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Robinson P, Sparrow AJ, Psaras Y, Steeples V, Simon JN, Broyles CN, Chang YF, Brook FA, Wang YJ, Blease A, Zhang X, Abassi YA, Geeves MA, Toepfer CN, Watkins H, Redwood C, Daniels MJ. Comparing the effects of chemical Ca 2+ dyes and R-GECO on contractility and Ca 2+ transients in adult and human iPSC cardiomyocytes. J Mol Cell Cardiol 2023; 180:44-57. [PMID: 37127261 PMCID: PMC10659987 DOI: 10.1016/j.yjmcc.2023.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 04/13/2023] [Accepted: 04/28/2023] [Indexed: 05/03/2023]
Abstract
We compared commonly used BAPTA-derived chemical Ca2+ dyes (fura2, Fluo-4, and Rhod-2) with a newer genetically encoded indicator (R-GECO) in single cell models of the heart. We assessed their performance and effects on cardiomyocyte contractility, determining fluorescent signal-to-noise ratios and sarcomere shortening in primary ventricular myocytes from adult mouse and guinea pig, and in human iPSC-derived cardiomyocytes. Chemical Ca2+ dyes displayed dose-dependent contractile impairment in all cell types, and we observed a negative correlation between contraction and fluorescence signal-to-noise ratio, particularly for fura2 and Fluo-4. R-GECO had no effect on sarcomere shortening. BAPTA-based dyes, but not R-GECO, inhibited in vitro acto-myosin ATPase activity. The presence of fura2 accentuated or diminished changes in contractility and Ca2+ handling caused by small molecule modulators of contractility and intracellular ionic homeostasis (mavacamten, levosimendan, and flecainide), but this was not observed when using R-GECO in adult guinea pig left ventricular cardiomyocytes. Ca2+ handling studies are necessary for cardiotoxicity assessments of small molecules intended for clinical use. Caution should be exercised when interpreting small molecule studies assessing contractile effects and Ca2+ transients derived from BAPTA-like chemical Ca2+ dyes in cellular assays, a common platform for cardiac toxicology testing and mechanistic investigation of cardiac disease physiology and treatment.
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Affiliation(s)
- Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK.
| | - Alexander J Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Yiangos Psaras
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Violetta Steeples
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Jillian N Simon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Connor N Broyles
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Yu-Fen Chang
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Frances A Brook
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Ying-Jie Wang
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Andrew Blease
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Xiaoyu Zhang
- Agilent Biosciences, Inc., San Diego, CA 92121, USA
| | | | | | - Christopher N Toepfer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK; Department of Cardiology, Oxford University NHS Hospitals Trust, Oxford, UK
| | - Charles Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Matthew J Daniels
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; BHF Centre of Research Excellence, University of Oxford, Oxford, UK; Department of Cardiology, Oxford University NHS Hospitals Trust, Oxford, UK; Department of Cardiovascular Sciences, University of Manchester, Manchester, UK.
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2
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Psaras Y, Margara F, Cicconet M, Sparrow AJ, Repetti GG, Schmid M, Steeples V, Wilcox JA, Bueno-Orovio A, Redwood CS, Watkins HC, Robinson P, Rodriguez B, Seidman JG, Seidman CE, Toepfer CN. CalTrack: High-Throughput Automated Calcium Transient Analysis in Cardiomyocytes. Circ Res 2021; 129:326-341. [PMID: 34018815 PMCID: PMC8260473 DOI: 10.1161/circresaha.121.318868] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 05/06/2021] [Accepted: 05/20/2021] [Indexed: 11/21/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Yiangos Psaras
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
| | - Francesca Margara
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
| | - Marcelo Cicconet
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
- Image and Data Analysis Core (M.C.), Harvard Medical School, Boston, MA
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
| | - Alexander J. Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
- Image and Data Analysis Core (M.C.), Harvard Medical School, Boston, MA
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
| | - Giuliana G. Repetti
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
| | - Manuel Schmid
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
- Image and Data Analysis Core (M.C.), Harvard Medical School, Boston, MA
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
| | - Violetta Steeples
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
- Image and Data Analysis Core (M.C.), Harvard Medical School, Boston, MA
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
| | - Jonathan A.L. Wilcox
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
| | | | - Charles S. Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
- Image and Data Analysis Core (M.C.), Harvard Medical School, Boston, MA
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
| | - Hugh C. Watkins
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
| | - Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
| | - Blanca Rodriguez
- Computer Science (F.M., A.B.-O., B.R.), University of Oxford, United Kingdom
| | - Jonathan G. Seidman
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
| | - Christine E. Seidman
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
| | - Christopher N. Toepfer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (Y.P., F.M., A.J.S., M.S., V.S., C.S.R., H.C.W., P.R., C.N.T.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (H.C.W., C.N.T.), University of Oxford, United Kingdom
- Genetics (G.G.R., J.A.L.W., J.G.S., C.E.S., C.N.T.), Harvard Medical School, Boston, MA
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3
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Moreira LM, Takawale A, Hulsurkar M, Menassa DA, Antanaviciute A, Lahiri SK, Mehta N, Evans N, Psarros C, Robinson P, Sparrow AJ, Gillis MA, Ashley N, Naud P, Barallobre-Barreiro J, Theofilatos K, Lee A, Norris M, Clarke MV, Russell PK, Casadei B, Bhattacharya S, Zajac JD, Davey RA, Sirois M, Mead A, Simmons A, Mayr M, Sayeed R, Krasopoulos G, Redwood C, Channon KM, Tardif JC, Wehrens XHT, Nattel S, Reilly S. Paracrine signalling by cardiac calcitonin controls atrial fibrogenesis and arrhythmia. Nature 2020; 587:460-465. [PMID: 33149301 DOI: 10.1038/s41586-020-2890-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 08/13/2020] [Indexed: 11/10/2022]
Abstract
Atrial fibrillation, the most common cardiac arrhythmia, is an important contributor to mortality and morbidity, and particularly to the risk of stroke in humans1. Atrial-tissue fibrosis is a central pathophysiological feature of atrial fibrillation that also hampers its treatment; the underlying molecular mechanisms are poorly understood and warrant investigation given the inadequacy of present therapies2. Here we show that calcitonin, a hormone product of the thyroid gland involved in bone metabolism3, is also produced by atrial cardiomyocytes in substantial quantities and acts as a paracrine signal that affects neighbouring collagen-producing fibroblasts to control their proliferation and secretion of extracellular matrix proteins. Global disruption of calcitonin receptor signalling in mice causes atrial fibrosis and increases susceptibility to atrial fibrillation. In mice in which liver kinase B1 is knocked down specifically in the atria, atrial-specific knockdown of calcitonin promotes atrial fibrosis and increases and prolongs spontaneous episodes of atrial fibrillation, whereas atrial-specific overexpression of calcitonin prevents both atrial fibrosis and fibrillation. Human patients with persistent atrial fibrillation show sixfold lower levels of myocardial calcitonin compared to control individuals with normal heart rhythm, with loss of calcitonin receptors in the fibroblast membrane. Although transcriptome analysis of human atrial fibroblasts reveals little change after exposure to calcitonin, proteomic analysis shows extensive alterations in extracellular matrix proteins and pathways related to fibrogenesis, infection and immune responses, and transcriptional regulation. Strategies to restore disrupted myocardial calcitonin signalling thus may offer therapeutic avenues for patients with atrial fibrillation.
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Affiliation(s)
- Lucia M Moreira
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Abhijit Takawale
- Research Centre, Montreal Heart Institute and University of Montreal, Montreal, Quebec, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Mohit Hulsurkar
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - David A Menassa
- Clinical Neurology, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
- Biological Sciences, Faculty of Life and Environmental Sciences, University of Southampton, Southampton, UK
| | - Agne Antanaviciute
- Medical Research Council (MRC) Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Satadru K Lahiri
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Neelam Mehta
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Neil Evans
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Constantinos Psarros
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Alexander J Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Marc-Antoine Gillis
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Neil Ashley
- Single-Cell Genomics Facility, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Patrice Naud
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | | | | | - Angela Lee
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Mary Norris
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Michele V Clarke
- Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
| | - Patricia K Russell
- Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
| | - Barbara Casadei
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Shoumo Bhattacharya
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Jeffrey D Zajac
- Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
| | - Rachel A Davey
- Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
| | - Martin Sirois
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Adam Mead
- Medical Research Council (MRC) Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Alison Simmons
- Medical Research Council (MRC) Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Manuel Mayr
- King's British Heart Foundation Centre, King's College London, London, UK
| | - Rana Sayeed
- Cardiothoracic Surgery, Oxford Heart Centre, John Radcliffe Hospital, Oxford, UK
| | - George Krasopoulos
- Cardiothoracic Surgery, Oxford Heart Centre, John Radcliffe Hospital, Oxford, UK
| | - Charles Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Keith M Channon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Jean-Claude Tardif
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Stanley Nattel
- Research Centre, Montreal Heart Institute and University of Montreal, Montreal, Quebec, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- IHU LIRYC, Fondation Bordeaux Université, Bordeaux, France
| | - Svetlana Reilly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford, UK.
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Robinson P, Sparrow AJ, Patel S, Malinowska M, Reilly SN, Zhang YH, Casadei B, Watkins H, Redwood C. Dilated cardiomyopathy mutations in thin-filament regulatory proteins reduce contractility, suppress systolic Ca 2+, and activate NFAT and Akt signaling. Am J Physiol Heart Circ Physiol 2020; 319:H306-H319. [PMID: 32618513 PMCID: PMC7473929 DOI: 10.1152/ajpheart.00272.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Dilated cardiomyopathy (DCM) is clinically characterized by dilated ventricular cavities and reduced ejection fraction, leading to heart failure and increased thromboembolic risk. Mutations in thin-filament regulatory proteins can cause DCM and have been shown in vitro to reduce contractility and myofilament Ca2+-affinity. In this work we have studied the functional consequences of mutations in cardiac troponin T (R131W), cardiac troponin I (K36Q) and α-tropomyosin (E40K) using adenovirally transduced isolated guinea pig left ventricular cardiomyocytes. We find significantly reduced fractional shortening with reduced systolic Ca2+. Contraction and Ca2+ reuptake times were slowed, which contrast with some findings in murine models of myofilament Ca2+ desensitization. We also observe increased sarcoplasmic reticulum (SR) Ca2+ load and smaller fractional SR Ca2+ release. This corresponds to a reduction in SR Ca2+-ATPase activity and increase in sodium-calcium exchanger activity. We also observe dephosphorylation and nuclear translocation of the nuclear factor of activated T cells (NFAT), with concordant RAC-α-serine/threonine protein kinase (Akt) phosphorylation but no change to extracellular signal-regulated kinase activation in chronically paced cardiomyocytes expressing DCM mutations. These changes in Ca2+ handling and signaling are common to all three mutations, indicating an analogous pathway of disease pathogenesis in thin-filament sarcomeric DCM. Previous work has shown that changes to myofilament Ca2+ sensitivity caused by DCM mutations are qualitatively opposite from hypertrophic cardiomyopathy (HCM) mutations in the same genes. However, we find several common pathways such as increased relaxation times and NFAT activation that are also hallmarks of HCM. This suggests more complex intracellular signaling underpinning DCM, driven by the primary mutation.NEW & NOTEWORTHY Dilated cardiomyopathy (DCM) is a frequently occurring cardiac disorder with a degree of genetic inheritance. We have found that DCM mutations in proteins that regulate the contractile machinery cause alterations to contraction, calcium-handling, and some new signaling pathways that provide stimuli for disease development. We have used guinea pig cells that recapitulate human calcium-handling and introduced the mutations using adenovirus gene transduction to look at the initial triggers of disease before remodeling.
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Affiliation(s)
- Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Alexander J Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Suketu Patel
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Marta Malinowska
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Svetlana N Reilly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Yin-Hua Zhang
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Barbara Casadei
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Charles Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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Sparrow AJ, Watkins H, Daniels MJ, Redwood C, Robinson P. Mavacamten rescues increased myofilament calcium sensitivity and dysregulation of Ca 2+ flux caused by thin filament hypertrophic cardiomyopathy mutations. Am J Physiol Heart Circ Physiol 2020; 318:H715-H722. [PMID: 32083971 PMCID: PMC7099453 DOI: 10.1152/ajpheart.00023.2020] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thin filament hypertrophic cardiomyopathy (HCM) mutations increase myofilament Ca2+ sensitivity and alter Ca2+ handling and buffering. The myosin inhibitor mavacamten reverses the increased contractility caused by HCM thick filament mutations, and we here test its effect on HCM thin filament mutations where the mode of action is not known. Mavacamten (250 nM) partially reversed the increased Ca2+ sensitivity caused by HCM mutations Cardiac troponin T (cTnT) R92Q, and cardiac troponin I (cTnI) R145G in in vitro ATPase assays. The effect of mavacamten was also analyzed in cardiomyocyte models of cTnT R92Q and cTnI R145G containing cytoplasmic and myofilament specific Ca2+ sensors. While mavacamten rescued the hypercontracted basal sarcomere length, the reduced fractional shortening did not improve with mavacamten. Both mutations caused an increase in peak systolic Ca2+ detected at the myofilament, and this was completely rescued by 250 nM mavacamten. Systolic Ca2+ detected by the cytoplasmic sensor was also reduced by mavacamten treatment, although only R145G increased cytoplasmic Ca2+. There was also a reversal of Ca2+ decay time prolongation caused by both mutations at the myofilament but not in the cytoplasm. We thus show that mavacamten reverses some of the Ca2+-sensitive molecular and cellular changes caused by the HCM mutations, particularly altered Ca2+ flux at the myofilament. The reduction of peak systolic Ca2+ as a consequence of mavacamten treatment represents a novel mechanism by which the compound is able to reduce contractility, working synergistically with its direct effect on the myosin motor. NEW & NOTEWORTHY Mavacamten, a myosin inhibitor, is currently in phase-3 clinical trials as a pharmacotherapy for hypertrophic cardiomyopathy (HCM). Its efficacy in HCM caused by mutations in thin filament proteins is not known. We show in reductionist and cellular models that mavacamten can rescue the effects of thin filament mutations on calcium sensitivity and calcium handling although it only partially rescues the contractile cellular phenotype and, in some cases, exacerbates the effect of the mutation.
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Affiliation(s)
- Alexander J Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Matthew J Daniels
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom.,Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Charles Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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Sparrow AJ, Sievert K, Patel S, Chang YF, Broyles CN, Brook FA, Watkins H, Geeves MA, Redwood CS, Robinson P, Daniels MJ. Measurement of Myofilament-Localized Calcium Dynamics in Adult Cardiomyocytes and the Effect of Hypertrophic Cardiomyopathy Mutations. Circ Res 2020; 124:1228-1239. [PMID: 30732532 PMCID: PMC6485313 DOI: 10.1161/circresaha.118.314600] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Supplemental Digital Content is available in the text. Rationale: Subcellular Ca2+ indicators have yet to be developed for the myofilament where disease mutation or small molecules may alter contractility through myofilament Ca2+ sensitivity. Here, we develop and characterize genetically encoded Ca2+ indicators restricted to the myofilament to directly visualize Ca2+ changes in the sarcomere. Objective: To produce and validate myofilament-restricted Ca2+ imaging probes in an adenoviral transduction adult cardiomyocyte model using drugs that alter myofilament function (MYK-461, omecamtiv mecarbil, and levosimendan) or following cotransduction of 2 established hypertrophic cardiomyopathy disease-causing mutants (cTnT [Troponin T] R92Q and cTnI [Troponin I] R145G) that alter myofilament Ca2+ handling. Methods and Results: When expressed in adult ventricular cardiomyocytes RGECO-TnT (Troponin T)/TnI (Troponin I) sensors localize correctly to the sarcomere without contractile impairment. Both sensors report cyclical changes in fluorescence in paced cardiomyocytes with reduced Ca2+ on and increased Ca2+ off rates compared with unconjugated RGECO. RGECO-TnT/TnI revealed changes to localized Ca2+ handling conferred by MYK-461 and levosimendan, including an increase in Ca2+ binding rates with both levosimendan and MYK-461 not detected by an unrestricted protein sensor. Coadenoviral transduction of RGECO-TnT/TnI with hypertrophic cardiomyopathy causing thin filament mutants showed that the mutations increase myofilament [Ca2+] in systole, lengthen time to peak systolic [Ca2+], and delay [Ca2+] release. This contrasts with the effect of the same mutations on cytoplasmic Ca2+, when measured using unrestricted RGECO where changes to peak systolic Ca2+ are inconsistent between the 2 mutations. These data contrast with previous findings using chemical dyes that show no alteration of [Ca2+] transient amplitude or time to peak Ca2+. Conclusions: RGECO-TnT/TnI are functionally equivalent. They visualize Ca2+ within the myofilament and reveal unrecognized aspects of small molecule and disease-associated mutations in living cells.
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Affiliation(s)
- Alexander J Sparrow
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Kolja Sievert
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Suketu Patel
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Yu-Fen Chang
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Connor N Broyles
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Frances A Brook
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Hugh Watkins
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,Department of Cardiology, Oxford University NHS Hospitals Trust, United Kingdom (H.W., M.J.D.)
| | - Michael A Geeves
- Department of Biosciences, University of Kent, Canterbury, United Kingdom (M.A.G.)
| | - Charles S Redwood
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Paul Robinson
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom
| | - Matthew J Daniels
- From the Division of Cardiovascular Medicine, Radcliffe Department of Medicine (A.J.S., K.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Research Excellence (A.J.S., S.P., Y.-F.C., C.N.B., F.A.B., H.W., C.S.R., P.R., M.J.D.), University of Oxford, United Kingdom.,BHF Centre of Regenerative Medicine (M.J.D.), University of Oxford, United Kingdom.,Department of Cardiology, Oxford University NHS Hospitals Trust, United Kingdom (H.W., M.J.D.).,Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan (M.J.D.)
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Sparrow AJ, Sweetman D, Welham SJM. LIM kinase function and renal growth: Potential role for LIM kinases in fetal programming of kidney development. Life Sci 2017; 186:17-24. [PMID: 28774704 DOI: 10.1016/j.lfs.2017.07.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/27/2017] [Accepted: 07/30/2017] [Indexed: 12/24/2022]
Abstract
AIMS Maternal dietary restriction during pregnancy impairs nephron development and results in offspring with fewer nephrons. Cell turnover in the early developing kidney is altered by exposure to maternal dietary restriction and may be regulated by the LIM-kinase family of enzymes. We set out to establish whether disturbance of LIM-kinase activity might play a role in the impairment of nephron formation. MAIN METHODS E12.5 metanephric kidneys and HK2 cells were grown in culture with the pharmacological LIM-kinase inhibitor BMS5. Organs were injected with DiI, imaged and cell numbers measured over 48h to assess growth. Cells undergoing mitosis were visualised by pH3 labelling. KEY FINDINGS Growth of cultured kidneys reduced to 83% of controls after exposure to BMS5 and final cell number to 25% of control levels after 48h. Whilst control and BMS5 treated organs showed cells undergoing mitosis (100±11 cells/field vs 113±18 cells/field respectively) the proportion in anaphase was considerably diminished with BMS5 treatment (7.8±0.8% vs 0.8±0.6% respectively; P<0.01). This was consistent with effects on HK2 cells highlighting a severe impact of BMS5 on formation of the mitotic spindle and centriole positioning. DiI labelled cells migrated in 100% of control cultures vs 0% BMS5 treated organs. The number of nephrogenic precursor cells appeared depleted in whole organs and formation of new nephrons was blocked by exposure to BMS5. SIGNIFICANCE Pharmacological blockade of LIM-kinase function in the early developing kidney results in failure of renal development. This is likely due to prevention of dividing cells from completion of mitosis with their resultant loss.
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Affiliation(s)
- Alexander J Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Dylan Sweetman
- Zoetis VMRD GTR, Livestock Wellness and Performance, 333 Portage Street, Kalamazoo, MI 49007, USA
| | - Simon J M Welham
- School of Biosciences, University of Nottingham, Nottingham, UK.
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Welham SJM, Sparrow AJ, Gardner DS, Elmes MJ. Acetylsalicylic acid interferes with embryonic kidney growth and development by a prostaglandin-independent mechanism. World J Nephrol 2017; 6:21-28. [PMID: 28101448 PMCID: PMC5215205 DOI: 10.5527/wjn.v6.i1.21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/14/2016] [Accepted: 10/24/2016] [Indexed: 02/06/2023] Open
Abstract
AIM To evaluate the effects of the non-selective, non-steroidal anti-inflammatory drug (NSAID) acetylsalicylic acid (ASA), on ex vivo embryonic kidney growth and development.
METHODS Pairs of fetal mouse kidneys at embryonic day 12.5 were cultured ex vivo in increasing concentrations of ASA (0.04-0.4 mg/mL) for up to 7 d. One organ from each pair was grown in control media and was used as the internal control for the experimental contralateral organ. In some experiments, organs were treated with ASA for 48 h and then transferred either to control media alone or control media containing 10 μmol/L prostaglandin E2 (PGE2) for a further 5 d. Fetal kidneys were additionally obtained from prostaglandin synthase 2 homozygous null or heterozygous (PTGS2-/- and PTGS2-/+) embryos and grown in culture. Kidney cross-sectional area was used to determine treatment effects on kidney growth. Whole-mount labelling to fluorescently detect laminin enabled crude determination of epithelial branching using confocal microscopy.
RESULTS Increasing ASA concentration (0.1, 0.2 and 0.4 mg/mL) significantly inhibited metanephric growth (P < 0.05). After 7 d of culture, exposure to 0.2 mg/mL and 0.4 mg/mL reduced organ size to 53% and 23% of control organ size respectively (P < 0.01). Addition of 10 μmol/L PGE2 to culture media after exposure to 0.2 mg/mL ASA for 48 h resulted in a return of growth area to control levels. Application of control media alone after cessation of ASA exposure showed no benefit on kidney growth. Despite the apparent recovery of growth area with 10 μmol/L PGE2, no obvious renal tubular structures were formed. The number of epithelial tips generated after 48 h exposure to ASA was reduced by 40% (0.2 mg/mL; P < 0.05) and 47% (0.4 mg/mL; P < 0.01). Finally, growth of PTGS2-/- and PTGS2+/- kidneys in organ culture showed no differences, indicating that PTGS2 derived PGE2 may at best have a minor role.
CONCLUSION ASA reduces early renal growth and development but the role of prostaglandins in this may be minor.
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Gray C, Al-Dujaili EA, Sparrow AJ, Gardiner SM, Craigon J, Welham SJ, Gardner DS. Excess maternal salt intake produces sex-specific hypertension in offspring: putative roles for kidney and gastrointestinal sodium handling. PLoS One 2013; 8:e72682. [PMID: 23991143 PMCID: PMC3749995 DOI: 10.1371/journal.pone.0072682] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 07/17/2013] [Indexed: 12/21/2022] Open
Abstract
Hypertension is common and contributes, via cardiovascular disease, towards a large proportion of adult deaths in the Western World. High salt intake leads to high blood pressure, even when occurring prior to birth – a mechanism purported to reside in altered kidney development and later function. Using a combination of in vitro and in vivo approaches we tested whether increased maternal salt intake influences fetal kidney development to render the adult individual more susceptible to salt retention and hypertension. We found that salt-loaded pregnant rat dams were hypernatraemic at day 20 gestation (147±5 vs. 128±5 mmoles/L). Increased extracellular salt impeded murine kidney development in vitro, but had little effect in vivo. Kidneys of the adult offspring had few structural or functional abnormalities, but male and female offspring were hypernatraemic (166±4 vs. 149±2 mmoles/L), with a marked increase in plasma corticosterone (e.g. male offspring; 11.9 [9.3–14.8] vs. 2.8 [2.0–8.3] nmol/L median [IQR]). Furthermore, adult male, but not female, offspring had higher mean arterial blood pressure (effect size, +16 [9–21] mm Hg; mean [95% C.I.]. With no clear indication that the kidneys of salt-exposed offspring retained more sodium per se, we conducted a preliminary investigation of their gastrointestinal electrolyte handling and found increased expression of proximal colon solute carrier family 9 (sodium/hydrogen exchanger), member 3 (SLC9A3) together with altered faecal characteristics and electrolyte handling, relative to control offspring. On the basis of these data we suggest that excess salt exposure, via maternal diet, at a vulnerable period of brain and gut development in the rat neonate lays the foundation for sustained increases in blood pressure later in life. Hence, our evidence further supports the argument that excess dietary salt should be avoided per se, particularly in the range of foods consumed by physiologically immature young.
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Affiliation(s)
- Clint Gray
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, United Kingdom
- * E-mail: (CG); (SW); (DG)
| | | | | | - Sheila M. Gardiner
- School of Biomedical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jim Craigon
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Simon J.M. Welham
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
- * E-mail: (CG); (SW); (DG)
| | - David S. Gardner
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, United Kingdom
- * E-mail: (CG); (SW); (DG)
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Oesch F, Beermann D, Sparrow AJ, Bentley P, Vogel-Bindel U. A highly sensitive assay for epoxide hydrolase using an endogenous epoxide as substrate: 16 alpha, 17 alpha-epoxyandrost-4-en-3-one. Anal Biochem 1981; 117:223-30. [PMID: 7325363 DOI: 10.1016/0003-2697(81)90715-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Kabachnik MI, Malakhov IG, Tsvetkov EN, Johnson KF, Katritzky AR, Sparrow AJ, Topsom RD. Infrared intensities as a quantitative measure of intramolecular interactions. XL. Di-para-substituted aryl phosphines. Aust J Chem 1975. [DOI: 10.1071/ch9750755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The infrared intensities
for the v8 ring stretching band of some meta- and para-substituted
phenyl-dialkylphosphines, -dichlorophosphines, and
-dialkoxyphosphines determine the σR values: PH2,
-0.05; PMe2, -0.08; PEt2, -0.08; PCl2, 0.07;
P(OEt)2, 0.06.
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