1
|
Rapöhn M, Cyganek L, Voigt N, Hasenfuß G, Lehnart SE, Wegener JW. Noninvasive analysis of contractility during identical maturations revealed two phenotypes in ventricular but not in atrial iPSC-CM. Am J Physiol Heart Circ Physiol 2024; 326:H599-H611. [PMID: 38180453 DOI: 10.1152/ajpheart.00527.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 08/28/2023] [Revised: 12/06/2023] [Accepted: 01/02/2024] [Indexed: 01/06/2024]
Abstract
Patient-derived induced pluripotent stem cells (iPSCs) can be differentiated into atrial and ventricular cardiomyocytes to allow for personalized drug screening. A hallmark of differentiation is the manifestation of spontaneous beating in a two-dimensional (2-D) cell culture. However, an outstanding observation is the high variability in this maturation process. We valued that contractile parameters change during differentiation serving as an indicator of maturation. Consequently, we recorded noninvasively spontaneous motion activity during the differentiation of male iPSC toward iPSC cardiomyocytes (iPSC-CMs) to further analyze similar maturated iPSC-CMs. Surprisingly, our results show that identical differentiations into ventricular iPSC-CMs are variable with respect to contractile parameters resulting in two distinct subpopulations of ventricular-like cells. In contrast, differentiation into atrial iPSC-CMs resulted in only one phenotype. We propose that the noninvasive and cost-effective recording of contractile activity during maturation using a smartphone device may help to reduce the variability in results frequently reported in studies on ventricular iPSC-CMs.NEW & NOTEWORTHY Differentiation of induced pluripotent stem cells (iPSCs) into iPSC-derived cardiomyocytes (iPSC-CMs) exhibits a high variability in mature parameters. Here, we monitored noninvasively contractile parameters of iPSC-CM during full-time differentiation using a smartphone device. Our results show that parallel maturations of iPSCs into ventricular iPSC-CMs, but not into atrial iPSC-CMs, resulted in two distinct subpopulations of iPSC-CMs. These findings suggest that our cost-effective method may help to compare iPSC-CMs at the same maturation level.
Collapse
Affiliation(s)
- Marcel Rapöhn
- Department of Cardiology and Pulmonology, University Medical Center of Göttingen, Göttingen, Germany
| | - Lukas Cyganek
- Department of Cardiology and Pulmonology, University Medical Center of Göttingen, Göttingen, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung), Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells," University of Göttingen, Göttingen, Germany
| | - Niels Voigt
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung), Göttingen, Germany
- Department of Pharmacology and Toxicology, University Medical Center of Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells," University of Göttingen, Göttingen, Germany
| | - Gerd Hasenfuß
- Department of Cardiology and Pulmonology, University Medical Center of Göttingen, Göttingen, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung), Göttingen, Germany
| | - Stephan E Lehnart
- Department of Cardiology and Pulmonology, University Medical Center of Göttingen, Göttingen, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung), Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells," University of Göttingen, Göttingen, Germany
| | - Jörg W Wegener
- Department of Cardiology and Pulmonology, University Medical Center of Göttingen, Göttingen, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung), Göttingen, Germany
| |
Collapse
|
2
|
Wegener JW, Mitronova GY, ElShareif L, Quentin C, Belov V, Pochechueva T, Hasenfuss G, Ackermann L, Lehnart SE. A dual-targeted drug inhibits cardiac ryanodine receptor Ca 2+ leak but activates SERCA2a Ca 2+ uptake. Life Sci Alliance 2024; 7:e202302278. [PMID: 38012000 PMCID: PMC10681910 DOI: 10.26508/lsa.202302278] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 07/17/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 11/29/2023] Open
Abstract
In the heart, genetic or acquired mishandling of diastolic [Ca2+] by ryanodine receptor type 2 (RyR2) overactivity correlates with risks of arrhythmia and sudden cardiac death. Strategies to avoid these risks include decrease of Ca2+ release by drugs modulating RyR2 activity or increase in Ca2+ uptake by drugs modulating SR Ca2+ ATPase (SERCA2a) activity. Here, we combine these strategies by developing experimental compounds that act simultaneously on both processes. Our screening efforts identified the new 1,4-benzothiazepine derivative GM1869 as a promising compound. Consequently, we comparatively studied the effects of the known RyR2 modulators Dantrolene and S36 together with GM1869 on RyR2 and SERCA2a activity in cardiomyocytes from wild type and arrhythmia-susceptible RyR2R2474S/+ mice by confocal live-cell imaging. All drugs reduced RyR2-mediated Ca2+ spark frequency but only GM1869 accelerated SERCA2a-mediated decay of Ca2+ transients in murine and human cardiomyocytes. Our data indicate that S36 and GM1869 are more suitable than dantrolene to directly modulate RyR2 activity, especially in RyR2R2474S/+ mice. Remarkably, GM1869 may represent a new dual-acting lead compound for maintenance of diastolic [Ca2+].
Collapse
Affiliation(s)
- Jörg W Wegener
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Gyuzel Y Mitronova
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Lina ElShareif
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
| | - Christine Quentin
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Vladimir Belov
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Tatiana Pochechueva
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Gerd Hasenfuss
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Lutz Ackermann
- Georg-August University of Göttingen, Institute of Organic and Biomolecular Chemistry, Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Stephan E Lehnart
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| |
Collapse
|
3
|
Mitronova GY, Quentin C, Belov VN, Wegener JW, Kiszka KA, Lehnart SE. 1,4-Benzothiazepines with Cyclopropanol Groups and Their Structural Analogues Exhibit Both RyR2-Stabilizing and SERCA2a-Stimulating Activities. J Med Chem 2023; 66:15761-15775. [PMID: 37991191 PMCID: PMC10726367 DOI: 10.1021/acs.jmedchem.3c01235] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 07/07/2023] [Revised: 10/24/2023] [Accepted: 11/07/2023] [Indexed: 11/23/2023]
Abstract
To discover new multifunctional agents for the treatment of cardiovascular diseases, we designed and synthesized a series of compounds with a cyclopropyl alcohol moiety and evaluated them in biochemical assays. Biological screening identified derivatives with dual activity: preventing Ca2+ leak through ryanodine receptor 2 (RyR2) and enhancing cardiac sarco-endoplasmic reticulum (SR) Ca2+ load by activation of Ca2+-dependent ATPase 2a (SERCA2a). The compounds that stabilize RyR2 at micro- and nanomolar concentrations are either structurally related to RyR-stabilizing drugs or Rycals or have structures similar to them. The novel compounds also demonstrate a good ability to increase ATP hydrolysis mediated by SERCA2a activity in cardiac microsomes, e.g., the half-maximal effective concentration (EC50) was as low as 383 nM for compound 12a, which is 1,4-benzothiazepine with two cyclopropanol groups. Our findings indicate that these derivatives can be considered as new lead compounds to improve cardiac function in heart failure.
Collapse
Affiliation(s)
- Gyuzel Y. Mitronova
- Department
of NanoBiophotonics, Max Planck Institute
for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
- German
Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen 37075, Germany
| | - Christine Quentin
- Department
of NanoBiophotonics, Max Planck Institute
for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Vladimir N. Belov
- Department
of NanoBiophotonics, Max Planck Institute
for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Jörg W. Wegener
- Department
of Cardiology & Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Robert-Koch-Strasse 42a, Göttingen 37075, Germany
- German
Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen 37075, Germany
| | - Kamila A. Kiszka
- Department
of NanoBiophotonics, Max Planck Institute
for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Stephan E. Lehnart
- Department
of Cardiology & Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Robert-Koch-Strasse 42a, Göttingen 37075, Germany
- German
Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen 37075, Germany
| |
Collapse
|
4
|
Brandenburg S, Pawlowitz J, Steckmeister V, Subramanian H, Uhlenkamp D, Scardigli M, Mushtaq M, Amlaz SI, Kohl T, Wegener JW, Arvanitis DA, Sanoudou D, Sacconi L, Hasenfuss G, Voigt N, Nikolaev VO, Lehnart SE. A junctional cAMP compartment regulates rapid Ca 2+ signaling in atrial myocytes. J Mol Cell Cardiol 2022; 165:141-157. [PMID: 35033544 DOI: 10.1016/j.yjmcc.2022.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 12/15/2021] [Accepted: 01/08/2022] [Indexed: 10/19/2022]
Abstract
Axial tubule junctions with the sarcoplasmic reticulum control the rapid intracellular Ca2+-induced Ca2+ release that initiates atrial contraction. In atrial myocytes we previously identified a constitutively increased ryanodine receptor (RyR2) phosphorylation at junctional Ca2+ release sites, whereas non-junctional RyR2 clusters were phosphorylated acutely following β-adrenergic stimulation. Here, we hypothesized that the baseline synthesis of 3',5'-cyclic adenosine monophosphate (cAMP) is constitutively augmented in the axial tubule junctional compartments of atrial myocytes. Confocal immunofluorescence imaging of atrial myocytes revealed that junctin, binding to RyR2 in the sarcoplasmic reticulum, was densely clustered at axial tubule junctions. Interestingly, a new transgenic junctin-targeted FRET cAMP biosensor was exclusively co-clustered in the junctional compartment, and hence allowed to monitor cAMP selectively in the vicinity of junctional RyR2 channels. To dissect local cAMP levels at axial tubule junctions versus subsurface Ca2+ release sites, we developed a confocal FRET imaging technique for living atrial myocytes. A constitutively high adenylyl cyclase activity sustained increased local cAMP levels at axial tubule junctions, whereas β-adrenergic stimulation overcame this cAMP compartmentation resulting in additional phosphorylation of non-junctional RyR2 clusters. Adenylyl cyclase inhibition, however, abolished the junctional RyR2 phosphorylation and decreased L-type Ca2+ channel currents, while FRET imaging showed a rapid cAMP decrease. In conclusion, FRET biosensor imaging identified compartmentalized, constitutively augmented cAMP levels in junctional dyads, driving both the locally increased phosphorylation of RyR2 clusters and larger L-type Ca2+ current density in atrial myocytes. This cell-specific cAMP nanodomain is maintained by a constitutively increased adenylyl cyclase activity, contributing to the rapid junctional Ca2+-induced Ca2+ release, whereas β-adrenergic stimulation overcomes the junctional cAMP compartmentation through cell-wide activation of non-junctional RyR2 clusters.
Collapse
Affiliation(s)
- Sören Brandenburg
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany; DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany.
| | - Jan Pawlowitz
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Vanessa Steckmeister
- Heart Research Center Göttingen, Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany
| | - Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Dennis Uhlenkamp
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Marina Scardigli
- Department of Physics and Astronomy, University of Florence, Florence, Italy; European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy
| | - Mufassra Mushtaq
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Saskia I Amlaz
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
| | - Tobias Kohl
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
| | - Jörg W Wegener
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
| | - Demetrios A Arvanitis
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Despina Sanoudou
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy; Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Gerd Hasenfuss
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany; DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
| | - Niels Voigt
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany; Heart Research Center Göttingen, Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany
| | - Stephan E Lehnart
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, Department of Cardiology & Pneumology, University Medical Center Göttingen, Göttingen, Germany; DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany; BioMET, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| |
Collapse
|
5
|
Wegener JW, Wagdi A, Wagner E, Katschinski DM, Hasenfuss G, Bruegmann T, Lehnart SE. The RyR2-R2474S Mutation Sensitizes Cardiomyocytes and Hearts to Catecholaminergic Stress-Induced Oxidation of the Mitochondrial Glutathione Pool. Front Physiol 2021; 12:777770. [PMID: 34955889 PMCID: PMC8696262 DOI: 10.3389/fphys.2021.777770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/19/2021] [Indexed: 11/24/2022] Open
Abstract
Missense mutations in the cardiac ryanodine receptor type 2 (RyR2) characteristically cause catecholaminergic arrhythmias. Reminiscent of the phenotype in patients, RyR2-R2474S knockin mice develop exercise-induced ventricular tachyarrhythmias. In cardiomyocytes, increased mitochondrial matrix Ca2+ uptake was recently linked to non-linearly enhanced ATP synthesis with important implications for cardiac redox metabolism. We hypothesize that catecholaminergic stimulation and contractile activity amplify mitochondrial oxidation pathologically in RyR2-R2474S cardiomyocytes. To investigate this question, we generated double transgenic RyR2-R2474S mice expressing a mitochondria-restricted fluorescent biosensor to monitor the glutathione redox potential (EGSH). Electrical field pacing-evoked RyR2-WT and RyR2-R2474S cardiomyocyte contractions resulted in a small but significant baseline EGSH increase. Importantly, β-adrenergic stimulation resulted in excessive EGSH oxidization of the mitochondrial matrix in RyR2-R2474S cardiomyocytes compared to baseline and RyR2-WT control. Physiologically β-adrenergic stimulation significantly increased mitochondrial EGSH further in intact beating RyR2-R2474S but not in RyR2-WT control Langendorff perfused hearts. Finally, this catecholaminergic EGSH increase was significantly attenuated following treatment with the RyR2 channel blocker dantrolene. Together, catecholaminergic stimulation and increased diastolic Ca2+ leak induce a strong, but dantrolene-inhibited mitochondrial EGSH oxidization in RyR2-R2474S cardiomyocytes.
Collapse
Affiliation(s)
- Jörg W Wegener
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), Georg-August University of Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Ahmed Wagdi
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.,Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany
| | - Eva Wagner
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany
| | - Dörthe M Katschinski
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.,Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany
| | - Gerd Hasenfuss
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Tobias Bruegmann
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), Georg-August University of Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.,Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany
| | - Stephan E Lehnart
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), Georg-August University of Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| |
Collapse
|
6
|
Berisha F, Götz KR, Wegener JW, Brandenburg S, Subramanian H, Molina CE, Rüffer A, Petersen J, Bernhardt A, Girdauskas E, Jungen C, Pape U, Kraft AE, Warnke S, Lindner D, Westermann D, Blankenberg S, Meyer C, Hasenfuß G, Lehnart SE, Nikolaev VO. cAMP Imaging at Ryanodine Receptors Reveals β 2-Adrenoceptor Driven Arrhythmias. Circ Res 2021; 129:81-94. [PMID: 33902292 DOI: 10.1161/circresaha.120.318234] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
[Figure: see text].
Collapse
Affiliation(s)
- Filip Berisha
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (F.B., H.S., C.E.M., A.E.K., V.O.N.).,Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Konrad R Götz
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, Georg August University Medical Center, Germany (K.R.G., J.W.W., S. Brandenburg, G.H., S.E.L.)
| | - Jörg W Wegener
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, Georg August University Medical Center, Germany (K.R.G., J.W.W., S. Brandenburg, G.H., S.E.L.).,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany (J.W.W., S. Brandenburg, G.H., S.E.L.)
| | - Sören Brandenburg
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, Georg August University Medical Center, Germany (K.R.G., J.W.W., S. Brandenburg, G.H., S.E.L.).,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany (J.W.W., S. Brandenburg, G.H., S.E.L.)
| | - Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (F.B., H.S., C.E.M., A.E.K., V.O.N.).,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Cristina E Molina
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (F.B., H.S., C.E.M., A.E.K., V.O.N.).,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - André Rüffer
- Department of Cardiovascular Surgery, University Heart and Vascular Center Hamburg, Germany (A.R., J.P., A.B., E.G.)
| | - Johannes Petersen
- Department of Cardiovascular Surgery, University Heart and Vascular Center Hamburg, Germany (A.R., J.P., A.B., E.G.)
| | - Alexander Bernhardt
- Department of Cardiovascular Surgery, University Heart and Vascular Center Hamburg, Germany (A.R., J.P., A.B., E.G.)
| | - Evaldas Girdauskas
- Department of Cardiovascular Surgery, University Heart and Vascular Center Hamburg, Germany (A.R., J.P., A.B., E.G.)
| | - Christiane Jungen
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology-Electrophysiology, cNEP (Cardiac Neuro- and Electrophysiology Research Group) (C.J., U.P., C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ulrike Pape
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology-Electrophysiology, cNEP (Cardiac Neuro- and Electrophysiology Research Group) (C.J., U.P., C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Axel E Kraft
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (F.B., H.S., C.E.M., A.E.K., V.O.N.).,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Svenja Warnke
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Diana Lindner
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Dirk Westermann
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Stefan Blankenberg
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| | - Christian Meyer
- Department of Cardiology (F.B., C.J., U.P., S.W., D.L., D.W., S. Blankenberg, C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology-Electrophysiology, cNEP (Cardiac Neuro- and Electrophysiology Research Group) (C.J., U.P., C.M.), University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gerd Hasenfuß
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, Georg August University Medical Center, Germany (K.R.G., J.W.W., S. Brandenburg, G.H., S.E.L.).,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany (J.W.W., S. Brandenburg, G.H., S.E.L.)
| | - Stephan E Lehnart
- DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany (J.W.W., S. Brandenburg, G.H., S.E.L.)
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (F.B., H.S., C.E.M., A.E.K., V.O.N.).,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (F.B., H.S., C.E.M., A.E., S.W., D.L., D.W., S. Blankenberg, V.O.N.)
| |
Collapse
|
7
|
Dongmo AB, Nkeng-Efouet PA, Devkota KP, Wegener JW, Sewald N, Wagner H, Vierling W. Tetra-acetylajugasterone a new constituent of Vitex cienkowskii with vasorelaxant activity. Phytomedicine 2014; 21:787-792. [PMID: 24680617 DOI: 10.1016/j.phymed.2014.02.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/16/2014] [Accepted: 02/24/2014] [Indexed: 06/03/2023]
Abstract
Tetra-acetylajugasterone C (TAAC) was found to be one of the naturally occurring compounds of the Cameroonian medicinal plant Vitex cienkowskii which is responsible for a vasorelaxant activity of an extract of this plant. The evaluation of the underlying mechanisms for the relaxing effect of TAAC was determined using aortic rings of rats and mice. TAAC produced a concentration-dependent relaxation in rat artery rings pre-contracted with 1μM noradrenaline (IC50: 8.40μM) or 60mM KCl (IC50: 36.30μM). The nitric oxide synthase inhibitor l-NAME (100μM) and the soluble guanylate cyclase inhibitor ODQ (10μM) significantly attenuated the vasodilatory effect of TAAC. TAAC also exerted a relaxing effect in aorta of wild-type mice (cGKI(+/+); IC50=13.04μM) but a weaker effect in aorta of mice lacking cGMP-dependent protein kinase I (cGKI(-/-); IC50=36.12μM). The involvement of calcium channels was studied in rings pre-incubated in calcium-free buffer and primed with 1μM noradrenaline prior to addition of calcium to elicit contraction. TAAC (100μM) completely inhibited the resulting calcium-induced vasoconstriction. The same concentration of TAAC showed a stronger effect on the tonic than on the phasic component of noradrenaline-induced contraction. This study shows that TAAC, a newly detected constituent of Vitex cienkowskii contributes to the relaxing effect of an extract of the plant. The effect is partially mediated by the involvement of the NO/cGMP pathway of the smooth muscle but additionally inhibition of calcium influx into the cell may play a role.
Collapse
Affiliation(s)
- Alain Bertrand Dongmo
- Department of Animal Biology, Faculty of Science, University of Douala, P.O. Box 24157, Douala, Cameroon.
| | | | - Krishna Prasad Devkota
- Institute of Forestry, Tribhuvan University, Pokhara Campus, P.O. Box 43, Pokhara, Nepal
| | - Jörg W Wegener
- Institute of Pharmacology and Toxicology, Technical University of Munich, Biedersteiner Str. 29, 80802 Munich, Germany
| | - Norbert Sewald
- Chemistry Department, Organic and Bioorganic Chemistry, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany
| | - Hildebert Wagner
- Institute of Pharmaceutical Biology, Butenandt Str. 5 - 13 B, 81377 Munich, Germany
| | - Wolfgang Vierling
- Institute of Pharmacology and Toxicology, Technical University of Munich, Biedersteiner Str. 29, 80802 Munich, Germany
| |
Collapse
|
8
|
Wegener JW, Loga F, Stegner D, Nieswandt B, Hofmann F. Phospholipase D1 is involved in α‐adrenergic contraction of murine vascular smooth muscle. FASEB J 2014; 28:1044-8. [DOI: 10.1096/fj.13-237925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jörg W. Wegener
- For 923, Institut für Pharmakologie and Toxikologie, Technische Universität MünchenMünchenGermany
| | - Florian Loga
- For 923, Institut für Pharmakologie and Toxikologie, Technische Universität MünchenMünchenGermany
| | - David Stegner
- Lehrstuhl für Experimentelle BiomedizinUniversitätsklinikum Würzburg and Rudolf‐Virchow‐ZentrumDeutsche Forschungsgemeinschaft (DFG) Forschungszentrum für Experimentelle BiomedizinUniversität WürzburgWürzburgGermany
| | - Bernhard Nieswandt
- Lehrstuhl für Experimentelle BiomedizinUniversitätsklinikum Würzburg and Rudolf‐Virchow‐ZentrumDeutsche Forschungsgemeinschaft (DFG) Forschungszentrum für Experimentelle BiomedizinUniversität WürzburgWürzburgGermany
| | - Franz Hofmann
- For 923, Institut für Pharmakologie and Toxikologie, Technische Universität MünchenMünchenGermany
| |
Collapse
|
9
|
Abstract
The L-type Cav1.2 calcium channel is present throughout the animal kingdom and is essential for some aspects of CNS function, cardiac and smooth muscle contractility, neuroendocrine regulation, and multiple other processes. The L-type CaV1.2 channel is built by up to four subunits; all subunits exist in various splice variants that potentially affect the biophysical and biological functions of the channel. Many of the CaV1.2 channel properties have been analyzed in heterologous expression systems including regulation of the L-type CaV1.2 channel by Ca(2+) itself and protein kinases. However, targeted mutations of the calcium channel genes confirmed only some of these in vitro findings. Substitution of the respective serines by alanine showed that β-adrenergic upregulation of the cardiac CaV1.2 channel did not depend on the phosphorylation of the in vitro specified amino acids. Moreover, well-established in vitro phosphorylation sites of the CaVβ2 subunit of the cardiac L-type CaV1.2 channel were found to be irrelevant for the in vivo regulation of the channel. However, the molecular basis of some kinetic properties, such as Ca(2+)-dependent inactivation and facilitation, has been approved by in vivo mutagenesis of the CaV1.2α1 gene. This article summarizes recent findings on the in vivo relevance of well-established in vitro results.
Collapse
|
10
|
Loga F, Domes K, Freichel M, Flockerzi V, Dietrich A, Birnbaumer L, Hofmann F, Wegener JW. Evidence for functional coupling of cGMP/cGKI signalling and TRPC channels in endothelium but not in vascular smooth muscle. BMC Pharmacol Toxicol 2013. [PMCID: PMC3765511 DOI: 10.1186/2050-6511-14-s1-p40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
11
|
Hofmann F, Loga F, Domes K, Patrucco E, Wegener JW. cGMP kinase: past, presence and future. BMC Pharmacol Toxicol 2013. [PMCID: PMC3765556 DOI: 10.1186/2050-6511-14-s1-o11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
12
|
Loga F, Domes K, Freichel M, Flockerzi V, Dietrich A, Birnbaumer L, Hofmann F, Wegener JW. The role of cGMP/cGKI signalling and Trpc channels in regulation of vascular tone. Cardiovasc Res 2013; 100:280-7. [PMID: 23832809 DOI: 10.1093/cvr/cvt176] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [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] [Indexed: 12/21/2022] Open
Abstract
AIMS Signalling via cGMP-dependent protein kinase I (cGKI) is the major pathway in vascular smooth muscle (SM), by which endothelial NO regulates vascular tone. Recent evidence suggests that canonical transient receptor potential (Trpc) channels are targets of cGKI in SM and mediate the relaxant effects of cGMP signalling. We tested this concept by investigating the role of cGMP/cGKI signalling on vascular tone and peripheral resistance using Trpc6(-/-), Trpc3(-/-), Trpc3(-/-)/6(-/-), Trpc1(-/-)/3(-/-)/6(-/-), and SM-specific cGKI(-/-) (sm-cGKI(-/-)) mice. METHODS AND RESULTS α-Adrenergic stimulation induced similar contractions in L-NG-nitroarginine methyl ester (l-NAME)-treated aorta and comparably increased peripheral pressure in hind limbs from all mouse lines investigated. After α-adrenergic stimulation, 8-Br-cGMP diminished similarly aortic tone and peripheral pressure in control, Trpc6(-/-), Trpc3(-/-), Trpc3(-/-)/6(-/-), and Trpc1(-/-)/3(-/-)/6(-/-) mice but not in sm-cGKI(-/-) mice. In untreated aorta, α-adrenergic stimulation induced similar contractions in the aorta from control and Trpc3(-/-) mice but larger contractions in sm-cGKI(-/-), Trpc6(-/-), Trpc3(-/-)/6(-/-), and Trpc1(-/-)/3(-/-)/6(-/-) mice, indicating a functional link between cGKI and Trpc6 channels. Trpc3 channels were detected by immunocytochemistry in both isolated aortic smooth muscle cells (SMCs) and aortic endothelial cells (ECs), whereas Trpc6 channels were detected only in ECs. Phenylephrine-stimulated Ca(2+) levels were similar in SMCs from control (Ctr) and Trpc6(-/-) mice. Carbachol-stimulated Ca(2+) levels were reduced in ECs from Trpc6(-/-) mice. Stimulated Ca(2+) levels were lowered by 8-Br-cGMP in Ctr but not in Trpc6(-/-) ECs. CONCLUSIONS The results suggest that cGKI and Trpc1,3,6 channels are not functionally coupled in vascular SM. Deletion of Trpc6 channels impaired endothelial cGKI signalling and vasodilator tone in the aorta.
Collapse
Affiliation(s)
- Florian Loga
- FOR 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29., 80802 Munich, Germany
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Abstract
cGMP-dependent protein kinases (cGK) are serine/threonine kinases that are widely distributed in eukaryotes. Two genes-prkg1 and prkg2-code for cGKs, namely, cGKI and cGKII. In mammals, two isozymes, cGKIα and cGKIβ, are generated from the prkg1 gene. The cGKI isozymes are prominent in all types of smooth muscle, platelets, and specific neuronal areas such as cerebellar Purkinje cells, hippocampal neurons, and the lateral amygdala. The cGKII prevails in the secretory epithelium of the small intestine, the juxtaglomerular cells, the adrenal cortex, the chondrocytes, and in the nucleus suprachiasmaticus. Both cGKs are major downstream effectors of many, but not all, signalling events of the NO/cGMP and the ANP/cGMP pathways. cGKI relaxes smooth muscle tone and prevents platelet aggregation, whereas cGKII inhibits renin secretion, chloride/water secretion in the small intestine, the resetting of the clock during early night, and endochondral bone growth. This chapter focuses on the involvement of cGKs in cardiovascular and non-cardiovascular processes including cell growth and metabolism.
Collapse
Affiliation(s)
- Franz Hofmann
- FOR 923, Institut für Pharmakologie und Toxikologie, der Technischen Universität München, Munich, Germany
| | | |
Collapse
|
14
|
Blaich A, Pahlavan S, Tian Q, Oberhofer M, Poomvanicha M, Lenhardt P, Domes K, Wegener JW, Moosmang S, Ruppenthal S, Scholz A, Lipp P, Hofmann F. Mutation of the calmodulin binding motif IQ of the L-type Ca(v)1.2 Ca2+ channel to EQ induces dilated cardiomyopathy and death. J Biol Chem 2012; 287:22616-25. [PMID: 22589547 DOI: 10.1074/jbc.m112.357921] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cardiac excitation-contraction coupling (EC coupling) links the electrical excitation of the cell membrane to the mechanical contractile machinery of the heart. Calcium channels are major players of EC coupling and are regulated by voltage and Ca(2+)/calmodulin (CaM). CaM binds to the IQ motif located in the C terminus of the Ca(v)1.2 channel and induces Ca(2+)-dependent inactivation (CDI) and facilitation (CDF). Mutation of Ile to Glu (Ile1624Glu) in the IQ motif abolished regulation of the channel by CDI and CDF. Here, we addressed the physiological consequences of such a mutation in the heart. Murine hearts expressing the Ca(v)1.2(I1624E) mutation were generated in adult heterozygous mice through inactivation of the floxed WT Ca(v)1.2(L2) allele by tamoxifen-induced cardiac-specific activation of the MerCreMer Cre recombinase. Within 10 days after the first tamoxifen injection these mice developed dilated cardiomyopathy (DCM) accompanied by apoptosis of cardiac myocytes (CM) and fibrosis. In Ca(v)1.2(I1624E) hearts, the activity of phospho-CaM kinase II and phospho-MAPK was increased. CMs expressed reduced levels of Ca(v)1.2(I1624E) channel protein and I(Ca). The Ca(v)1.2(I1624E) channel showed "CDI" kinetics. Despite a lower sarcoplasmic reticulum Ca(2+) content, cellular contractility and global Ca(2+) transients remained unchanged because the EC coupling gain was up-regulated by an increased neuroendocrine activity. Treatment of mice with metoprolol and captopril reduced DCM in Ca(v)1.2(I1624E) hearts at day 10. We conclude that mutation of the IQ motif to IE leads to dilated cardiomyopathy and death.
Collapse
Affiliation(s)
- Anne Blaich
- Forschergruppe, Institut für Pharmakologie und Toxikologie, Technische Universität München, 80802 München, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Brandmayr J, Poomvanicha M, Domes K, Ding J, Blaich A, Wegener JW, Moosmang S, Hofmann F. Deletion of the C-terminal phosphorylation sites in the cardiac β-subunit does not affect the basic β-adrenergic response of the heart and the Ca(v)1.2 channel. J Biol Chem 2012; 287:22584-92. [PMID: 22589548 DOI: 10.1074/jbc.m112.366484] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Phosphorylation of the cardiac β subunit (Ca(v)β(2)) of the Ca(v)1.2 L-type Ca(2+) channel complex has been proposed as a mechanism for regulation of L-type Ca(2+) channels by various protein kinases including PKA, CaMKII, Akt/PKB, and PKG. To test this hypothesis directly in vivo, we generated a knock-in mouse line with targeted mutation of the Ca(v)β(2) gene by insertion of a stop codon after proline 501 in exon 14 (mouse sequence Cacnb2; βStop mouse). This mutation prevented translation of the Ca(v)β(2) C terminus that contains the relevant phosphorylation sites for the above protein kinases. Homozygous cardiac βStop mice were born at Mendelian ratio, had a normal life expectancy, and normal basal L-type I(Ca). The regulation of the L-type current by stimulation of the β-adrenergic receptor was unaffected in vivo and in cardiomyocytes (CMs). βStop mice were cross-bred with mice expressing the Ca(v)1.2 gene containing the mutation S1928A (SAβStop) or S1512A and S1570A (SFβStop) in the C terminus of the α(1C) subunit. The β-adrenergic regulation of the cardiac I(Ca) was unaltered in these mouse lines. In contrast, truncation of the Ca(v)1.2 at Asp(1904) abolished β-adrenergic up-regulation of I(Ca) in murine embryonic CMs. We conclude that phosphorylation of the C-terminal sites in Ca(v)β(2), Ser(1928), Ser(1512), and Ser(1570) of the Ca(v)1.2 protein is functionally not involved in the adrenergic regulation of the murine cardiac Ca(v)1.2 channel.
Collapse
Affiliation(s)
- Julia Brandmayr
- Forschergruppe 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, 80802 München, Germany
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Singh AK, Spiessberger B, Zheng W, Xiao F, Lukowski R, Wegener JW, Weinmeister P, Saur D, Klein S, Schemann M, Krueger D, Seidler U, Hofmann F. Neuronal cGMP kinase I is essential for stimulation of duodenal bicarbonate secretion by luminal acid. FASEB J 2012; 26:1745-54. [PMID: 22253479 DOI: 10.1096/fj.11-200394] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Brief contact of the duodenal mucosa with luminal acid elicits a long-lasting bicarbonate (HCO(3)(-)) secretory response, which is believed to be the primary protective mechanism against mucosal damage. Here, we show that cGMP-dependent protein kinase type I-knockout (cGKI(-/-)) mice are unable to respond to a physiological H(+) stimulus with a HCO(3)(-) secretory response and spontaneously develop duodenal ulcerations. Smooth muscle-selective cGKI knock-in rescued the motility disturbance but not the defective HCO(3)(-) secretion. Proton-induced HCO(3)(-) secretion was not attenuated by selective inactivation of the cGKI gene in interstitial cells of Cajal or in enterocytes, but was abolished by inactivation of cGKI in neurons (ncGKI(-/-)). cGKI was expressed in the brainstem nucleus tractus solitarius that connects the afferent with the efferent N. vagus. Accordingly, truncation of the subdiaphragmal N. vagus significantly diminished proton-induced HCO(3)(-) secretion in wild-type mice, whereas stimulation of the subdiaphragmal N. vagus elicited a similar HCO(3)(-) secretory response in cGKI(-/-), ncGKI(-/-) and wild-type mice. These findings show that protection of the duodenum from acid injury requires neuronal cGKI.
Collapse
Affiliation(s)
- Anurag Kumar Singh
- Department of Gastroenterology, Hepatology, and Endocrinology, Hannover Medical School, Hannover, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Ertl C, Lukowski R, Sigl K, Schlossmann J, Hofmann F, Wegener JW. Kinetics of relaxation by cGMP/cGKI signaling in fundus smooth muscle. Eur J Pharmacol 2011; 670:266-71. [PMID: 21914444 DOI: 10.1016/j.ejphar.2011.07.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/14/2011] [Accepted: 07/30/2011] [Indexed: 01/17/2023]
Abstract
cGMP-dependent kinase I (cGKI) is a major mediator of smooth muscle relaxation and exists in two isoforms, α and β. Both isoforms are supposed to mediate their effects via different intracellular signaling pathways. To verify this concept, the kinetics of relaxation mediated by either isoform was analyzed in gastric fundus smooth muscle from mice. Muscles from mice that express selectively the Iα or Iβ isoform of cGKI in smooth muscle (sm-cGKIα or sm-cGKIβ mice) were compared to muscles from conventional cGKI(-/-) mice. Fundus muscles were contracted by carbachol and then relaxed by 8-Br-cGMP or by electrical field stimulation (EFS). The time course of relaxation by 8-Br-cGMP was not different between muscles from sm-cGKIα and sm-cGKIβ mice. EFS induced a fast transient relaxation in muscles from sm-cGKIα and sm-cGKIβ mice that was blocked by the NO synthase inhibitor L-NAME. Recovery from this relaxation was about 4-times slower in muscles from sm-cGKIα mice than in muscles from sm-cGKIβ mice. The different kinetic of recovery from relaxation after EFS in sm-cGKIα and sm-cGKIβ mice suggests that different signaling pathways exist for each cGKI isoform in vivo in fundus muscles.
Collapse
Affiliation(s)
- Claudia Ertl
- FOR923, Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
| | | | | | | | | | | |
Collapse
|
18
|
Domes K, Ding J, Lemke T, Blaich A, Wegener JW, Brandmayr J, Moosmang S, Hofmann F. Truncation of murine CaV1.2 at Asp-1904 results in heart failure after birth. J Biol Chem 2011; 286:33863-71. [PMID: 21832054 DOI: 10.1074/jbc.m111.252312] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The carboxyl-terminal intracellular tail of the L-type Ca(2+) channel CaV1.2 modulates various aspects of channel activity.For example, deletion of the carboxyl-terminal sequence at Ser-1905 increased CaV1.2 currents in an expression model. To verify this finding in an animal model, we inserted three stop codons at the corresponding Asp-1904 in the murine CaV1.2 gene. Mice homozygous for the Stop mutation (Stop/Stop mice)were born at a Mendelian ratio but died after birth. Stop/Stop hearts showed reduced beating frequencies and contractions.Surprisingly, Stop/Stop cardiomyocytes displayed reduced IBa and a minor expression of the CaV1.2Stop protein. In contrast,expression of the CaV1.2Stop protein was normal in pooled smooth muscle samples from Stop/Stop embryos. As the CaV1.2 channel exists in a cardiac and smooth muscle splice variant, HK1 and LK1, respectively, we analyzed the consequences of the deletion of the carboxyl terminus in the respective splice variant using the rabbit CaV1.2 clone expressed in HEK293 cells.HEK293 cells transfected with the HK1Stop channel showed a reduced IBa and CaV1.2 expression. Treatment with proteasome inhibitors increased the expression of HK1Stop protein and IBa in HEK293 cells and in Stop/Stop cardiomyocytes indicating that truncation of CaV1.2 containing the cardiac exon 1a amino terminus results in proteasomal degradation of the translated protein. In contrast, HEK293 cells transfected with the LK1Stop channel had normal IBa and CaV1.2 expression. These findings indicate that absence of the carboxyl-terminal tail differentially determines the fate of the cardiac and smooth muscle splice variant of the CaV1.2 channel in the mouse.
Collapse
Affiliation(s)
- Katrin Domes
- From the Forschergruppe 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Strasse 29, 80802 München, Germany
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Poomvanicha M, Wegener JW, Blaich A, Fischer S, Domes K, Moosmang S, Hofmann F. Facilitation and Ca2+-dependent inactivation are modified by mutation of the Ca(v)1.2 channel IQ motif. J Biol Chem 2011; 286:26702-7. [PMID: 21665954 DOI: 10.1074/jbc.m111.247841] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heart muscle responds to physiological needs with a short-term modulation of cardiac contractility. This process is determined mainly by properties of the cardiac L-type Ca(2+) channel (Ca(v)1.2), including facilitation and Ca(2+)-dependent inactivation (CDI). Both facilitation and CDI involve the interaction of calmodulin with the IQ motif of the Ca(v)1.2 channel, especially with Ile-1624. To verify this hypothesis, we created a mouse line in which Ile-1624 was mutated to Glu (Ca(v)1.2(I1624E) mice). Homozygous Ca(v)1.2(I1624E) mice were not viable. Therefore, we inactivated the floxed Ca(v)1.2 gene of heterozygous Ca(v)1.2(I1624E) mice by the α-myosin heavy chain-MerCreMer system. The resulting I/E mice were studied at day 10 after treatment with tamoxifen. Electrophysiological recordings in ventricular cardiomyocytes revealed a reduced Ca(v)1.2 current (I(Ca)) density in I/E mice. Steady-state inactivation and recovery from inactivation were modified in I/E versus control mice. In addition, voltage-dependent facilitation was almost abolished in I/E mice. The time course of I(Ca) inactivation in I/E mice was not influenced by the use of Ba(2+) as a charge carrier. Using 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid as a chelating agent for intracellular Ca(2+), inactivation of I(Ca) was slowed down in control but not I/E mice. The results show that the I/E mutation abolishes Ca(2+)/calmodulin-dependent regulation of Ca(v)1.2. The Ca(v)1.2(I1624E) mutation transforms the channel to a phenotype mimicking CDI.
Collapse
Affiliation(s)
- Montatip Poomvanicha
- Forschergruppe 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, 80802 Munich, Germany
| | | | | | | | | | | | | |
Collapse
|
20
|
Wegener JW, David S, Nieswandt B, Hofmann F. Phospholipase D regulates vascular smooth muscle tone in mice. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1115.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jörg W Wegener
- PharmacologyTechnische Universität MünchenMünchenGermany
| | | | | | - Franz Hofmann
- PharmacologyTechnische Universität MünchenMünchenGermany
| |
Collapse
|
21
|
Abstract
Here we present functional and biochemical evidence for a Ca(2+) channel (Ca(V)1.2)/protein kinase C (PKC) signaling complex being a key player in muscarinic regulation of urinary bladder smooth muscle. Muscarinic stimulation induced Ca(2+) signals and concomitant contractions in detrusor muscle from mice that were dependent on functional Ca(2+) channels. These signals were still present in muscles being depolarized by 85 mM extracellular K(+). Muscarinic-induced contractions were reduced by a PKC inhibitor [bisindolylmaleimide I (BIM-I)] and a phospholipase D (PLD) inhibitor (1-butanol). A phorbol ester (PDBu) enlarged muscarinic-induced Ca(2+) signals and contractions. The effects of BIM-I and PDBu were inhibited by isradipine and/or absent in muscles from Ca(V)1.2-deficient mice. Both carbachol and PDBu increased Ca(V)1.2 channel currents in isolated bladder myocytes. Blue native-PAGE electrophoresis revealed that Ca(V)1.2, PKC, and PLD are closely associated in muscles being previously stimulated by carbachol. Immunoprecipitation using anti-Ca(V)1.2 followed by Western blotting demonstrated that Ca(V)1.2 and PKC are coupled in stimulated muscles from wild-type mice. Autoradiography on immunoprecipitates showed that Ca(V)1.2 is a substrate for PKC-mediated phosphorylation. These findings suggest that a signaling complex consisting of Ca(V)1.2, PKC, and, probably, PLD controls muscarinic-mediated phasic contraction of urinary bladder smooth muscle.
Collapse
Affiliation(s)
- Maria Huster
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802 Munich, Germany
| | | | | | | |
Collapse
|
22
|
Desch M, Sigl K, Hieke B, Salb K, Kees F, Bernhard D, Jochim A, Spiessberger B, Höcherl K, Feil R, Feil S, Lukowski R, Wegener JW, Hofmann F, Schlossmann J. IRAG determines nitric oxide- and atrial natriuretic peptide-mediated smooth muscle relaxation. Cardiovasc Res 2010; 86:496-505. [PMID: 20080989 DOI: 10.1093/cvr/cvq008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Nitric oxide (NO) and atrial natriuretic peptide (ANP) signalling via cGMP controls smooth muscle tone. One important signalling pathway of cGMP-dependent protein kinase type I (cGKI) is mediated by IRAG (IP(3) receptor associated cGKI substrate) which is highly expressed in smooth muscle tissues. To elucidate the role of IRAG for NO- and ANP-mediated smooth muscle tone regulation, cGKI localization, and for its possible function in blood pressure adjustment, we generated IRAG-knockout mice by targeted deletion of exon 3. METHODS AND RESULTS IRAG deletion prevented stable interaction of IP(3) receptor type I (IP(3)RI) with cGKIbeta determined by cGMP affinity chromatography. Confocal microscopy in vascular smooth muscle cells (VSMCs) showed that localization of cGKIbeta and cGKIalpha did not change in absence of IRAG. NO-, ANP-, and cGMP-dependent relaxation of hormone-contracted aortic vessels and colon was significantly affected in IRAG-knockout mice. The suppression of cGMP-induced relaxation was not rescued by selective expression of cGKIbeta in smooth muscle from cGKIbeta-transgenic mice. NO-, ANP-, and cGMP-mediated inhibition of the hormone-induced increase in intracellular calcium concentration measured by Fura2 was suppressed in IRAG-deficient VSMC. Telemetric measurements revealed that IRAG-deficient animals exhibited normal basal tone, but were resistant to blood pressure reduction induced by lipopolysaccharide-treatment. CONCLUSION These findings indicate that signalling of cGKIbeta via IRAG is an essential functional part for regulation of smooth muscle tone and of intracellular calcium by NO (exogenously applicated or endogenously synthesized) and by ANP. IRAG signalling does not modulate basal tone but might be important for blood pressure regulation under pathophysiological conditions.
Collapse
Affiliation(s)
- Matthias Desch
- Pharmakologie und Toxikologie, Universität Regensburg, Universitätstr. 31, D-93055 Regensburg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Frei E, Huster M, Smital P, Schlossmann J, Hofmann F, Wegener JW. Calcium-dependent and calcium-independent inhibition of contraction by cGMP/cGKI in intestinal smooth muscle. Am J Physiol Gastrointest Liver Physiol 2009; 297:G834-9. [PMID: 19628652 DOI: 10.1152/ajpgi.00095.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
cGMP-dependent protein kinase I (cGKI) induces relaxation of smooth muscle via several pathways that include inhibition of intracellular Ca(2+) signaling and/or involve activation of myosin phosphatase. In the present study, we investigated these mechanisms comparatively in colon and jejunum longitudinal smooth muscle from mice. In simultaneous recordings from colon muscle, 8-bromo-cGMP (8-Br-cGMP) reduced both carbachol-induced tension and carbachol-induced increase in intracellular Ca(2+) concentration ([Ca(2+)](i)). These effects of 8-Br-cGMP were absent in colon from mice carrying a mutated inositol-1,4,5 trisphosphate receptor I-associated G kinase substrate (IRAG) gene or lacking cGKI. However, in jejunum, 8-Br-cGMP reduced carbachol-induced tension but did not change corresponding [Ca(2+)](i) signals. This setting was also observed in jejunum from mice carrying a mutated IRAG gene, whereas no response to 8-Br-cGMP was observed in jejunum from mice lacking cGKI. After inhibition of phosphatase activity by calyculin A, 8-Br-cGMP did not relax jejunum but still relaxed colon muscle. In Western blot analysis, 8-Br-cGMP reduced the signal for phosphorylated MYPT-1 in carbachol-stimulated jejunum but not in colon. These results suggest that cGMP/cGKI signaling differentially inhibits contraction in the muscles investigated: in jejunum, inhibition is performed without changing [Ca(2+)](i) and is dependent on phosphatase activity, whereas in colon, inhibition is mediated by inhibition of [Ca(2+)](i) signals.
Collapse
Affiliation(s)
- Eva Frei
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Munich, Germany
| | | | | | | | | | | |
Collapse
|
24
|
Frei E, Hofmann F, Wegener JW. Phospholipase C mediated Ca2+ signals in murine urinary bladder smooth muscle. Eur J Pharmacol 2009; 610:106-9. [PMID: 19303404 DOI: 10.1016/j.ejphar.2009.03.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 02/27/2009] [Accepted: 03/10/2009] [Indexed: 10/21/2022]
Abstract
Muscarinic stimulation of urinary bladder induces contraction via an increase in intracellular Ca(2+) concentration that results from Ca(2+) influx through Ca(2+) channels and/or IP(3)-mediated Ca(2+) release controlled by phospholipase C (PLC) signalling. The significance of PLC/IP(3) signalling in this cascade has recently been questioned because PLC inhibitors were without effect on carbachol-induced contractions in detrusor muscle strips. However, PLC/IP(3)-mediated Ca(2+) release was clearly observed in recordings of Ca(2+) signals in isolated myocytes. Therefore, we investigated the presence of PLC/IP(3)-dependent Ca(2+) release by directly monitoring Ca(2+) signals in intact detrusor muscle strips. Concomitant Ca(2+) signals from Ca(2+) channel activity were eliminated by the Ca(2+) channel antagonist isradipine (3 microM) or by the use of muscles from Ca(v)1.2 channel-deficient (SMACKO) mice. In absence of Ca(2+) channel activity, carbachol elicited contractions and Ca(2+) signals in muscles from wild type and SMACKO mice that were inhibited by the PLC inhibitor U73122 (10 microM). The results show that PLC/IP(3)-dependent Ca(2+) release is activated by stimulation with carbachol in urinary bladder smooth muscle but has a minor contribution to overall carbachol-induced Ca(2+) signals.
Collapse
Affiliation(s)
- Eva Frei
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, D-80802 München, Germany
| | | | | |
Collapse
|
25
|
Frei E, Huster M, Smital P, Schlossmann J, Hofmann F, Wegener JW. Different mechanisms of cGMP‐mediated relaxation in carbachol‐precontracted colon and jejunum smooth muscle from mice. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1206.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Eva Frei
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Maria Huster
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Petra Smital
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Jens Schlossmann
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Franz Hofmann
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Jörg W. Wegener
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| |
Collapse
|
26
|
Wegener JW, Huster M, Frei E, Hofmann F. Association of protein kinase C to the Ca
v
1.2 Ca
2+
channel improves muscarinic‐induced contraction of urinary bladder. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.937.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jörg W Wegener
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Maria Huster
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Eva Frei
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| | - Franz Hofmann
- Pharmakologie und ToxikologieTechnische Universität MünchenMünchenGermany
| |
Collapse
|
27
|
Angstenberger M, Wegener JW, Pichler BJ, Judenhofer MS, Feil S, Alberti S, Feil R, Nordheim A. Severe intestinal obstruction on induced smooth muscle-specific ablation of the transcription factor SRF in adult mice. Gastroenterology 2007; 133:1948-59. [PMID: 18054566 DOI: 10.1053/j.gastro.2007.08.078] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 08/16/2007] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS SRF (Serum Response Factor), a widely expressed transcription factor, controls expression of mitogen-responsive and muscle-specific genes, thereby regulating the contractile actin microfilament. Genetic Srf deletion studies showed SRF to be indispensable for in vivo skeletal and cardiac muscle cell development. We now investigated for the first time in vivo SRF functions in smooth muscle cells of adult mice. METHODS We conditionally deleted a floxed Srf allele (Srf(flex1)) in adult mice by inducible activation of the CreER(T2) recombinase expressed specifically in smooth muscle cells. Tamoxifen-induced CreER(T2) activity stimulated deletion of exon 1 coding sequences of Srf(flex1), thereby abolishing full-length SRF protein expression in adult smooth muscle cells of the analyzed organs: colon, bladder, and stomach. RESULTS Smooth muscle cell-specific ablation of full-length SRF protein in adult mice showed impaired contraction of intestinal smooth muscle, resulting in defective peristalsis. Mutant mice died within 2 weeks of tamoxifen treatment, displaying clear symptoms of ileus paralyticus. Cultured primary SRF-deficient colon smooth muscle cells were viable, but displayed drastic structural alterations and elevated senescence, paralleled by degeneration of the actin microfilament and impaired expression of smooth muscle-specific genes. CONCLUSIONS SRF plays a vital role in the contractile activity and cytoskeletal architecture of adult smooth muscle cells and is therefore essential for physiologic functions of the gastrointestinal tract in vivo. Our mouse genetic model may resemble features of human chronic intestinal pseudo-obstruction.
Collapse
Affiliation(s)
- Meike Angstenberger
- Interfaculty Institute for Cell Biology, Tuebingen University, Tuebingen, Germany
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Weber S, Bernhard D, Lukowski R, Weinmeister P, Wörner R, Wegener JW, Valtcheva N, Feil S, Schlossmann J, Hofmann F, Feil R. Rescue of cGMP kinase I knockout mice by smooth muscle specific expression of either isozyme. Circ Res 2007; 101:1096-103. [PMID: 17901360 DOI: 10.1161/circresaha.107.154351] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Smooth muscle expresses the Ialpha and the Ibeta isoforms of cGMP-dependent protein kinase I (cGKI). Inactivation of the murine cGKI gene prkg1 leads to multiple phenotypes and premature death at approximately 6 weeks. We reconstituted mice with the cGKIalpha or -Ibeta isozyme to test which isozyme was needed to support basic smooth muscle functions. Mice were generated by gene targeting. The cGKIalpha or the -Ibeta coding sequences were placed under the control of the SM22alpha promoter to express either isoform selectively in smooth muscle cells (SM-Ialpha or SM-Ibeta transgene). To generate smooth muscle-specific cGKIalpha or cGKIbeta rescue mice, the SM-Ialpha or SM-Ibeta transgenes were crossed on a cGKI-/- genetic background. The levels of cGKIalpha or -Ibeta expression were comparable to endogenous cGKI expression in wild-type aortic and intestinal smooth muscles. In cGKIalpha or -Ibeta rescue mice, expression of the isozymes was not detectable in non-smooth muscle tissues and cells. Median survival time of the Ialpha and Ibeta rescue mice was 52 weeks. Both isozymes mediated the 8-bromo-cGMP-induced relaxation of precontracted jejunum and aorta muscle strips. Activation of both isozymes reduced hormone- or K+-induced [Ca2+]i levels. The cGKIalpha and cGKIbeta rescue mice did not show a significant difference in intestinal passage time of BaSO4 in comparison with wild-type animals. Telemetric blood pressure measurements in conscious freely moving animals did not show differences between rescues and control mice in basal blood pressure and its regulation by DETA-NO, sodium nitroprusside, carbachol, or Y-27632. These results show that cGKI in smooth muscle is essential and that either cGKI isozyme alone can rescue basic vascular and intestinal smooth muscle functions.
Collapse
Affiliation(s)
- Silke Weber
- Institut für Pharmakologie und Toxikologie der Technischen Universität, Biedersteiner Str. 29, D-80802 München, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Hofmann F, Lukowski R, Bernhard D, Weinmeister P, Weber S, Feil S, Schlossmann J, Wegener JW, Feil R. Analysis of mice with genetic modifications of PKG I. BMC Pharmacol 2007. [DOI: 10.1186/1471-2210-7-s1-s15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
30
|
Desch MM, Sigl K, Spiessberger B, Bernhard D, Jochim A, Wegener JW, Hofmann F, Schlossmann J. Analysis of smooth muscle function in IRAG knockout mice. BMC Pharmacol 2007. [DOI: 10.1186/1471-2210-7-s1-p14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
31
|
Chandrinou S, Stasinakis AS, Thomaidis NS, Nikolaou A, Wegener JW. Distribution of organotin compounds in the bivalves of the Aegean Sea, Greece. Environ Int 2007; 33:226-32. [PMID: 17067676 DOI: 10.1016/j.envint.2006.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 09/04/2006] [Accepted: 09/18/2006] [Indexed: 05/12/2023]
Abstract
Five bivalve species--Mytilus galloprovinciallis (Mediterranean mussels), Venus gallina (stripped venus), Modiola barbatus L. (bearded horse mussels), Pecten jacobeus (scallops) and Callista chione (hard clams)--were collected from seven areas in Aegean Sea, Greece, between August 2001 and January 2003 and analyzed for organotins (OTs). The concentrations (as geometric means) found were 17.1 ng g-1 for tributyltin (TBT), 18.8 ng g-1 for dibutytltin (DBT), 7.8 ng g-1 for monobutyltin (MBT) and 13.0 ng g-1 for triphenyltin (TPhT) (wet weight), which are at similar or lower levels than those reported worldwide. Studying OTs distribution between different bivalve species, lower concentrations were observed in mediterranean mussels, possibly due to their growth in water column (grown on sea net pens in mussel farms), in contrast to the free-ranging species, collected from fishing grounds. Concentrations of the OTs in the examined bivalves varied seasonally.
Collapse
Affiliation(s)
- S Chandrinou
- Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, Panepistimioupolis Zografou, Athens 15 771, Greece
| | | | | | | | | |
Collapse
|
32
|
Abstract
GMP affects vascular tone by multiple mechanisms, including inhibition of the Rho/Rho kinase-mediated Ca(2+) sensitization, a process identified as Ca(2+) desensitization. Ca(2+) desensitization is mediated probably by both cGMP- and cAMP-dependent protein kinases (cGKI and PKA). We investigate to which extent Ca(2+) desensitization is initiated by cGKI and PKA. cGMP/cAMP-induced relaxation was studied at constant [Ca(2+)] in permeabilized aortas from wild-type and cGKI-deficient mice. [Ca(2+)] increased aortic tone in the absence and presence of 50 microM GTPgammaS with EC(50) values of 160 and 30 nM, respectively. In the absence of GTPgammaS, the EC(50) for [Ca(2+)] was shifted rightward from 0.16 microM to 0.43 and 0.82 microM by 1 and 300 microM 8-bromo-cGMP (8-Br-cGMP), and to 8 microM by 10 microM Y-27632. Contractions induced by 300 nM [Ca(2+)] were relaxed by 8-Br-cGMP with an EC(50) of 2.6 microM. Surprisingly, [Ca(2+)]-induced contractions were also relaxed by 8-Br-cGMP in aortas from cGKI(-/-) mice (EC(50) of 19 microM). Western blot analysis of the vasodilator-stimulated phosphoprotein indicated "cross"-activation of PKA by 1 mM 8-Br-cGMP in aortic smooth muscle cells from cGKI(-/-) mice. Indeed, the PKA inhibitor peptide (PKI 5-24) completely abolished the relaxant effect of 8-Br-cGMP in muscles from cGKI(-/-) mice and to 65% in wild-type aortas. The thromboxane analogue U-46619 induced contraction at constant [Ca(2+)], which was only partially relaxed by 8-Br-cGMP but completely relaxed by Y-27632. The effect of 8-Br-cGMP on U-46619-induced contraction was attenuated by PKI 5-24. These results show that cGKI has only a small inhibitory effect on Ca(2+) sensitization in murine aortas.
Collapse
Affiliation(s)
- René Wörner
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29, 80802 München, Germany
| | | | | | | |
Collapse
|
33
|
Abstract
Calcium influx through voltage gated L-type Ca2+ channels has evolved as one of the most widely used transmembrane signalling mechanisms in eukaryotic organisms. Although pharmacological inhibitors of L-type Ca2+ channels have an important place in medical therapy, the full therapeutic potential of the 4 L-type Ca2+ channel subtypes has not been explored yet. To dissect the physiological relevance of the L-type Ca2+ channel subtype diversity, gene-targeted mouse models carrying deletions of these channels ("knockout mice") have been generated. This review focuses on recent data from studies in mice lacking the Ca(v)1.2 and Ca(v)1.3 pore subunits, which have elucidated some of the roles of L-type Ca2+ channels as mediators of signalling between cell membrane and intracellular processes like blood pressure regulation, smooth muscle contractility, insulin secretion, cardiac development, and learning and memory.
Collapse
Affiliation(s)
- Sven Moosmang
- Institut für Pharmakologie, Technische Universität München, Biedersteiner Strasse 29, 80802, München, Germany.
| | | | | | | | | |
Collapse
|
34
|
Abstract
The Ca(v)1.2 L-type Ca2+ channel is the dominant voltage-activated Ca2+ channel in heart and smooth muscle. The functional significance of this channel was studied in intestinal smooth muscle from mice carrying a smooth muscle-specific, conditional inactivation of the Ca(v)1.2 gene (Ca(v)1.2SMACKO mice). Inactivation was complete within 4 wk after tamoxifen treatment and confirmed by RT-PCR, Western blot and functional analysis. Ca(v)1.2SMACKO mice show reduced feces excretion, absence of rhythmic contractions in small and large intestinal muscle and signs of paralytic ileus. Extracellular field stimulation evoked smaller contractions in jejunum muscles from Ca(v)1.2SMACKO than from CTR mice, whereas carbachol-induced contractions of similar magnitude in both muscles. The Ca2+ needed for contraction in jejunum was provided mainly by Ca(v)1.2 channels and by store-operated channels in muscles from CTR and Ca(v)1.2SMACKO mice, respectively. In conclusion, the Ca(v)1.2 channel is essential for electromechanical coupling and important for pharmaco-mechanical coupling in intestinal smooth muscle and cannot be substituted functionally by other Ca2+ entry pathways.
Collapse
Affiliation(s)
- Jörg W Wegener
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29, München 80802, Germany.
| | | | | | | | | | | |
Collapse
|
35
|
Wegener JW, Smital P, Schlossmann J, Hofmann F. IRAG is involved in cGMP/cGK-mediated relaxation of contractions induced by calcium entry. BMC Pharmacol 2005. [DOI: 10.1186/1471-2210-5-s1-p60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
36
|
Wörner R, Feil R, Hofmann F, Wegener JW. Protein kinase A mediates 8-Br-cGMP-induced Ca2+-desensitization in murine aorta. BMC Pharmacol 2005. [DOI: 10.1186/1471-2210-5-s1-p63] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
37
|
Welling A, Hofmann F, Wegener JW. Inhibition of L-Type Cav1.2 Ca2+Channels by 2,(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) and 2-[1-(3-Dimethyl-aminopropyl)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl) Maleimide (Gö6983). Mol Pharmacol 2004; 67:541-4. [PMID: 15537868 DOI: 10.1124/mol.104.006049] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phosphatidylinositol 3-kinase (PI3-K) is involved in physiological processes of cellular proliferation and inflammation and, as postulated recently, in the regulation of L-type Ca(2+) channels. The latter conclusion arose in part from the inhibitory action of the compound 2,(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), which has been established as a selective PI3-K inhibitor (IC(50) = 1.4 microM). Herein we show, however, that LY294002 and an inhibitor of protein kinase C (PKC), 2-[1-(3-dimethylaminopropyl)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl) maleimide (Go6983), act as direct Ca(2+)-channel inhibitors, with IC(50) values of approximately 20 and 10 microM, respectively. Because both drugs are commonly used at concentrations of approximately 10 microM or higher, the interpretation of such experiments is questionable with respect to a regulatory action of PI3-K or PKC on L-type Ca(2+) channels.
Collapse
Affiliation(s)
- A Welling
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29, 80802 München, Germany
| | | | | |
Collapse
|
38
|
Wegener JW, Schulla V, Lee TS, Koller A, Feil S, Feil R, Kleppisch T, Klugbauer N, Moosmang S, Welling A, Hofmann F. An essential role of Cav1.2 L-type calcium channel for urinary bladder function. FASEB J 2004; 18:1159-61. [PMID: 15132976 DOI: 10.1096/fj.04-1516fje] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mice deficient in the smooth muscle Cav1.2 calcium channel (SMACKO, smooth muscle alpha1c-subunit calcium channel knockout) have a severely reduced micturition and an increased bladder mass. L-type calcium current, protein, and spontaneous contractile activity were absent in the bladder of SMACKO mice. K+ and carbachol (CCh)-induced contractions were reduced to 10-fold in detrusor muscles from SMACKO mice. The dihydropyridine isradipine inhibited K+- and CCh-induced contractions of muscles from CTR but had no effect in muscles from SMACKO mice. CCh-induced contraction was blocked by removing extracellular Ca2+ but was unaffected by the PLC inhibitor U73122 or depletion of intracellular Ca2+ stores by thapsigargin. In muscles from CTR and SMACKO mice, CCh-induced contraction was partially inhibited by the Rho-kinase inhibitor Y27632. These results show that the Cav1.2 Ca2+ channel is essential for normal bladder function. The Rho-kinase and Ca2+-release pathways cannot compensate the lack of the L-type Ca2+ channel.
Collapse
Affiliation(s)
- Jörg W Wegener
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29, D-80802 München, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Moosmang S, Schulla V, Welling A, Feil R, Feil S, Wegener JW, Hofmann F, Klugbauer N. Dominant role of smooth muscle L-type calcium channel Cav1.2 for blood pressure regulation. EMBO J 2004; 22:6027-34. [PMID: 14609949 PMCID: PMC275441 DOI: 10.1093/emboj/cdg583] [Citation(s) in RCA: 235] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Blood pressure is regulated by a number of key molecules involving G-protein-coupled receptors, ion channels and monomeric small G-proteins. The relative contribution of these different signaling pathways to blood pressure regulation remains to be determined. Tamoxifen-induced, smooth muscle-specific inactivation of the L-type Cav1.2 Ca2+ channel gene in mice (SMAKO) reduced mean arterial blood pressure (MAP) in awake, freely moving animals from 120 +/- 4.5 to 87 +/- 8 mmHg. Phenylephrine (PE)- and angiotensin 2 (AT2)-induced MAP increases were blunted in SMAKO mice, whereas the Rho-kinase inhibitor Y-27632 reduced MAP to the same extent in control and SMAKO mice. Depolarization-induced contraction was abolished in tibialis arteries of SMAKO mice, and development of myogenic tone in response to intravascular pressure (Bayliss effect) was absent. Hind limb perfusion experiments suggested that 50% of the PE-induced resistance is due to calcium influx through the Cav1.2 channel. These results show that Cav1.2 calcium channels are key players in the hormonal regulation of blood pressure and development of myogenic tone.
Collapse
Affiliation(s)
- Sven Moosmang
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Strasse 29, D-80802 München, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Abstract
Thyroid hormones are known to influence various processes of cell differentiation. Recently, it was reported that hypothyroidism reduces the sensitivity to Ca2+-channel antagonists in the rat uterus. We examined the sensitivity to dihydropyridines of the uterus from mice that had reduced thyroid hormone levels. Isradipine relaxed with the same potency precontracted uterine muscle strips from control and hypothyroid mice, independently from a pseudo-pregnant state. These results demonstrate that hypothyroidism does not change dihydropyridine sensitivity (i.e., the pattern of Ca2+-channel expression) in the murine uterus.Key words: uterus, smooth muscle, Ca2+channel, isradipine.
Collapse
Affiliation(s)
- Jörg W Wegener
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Strasse 29, 80202 Munich, Germany.
| | | | | |
Collapse
|
41
|
Abstract
The effects of the dihydropyridine nifedipine and its more lipophilic congener, barnidipine, were investigated in smooth muscle preparations from the rat in resting and depolarizing conditions. Both drugs relaxed precontracted aortic rings more potently in depolarizing conditions, barnidipine being more potent than nifedipine. Currents through Ca2+ channels in rat vascular smooth muscle cells (A7r5) and in isolated rat cardiomyocytes were reduced more potently by both drugs at a holding potential of -40 mV than at -80 mV. However, barnidipine and nifedipine were more effective in reducing the current in A7r5 cells than in cardiomyocytes. The IC(50) obtained in aortic rings and in A7r5 cells were similar for barnidipine but an order of magnitude different for nifedipine. The results show that, in depolarizing conditions, barnidipine was more effective than nifedipine. It is suggested that the higher potency of barnidipine acting in vascular smooth muscle is related to both a higher affinity to the inactivated state of vascular Ca2+ channels and to a more lipophilic property as compared with nifedipine.
Collapse
Affiliation(s)
- J W Wegener
- Pharmakologisches Institut, Universität Mainz, Obere Zahlbacher Strasse 67, 55101 Mainz, Germany
| | | | | |
Collapse
|
42
|
Michel D, Wegener JW, Nawrath H. Effects of quinine and quinidine on the transient outward and on the L-type Ca(2+) current in rat ventricular cardiomyocytes. Pharmacology 2002; 65:187-92. [PMID: 12180412 DOI: 10.1159/000064342] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effects of the enantiomers quinine and quinidine on the transient outward current (I(to)) and on the L-type Ca(2+) current (I(ca)) were investigated in rat ventricular cardiomyocytes using the patch-clamp technique. At a stimulation frequency of 2 Hz, both quinine and quinidine depressed the magnitude of I(to) and I(Ca); the half-maximal effects on I(to) were achieved at 11 and 15 micromol/l, respectively, and those on I(Ca) at 14 and 10 micromol/l, respectively. At 0.2 Hz, both drugs depressed the magnitude of I(to), but not that of I(Ca). A change in extracellular pH from 7.3 to 8.3 did not significantly influence the effects of the drugs(which are protonated to 98% at pH 7.3) on I(to) or I(Ca). It is concluded that neither the different chemical structure nor the amount of protonation of quinine and quinidine controls their effects on I(to) or I(Ca).
Collapse
Affiliation(s)
- Delia Michel
- Pharmakologisches Institut, Johannes Gutenberg-Universität, Mainz, Deutschland
| | | | | |
Collapse
|
43
|
Abstract
1. The effects of the nitric oxide (NO) donors S-nitroso-N-acetylpenicillamine (SNAP), sodium(Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate), and (Z)-1-[N-(2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate) on force of contraction (F(c)) were studied in atrial and ventricular muscle strips obtained from wild-type (WT) and myoglobin-deficient (myo(-/-)) mice. 2. SNAP slightly reduced F(c) in preparations from WT mice at concentrations above 100 microM; this effect was more pronounced in myo(-/-) mice. 3. DEA-NONOate reduced F(c) in preparations from myo(-/-) mice to a larger extent than those from WT mice. 4. DETA-NONOate reduced F(c) in preparations from myo(-/-) but not from WT mice. 5. Pre-incubation with an inhibitor of the soluble guanylyl cyclase (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 100 microM) prevented the effects of SNAP, DEA-NONOate and DETA-NONOate on F(c) in myo(-/-) mice. 6. It is suggested that, in physiological conditions, myoglobin acts as intracellular scavenger preventing NO from reaching its intracellular receptors in cardiomyocytes, whereas, in myoglobin-deficient conditions, NO is able to reduce contractility via activation of the soluble guanylyl cyclase/cyclic GMP pathway.
Collapse
Affiliation(s)
- J W Wegener
- Pharmakologisches Institut, Universität Mainz, Obere Zahlbacher Str. 67, 55101 Mainz, Germany
| | | | | | | |
Collapse
|
44
|
Wegener JW, Nawrath H, Wolfsgruber W, Kühbandner S, Werner C, Hofmann F, Feil R. cGMP-dependent protein kinase I mediates the negative inotropic effect of cGMP in the murine myocardium. Circ Res 2002; 90:18-20. [PMID: 11786513 DOI: 10.1161/hh0102.103222] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To study the role of cGMP-dependent protein kinase I (cGKI) for cardiac contractility, force of contraction (F(c)) was studied in electrically driven heart muscle from wild-type (WT) mice and from conventional and conditional cGKI knockout mice. Both 8-Br-cGMP and 8-pCPT-cGMP reduced Fc in cardiac muscle from juvenile WT but not from juvenile cGKI-null mutants. Similarly, the cGMP analogues reduced F(c) in forskolin-stimulated ventricular muscle from WT mice but not from cGKI-null mutants. In contrast, carbachol reduced F(c) in both groups of animals. 8-Br-cGMP reduced F(c) also in heart muscle from adult WT mice but not from adult cardiomyocyte-specific cGKI-knockout mice. These results demonstrate that cGKI mediates the negative inotropic effect of cGMP in the myocardium of juvenile and adult mice.
Collapse
|
45
|
Budu CE, Balas N, Nawrath H, Wegener JW, Shainberg A. Increased cardiac alpha-1-adrenoceptor density in rats following treatment with amiodarone. J Basic Clin Physiol Pharmacol 2002; 12:33-47. [PMID: 11414506 DOI: 10.1515/jbcpp.2001.12.1.33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study was undertaken to investigate the interaction between amiodarone and alpha-1-adrenoceptors in rat cardiac cells. The level (Bmax) and affinity (Kd) of alpha-1-adrenoceptors in heart cells were determined by [3H]prazosin radioligand binding following amiodarone treatment. In cultured intact cardiocytes treated for 48 h with 10 microM amiodarone, [3H]prazosin binding increased by 31% compared with the control cells (p<0.05). The increase was both dose and time dependent and was found to be specific because no significant change occurred in creatine kinase activity. Additionally, under the same conditions, an increase in [3H]prazosin binding to cultured cardiocyte cell membranes was also obtained. Oral gavage of amiodarone to rats for 8 d resulted in a 25% increase in [3H]prazosin binding to isolated ventricle membranes compared with control rats (p<0.05). We conclude that amiodarone treatment can increase the response to alpha-1-adrenoceptors agonist in the heart due to an increase in the density of alpha-1-adrenoceptors.
Collapse
Affiliation(s)
- C E Budu
- Gonda (Goldschmied) Medical Diagnostic Research Center, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | | | | | | | | |
Collapse
|
46
|
Nawrath H, Wegener JW, Rupp J, Habermeier A, Closs EI. Voltage dependence of L-arginine transport by hCAT-2A and hCAT-2B expressed in oocytes from Xenopus laevis. Am J Physiol Cell Physiol 2000; 279:C1336-44. [PMID: 11029280 DOI: 10.1152/ajpcell.2000.279.5.c1336] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Membrane potential and currents were investigated with the two-electrode voltage-clamp technique in Xenopus laevis oocytes expressing hCAT-2A or hCAT-2B, the splice variants of the human cationic amino acid transporter hCAT-2. Both hCAT-2A- and hCAT-2B-expressing oocytes exhibited a negative extracellular L-arginine concentration ([L-Arg](o))-sensitive membrane potential, additive to the K(+) diffusion potential, when cells were incubated in Leibovitz medium (containing 1.45 mM L-Arg and 0.25 mM L-lysine). The two carrier proteins produced inward and outward currents, which were dependent on the L-Arg gradient and membrane potential. Ion substitution experiments showed that the hCAT-induced currents were independent of external Na(+), K(+), Ca(2+), or Mg(2+). The apparent Michaelis-Menten constant values at -60 mV, obtained from plots of L-Arg-induced currents against [L-Arg](o), were 0.97 and 0.13 mM in oocytes expressing hCAT-2A and hCAT-2B, respectively; maximal currents amounted to -194 +/- 8 and -84 +/- 2 nA, respectively. At saturating [L-Arg](o), the current-voltage relationships of hCAT-2A-expressing oocytes became steeper, yielding an additional conductance up to 2 microS/oocyte, whereas those of hCAT-2B-expressing oocytes were simply shifted to the right, resulting in voltage-independent difference currents. The distinct electrochemical properties of the two isoforms of hCAT-2 are assumed to contribute differentially to the membrane transport and the maintenance of cationic amino acids in various tissues.
Collapse
Affiliation(s)
- H Nawrath
- Department of Pharmacology, Johannes Gutenberg University, 55101 Mainz, Germany.
| | | | | | | | | |
Collapse
|
47
|
Vulcu SD, Wegener JW, Nawrath H. Differences in the nitric oxide/soluble guanylyl cyclase signalling pathway in the myocardium of neonatal and adult rats. Eur J Pharmacol 2000; 406:247-55. [PMID: 11020488 DOI: 10.1016/s0014-2999(00)00654-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effects of a nitric oxide-donor, S-nitroso-N-acetylpenicillamine, and a direct activator of soluble guanylyl cyclase, 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), on force of contraction (F(c)) and L-type Ca(2+) currents (I(Ca(L))) were investigated in myocardial preparations from neonatal and adult rats. Since hearts from adult and neonatal animals contained 160 and 47 mg/100 g wet weight myoglobin, respectively, its possible interaction with both drugs was also investigated. Both S-nitroso-N-acetylpenicillamine (100 microM) and YC-1 (30 microM) were ineffective in myocardial preparations from adult rats but reduced the magnitude of I(Ca(L)) and F(c) in preparations from neonatal rats. The latter effects were antagonised by 1H-[1,2, 4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 50 microM) and attenuated by myoglobin (30-300 microM), which also attenuated the effects of both drugs on pre-contracted aortic rings. The differential effects of S-nitroso-N-acetylpenicillamine and YC-1 in the myocardium from adult and neonatal rats may result from developmental changes in the content of myoglobin and/or in the NO/soluble guanylyl cyclase signal pathway.
Collapse
Affiliation(s)
- S D Vulcu
- Department of Pharmacology, Johannes Gutenberg University, 55101, Mainz, Germany
| | | | | |
Collapse
|
48
|
Abstract
The effects of barnidipine and nifedipine on L-type Ca(2+) current (I(Ca(L))) were investigated in ventricular cardiomyocytes from rats. Both barnidipine and nifedipine reduced I(Ca(L)) in a concentration and voltage dependent manner; the EC(50) were 80 and 130 nM at a holding potential of -80 mV, respectively, and 18 and 6 nM at -40 mV, respectively. Both drugs induced a leftward shift of the steady-state inactivation curve of I(Ca(L)). Using a twin pulse protocol, the relationships between the amount of block of I(Ca(L)) by either drug, seen during the second pulse, and the length of the first pulse were described by monoexponential functions reflecting onset of block, dependent on drug concentration. The onset of block by barnidipine was three times faster than that by nifedipine. With both drugs, recovery of I(Ca(L)) was 50 times slower than under control conditions and described by monoexponential functions reflecting offset of block (independent of drug concentration). The offset of block with barnidipine was three times slower than that with nifedipine. The time constants of block and unblock of I(Ca(L)) by both drugs were used to calculate binding and unbinding and to predict their effects at two frequencies. It is suggested that barnidipine exhibits a higher affinity to the inactivated Ca(2+) channel state as compared to nifedipine.
Collapse
Affiliation(s)
- J W Wegener
- Pharmakologisches Institut der Universität Mainz, D-55101 Mainz, Germany.
| | | | | | | |
Collapse
|
49
|
Seitz S, Wegener JW, Rupp J, Watanabe M, Jost A, Gerhard R, Shainberg A, Ochi R, Nawrath H. Involvement of K(+) channels in the relaxant effects of YC-1 in vascular smooth muscle. Eur J Pharmacol 1999; 382:11-8. [PMID: 10556499 DOI: 10.1016/s0014-2999(99)00574-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study addresses the question whether K(+) channels are involved in the vasorelaxant effects of 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl-indazole (YC-1 ). In rat aorta, guinea pig aorta, and guinea pig a. carotis, YC-1 inhibited contractions induced by phenylephrine (3 microM) more potently than those induced by K(+)(48 mM). In rat aorta, tetraethylammonium (10 mM), charybdotoxin (0.2 microM), and iberiotoxin (0.1 microM), but not glibenclamide (10 microM), attenuated the relaxant effects of YC-1. In guinea pig a. carotis, YC-1 (30 microM) induced a hyperpolarisation which was antagonised by 1H-[1,2,4]oxadiazolo[4, 3-a]quinoxalin-1-one (ODQ; 50 microM). In rat aorta, YC-1 (30 microM) increased the rate constant of 86Rb-efflux. The effect of YC-1 was potentiated by zaprinast (10 microM), but inhibited by ODQ (50 microM) or charybdotoxin (0.2 microM). In smooth muscle cells from rat aorta, YC-1 (10 microM) increased BK(Ca) channel activity. It is suggested that YC-1-induced vasorelaxation is partially mediated by the activation of K(+) channels.
Collapse
Affiliation(s)
- S Seitz
- Pharmakologisches Institut der Universität Mainz, Obere Zahlbacher Str. 67, D-55101, Mainz, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Abstract
The effects of fendiline on the transient outward current (Ito) were investigated in rat ventricular cardiomyocytes. Extracellularly applied fendiline reduced peak and steady-state current amplitude of Ito; the inactivation of Ito was accelerated by the drug, which reflects onset of block. The described effects were concentration dependent: half-maximal effects were achieved at approximately 3 microM fendiline. Intracellularly applied fendiline (3 microM) did not affect Ito within 5 min. The steady-state current amplitude of Ito was more efficiently suppressed by the drug at 22 +/- 1 degrees C than at 36 +/- 1 degrees C. The recovery of Ito was analyzed by the application of twin depolarizing voltage pulses, interrupted by variable pulse intervals. In the presence of fendiline, recovery of Ito was about twofold slower than that under control conditions, independent of the drug concentration used, which reflects offset from block. Concentration-dependent onset but concentration-independent offset of block suggest that the described time constants correspond to voltage-dependent net binding and unbinding, respectively, of fendiline at its receptor sites. It is proposed that fendiline binds extracellularly at positive potentials to Ito channels in their open state and dissociates from the channels at rest.
Collapse
Affiliation(s)
- V Fassbender
- Pharmakologisches Institut der Universität Mainz, Germany
| | | | | | | |
Collapse
|