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Qian H, Patriarchi T, Price JL, Matt L, Lee B, Nieves-Cintrón M, Buonarati OR, Chowdhury D, Nanou E, Nystoriak MA, Catterall WA, Poomvanicha M, Hofmann F, Navedo MF, Hell JW. Phosphorylation of Ser1928 mediates the enhanced activity of the L-type Ca2+ channel Cav1.2 by the β2-adrenergic receptor in neurons. Sci Signal 2017; 10:10/463/eaaf9659. [PMID: 28119465 DOI: 10.1126/scisignal.aaf9659] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The L-type Ca2+ channel Cav1.2 controls multiple functions throughout the body including heart rate and neuronal excitability. It is a key mediator of fight-or-flight stress responses triggered by a signaling pathway involving β-adrenergic receptors (βARs), cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA). PKA readily phosphorylates Ser1928 in Cav1.2 in vitro and in vivo, including in rodents and humans. However, S1928A knock-in (KI) mice have normal PKA-mediated L-type channel regulation in the heart, indicating that Ser1928 is not required for regulation of cardiac Cav1.2 by PKA in this tissue. We report that augmentation of L-type currents by PKA in neurons was absent in S1928A KI mice. Furthermore, S1928A KI mice failed to induce long-term potentiation in response to prolonged theta-tetanus (PTT-LTP), a form of synaptic plasticity that requires Cav1.2 and enhancement of its activity by the β2-adrenergic receptor (β2AR)-cAMP-PKA cascade. Thus, there is an unexpected dichotomy in the control of Cav1.2 by PKA in cardiomyocytes and hippocampal neurons.
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Affiliation(s)
- Hai Qian
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - Jennifer L Price
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - Lucas Matt
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - Boram Lee
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | | | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | | | - Evanthia Nanou
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - Matthew A Nystoriak
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - Montatip Poomvanicha
- Department of Pharmacology and Toxicology, Technical University of Munich, D-80802 Munich, Germany
| | - Franz Hofmann
- Department of Pharmacology and Toxicology, Technical University of Munich, D-80802 Munich, Germany
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA.
| | - Johannes W Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA. .,Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
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2
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Bond RC, Choisy SCM, Bryant SM, Hancox JC, James AF. Inhibition of a TREK-like K+ channel current by noradrenaline requires both β1- and β2-adrenoceptors in rat atrial myocytes. Cardiovasc Res 2014; 104:206-15. [PMID: 25205295 PMCID: PMC4174890 DOI: 10.1093/cvr/cvu192] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
AIMS Noradrenaline plays an important role in the modulation of atrial electrophysiology. However, the identity of the modulated channels, their mechanisms of modulation, and their role in the action potential remain unclear. This study aimed to investigate the noradrenergic modulation of an atrial steady-state outward current (IKss). METHODS AND RESULTS Rat atrial myocyte whole-cell currents were recorded at 36°C. Noradrenaline potently inhibited IKss (IC50 = 0.90 nM, 42.1 ± 4.3% at 1 µM, n = 7) and potentiated the L-type Ca(2+) current (ICaL, EC50 = 136 nM, 205 ± 40% at 1 µM, n = 6). Noradrenaline-sensitive IKss was weakly voltage-dependent, time-independent, and potentiated by the arachidonic acid analogue, 5,8,11,14-eicosatetraynoic acid (EYTA; 10 µM), or by osmotically induced membrane stretch. Noise analysis revealed a unitary conductance of 8.4 ± 0.42 pS (n = 8). The biophysical/pharmacological properties of IKss indicate a TREK-like K(+) channel. The effect of noradrenaline on IKss was abolished by combined β1-/β2-adrenoceptor antagonism (1 µM propranolol or 10 µM β1-selective atenolol and 100 nM β2-selective ICI-118,551 in combination), but not by β1- or β2-antagonist alone. The action of noradrenaline could be mimicked by β2-agonists (zinterol and fenoterol) in the presence of β1-antagonist. The action of noradrenaline on IKss, but not on ICaL, was abolished by pertussis toxin (PTX) treatment. The action of noradrenaline on ICaL was mediated by β1-adrenoceptors via a PTX-insensitive pathway. Noradrenaline prolonged APD30 by 52 ± 19% (n = 5; P < 0.05), and this effect was abolished by combined β1-/β2-antagonism, but not by atenolol alone. CONCLUSION Noradrenaline inhibits a rat atrial TREK-like K(+) channel current via a PTX-sensitive mechanism involving co-operativity of β1-/β2-adrenoceptors that contributes to atrial APD prolongation.
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Affiliation(s)
- Richard C Bond
- Bristol Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Stéphanie C M Choisy
- Bristol Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Simon M Bryant
- Bristol Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Jules C Hancox
- Bristol Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Andrew F James
- Bristol Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
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3
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Distasi MR, Case J, Ziegler MA, Dinauer MC, Yoder MC, Haneline LS, Dalsing MC, Miller SJ, Labarrere CA, Murphy MP, Ingram DA, Unthank JL. Suppressed hindlimb perfusion in Rac2-/- and Nox2-/- mice does not result from impaired collateral growth. Am J Physiol Heart Circ Physiol 2009; 296:H877-86. [PMID: 19151256 PMCID: PMC2660231 DOI: 10.1152/ajpheart.00772.2008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 01/12/2009] [Indexed: 11/22/2022]
Abstract
While tissue perfusion and angiogenesis subsequent to acute femoral artery occlusion are suppressed in NADPH oxidase 2 (Nox2)-null (Nox2(-/-)) mice, studies have not established the role of Nox2 in collateral artery enlargement. Rac2 is a small GTPase that binds Nox2 and activates Nox2-based NAD(P)H oxidase but, unlike Nox2, is primarily restricted to bone marrow-derived cells. In this study, we used Rac2-null (Rac2(-/-)) and Nox2(-/-) mice with a novel method of identifying primary hindlimb collaterals to investigate the hypothesis that collateral growth requires these molecules. When initial experiments performed with femoral ligation demonstrated similar perfusion and collateral growth in Rac2(-/-) and wild-type C57BL/6J (BL6) mice, subsequent experiments were performed with a more severe ischemia model, femoral artery excision. After femoral excision, tissue perfusion was suppressed in Rac2(-/-) mice relative to BL6 mice. Histological assessment of ischemic injury including necrotic and regenerated muscle fibers and lipid and collagen deposition demonstrated greater injury in Rac2(-/-) mice. The diameters of primary collaterals identified during Microfil injection with intravital microscopy were enlarged to a similar extent in BL6 and Rac2(-/-) mice. Intimal cells in collateral cross sections were increased in number in both strains and were CD31 positive and CD45 negative. Circulating leukocytes and CD11b(+) cells were increased more in Rac2(-/-) than BL6 animals. Experiments performed in Nox2(-/-) mice to verify that the unexpected results related to collateral growth were not unique to Rac2(-/-) mice gave equivalent results. The data demonstrate that, subsequent to acute femoral artery excision, perfusion recovery is impaired in Rac2(-/-) and Nox2(-/-) mice but that collateral luminal expansion and intimal cell recruitment/proliferation are normal. These novel results indicate that collateral luminal expansion and intimal cell recruitment/proliferation are not mediated by Rac2 and Nox2.
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Affiliation(s)
- Matthew R Distasi
- Department of Cellular and Integrative Physiology, Indiana Univ. School of Medicine, 1001 W. 10th St., WD OPW 425 E, Indianapolis, IN 46202, USA
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4
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Iancu RV, Ramamurthy G, Warrier S, Nikolaev VO, Lohse MJ, Jones SW, Harvey RD. Cytoplasmic cAMP concentrations in intact cardiac myocytes. Am J Physiol Cell Physiol 2008; 295:C414-22. [PMID: 18550706 DOI: 10.1152/ajpcell.00038.2008] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In cardiac myocytes there is evidence that activation of some receptors can regulate protein kinase A (PKA)-dependent responses by stimulating cAMP production that is limited to discrete intracellular domains. We previously developed a computational model of compartmentalized cAMP signaling to investigate the feasibility of this idea. The model was able to reproduce experimental results demonstrating that both beta(1)-adrenergic and M(2) muscarinic receptor-mediated cAMP changes occur in microdomains associated with PKA signaling. However, the model also suggested that the cAMP concentration throughout most of the cell could be significantly higher than that found in PKA-signaling domains. In the present study we tested this counterintuitive hypothesis using a freely diffusible fluorescence resonance energy transfer-based biosensor constructed from the type 2 exchange protein activated by cAMP (Epac2-camps). It was determined that in adult ventricular myocytes the basal cAMP concentration detected by the probe is approximately 1.2 muM, which is high enough to maximally activate PKA. Furthermore, the probe detected responses produced by both beta(1) and M(2) receptor activation. Modeling suggests that responses detected by Epac2-camps mainly reflect what is happening in a bulk cytosolic compartment with little contribution from microdomains where PKA signaling occurs. These results support the conclusion that even though beta(1) and M(2) receptor activation can produce global changes in cAMP, compartmentation plays an important role by maintaining microdomains where cAMP levels are significantly below that found throughout most of the cell. This allows receptor stimulation to regulate cAMP activity over concentration ranges appropriate for modulating both higher (e.g., PKA) and lower affinity (e.g., Epac) effectors.
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Affiliation(s)
- Radu V Iancu
- Dept. of Physiology and Biophysics, Case Western Reserve Univ., 10900 Euclid Ave., Cleveland, OH 44106-4970, USA
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5
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Faucher FA, Gannier FE, Lignon JM, Cosnay P, Malécot CO. Roles of PKA, PI3K, and cPLA2 in the NO-mediated negative inotropic effect of β2-adrenoceptor agonists in guinea pig right papillary muscles. Am J Physiol Cell Physiol 2008; 294:C106-17. [DOI: 10.1152/ajpcell.00231.2007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although β2-adrenoceptors represent 15–25% of β-adrenoceptors in the guinea pig heart, their functionality is controversial. We assessed the inotropic effects of β2-adrenoceptor partial agonists in right papillary muscles. Salbutamol induced a small but significant concentration-dependent negative inotropic effect (NIE, −5% at 60 nM) followed by a moderate positive inotropic effect (+36% at 6 μM) due to activation of β1-adrenoceptors. In the presence of 4 μM atenolol, the concentration-dependent NIE (−12% at 6 μM) was biphasic, best described by a double logistic equation with respective EC50 values of 3 and ∼420 nM, and was insensitive to SR59230A. In muscles from pertussis toxin-treated guinea pigs, the salbutamol-induced positive inotropic effect was sensitive to low concentrations of ICI-118551 in an unusual manner. Experiments in reserpinized animals revealed the importance of the phosphorylation-dephosphorylation processes. PKA inhibition reduced and suppressed the effects obtained at low and high concentrations, respectively, indicating that its activation was a prerequisite to the NIE. The effect occurring at nanomolar concentrations depended upon PKA/phosphatidylinositol 3-kinase/cytosolic phospholipase A2 (cPLA2) activations leading to nitric oxide (NO) release via the arachidonic acid/cyclooxygenase pathway. NO release via PKA-dependent phosphorylation of the receptor was responsible for the inotropic effect observed at submicromolar concentrations, which is negatively controlled by cPLA2. The possibility that these effects are due to an equilibrium between different affinity states of the receptor (Gs/Gi coupled and Gi independent with different signaling pathways) that can be displaced by ICI-118551 is discussed. We conclude that β2-adrenoceptors are functional in guinea pig heart and can modulate the inotropic state.
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6
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Tsujikawa H, Song Y, Watanabe M, Masumiya H, Gupte SA, Ochi R, Okada T. Cholesterol depletion modulates basal L-type Ca2+ current and abolishes its -adrenergic enhancement in ventricular myocytes. Am J Physiol Heart Circ Physiol 2007; 294:H285-92. [PMID: 17982015 DOI: 10.1152/ajpheart.00824.2007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholesterol is a primary constituent of the plasmalemma, including the lipid rafts/caveolae, where various G protein-coupled receptors colocalize with signaling proteins and channels. By manipulating cholesterol in rabbit and rat ventricular myocytes using methyl-beta-cyclodextrin (MbetaCD), we studied the role of cholesterol in the modulation of L-type Ca(2+) currents (I(Ca,L)). MbetaCD was mainly dialyzed from BAPTA-containing pipette solution during whole cell clamp. In rabbit myocytes dialyzed with 30 mM MbetaCD for 10 min, a positive shift in membrane potential at half-maximal activation (V(0.5)) from -8 to -2 mV developed and was associated with an increase in current density at positive potentials (42% at +20 mV vs. time-matched controls). Isoproterenol (ISO) increased I(Ca,L) approximately threefold and caused a negative shift in V(0.5) in control cells, but it did not increase I(Ca,L) in MbetaCD-treated myocytes, nor did it shift V(0.5). The effect of MbetaCD (10 or 30 mM) was concentration dependent: 30 mM MbetaCD suppressed the ISO-induced increase in I(Ca,L) more effectively than 10 mM MbetaCD. MbetaCD dialysis also abolished the increase in I(Ca,L) elicited by forskolin or dibutyryl cAMP, but not that elicited by (-)BAY K 8644. External application of MbetaCD-cholesterol complex to rat myocytes attenuated the MbetaCD-mediated inhibition of the ISO-induced increase of I(Ca,L). Biochemical analysis confirmed that the myocytes' cholesterol content was diminished by MbetaCD and increased by MbetaCD-cholesterol complex. Cholesterol thus appears to contribute to the regulation of basal I(Ca,L) and beta-adrenergic cAMP/PKA-mediated increases in I(Ca,L). We suggest that cholesterol affects the structural coupling between L-type Ca(2+) channels and adjacent regulatory proteins.
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Affiliation(s)
- Hiroto Tsujikawa
- Department of Physiology, New York Medical College, Valhalla, NY 10595, USA
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7
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Iancu RV, Jones SW, Harvey RD. Compartmentation of cAMP signaling in cardiac myocytes: a computational study. Biophys J 2007; 92:3317-31. [PMID: 17293406 PMCID: PMC1852367 DOI: 10.1529/biophysj.106.095356] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Receptor-mediated changes in cAMP production play an essential role in sympathetic and parasympathetic regulation of the electrical, mechanical, and metabolic activity of cardiac myocytes. However, responses to receptor activation cannot be easily ascribed to a uniform increase or decrease in cAMP activity throughout the entire cell. In this study, we used a computational approach to test the hypothesis that in cardiac ventricular myocytes the effects of beta(1)-adrenergic receptor (beta(1)AR) and M(2) muscarinic receptor (M(2)R) activation involve compartmentation of cAMP. A model consisting of two submembrane (caveolar and extracaveolar) microdomains and one bulk cytosolic domain was created using published information on the location of beta(1)ARs and M(2)Rs, as well as the location of stimulatory (G(s)) and inhibitory (G(i)) G-proteins, adenylyl cyclase isoforms inhibited (AC5/6) and stimulated (AC4/7) by G(i), and multiple phosphodiesterase isoforms (PDE2, PDE3, and PDE4). Results obtained with the model indicate that: 1), bulk basal cAMP can be high ( approximately 1 microM) and only modestly stimulated by beta(1)AR activation ( approximately 2 microM), but caveolar cAMP varies in a range more appropriate for regulation of protein kinase A ( approximately 100 nM to approximately 2 microM); 2), M(2)R activation strongly reduces the beta(1)AR-induced increases in caveolar cAMP, with less effect on bulk cAMP; and 3), during weak beta(1)AR stimulation, M(2)R activation not only reduces caveolar cAMP, but also produces a rebound increase in caveolar cAMP following termination of M(2)R activity. We conclude that compartmentation of cAMP can provide a quantitative explanation for several aspects of cardiac signaling.
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Affiliation(s)
- Radu V Iancu
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106, USA
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8
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Warrier S, Ramamurthy G, Eckert RL, Nikolaev VO, Lohse MJ, Harvey RD. cAMP microdomains and L-type Ca2+ channel regulation in guinea-pig ventricular myocytes. J Physiol 2007; 580:765-76. [PMID: 17289786 PMCID: PMC2075464 DOI: 10.1113/jphysiol.2006.124891] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Many different receptors can stimulate cAMP synthesis in the heart, but not all elicit the same functional responses. For example, it has been recognized for some time that prostaglandins such as PGE1 increase cAMP production and activate PKA, but they do not elicit responses like those produced by beta-adrenergic receptor (betaAR) agonists such as isoproterenol (isoprenaline), even though both stimulate the same signalling pathway. In the present study, we confirm that isoproterenol, but not PGE1, is able to produce cAMP-dependent stimulation of the L-type Ca(2+) current in guinea pig ventricular myocytes. This is despite finding evidence that these cells express EP(4) prostaglandin receptors, which are known to activate G(s)-dependent signalling pathways. Using fluorescence resonance energy transfer-based biosensors that are either freely diffusible or bound to A kinase anchoring proteins, we demonstrate that the difference is due to the ability of isoproterenol to stimulate cAMP production in cytosolic and caveolar compartments of intact cardiac myocytes, while PGE1 only stimulates cAMP production in the cytosolic compartment. Unlike other receptor-mediated responses, compartmentation of PGE1 responses was not due to concurrent activation of a G(i)-dependent signalling pathway or phosphodiesterase activity. Instead, compartmentation of the PGE1 response in cardiac myocytes appears to be due to transient stimulation of cAMP in a microdomain that can communicate directly with the bulk cytosolic compartment but not the caveolar compartment associated with betaAR regulation of L-type Ca(2+) channel function.
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Affiliation(s)
- Sunita Warrier
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA
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9
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Hutchinson DS, Chernogubova E, Sato M, Summers RJ, Bengtsson T. Agonist effects of zinterol at the mouse and human beta(3)-adrenoceptor. Naunyn Schmiedebergs Arch Pharmacol 2006; 373:158-68. [PMID: 16601951 DOI: 10.1007/s00210-006-0056-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 02/28/2006] [Indexed: 10/24/2022]
Abstract
The present study investigates the action of zinterol at beta(3)-adrenoceptors. We used mouse primary brown adipocytes and Chinese hamster ovary (CHO-K1) cells expressing the mouse or human beta(3)-adrenoceptor. Zinterol was a full agonist at increasing cyclic AMP levels in primary brown adipocytes (which express beta(1)- and beta(3)-adrenoceptors but not beta(2)-adrenoceptors), and this effect was almost totally abolished in adipocytes derived from beta(3)-adrenoceptor knock-out (KO) mice. Zinterol was also a full agonist at increasing another biological end-point, glucose uptake in brown adipocytes. This effect was reduced in adipocytes derived from beta(3)-adrenoceptor KO mice, with the remaining response sensitive to beta(1)-adrenoceptor antagonism. To determine whether the effect of zinterol on beta(3)-adrenoceptors in primary brown adipocytes can be replicated in a recombinant system, we used CHO-K1 cells expressing the mouse or human beta(3)-adrenoceptor. Zinterol was a full agonist at mouse and human receptors with respect to increasing cyclic AMP levels, with pEC(50) values similar to that of the selective beta(3)-adrenoceptor agonist (R, R)-5-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]-amino]-propyl]1,3-benzodioxole-2,2-dicarboxylate (CL316243) at the mouse receptor. At the human receptor, zinterol was more potent at increasing cyclic AMP levels than CL316243. In cytosensor microphysiometer studies, zinterol was a full agonist for increases in extracellular acidification rates at the mouse and human beta(3)-adrenoceptor. Therefore, we have shown that zinterol is a potent, high-efficacy beta(3)-adrenoceptor agonist at the endogenous mouse beta(3)-adrenoceptor in primary brown adipocytes and at the cloned mouse and human beta(3)-adrenoceptor expressed in CHO-K1 cells. Zinterol is therefore one of few beta-adrenoceptor agonists with high potency and efficacy at the human beta(3)-adrenoceptor.
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Affiliation(s)
- Dana S Hutchinson
- Department of Physiology, The Wenner-Gren Institute, Arrhenius Laboratory F3, Stockholm University, 10691 Stockholm, Sweden
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10
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Belevych AE, Juranek I, Harvey RD. Protein kinase C regulates functional coupling of beta1-adrenergic receptors to Gi/o-mediated responses in cardiac myocytes. FASEB J 2003; 18:367-9. [PMID: 14688202 DOI: 10.1096/fj.03-0647fje] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The effect of protein kinase C (PKC) activation on beta1-adrenergic receptor (beta1-AR) regulation of the cardiac L-type Ca2+ current (ICa,L) was studied using the whole-cell patch clamp technique. Treatment of guinea pig ventricular myocytes with phorbol-12,13-dibutyrate (PDBu) caused a significant decrease in ICa,L sensitivity to stimulation by submaximal beta1-AR activation using isoproterenol (Iso). This decrease in sensitivity was also associated with the ability of higher concentrations of Iso to directly inhibit the stimulatory response. PDBu treatment produced similar effects on H2 histamine receptor-mediated ICa,L responses. In the presence of PDBu, higher concentrations of Iso inhibited the histamine stimulated ICa,L, and this effect was blocked by a selective beta1-AR antagonist. Higher concentrations of histamine also inhibited the Iso stimulated ICa,L, and this effect was blocked by a selective H2 receptor antagonist. The effects of PDBu were blocked by the PKC inhibitor bisindolylmaleimide I, and they were not mimicked by the inactive phorbol ester 4alpha-phorbol-12,13-didecanoate. The inhibitory effects of Iso and histamine were significantly reduced when Gi/o mediated responses were blocked with pertussis toxin. These results suggest that PKC promotes coupling of cardiac beta1-adrenergic and H2 histamine receptors to Gi/o mediated inhibitory responses.
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MESH Headings
- Adrenergic beta-1 Receptor Agonists
- Adrenergic beta-1 Receptor Antagonists
- Animals
- Calcium/metabolism
- Calcium Channels, L-Type/metabolism
- Electric Conductivity
- Enzyme Activation/drug effects
- GTP-Binding Protein alpha Subunits, Gi-Go/antagonists & inhibitors
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Guinea Pigs
- Histamine/pharmacology
- Indoles/pharmacology
- Maleimides/pharmacology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/metabolism
- Pertussis Toxin/pharmacology
- Phorbol 12,13-Dibutyrate/pharmacology
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- Receptors, Adrenergic, beta-1/metabolism
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Affiliation(s)
- Andriy E Belevych
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4970, USA
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11
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Kovács A, Magyar J, Bányász T, Nánási PP, Szénási G. Beta-adrenoceptor activation plays a role in the reverse rate-dependency of effective refractory period lengthening by dofetilide in the guinea-pig atrium, in vitro. Br J Pharmacol 2003; 139:1555-63. [PMID: 12922944 PMCID: PMC1573989 DOI: 10.1038/sj.bjp.0705395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2003] [Revised: 04/18/2003] [Accepted: 05/22/2003] [Indexed: 11/08/2022] Open
Abstract
1. Blockers of the rapid component of the delayed rectifier potassium current (I(Kr)) prolong cardiac action potential duration (APD) and effective refractory period (ERP) in a reverse rate-dependent manner. Since activation of beta-adrenoceptors attenuates prolongation of APD evoked by I(Kr) blockers, rate-dependent neuronal noradrenaline liberation in the myocardium may contribute to the reverse rate-dependent nature of the effects of I(Kr) blockers. In order to test this hypothesis, we studied the effects of dofetilide, a pure I(Kr) blocker, on ERP after activation or blockade of beta-adrenoceptors and after catecholamine depletion in guinea-pig left atrial myocardium paced at 3, 2 and 1 Hz, in vitro. 2. Dofetilide (100 nM) lengthened ERP in a reverse rate-dependent manner in the left atrial myocardium of guinea-pigs. Strong activation of beta-adrenoceptors using 10 nM isoproterenol abolished the dofetilide-induced lengthening of ERP at all pacing rates. 3. Blockade of the beta-adrenoceptors with metoprolol (1 micro M), atenolol (3 micro M) or propranolol (300 nM) increased the dofetilide-evoked prolongation of ERP at 3 and 2 Hz, but not at 1 Hz. As a consequence, metoprolol attenuated while propranolol and atenolol fully eliminated the reverse rate-dependent nature of the dofetilide-induced ERP lengthening. In catecholamine-depleted atrial preparations of the guinea-pig (24 h pretreatment with 5 mg kg(-1) reserpine i.p.), the effect of dofetilide on ERP was not frequency dependent, and propranolol did not alter the effects of dofetilide. 4. In contrast to results obtained in guinea-pig atrial preparations, propranolol failed to change the reverse rate-dependent effect of dofetilide on ERP in the right ventricular papillary muscles of rabbits and guinea-pigs. 5. As an indication of the functional consequences of rate-dependent noradrenaline liberation, propranolol decreased twitch tension at 3 and 2 Hz but not at 1 Hz in the atrial myocardium of control guinea-pigs, whereas no such effect was detected in catecholamine-depleted atrial preparations. Propranolol failed to change contractility of ventricular myocardium in guinea-pigs and rabbits. 6. It is concluded that rate-dependent noradrenaline release and the ensuing beta-adrenoceptor activation contributed to the reverse rate-dependent nature of ERP prolongation caused by I(Kr) blockers in isolated guinea-pig atrial myocardium.
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Affiliation(s)
- Anikó Kovács
- Pharmacology Laboratory I, EGIS Pharmaceuticals Ltd., Keresztúri út 34, Budapest 10, PO Box 100, Budapest H-1475, Hungary
| | - János Magyar
- Department of Physiology, Medical University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Medical University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Medical University of Debrecen, Debrecen, Hungary
| | - Gábor Szénási
- Pharmacology Laboratory I, EGIS Pharmaceuticals Ltd., Keresztúri út 34, Budapest 10, PO Box 100, Budapest H-1475, Hungary
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12
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Belevych AE, Nulton-Persson A, Sims C, Harvey RD. Role of tyrosine kinase activity in alpha-adrenergic inhibition of the beta-adrenergically regulated L-type Ca(2+) current in guinea-pig ventricular myocytes. J Physiol 2001; 537:779-92. [PMID: 11744754 PMCID: PMC2278981 DOI: 10.1111/j.1469-7793.2001.00779.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. The purpose of this study was to investigate the hypothesis that tyrosine kinase activity contributes to alpha(1)-adrenergic inhibition of beta-adrenergic responses in cardiac myocytes. We addressed this question by studying the pharmacological regulation of the L-type Ca(2+) current in acutely isolated adult guinea-pig ventricular myocytes using the whole-cell patch-clamp technique. 2. The selective alpha(1)-adrenergic receptor agonist methoxamine had no effect on the basal L-type Ca(2+) current. Methoxamine also had no effect on cAMP-dependent stimulation of the Ca(2+) current mediated by H(2) histamine receptor activation. However, methoxamine did inhibit cAMP-dependent stimulation of the Ca(2+) current mediated by beta-adrenergic receptor activation. The ability of methoxamine to inhibit beta-adrenergic regulation of the Ca(2+) current was significantly antagonized by the tyrosine kinase inhibitors genistein and lavendustin A. 3. The inhibitory effect of methoxamine was also mimicked by the phosphotyrosine phosphatase inhibitor pervanadate (PVN). PVN had no effect on basal Ca(2+) current or Ca(2+) current stimulated by histamine, but it did inhibit Ca(2+) current stimulated by beta-adrenergic receptor activation. Furthermore, the ability of PVN to inhibit beta-adrenergic stimulation of the Ca(2+) current was antagonized by lavendustin A. 4. These results are consistent with the conclusion that in guinea-pig ventricular myocytes alpha-adrenergic inhibition of beta-adrenergic responses involves a tyrosine kinase-dependent signalling pathway. The fact that methoxamine and PVN antagonized cAMP-dependent responses mediated by beta-adrenergic, but not H(2) histamine, receptor activation suggests that the inhibitory effect of alpha-adrenergic stimulation and tyrosine kinase activity is at the level of the beta-adrenergic receptor.
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Affiliation(s)
- A E Belevych
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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13
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Belevych AE, Sims C, Harvey RD. ACh-induced rebound stimulation of L-type Ca(2+) current in guinea-pig ventricular myocytes, mediated by Gbetagamma-dependent activation of adenylyl cyclase. J Physiol 2001; 536:677-92. [PMID: 11691864 PMCID: PMC2278900 DOI: 10.1111/j.1469-7793.2001.00677.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
1. The effects that muscarinic receptor stimulation have on the cAMP-dependent regulation of L-type Ca(2+) currents were studied in isolated guinea-pig ventricular myocytes using the whole-cell configuration of the patch-clamp technique. 2. The muscarinic agonist ACh inhibited the Ca(2+) current stimulated by the beta-adrenergic agonist isoprenaline (Iso), and washout of ACh revealed a stimulatory response that appeared as a transient rebound increase in the amplitude of the Ca(2+) current. The ACh-induced stimulatory effect was not observed in the absence of Iso. 3. ACh-induced rebound stimulation was also observed in the presence of H(2) histamine receptor activation and cholera toxin treatment, which like beta-adrenergic receptor activation enhance adenylyl cyclase (AC) activity in a stimulatory G protein (G(s))-dependent manner. ACh-induced rebound stimulation was not observed in the presence of forskolin, which enhances AC activity in a G(s)-independent manner. 4. Pertussis toxin (PTX) treatment blocked both the stimulatory and inhibitory effects of ACh. Intracellular dialysis with QEHA, a peptide that binds free G protein betagamma subunits, selectively antagonized the stimulatory effect, leaving an enhanced inhibitory effect. 5. Evidence for the expression of AC4, an isoform of AC that can be stimulated by Gbetagamma but only in the presence of Galpha(s), was obtained by Western blot analysis of guinea-pig ventricular myocyte membrane preparations. 6. These results suggest that muscarinic receptor stimulation facilitates as well as inhibits cAMP-dependent regulation of the Ca(2+) current and that the net response is a balance between these two actions. We suggest that the stimulatory effect is due to a direct activation of AC4 by the betagamma subunits of a PTX-sensitive G protein.
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Affiliation(s)
- A E Belevych
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106-4970, USA
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14
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Song Y, Shryock JC, Knot HJ, Belardinelli L. Selective attenuation by adenosine of arrhythmogenic action of isoproterenol on ventricular myocytes. Am J Physiol Heart Circ Physiol 2001; 280:H2789-95. [PMID: 11356637 DOI: 10.1152/ajpheart.2001.280.6.h2789] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined whether adenosine equally attenuated the stimulatory effects of isoproterenol on arrhythmic activity and twitch shortening of guinea pig isolated ventricular myocytes. Transmembrane voltages and whole cell currents were recorded with patch electrodes, and cell twitch shortening was measured using a video-motion detector. Isoproterenol increased the action potential duration at 50% repolarization (APD50), L-type Ca2+ current [ I Ca(L)], and cell twitch shortening and induced delayed afterdepolarizations (DAD), transient inward current ( I Ti), and aftercontractions. Adenosine attenuated the arrhythmogenic actions of isoproterenol more than it attenuated the effects of isoproterenol on APD50, I Ca(L), or twitch shortening. Adenosine (0.1–100 μmol/l) decreased the amplitude of DADs by 30 ± 6% to 92 ± 5% but attenuated isoproterenol-induced prolongation of the APD50 by only 14 ± 4% to 59 ± 4% and had no effect on the voltage of action potential plateau. Adenosine (30 μmol/l) inhibited I Ti by 91 ± 4% but decreased isoproterenol-stimulated I Ca(L) by only 30 ± 12%. Isoproterenol-induced aftercontractions were abolished by adenosine (10 μmol/l), whereas the amplitude of twitch shortening was not reduced. The effects of adenosine on twitch shortenings and aftercontractions were mimicked by the A1-adenosine receptor agonist CPA ( N 6-cyclopentyladenosine) and by ryanodine. In conclusion, adenosine antagonized the proarrhythmic effect of β-adrenergic stimulation on ventricular myocytes without reducing cell twitch shortening.
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Affiliation(s)
- Y Song
- Department of Medicine, University of Florida, Gainesville, Florida 32610, USA
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15
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Heubach JF, Graf EM, Molenaar P, Jäger A, Schröder F, Herzig S, Harding SE, Ravens U. Murine ventricular L-type Ca(2+) current is enhanced by zinterol via beta(1)-adrenoceptors, and is reduced in TG4 mice overexpressing the human beta(2)-adrenoceptor. Br J Pharmacol 2001; 133:73-82. [PMID: 11325796 PMCID: PMC1572761 DOI: 10.1038/sj.bjp.0704045] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The functional coupling of beta(2)-adrenoceptors (beta(2)-ARs) to murine L-type Ca(2+) current (I(Ca(L))) was investigated with two different approaches. The beta(2)-AR signalling cascade was activated either with the beta(2)-AR selective agonist zinterol (myocytes from wild-type mice), or by spontaneously active, unoccupied beta(2)-ARs (myocytes from TG4 mice with 435 fold overexpression of human beta(2)-ARs). Ca(2+) and Ba(2+) currents were recorded in the whole-cell and cell-attached configuration of the patch-clamp technique, respectively. 2. Zinterol (10 microM) significantly increased I(Ca(L)) amplitude of wild-type myocytes by 19+/-5%, and this effect was markedly enhanced after inactivation of Gi-proteins with pertussis-toxin (PTX; 76+/-13% increase). However, the effect of zinterol was entirely mediated by the beta(1)-AR subtype, since it was blocked by the beta(1)-AR selective antagonist CGP 20712A (300 nM). The beta(2)-AR selective antagonist ICI 118,551 (50 nM) did not affect the response of I(Ca(L)) to zinterol. 3. In myocytes with beta(2)-AR overexpression I(Ca(L)) was not stimulated by the activated signalling cascade. On the contrary, I(Ca(L)) was lower in TG4 myocytes and a significant reduction of single-channel activity was identified as a reason for the lower whole-cell I(Ca(L)). The beta(2)-AR inverse agonist ICI 118,551 did not further decrease I(Ca(L)). PTX-treatment increased current amplitude to values found in control myocytes. 4. In conclusion, there is no evidence for beta(2)-AR mediated increases of I(Ca(L)) in wild-type mouse ventricular myocytes. Inactivation of Gi-proteins does not unmask beta(2)-AR responses to zinterol, but augments beta(1)-AR mediated increases of I(Ca(L)). In the mouse model of beta(2)-AR overexpression I(Ca(L)) is reduced due to tonic activation of Gi-proteins.
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MESH Headings
- Adrenergic beta-1 Receptor Agonists
- Adrenergic beta-2 Receptor Agonists
- Adrenergic beta-Agonists/pharmacology
- Adrenergic beta-Antagonists/pharmacology
- Animals
- Barium/metabolism
- Binding Sites
- Calcium/metabolism
- Calcium Channels, L-Type/metabolism
- Electric Conductivity
- Ethanolamines/pharmacology
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Heart Ventricles/cytology
- Heart Ventricles/drug effects
- Heart Ventricles/metabolism
- Humans
- Imidazoles/pharmacology
- Ion Channel Gating/drug effects
- Isoproterenol/antagonists & inhibitors
- Isoproterenol/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Myocardium/cytology
- Myocardium/metabolism
- Pertussis Toxin
- Propanolamines/pharmacology
- Protein Binding
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Virulence Factors, Bordetella/pharmacology
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Affiliation(s)
- J F Heubach
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät Carl Gustav Carus der TU Dresden, D-01307 Dresden, Germany.
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16
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Nagykaldi Z, Kem D, Lazzara R, Szabo B. Conditioning of beta(1)-adrenoceptor effect via beta(2)-subtype on L-type Ca(2+) current in canine ventricular myocytes. Am J Physiol Heart Circ Physiol 2000; 279:H1329-37. [PMID: 10993800 DOI: 10.1152/ajpheart.2000.279.3.h1329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the roles of beta(1)- and beta(2)-receptors (beta-AR) in adrenergic enhancement of L-type Ca(2+) current (I(CaL)) in canine ventricular myocytes. Isoproterenol and l-norepinephrine produced a monophasic and a biphasic concentration-I(CaL) relationship (CR), respectively. alpha(1)-AR inhibition with prazosin and beta(2)-AR stimulation with zinterol or l-epinephrine shifted the CR of l-norepinephrine leftward. Zinterol (50 nM) and l-epinephrine (10 nM), but not prazosin, altered the biphasic CR of l-norepinephrine to a monophasic CR. Zinterol and l-epinephrine applied after l-norepinephrine had no effect on I(CaL). beta(2)-AR inhibition with ICI-118551 reduced the E(max) of isoproterenol and l-norepinephrine by 60% and abolished the augmentation of l-norepinephrine by zinterol and l-epinephrine. Carbachol (100 nM) modestly reduced the I(CaL) response to beta(1)-AR stimulation but abolished the enhancement via beta(2)-AR. Zinterol augmented the enhancement of I(CaL) by forskolin, IBMX, and theophylline, but not in the presence of CGP-20712A. We conclude that selective beta(2)-AR stimulation does not increase I(CaL) but enhances adenylyl cyclase activity when stimulated via beta(1)-AR and with forskolin. beta(2)-AR activity preconditions adenylyl cyclase for beta(1)-AR stimulation.
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Affiliation(s)
- Z Nagykaldi
- Section of Endocrinology, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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17
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Schäfer M, Frischkopf K, Taimor G, Piper HM, Schlüter KD. Hypertrophic effect of selective beta(1)-adrenoceptor stimulation on ventricular cardiomyocytes from adult rat. Am J Physiol Cell Physiol 2000; 279:C495-503. [PMID: 10913016 DOI: 10.1152/ajpcell.2000.279.2.c495] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether selective beta(1)-adrenoceptor stimulation causes hypertrophic growth on isolated ventricular cardiomyocytes from adult rat. As parameters for the induction of hypertrophic growth, the increases of [(14)C]phenylalanine incorporation, protein and RNA mass, and cell size were determined. Isoproterenol (Iso, 10 microM) alone had no growth effect. In the presence of the beta(2)-adrenoceptor antagonist ICI-118551 (ICI, 10 microM), Iso caused an increase in [(14)C]phenylalanine incorporation, protein and RNA mass, cell volume, and cross-sectional area. We showed for phenylalanine incorporation that the growth effect of Iso+ICI could be antagonized by beta(1)-adrenoceptor blockade with atenolol (10 microM) or metoprolol (10 microM), indicating that it was caused by selective beta(1)-adrenoceptor stimulation. The growth response to Iso+ICI was accompanied by an increase in ornithine decarboxylase (ODC) activity and expression. Inhibition of ODC by the ODC antagonist difluoromethylornithine (1 mM) attenuated this hypertrophic response, indicating that ODC induction is causally involved. The growth response to Iso+ICI was found to be cAMP independent but was sensitive to genistein (100 microM) or rapamycin (0.1 microM). The reaction was enhanced in the presence of pertussis toxin (10 microM). We conclude that selective beta(1)-adrenoceptor stimulation causes hypertrophic growth of ventricular cardiomyocytes by a mechanism that is independent of cAMP but dependent on a tyrosine kinase and ODC.
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Affiliation(s)
- M Schäfer
- Physiologisches Institut, Justus-Liebig-Universität, Giessen, Germany
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18
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Ranu HK, Mak JC, Barnes PJ, Harding SE. G(i)-dependent suppression of beta(1)-adrenoceptor effects in ventricular myocytes from NE-treated guinea pigs. Am J Physiol Heart Circ Physiol 2000; 278:H1807-14. [PMID: 10843876 DOI: 10.1152/ajpheart.2000.278.6.h1807] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It has been suggested that there is a preferential coupling in heart muscle between the inhibitory G protein (G(i)) and the beta(2)-subtype of the beta-adrenergic receptor (beta-AR), since pertussis toxin (which inactivates G(i)) reveals latent beta(2)-ARs in rat and mouse myocytes. We have previously shown that guinea pigs treated with norepinephrine (NE) for 7 days have myocytes that are desensitized to beta-AR-agonist stimulation, and that pertussis toxin restores these responses. The purpose of the present investigation was to determine whether pertussis toxin specifically upregulated beta(2)-ARs in myocytes from NE-treated guinea pigs. The sole beta-AR subtype in control guinea pig myocytes was confirmed as beta(1)-AR by radioligand binding, single-cell autoradiography, and concentration-response curves to isoproterenol in contracting myocytes. In contrast, a minor pool of beta(2)-ARs was observed in rat myocytes by use of the same methods. NE treatment decreased the maximum isoproterenol response (relative to high Ca(2+)) from 0.89 +/- 0.06 to 0.58 +/- 0.08 (n = 7, P < 0.01) and the pD(2) (-log EC(50)) from 8.8 +/- 0.2 to 7.5 +/- 0.2 (n = 7, P < 0.01). Pertussis toxin treatment increased the isoproterenol-to-Ca(2+) ratio to 0.88 +/- 0.04 (n = 6, P < 0.05) and the pD(2) to 8.6 +/- 0.3 (P < 0.01). This was not mediated by increases in either number or function of beta(2)-ARs. G(i) is therefore able to modulate beta(1)-AR responses in guinea pig myocytes.
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Affiliation(s)
- H K Ranu
- Cardiac Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London, United Kingdom
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