects of arginine vasopressin (AVP) on Ca(2+) sparks and oscillations and on sarcoplasmic reticulum (SR) Ca(2+) content in retinal arteriolar myocytes. METHODS Fluo-4-loaded smooth muscle in intact segments of freshly isolated porcine retinal arteriole was imaged by confocal laser microscopy. SR Ca(2+) store content was assessed by recording caffeine-induced Ca(2+) transients with microfluorimetry and fura-2. RESULTS The frequencies of Ca(2+) sparks and oscillations were increased both during exposure to, and 10 minutes after washout of AVP (10 nM). Caffeine transients were increased in amplitude 10 and 90 minutes after a 3-minute application of AVP. Both AVP-induced Ca(2+) transients and the enhancement of caffeine responses after AVP washout were inhibited by SR 49059, a V(1a) receptor blocker. Forskolin, an activator of adenylyl cyclase, also persistently enhanced caffeine transients. Rp-8-HA-cAMPS, a membrane-permeant PKA inhibitor, prevented enhancement of caffeine transients by both AVP and forskolin. Forskolin, but not AVP, produced a reversible, Rp-8-HA-cAMPS insensitive reduction in basal [Ca(2+)](i). CONCLUSIONS AVP activates a cAMP/PKA-dependent pathway via V(1a) receptors in retinal arteriolar smooth muscle. This effect persistently increases SR Ca(2+) loading, upregulating Ca(2+) sparks and oscillations, and may favor prolonged agonist activity despite receptor desensitization.
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Affiliation(s)
- Owen Jeffries
- Centre for Vision and Vascular Science, Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, Belfast, Northern Ireland, United Kingdom
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Brueggemann L, Markun D, Barakat J, Chen H, Byron K. Evidence against reciprocal regulation of Ca2+ entry by vasopressin in A7r5 rat aortic smooth-muscle cells. Biochem J 2009; 388:237-44. [PMID: 15603557 PMCID: PMC1186712 DOI: 10.1042/bj20041360] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent studies by Moneer and Taylor [(2002) Biochem. J. 362, 13-21] have proposed a reciprocal regulation of two Ca2+-entry pathways by AVP ([Arg8]-vasopressin) in A7r5 vascular smooth-amuscle cells. Their model proposes that AVP inhibits CCE (capacitative Ca2+ entry) and predicts a rebound of CCE after the removal of AVP. In the present study, we used whole-cell perforated patch-clamp techniques to measure ISOC (store-operated current) corresponding to CCE in A7r5 cells. When 100 nM AVP is present, it activates ISOC with no apparent rebound on removal of AVP. ISOC activated by thapsigargin or cyclopiazonic acid was not inhibited by 100 nM AVP. We also used fura 2 fluorescence techniques to re-examine the model of Moneer and Taylor, specifically focusing on the proposed inhibition of CCE by AVP. We find that 100 nM AVP activates capacitative Mn2+ entry and does not inhibit thapsigargin- or cyclopiazonic acid-activated Mn2+ entry. Moreover, Ca2+ entry after depletion of intracellular Ca2+ stores is enhanced by AVP and we detect no rebound of Ca2+ or Mn2+ entry after AVP removal. On the basis of these findings, we conclude that AVP does not inhibit CCE in A7r5 cells.
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Affiliation(s)
- Lioubov I. Brueggemann
- *Department of Medicine, Cardiovascular Institute, Loyola University Chicago, Maywood, IL 60153, U.S.A
| | - Daniel R. Markun
- *Department of Medicine, Cardiovascular Institute, Loyola University Chicago, Maywood, IL 60153, U.S.A
| | - John A. Barakat
- *Department of Medicine, Cardiovascular Institute, Loyola University Chicago, Maywood, IL 60153, U.S.A
| | - Haiyan Chen
- †Department of Physiology, Cardiovascular Institute, Loyola University Chicago, Maywood, IL 60153, U.S.A
| | - Kenneth L. Byron
- *Department of Medicine, Cardiovascular Institute, Loyola University Chicago, Maywood, IL 60153, U.S.A
- To whom correspondence should be addressed (email )
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McCarron JG, Olson ML, Currie S, Wright AJ, Anderson KI, Girkin JM. Elevations of intracellular calcium reflect normal voltage-dependent behavior, and not constitutive activity, of voltage-dependent calcium channels in gastrointestinal and vascular smooth muscle. ACTA ACUST UNITED AC 2009; 133:439-57. [PMID: 19289573 PMCID: PMC2699105 DOI: 10.1085/jgp.200810189] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In smooth muscle, the gating of dihydropyridine-sensitive Ca2+ channels may either be stochastic and voltage dependent or coordinated among channels and constitutively active. Each form of gating has been proposed to be largely responsible for Ca2+ influx and determining the bulk average cytoplasmic Ca2+ concentration. Here, the contribution of voltage-dependent and constitutively active channel behavior to Ca2+ signaling has been studied in voltage-clamped single vascular and gastrointestinal smooth muscle cells using wide-field epifluorescence with near simultaneous total internal reflection fluorescence microscopy. Depolarization (−70 to +10 mV) activated a dihydropyridine-sensitive voltage-dependent Ca2+ current (ICa) and evoked a rise in [Ca2+] in each of the subplasma membrane space and bulk cytoplasm. In various regions of the bulk cytoplasm the [Ca2+] increase ([Ca2+]c) was approximately uniform, whereas that of the subplasma membrane space ([Ca2+]PM) had a wide range of amplitudes and time courses. The variations that occurred in the subplasma membrane space presumably reflected an uneven distribution of active Ca2+ channels (clusters) across the sarcolemma, and their activation appeared consistent with normal voltage-dependent behavior. Indeed, in the present study, dihydropyridine-sensitive Ca2+ channels were not normally constitutively active. The repetitive localized [Ca2+]PM rises (“persistent Ca2+ sparklets”) that characterize constitutively active channels were observed rarely (2 of 306 cells). Neither did dihydropyridine-sensitive constitutively active Ca2+ channels regulate the bulk average [Ca2+]c. A dihydropyridine blocker of Ca2+ channels, nimodipine, which blocked ICa and accompanying [Ca2+]c rise, reduced neither the resting bulk average [Ca2+]c (at −70 mV) nor the rise in [Ca2+]c, which accompanied an increased electrochemical driving force on the ion by hyperpolarization (−130 mV). Activation of protein kinase C with indolactam-V did not induce constitutive channel activity. Thus, although voltage-dependent Ca2+ channels appear clustered in certain regions of the plasma membrane, constitutive activity is unlikely to play a major role in [Ca2+]c regulation. The stochastic, voltage-dependent activity of the channel provides the major mechanism to generate rises in [Ca2+].
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Affiliation(s)
- John G McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, SUPA, University of Strathclyde, Glasgow G4 0NR, Scotland, UK.
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Radially expanding transglial calcium waves in the intact cerebellum. Proc Natl Acad Sci U S A 2009; 106:3496-501. [PMID: 19211787 DOI: 10.1073/pnas.0809269106] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multicellular glial calcium waves may locally regulate neural activity or brain energetics. Here, we report a diffusion-driven astrocytic signal in the normal, intact brain that spans many astrocytic processes in a confined volume without fully encompassing any one cell. By using 2-photon microscopy in rodent cerebellar cortex labeled with fluorescent indicator dyes or the calcium-sensor protein G-CaMP2, we discovered spontaneous calcium waves that filled approximately ellipsoidal domains of Bergmann glia processes. Waves spread in 3 dimensions at a speed of 4-11 microm/s to a diameter of approximately 50 microm, slowed during expansion, and were reversibly blocked by P2 receptor antagonists. Consistent with the hypothesis that ATP acts as a diffusible trigger of calcium release waves, local ejection of ATP triggered P2 receptor-mediated waves that were refractory to repeated activation. Transglial waves represent a means for purinergic signals to act with local specificity to modulate activity or energetics in local neural circuits.
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Soe NN, Ishida T, Miho N, Ishida M, Sawano M, Abe K, Chayama K, Kihara Y, Yoshizumi M. Nifedipine Interferes with Migration of Vascular Smooth Muscle Cells via Inhibition of Pyk2-Src Axis. J Atheroscler Thromb 2009; 16:230-8. [DOI: 10.5551/jat.e422] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Bkaily G, Choufani S, Avedanian L, Ahmarani L, Nader M, Jacques D, D'Orléans-Juste P, Al Khoury J. Nonpeptidic antagonists of ETA and ETB receptors reverse the ET-1-induced sustained increase of cytosolic and nuclear calcium in human aortic vascular smooth muscle cells. Can J Physiol Pharmacol 2008; 86:546-56. [PMID: 18758503 DOI: 10.1139/y08-048] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our previous work showed that ET-1 induced a concentration-dependent increase of cytosolic Ca2+ ([Ca]c) and nuclear Ca2+ ([Ca]n) in human aortic vascular smooth muscle cells (hVSMCs). In the present study, using hVSMCs and 3-dimensional confocal microscopy coupled to the Ca2+ fluorescent probe Fluo-3, we showed that peptidic antagonists of ETA and ETB receptors (BQ-123 (10(-6) mol/L) and BQ-788 (10(-7) mol/L), respectively) prevented, but did not reverse, ET-1-induced sustained increase of [Ca]c and [Ca]n. In contrast, nonpeptidic antagonists of ETA and ETB (respectively, BMS-182874 (10(-8)-10(-6) mol/L) and A-192621 (10(-7) mol/L)) both prevented and reversed ET-1-induced sustained increase of [Ca]c and [Ca]n. Furthermore, activation of the ETB receptor alone using the specific agonist IRL-1620 (10(-9) mol/L) induced sustained increases of [Ca]c and [Ca]n, and subsequent administration of ET-1 (10(-7) mol/L) further increased nuclear Ca2+. ET-1-induced increase of [Ca]c and [Ca]n was completely blocked by extracellular application of the Ca2+ chelator EGTA. Pretreatment with the G protein inhibitors pertussis toxin (PTX) and cholera toxin (CTX) also prevented the ET-1 response; however, strong membrane depolarization with KCl (30 mmol/L) subsequently induced sustained increase of [Ca]c and [Ca]n. Pretreatment of hVSMCs with either the PKC activator phorbol-12,13-dibutyrate or the PKC inhibitor bisindolylmaleimide did not affect ET-1-induced sustained increase of intracellular Ca2+. These results suggest that both ETA- and ETB-receptor activation contribute to ET-1-induced sustained increase of [Ca]c and [Ca]n in hVSMCs. Moreover, in contrast to the peptidic antagonists of ET-1 receptors, the nonpeptidic ETA-receptor antagonist BMS-182874 and the nonpeptidic ETB-receptor antagonist A-192621 were able to reverse the effect of ET-1. Nonpeptidic ETA- and ETB-receptor antagonists may therefore be better pharmacological tools for blocking ET-1-induced sustained increase of intracellular Ca2+ in hVSMCs. Our results also suggest that the ET-1-induced sustained increase of [Ca]c and [Ca]n is not mediated via activation of PKC, but via a PTX- and CTX-sensitive G protein calcium influx through the R-type Ca2+ channel.
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Affiliation(s)
- Ghassan Bkaily
- Department of Anatomy and Cell Biology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada.
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Poley RN, Dosier CR, Speich JE, Miner AS, Ratz PH. Stimulated calcium entry and constitutive RhoA kinase activity cause stretch-induced detrusor contraction. Eur J Pharmacol 2008; 599:137-45. [PMID: 18929558 DOI: 10.1016/j.ejphar.2008.09.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 09/25/2008] [Accepted: 09/29/2008] [Indexed: 11/26/2022]
Abstract
Urinary bladder wall muscle (i.e., detrusor smooth muscle; DSM) contracts in response to a quick-stretch, but this response is neither fully characterized, nor completely understood at the subcellular level. Strips of rabbit DSM were quick-stretched (5 ms) and held isometric for 10 s to measure the resulting peak quick-stretch contractile response (PQSR). The ability of selective Ca(2+) channel blockers and kinase inhibitors to alter the PQSR was measured, and the phosphorylation levels of myosin light chain (MLC) and myosin phosphatase targeting regulatory subunit (MYPT1) were recorded. DSM responded to a quick-stretch with a biphasic response consisting of an initial contraction peaking at 0.24+/-0.02-fold the maximum KCl-induced contraction (F(o)) by 1.48+/-0.17 s (PQSR) before falling to a weaker tonic (10 s) level (0.12+/-0.03-fold F(o)). The PQSR was dependent on the rate and degree of muscle stretch, displayed a refractory period, and was converted to a sustained response in the presence of muscarinic receptor stimulation. The PQSR was inhibited by nifedipine, 2-aminoethoxydiphenyl borate (2-APB), 100 microM gadolinium and Y-27632, but not by atropine, 10 microM gadolinium, LOE-908, cyclopiazonic acid, or GF-109203X. Y-27632 and nifedipine abolished the increase in MLC phosphorylation induced by a quick-stretch. Y-27632, but not nifedipine, inhibited basal MYPT1 phosphorylation, and a quick-stretch failed to increase phosphorylation of this rhoA kinase (ROCK) substrate above the basal level. These data support the hypothesis that constitutive ROCK activity is required for a quick-stretch to activate Ca(2+) entry and cause a myogenic contraction of DSM.
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Affiliation(s)
- Rainer N Poley
- Department of Biochemistry & Molecular Biology, Virginia Commonwealth University, School of Medicine, PO Box 980614, Richmond, VA 23298-0614, United States
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40
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Proliferation of human lens epithelial cells (HLE-B3) is inhibited by blocking of voltage-gated calcium channels. Pflugers Arch 2008; 457:47-59. [DOI: 10.1007/s00424-008-0514-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 03/19/2008] [Accepted: 04/04/2008] [Indexed: 10/22/2022]
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Leung FP, Yung LM, Yao X, Laher I, Huang Y. Store-operated calcium entry in vascular smooth muscle. Br J Pharmacol 2007; 153:846-57. [PMID: 17876304 PMCID: PMC2267267 DOI: 10.1038/sj.bjp.0707455] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In non-excitable cells, activation of G-protein-coupled phospholipase C (PLC)-linked receptors causes the release of Ca(2+) from intracellular stores, which is followed by transmembrane Ca(2+) entry. This Ca(2+) entry underlies a small and sustained phase of the cellular [Ca(2+)](i) increases and is important for several cellular functions including gene expression, secretion and cell proliferation. This form of transmembrane Ca(2+) entry is supported by agonist-activated Ca(2+)-permeable ion channels that are activated by store depletion and is referred to as store-operated Ca(2+) entry (SOCE) and represents a major pathway for agonist-induced Ca(2+) entry. In excitable cells such as smooth muscle cells, Ca(2+) entry mechanisms responsible for sustained cellular activation are normally considered to be mediated via either voltage-operated or receptor-operated Ca(2+) channels. Although SOCE occurs following agonist activation of smooth muscle, this was thought to be more important in replenishing Ca(2+) stores rather than acting as a source of activator Ca(2+) for the contractile process. This review summarizes our current knowledge of SOCE as a regulator of vascular smooth muscle tone and discusses its possible role in the cardiovascular function and disease. We propose a possible hypothesis for its activation and suggest that SOCE may represent a novel target for pharmacological therapeutic intervention.
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Affiliation(s)
- F P Leung
- Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Hong Kong, China
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
| | - L M Yung
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
| | - X Yao
- Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Hong Kong, China
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
- Institute of Vascular Medicine, Chinese University of Hong Kong Hong Kong, China
| | - I Laher
- Department of Pharmacology and Therapeutics, University of British Columbia Vancouver, Canada
| | - Y Huang
- Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Hong Kong, China
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
- Institute of Vascular Medicine, Chinese University of Hong Kong Hong Kong, China
- Author for correspondence:
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Langager AM, Hammerberg BE, Rotella DL, Stauss HM. Very low-frequency blood pressure variability depends on voltage-gated L-type Ca2+ channels in conscious rats. Am J Physiol Heart Circ Physiol 2007; 292:H1321-7. [PMID: 17056668 DOI: 10.1152/ajpheart.00874.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms generating high- frequency (HF) and low-frequency (LF) blood pressure variability (BPV) are reasonably well understood. However, little is known about the origin of very low-frequency (VLF) BPV. We tested the hypothesis that VLF BPV is generated by L-type Ca2+ channel-dependent mechanisms. In conscious rats, arterial blood pressure was recorded during control conditions ( n = 8) and ganglionic blockade ( n = 7) while increasing doses (0.01–5.0 mg·100 μl−1·h−1) of the L-type Ca2+ channel blocker nifedipine were infused intravenously. VLF (0.02–0.2 Hz), LF (0.2–0.6 Hz), and HF (0.6–3.0 Hz) BPV were assessed by spectral analysis of systolic blood pressure. During control conditions, nifedipine caused dose-dependent declines in VLF and LF BPV, whereas HF BPV was not affected. At the highest dose of nifedipine, VLF BPV was reduced by 86% compared with baseline, indicating that VLF BPV is largely mediated by L-type Ca2+ channel-dependent mechanisms. VLF BPV appeared to be relatively more dependent on L-type Ca2+ channels than LF BPV because lower doses of nifedipine were required to significantly reduce VLF BPV than to reduce LF BPV. Ganglionic blockade markedly reduced VLF and LF BPV and abolished the nifedipine-induced dose-dependent declines in VLF and LF BPV, suggesting that VLF and LF BPV require sympathetic activity to be evident. In conclusion, VLF BPV is largely mediated by L-type Ca2+ channel-dependent mechanisms. We speculate that VLF BPV is generated by myogenic vascular responses to spontaneously occurring perturbations of blood pressure. Other factors, such as sympathetic nervous system activity, may elicit a permissive effect on VLF BPV by increasing vascular myogenic responsiveness.
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Affiliation(s)
- Amanda M Langager
- Dept of Integrative Physiology, The Univ of Iowa, Iowa City, IA 52242, USA
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McGahon MK, Dawicki JM, Arora A, Simpson DA, Gardiner TA, Stitt AW, Scholfield CN, McGeown JG, Curtis TM. Kv1.5 is a major component underlying the A-type potassium current in retinal arteriolar smooth muscle. Am J Physiol Heart Circ Physiol 2006; 292:H1001-8. [PMID: 17040965 PMCID: PMC2593469 DOI: 10.1152/ajpheart.01003.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Little is known about the molecular characteristics of the voltage-activated K+ (Kv) channels that underlie the A-type K+ current in vascular smooth muscle cells of the systemic circulation. We investigated the molecular identity of the A-type K+ current in retinal arteriolar myocytes using patch-clamp techniques, RT-PCR, immunohistochemistry, and neutralizing antibody studies. The A-type K+ current was resistant to the actions of specific inhibitors for Kv3 and Kv4 channels but was blocked by the Kv1 antagonist correolide. No effects were observed with pharmacological agents against Kv1.1/2/3/6 and 7 channels, but the current was partially blocked by riluzole, a Kv1.4 and Kv1.5 inhibitor. The current was not altered by the removal of extracellular K+ but was abolished by flecainide, indicative of Kv1.5 rather than Kv1.4 channels. Transcripts encoding Kv1.5 and not Kv1.4 were identified in freshly isolated retinal arterioles. Immunofluorescence labeling confirmed a lack of Kv1.4 expression and revealed Kv1.5 to be localized to the plasma membrane of the arteriolar smooth muscle cells. Anti-Kv1.5 antibody applied intracellularly inhibited the A-type K+ current, whereas anti-Kv1.4 antibody had no effect. Co-expression of Kv1.5 with Kvβ1 or Kvβ3 accessory subunits is known to transform Kv1.5 currents from delayed rectifers into A-type currents. Kvβ1 mRNA expression was detected in retinal arterioles, but Kvβ3 was not observed. Kvβ1 immunofluorescence was detected on the plasma membrane of retinal arteriolar myocytes. The findings of this study suggest that Kv1.5, most likely co-assembled with Kvβ1 subunits, comprises a major component underlying the A-type K+ current in retinal arteriolar smooth muscle cells.
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Affiliation(s)
- Mary K McGahon
- Centre of Vision Sciences, The Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA. UK
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Tumelty J, Scholfield N, Stewart M, Curtis T, McGeown G. Ca2+-sparks constitute elementary building blocks for global Ca2+-signals in myocytes of retinal arterioles. Cell Calcium 2006; 41:451-66. [PMID: 17027081 PMCID: PMC2638024 DOI: 10.1016/j.ceca.2006.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 08/21/2006] [Accepted: 08/26/2006] [Indexed: 11/04/2022]
Abstract
Spontaneous Ca2+-events were imaged in myocytes within intact retinal arterioles (diameter <40 μm) freshly isolated from rat eyes. Ca2+-sparks were often observed to spread across the width of these small cells, and could summate to produce prolonged Ca2+-oscillations and contraction. Application of cyclopiazonic acid (20 μM) transiently increased spark frequency and oscillation amplitude, but inhibited both sparks and oscillations within 60 s. Both ryanodine (100 μM) and tetracaine (100 μM) reduced the frequency of sparks and oscillations, while tetracaine also reduced oscillation amplitude. None of these interventions affected spark amplitude. Nifedipine, which blocks store filling independently of any action on L-type Ca2+-channels in these cells, reduced the frequency and amplitude of both sparks and oscillations. Removal of external [Ca2+] (1 mM EGTA) also reduced the frequency of sparks and oscillations but these reductions were slower in onset than those in the presence of tetracaine or cyclopiazonic acid. Cyclopiazonic acid, nifedipine and low external [Ca2+] all reduced SR loading, as indicated by the amplitude of caffeine evoked Ca2+-transients. This study demonstrates for the first time that spontaneous Ca2+-events in small arterioles of the eye result from activation of ryanodine receptors in the SR and suggests that this activation is not tightly coupled to Ca2+-influx. The data also supports a model in which Ca2+-sparks act as building blocks for more prolonged, global Ca2+-signals.
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Affiliation(s)
- James Tumelty
- Cell and Metabolic Signalling Group, School of Medicine and Dentistry, The Queen's University of Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, United Kingdom
- Centre of Vision Sciences, The Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, Northern Ireland, United Kingdom
| | - Norman Scholfield
- Cell and Metabolic Signalling Group, School of Medicine and Dentistry, The Queen's University of Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, United Kingdom
| | - Michael Stewart
- Cell and Metabolic Signalling Group, School of Medicine and Dentistry, The Queen's University of Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, United Kingdom
| | - Tim Curtis
- Centre of Vision Sciences, The Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, Northern Ireland, United Kingdom
| | - Graham McGeown
- Cell and Metabolic Signalling Group, School of Medicine and Dentistry, The Queen's University of Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, United Kingdom
- Corresponding author. Tel.: +44 28 90972090.
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Zhang J, Berra-Romani R, Sinnegger-Brauns MJ, Striessnig J, Blaustein MP, Matteson DR. Role of Cav1.2 L-type Ca2+ channels in vascular tone: effects of nifedipine and Mg2+. Am J Physiol Heart Circ Physiol 2006; 292:H415-25. [PMID: 16980345 DOI: 10.1152/ajpheart.01214.2005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ca(2+) entry via L-type voltage-gated Ca(2+) channels (LVGCs) is a key factor in generating myogenic tone (MT), as dihydropyridines (DHPs) and other LVGC blockers, including Mg(2+), markedly reduce MT. Recent reports suggest, however, that elevated external Mg(2+) concentration and DHPs may also inhibit other Ca(2+)-entry pathways. Here, we explore the contribution of LVGCs to MT in intact, pressurized mesenteric small arteries using mutant mice (DHP(R/R)) expressing functional but DHP-insensitive Ca(v)1.2 channels. In wild-type (WT), but not DHP(R/R), mouse arteries, nifedipine (0.3-1.0 microM) markedly reduced MT and vasoconstriction induced by high external K(+) concentrations ([K(+)](o)), a measure of LVGC-mediated Ca(2+) entry. Blocking MT and high [K(+)](o)-induced vasoconstriction by <1 microM nifedipine in WT but not in DHP(R/R) arteries implies that Ca(2+) entry via Ca(v)1.2 LVGCs is obligatory for MT and that nifedipine inhibits MT exclusively by blocking LVGCs. We also examined the effects of Mg(2+) on MT and LVGCs. High external Mg(2+) concentration (10 mM) blocked MT, slowed the high [K(+)](o)-induced vasoconstrictions, and decreased their amplitude in WT and DHP(R/R) arteries. To verify that these effects of Mg(2+) are due to block of LVGCs, we characterized the effects of extracellular and intracellular Mg(2+) on LVGC currents in isolated mesenteric artery myocytes. DHP-sensitive LVGC currents are inhibited by both external and internal Mg(2+). The results indicate that Mg(2+) relaxes MT by inhibiting Ca(2+) influx through LVGCs. These data provide new information about the central role of Ca(v)1.2 LVGCs in generating and maintaining MT in mouse mesenteric small arteries.
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MESH Headings
- Animals
- Calcium Channel Blockers/administration & dosage
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Cells, Cultured
- Dose-Response Relationship, Drug
- Ion Channel Gating/drug effects
- Ion Channel Gating/physiology
- Magnesium/administration & dosage
- Male
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/physiology
- Nifedipine/administration & dosage
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- Jin Zhang
- Dept. of Physiology, Univ. of Maryland School of Medicine, 655 W. Baltimore St., Baltimore, MD 21201, USA
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Yao DM, Fang SM, Yang CJ, Xiu HM, Su SW, Yao XX. Effects of radix salviae miltiorrhizae on endothelin-1-induced calcium changes in hepatic stellate cells. Shijie Huaren Xiaohua Zazhi 2006; 14:2488-2492. [DOI: 10.11569/wcjd.v14.i25.2488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of radix salviae miltiorrhizae (RSM) on the changes of [Ca2+]i induced by endothelin-1 (ET-1) in hepatic stellate cells (HSCs).
METHODS: After preparation of RSM cream, the effects of RSM on ET-1-induced changes of HSCs [Ca2+]i were observed by laser scanning confocal microscopy.
RESULTS: In normal buffer (including Ca2+, buffer A), the fluorescence intensity was enhanced accordingly with the increase of ET-1 concentration. The cumulative-response curve showed EC50 was 1.1×10-9 mol/L. After incubation of HSCs with ET-1 in buffer A and buffer B (absence of extracellular calcium, EGTA), the duration of calcium peak had significant difference (165.2 ± 10.1 s vs 91.0 ± 7.2 s, P < 0.01), while the value of calcium peak had no significant difference. The ET-1-induced duration of calcium wave decreased markedly in the cells pretreated with RSM in buffer A as compared with that in the ones treated by ET-1 alone (69.1 ± 12.5 s vs 165.2 ± 10.1 s, P < 0.01). The calcium peak value and duration of calcium wave had no significant changes between the cells pre-incubated with RSM in buffer B and A (P > 0.05). In the cells pre-incubated with RSM, KCl-induced elevation of [Ca2+]i was decreased, and the calcium peak value (78.0% ± 6.1% → 26.3% ± 1.2%, P < 0.01) and duration of calcium wave (70.8 ± 10.4 s → 15.9 ± 5.1 s, P < 0.01) were decreased significantly.
CONCLUSION: RSM inhibits ET-1-induced depletion of intracellular calcium, which has no correlations with the influx of extracellular calcium. RSM can also inhibit KCl-induced influx of calcium, indicating its characteristic of blocking voltage-operated Ca2+ channel.
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Kachoei BA, Knox RJ, Uthuza D, Levy S, Kaczmarek LK, Magoski NS. A store-operated Ca(2+) influx pathway in the bag cell neurons of Aplysia. J Neurophysiol 2006; 96:2688-98. [PMID: 16885525 PMCID: PMC2894935 DOI: 10.1152/jn.00118.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although store-operated Ca(2+) influx has been well-studied in nonneuronal cells, an understanding of its nature in neurons remains poor. In the bag cell neurons of Aplysia californica, prior work has suggested that a Ca(2+) entry pathway can be activated by Ca(2+) store depletion. Using fura-based imaging of intracellular Ca(2+) in cultured bag cell neurons, we now characterize this pathway as store-operated Ca(2+) influx. In the absence of extracellular Ca(2+), the endoplasmic reticulum Ca(2+)-ATPase inhibitors, cyclopiazonic acid (CPA) or thapsigargin, depleted intracellular stores and elevated intracellular free Ca(2+). With the subsequent addition of extracellular Ca(2+), a prominent Ca(2+) influx was observed. The ryanodine receptor agonist, chloroethylphenol (CEP), also increased intracellular Ca(2+) but did not initiate store-operated Ca(2+) influx, despite overlap between CEP- and CPA-sensitive stores. Bafilomycin A, a vesicular H(+)-ATPase inhibitor, liberated intracellular Ca(2+) from acidic stores and attenuated subsequent Ca(2+) influx, presumably by replenishing CPA-depleted stores. Store-operated Ca(2+) influx was partially blocked by low concentrations of La(3+) or BTP2, and strongly inhibited by either 1-[b-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365) or a high concentration of Ni(2+). Regarding IP(3) receptor blockers, 2-aminoethyldiphenyl borate, but not xestospongin C, prevented store-operated Ca(2+) influx. However, jasplakinolide, an actin stabilizer reported to inhibit this pathway in smooth muscle cell lines, was ineffective. The bag cell neurons initiate reproductive behavior through a prolonged afterdischarge associated with intracellular Ca(2+) release and neuropeptide secretion. Store-operated Ca(2+) influx may serve to replenish stores depleted during the afterdischarge or participate in the release of peptide that triggers behavior.
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Affiliation(s)
- Babak A Kachoei
- Department of Physiology, Queen's University, 4th Floor, Botterell Hall, 18 Stuart St., Kingston, ON, K7L 3N6, Canada
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Ratz PH, Berg KM. 2-Aminoethoxydiphenyl borate inhibits KCl-induced vascular smooth muscle contraction. Eur J Pharmacol 2006; 541:177-83. [PMID: 16765942 DOI: 10.1016/j.ejphar.2006.05.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 05/03/2006] [Accepted: 05/10/2006] [Indexed: 11/23/2022]
Abstract
K(+)-depolarization (KCl)-activated Ca(2+) entry permitting sustained force-maintenance in tonic vascular smooth muscle has long been attributed solely to activation of L-type voltage-operated Ca(2+) channels (VOCs). We used the transient receptor potential channel (TRP) blocker, 2-aminoethoxydiphenyl borate (2-APB), to test the hypothesis that KCl activates additional Ca(2+) entry pathways. 2-APB alone caused a transient weak increase in force, a sustained weak increase in basal [Ca(2+)](i) and myosin light chain phosphorylation, and inhibition of KCl-induced force, [Ca(2+)](i) and myosin light chain phosphorylation. 2-APB did not appear to block VOCs, because 2-APB did not inhibit 30 nM Bay k 8644-induced increases in [Ca(2+)](i). Moreover, although 1 microM nifedipine abolished the increase in [Ca(2+)](i) produced by alpha-adrenergic receptor activation, 2-APB produced an additional reduction in [Ca(2+)](i) below the basal level. These data support the conclusion that membrane depolarization activates 2-APB-sensitive TRPs in addition to VOCs to permit strong force-maintenance in tonic vascular smooth muscle.
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Affiliation(s)
- Paul H Ratz
- Department of Biochemistry, Virginia Commonwealth University, School of Medicine, Richmond, 23298-0614, USA.
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Brueggemann LI, Markun DR, Henderson KK, Cribbs LL, Byron KL. Pharmacological and Electrophysiological Characterization of Store-Operated Currents and Capacitative Ca2+Entry in Vascular Smooth Muscle Cells. J Pharmacol Exp Ther 2006; 317:488-99. [PMID: 16415091 DOI: 10.1124/jpet.105.095067] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Capacitative Ca(2+) entry (CCE) in vascular smooth muscle cells contributes to vasoconstrictor and mitogenic effects of vasoactive hormones. In A7r5 rat aortic smooth muscle cells, measurements of cytosolic free Ca(2+) concentration ([Ca(2+)](i)) have demonstrated that depletion of intracellular Ca(2+) stores activates CCE. However, there is disagreement in published studies regarding the regulation of this mechanism by the vasoconstrictor hormone [Arg(8)]-vasopressin (AVP). We have employed electrophysiological methods to characterize the membrane currents activated by store depletion [store-operated current (I(SOC))]. Because of different recording conditions, it has not been previously determined whether I(SOC) corresponds to CCE measured using fura-2; nor has the channel protein responsible for CCE been identified. In the present study, the pharmacological characteristics of I(SOC), including its sensitivity to blockade by 2-aminoethoxydiphenylborane, diethylstilbestrol, or micromolar Gd(3+), were found to parallel the effects of these drugs on thapsigargin- or AVP-activated CCE measured under identical external ionic conditions using fura-2. Thapsigargin-stimulated I(SOC) was also measured in freshly isolated rat mesenteric artery smooth muscle cells (MASMC). Members of the transient receptor potential (TRP) family of nonselective cation channels, TRPC1, TRPC4, and TRPC6, were detected by reverse transcription-polymerase chain reaction and Western blot in both A7r5 cells and MASMC. TRPC1 expression was reduced in a stable A7r5 cell line expressing a small interfering RNA (siRNA) or by infection of A7r5 cells with an adenovirus expressing a TRPC1 antisense nucleotide sequence. Thapsigargin-stimulated I(SOC) was reduced in both the TRPC1 siRNA- and TRPC1 antisense-expressing cells, suggesting that the TRPC1 channel contributes to the I(SOC)/CCE pathway.
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Affiliation(s)
- Lioubov I Brueggemann
- Department of Pharmacology and Experimental Therapeutics, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153, USA
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50
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Affiliation(s)
- E Kenneth Weir
- Department of Medicine, Minneapolis Veterans Affairs Medical Center and University of Minnesota, Minneapolis 55417, USA.
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