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Paulussen F, Kulkarni CP, Stolz F, Lescrinier E, De Graeve S, Lambin S, Marchand A, Chaltin P, In't Veld P, Mebis J, Tavernier J, Van Dijck P, Luyten W, Thevelein JM. The β2-adrenergic receptor in the apical membrane of intestinal enterocytes senses sugars to stimulate glucose uptake from the gut. Front Cell Dev Biol 2023; 10:1041930. [PMID: 36699012 PMCID: PMC9869975 DOI: 10.3389/fcell.2022.1041930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 12/14/2022] [Indexed: 01/12/2023] Open
Abstract
The presence of sugar in the gut causes induction of SGLT1, the sodium/glucose cotransporter in intestinal epithelial cells (enterocytes), and this is accompanied by stimulation of sugar absorption. Sugar sensing was suggested to involve a G-protein coupled receptor and cAMP - protein kinase A signalling, but the sugar receptor has remained unknown. We show strong expression and co-localization with SGLT1 of the β2-adrenergic receptor (β 2-AR) at the enterocyte apical membrane and reveal its role in stimulating glucose uptake from the gut by the sodium/glucose-linked transporter, SGLT1. Upon heterologous expression in different reporter systems, the β 2-AR responds to multiple sugars in the mM range, consistent with estimated gut sugar levels after a meal. Most adrenergic receptor antagonists inhibit sugar signaling, while some differentially inhibit epinephrine and sugar responses. However, sugars did not inhibit binding of I125-cyanopindolol, a β 2-AR antagonist, to the ligand-binding site in cell-free membrane preparations. This suggests different but interdependent binding sites. Glucose uptake into everted sacs from rat intestine was stimulated by epinephrine and sugars in a β 2-AR-dependent manner. STD-NMR confirmed direct physical binding of glucose to the β 2-AR. Oral administration of glucose with a non-bioavailable β 2-AR antagonist lowered the subsequent increase in blood glucose levels, confirming a role for enterocyte apical β 2-ARs in stimulating gut glucose uptake, and suggesting enterocyte β 2-AR as novel drug target in diabetic and obese patients. Future work will have to reveal how glucose sensing by enterocytes and neuroendocrine cells is connected, and whether β 2-ARs mediate glucose sensing also in other tissues.
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Affiliation(s)
- Frederik Paulussen
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,2Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Belgium
| | - Chetan P. Kulkarni
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,3Functional Genomics and Proteomics Research Unit, Department of Biology, KU Leuven, Leuven, Belgium
| | - Frank Stolz
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,2Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Belgium
| | - Eveline Lescrinier
- 4Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | - Stijn De Graeve
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,2Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Belgium
| | - Suzan Lambin
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,2Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Belgium
| | | | | | - Peter In't Veld
- 6Department of Pathology, Free University of Brussels, Brussels, Belgium
| | - Joseph Mebis
- 7Department of Pathology, KU Leuven, Flanders, Belgium
| | - Jan Tavernier
- 8Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium,9Center for Medical Biotechnology, VIB, Ghent, Belgium
| | - Patrick Van Dijck
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,2Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Belgium
| | - Walter Luyten
- 3Functional Genomics and Proteomics Research Unit, Department of Biology, KU Leuven, Leuven, Belgium
| | - Johan M. Thevelein
- 1Center for Microbiology, VIB, Leuven-Heverlee, Belgium,2Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Belgium,10NovelYeast bv, Bio-Incubator BIO4, Gaston Geenslaan 3, Leuven-Heverlee,, Belgium,*Correspondence: Johan M. Thevelein,
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2
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Bruce CR, Hamley S, Ang T, Howlett KF, Shaw CS, Kowalski GM. Translating glucose tolerance data from mice to humans: Insights from stable isotope labelled glucose tolerance tests. Mol Metab 2021; 53:101281. [PMID: 34175474 PMCID: PMC8313600 DOI: 10.1016/j.molmet.2021.101281] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 11/29/2022] Open
Abstract
Objective The glucose tolerance test (GTT) is widely used in human and animal biomedical and pharmaceutical research. Despite its prevalent use, particularly in mouse metabolic phenotyping, to the best of our knowledge we are not aware of any studies that have attempted to qualitatively compare the metabolic events during a GTT in mice with those performed in humans. Methods Stable isotope labelled oral glucose tolerance tests (siOGTTs; [6,6-2H2]glucose) were performed in both human and mouse cohorts to provide greater resolution into postprandial glucose kinetics. The siOGTT allows for the partitioning of circulating glucose into that derived from exogenous and endogenous sources. Young adults spanning the spectrum of normal glucose tolerance (n = 221), impaired fasting (n = 14), and impaired glucose tolerance (n = 19) underwent a 75g siOGTT, whereas a 50 mg siOGTT was performed on chow (n = 43) and high-fat high-sucrose fed C57Bl6 male mice (n = 46). Results During the siOGTT in humans, there is a long period (>3hr) of glucose absorption and, accordingly, a large, sustained insulin response and robust suppression of lipolysis and endogenous glucose production (EGP), even in the presence of glucose intolerance. In contrast, mice appear to be highly reliant on glucose effectiveness to clear exogenous glucose and experience only modest, transient insulin responses with little, if any, suppression of EGP. In addition to the impaired stimulation of glucose uptake, mice with the worst glucose tolerance appear to have a paradoxical and persistent rise in EGP during the OGTT, likely related to handling stress. Conclusions The metabolic response to the OGTT in mice and humans is highly divergent. The potential reasons for these differences and their impact on the interpretation of mouse glucose tolerance data and their translation to humans are discussed. We compared the mechanisms governing glucose handling in humans and mice. Humans and mice underwent stable isotope labelled oral glucose tolerance tests. Metabolic responses between humans and mice were highly divergent. Unlike humans, most mice exhibit little EGP suppression or insulin response.
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Affiliation(s)
- Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia
| | - Steven Hamley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia
| | - Teddy Ang
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia
| | - Kirsten F Howlett
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia
| | - Christopher S Shaw
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia; Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Waurn Ponds, Victoria, 3216, Australia.
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3
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Targeting Adrenergic Receptors in Metabolic Therapies for Heart Failure. Int J Mol Sci 2021; 22:ijms22115783. [PMID: 34071350 PMCID: PMC8198887 DOI: 10.3390/ijms22115783] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 12/14/2022] Open
Abstract
The heart has a reduced capacity to generate sufficient energy when failing, resulting in an energy-starved condition with diminished functions. Studies have identified numerous changes in metabolic pathways in the failing heart that result in reduced oxidation of both glucose and fatty acid substrates, defects in mitochondrial functions and oxidative phosphorylation, and inefficient substrate utilization for the ATP that is produced. Recent early-phase clinical studies indicate that inhibitors of fatty acid oxidation and antioxidants that target the mitochondria may improve heart function during failure by increasing compensatory glucose oxidation. Adrenergic receptors (α1 and β) are a key sympathetic nervous system regulator that controls cardiac function. β-AR blockers are an established treatment for heart failure and α1A-AR agonists have potential therapeutic benefit. Besides regulating inotropy and chronotropy, α1- and β-adrenergic receptors also regulate metabolic functions in the heart that underlie many cardiac benefits. This review will highlight recent studies that describe how adrenergic receptor-mediated metabolic pathways may be able to restore cardiac energetics to non-failing levels that may offer promising therapeutic strategies.
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4
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Perez DM. Current Developments on the Role of α 1-Adrenergic Receptors in Cognition, Cardioprotection, and Metabolism. Front Cell Dev Biol 2021; 9:652152. [PMID: 34113612 PMCID: PMC8185284 DOI: 10.3389/fcell.2021.652152] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/29/2021] [Indexed: 12/13/2022] Open
Abstract
The α1-adrenergic receptors (ARs) are G-protein coupled receptors that bind the endogenous catecholamines, norepinephrine, and epinephrine. They play a key role in the regulation of the sympathetic nervous system along with β and α2-AR family members. While all of the adrenergic receptors bind with similar affinity to the catecholamines, they can regulate different physiologies and pathophysiologies in the body because they couple to different G-proteins and signal transduction pathways, commonly in opposition to one another. While α1-AR subtypes (α1A, α1B, α1C) have long been known to be primary regulators of vascular smooth muscle contraction, blood pressure, and cardiac hypertrophy, their role in neurotransmission, improving cognition, protecting the heart during ischemia and failure, and regulating whole body and organ metabolism are not well known and are more recent developments. These advancements have been made possible through the development of transgenic and knockout mouse models and more selective ligands to advance their research. Here, we will review the recent literature to provide new insights into these physiological functions and possible use as a therapeutic target.
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Affiliation(s)
- Dianne M Perez
- The Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH, United States
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5
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Bertrand L, Auquier J, Renguet E, Angé M, Cumps J, Horman S, Beauloye C. Glucose transporters in cardiovascular system in health and disease. Pflugers Arch 2020; 472:1385-1399. [PMID: 32809061 DOI: 10.1007/s00424-020-02444-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/28/2020] [Accepted: 07/31/2020] [Indexed: 12/13/2022]
Abstract
Glucose transporters are essential for the heart to sustain its function. Due to its nature as a high energy-consuming organ, the heart needs to catabolize a huge quantity of metabolic substrates. For optimized energy production, the healthy heart constantly switches between various metabolites in accordance with substrate availability and hormonal status. This metabolic flexibility is essential for the maintenance of cardiac function. Glucose is part of the main substrates catabolized by the heart and its use is fine-tuned via complex molecular mechanisms that include the regulation of the glucose transporters GLUTs, mainly GLUT4 and GLUT1. Besides GLUTs, glucose can also be transported by cotransporters of the sodium-glucose cotransporter (SGLT) (SLC5 gene) family, in which SGLT1 and SMIT1 were shown to be expressed in the heart. This SGLT-mediated uptake does not seem to be directly linked to energy production but is rather associated with intracellular signalling triggering important processes such as the production of reactive oxygen species. Glucose transport is markedly affected in cardiac diseases such as cardiac hypertrophy, diabetic cardiomyopathy and heart failure. These alterations are not only fingerprints of these diseases but are involved in their onset and progression. The present review will depict the importance of glucose transport in healthy and diseased heart, as well as proposed therapies targeting glucose transporters.
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Affiliation(s)
- Luc Bertrand
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium.
| | - Julien Auquier
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium
| | - Edith Renguet
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium
| | - Marine Angé
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium
| | - Julien Cumps
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium
| | - Sandrine Horman
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium
| | - Christophe Beauloye
- Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Université catholique de Louvain, Avenue Hippocrate 55, B1.55.05, B-1200, Brussels, Belgium.,Division of Cardiology, Cliniques Universitaires Saint-Luc, Brussels, Belgium
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6
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Contemporary Advances in Myocardial Metabolic Imaging and Their Impact on Clinical Care: a Focus on Positron Emission Tomography (PET). CURRENT CARDIOVASCULAR IMAGING REPORTS 2018. [DOI: 10.1007/s12410-018-9444-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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7
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Glucose transporters in healthy heart and in cardiac disease. Int J Cardiol 2017; 230:70-75. [DOI: 10.1016/j.ijcard.2016.12.083] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/12/2016] [Accepted: 12/16/2016] [Indexed: 12/21/2022]
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8
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Abstract
The heart is a biological pump that converts chemical to mechanical energy. This process of energy conversion is highly regulated to the extent that energy substrate metabolism matches energy use for contraction on a beat-to-beat basis. The biochemistry of cardiac metabolism includes the biochemistry of energy transfer, metabolic regulation, and transcriptional, translational as well as posttranslational control of enzymatic activities. Pathways of energy substrate metabolism in the heart are complex and dynamic, but all of them conform to the First Law of Thermodynamics. The perspectives expand on the overall idea that cardiac metabolism is inextricably linked to both physiology and molecular biology of the heart. The article ends with an outlook on emerging concepts of cardiac metabolism based on new molecular models and new analytical tools. © 2016 American Physiological Society. Compr Physiol 6:1675-1699, 2016.
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Affiliation(s)
- Heinrich Taegtmeyer
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston
| | - Truong Lam
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston
| | - Giovanni Davogustto
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston
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9
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Shi T, Papay RS, Perez DM. The role of α 1-adrenergic receptors in regulating metabolism: increased glucose tolerance, leptin secretion and lipid oxidation. J Recept Signal Transduct Res 2016; 37:124-132. [PMID: 27277698 DOI: 10.1080/10799893.2016.1193522] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The role of α1-adrenergic receptors (α1-ARs) and their subtypes in metabolism is not well known. Most previous studies were performed before the advent of transgenic mouse models and utilized transformed cell lines and poorly selective antagonists. We have now studied the metabolic regulation of the α1A- and α1B-AR subtypes in vivo using knock-out (KO) and transgenic mice that express a constitutively active mutant (CAM) form of the receptor, assessing subtype-selective functions. CAM mice increased glucose tolerance while KO mice display impaired glucose tolerance. CAM mice increased while KO decreased glucose uptake into white fat tissue and skeletal muscle with the CAM α1A-AR showing selective glucose uptake into the heart. Using indirect calorimetry, both CAM mice demonstrated increased whole body fatty acid oxidation, while KO mice preferentially oxidized carbohydrate. CAM α1A-AR mice displayed significantly decreased fasting plasma triglycerides and glucose levels while α1A-AR KO displayed increased levels of triglycerides and glucose. Both CAM mice displayed increased plasma levels of leptin while KO mice decreased leptin levels. Most metabolic effects were more efficacious with the α1A-AR subtype. Our results suggest that stimulation of α1-ARs results in a favorable metabolic profile of increased glucose tolerance, cardiac glucose uptake, leptin secretion and increased whole body lipid metabolism that may contribute to its previously recognized cardioprotective and neuroprotective benefits.
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Affiliation(s)
- Ting Shi
- a Department of Molecular Cardiology , Lerner Research Institute, Cleveland Clinic Foundation , Cleveland , OH , USA
| | - Robert S Papay
- a Department of Molecular Cardiology , Lerner Research Institute, Cleveland Clinic Foundation , Cleveland , OH , USA
| | - Dianne M Perez
- a Department of Molecular Cardiology , Lerner Research Institute, Cleveland Clinic Foundation , Cleveland , OH , USA
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10
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Abstract
The heart is adapted to utilize all classes of substrates to meet the high-energy demand, and it tightly regulates its substrate utilization in response to environmental changes. Although fatty acids are known as the predominant fuel for the adult heart at resting stage, the heart switches its substrate preference toward glucose during stress conditions such as ischemia and pathological hypertrophy. Notably, increasing evidence suggests that the loss of metabolic flexibility associated with increased reliance on glucose utilization contribute to the development of cardiac dysfunction. The changes in glucose metabolism in hypertrophied hearts include altered glucose transport and increased glycolysis. Despite the role of glucose as an energy source, changes in other nonenergy producing pathways related to glucose metabolism, such as hexosamine biosynthetic pathway and pentose phosphate pathway, are also observed in the diseased hearts. This article summarizes the current knowledge regarding the regulation of glucose transporter expression and translocation in the heart during physiological and pathological conditions. It also discusses the signaling mechanisms governing glucose uptake in cardiomyocytes, as well as the changes of cardiac glucose metabolism under disease conditions.
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Affiliation(s)
- Dan Shao
- Mitochondria and Metabolism Center, University of Washington, Seattle, Washington, USA
| | - Rong Tian
- Mitochondria and Metabolism Center, University of Washington, Seattle, Washington, USA
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11
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Fujikawa T, Coppari R. Living without insulin: the role of leptin signaling in the hypothalamus. Front Neurosci 2015; 9:108. [PMID: 25870537 PMCID: PMC4375980 DOI: 10.3389/fnins.2015.00108] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/13/2015] [Indexed: 01/31/2023] Open
Abstract
Since its discovery in 1922, insulin has been thought to be required for normal metabolic homeostasis and survival. However, this view would need to be revised as recent results from different laboratories have convincingly indicated that life without insulin is possible in rodent models. These data indicate that particular neuronal circuitries, which include hypothalamic leptin-responsive neurons, are empowered with the capability of permitting life in complete absence of insulin. Here, we review the neuronal and peripheral mechanisms by which leptin signaling in the central nervous system (CNS) regulates glucose metabolism in an insulin-independent manner.
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Affiliation(s)
- Teppei Fujikawa
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Roberto Coppari
- Department of Cellular Physiology and Metabolism, University of Geneva Geneva, Switzerland
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Vimercati C, Qanud K, Ilsar I, Mitacchione G, Sarnari R, Mania D, Faulk R, Stanley WC, Sabbah HN, Recchia FA. Acute vagal stimulation attenuates cardiac metabolic response to β-adrenergic stress. J Physiol 2012; 590:6065-74. [PMID: 22966163 DOI: 10.1113/jphysiol.2012.241943] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The effects of vagal stimulation (VS) on cardiac energy substrate metabolism are unknown. We tested the hypothesis that acute VS alters the balance between free fatty acid (FFA) and carbohydrate oxidation and opposes the metabolic effects of β-adrenergic stimulation. A clinical-type selective stimulator of the vagal efferent fibres was connected to the intact right vagus in chronically instrumented dogs. VS was set to reduce heart rate by 30 beats min(-1), and the confounding effects of bradycardia were then eliminated by pacing the heart at 165 beats min(-1). [(3)H]Oleate and [(14)C]glucose were infused to measure FFA and glucose oxidation. The heart was subjected to β-adrenergic stress by infusing dobutamine at 5, 10 and 15 μg kg(-1) min(-1) before and during VS. VS did not significantly affect baseline cardiac performance, haemodynamics or myocardial metabolism. However, at peak dobutamine stress, VS attenuated the increase in left ventricular pressure-diameter area from 235.9 ± 72.8 to 167.3 ± 55.8%, and in cardiac oxygen consumption from 173.9 ± 23.3 to 127.89 ± 6.2% (both P < 0.05), and thus mechanical efficiency was not enhanced. The increase in glucose oxidation fell from 289.3 ± 55.5 to 131.1 ± 20.9% (P < 0.05), while FFA oxidation was not increased by β-adrenergic stress and fell below baseline during VS only at the lowest dose of dobutamine. The functional and in part the metabolic changes were reversed by 0.1 mg kg(-1) atropine i.v. Our data show that acute right VS does not affect baseline cardiac metabolism, but attenuates myocardial oxygen consumption and glucose oxidation in response to adrenergic stress, thus functioning as a cardio-selective antagonist to β-adrenergic activation.
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Affiliation(s)
- Claudio Vimercati
- Department of Physiology, New York Medical College, Valhalla, NY, USA
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13
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5'-AMP-activated protein kinase is inactivated by adrenergic signalling in adult cardiac myocytes. Biosci Rep 2012; 32:197-213. [PMID: 21851339 DOI: 10.1042/bsr20110076] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In adult rat cardiac myocytes adrenaline decreased AMPK (AMP-activated protein kinase) activity with a half-time of approximately 4 min, decreased phosphorylation of AMPK (α-Thr172) and decreased phosphorylation of ACC (acetyl-CoA carboxylase). Inactivation of AMPK by adrenaline was through both α1- and β-ARs (adrenergic receptors), but did not involve cAMP or calcium signalling, was not blocked by the PKC (protein kinase C) inhibitor BIM I (bisindoylmaleimide I), by the ERK (extracellular-signal-regulated kinase) cascade inhibitor U0126 or by PTX (pertussis toxin). Adrenaline caused no measurable change in LKB1 activity. Adrenaline decreased AMPK activity through a process that was distinct from AMPK inactivation in response to insulin or PMA. Neither adrenaline nor PMA altered the myocyte AMP:ATP ratio although the adrenaline effect was attenuated by oligomycin and by AICAR (5-amino-4-imidazolecarboxamide-1-β-D-ribofuranoside), agents that mimic 'metabolic stress'. Inactivation of AMPK by adrenaline was abolished by 1 μM okadaic acid suggesting that activation of PP2A (phosphoprotein phosphatase 2A) might mediate the adrenaline effect. However, no change in PP2A activity was detected in myocyte extracts. Adrenaline increased phosphorylation of the AMPK β-subunit in vitro but there was no detectable change in vivo in phosphorylation of previously identified AMPK sites (β-Ser24, β-Ser108 or β-Ser182) suggesting that another site(s) is targeted.
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14
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Leichman JG, Lavis VR, Aguilar D, Wilson CR, Taegtmeyer H. The metabolic syndrome and the heart--a considered opinion. Clin Res Cardiol 2008; 95 Suppl 1:i134-41. [PMID: 16598541 DOI: 10.1007/s00392-006-1119-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The metabolic syndrome (MS) is a multifactorial, heterogeneous group of risk factors for the development of cardiovascular disease. Here we review the evidence in support of the hypothesis that metabolic dysregulation of the body as a whole leads to contractile dysfunction of the heart due to an imbalance of substrate uptake (increased) and substrate oxidation (decreased). The consequences of this imbalance were already recognized 150 years ago by Virchow when he described "fatty atrophy" of the heart as a "true metamorphosis of the heart muscle cell."
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Affiliation(s)
- J G Leichman
- The University of Texas Houston Medical School, Department of Internal Medicine, Division of Cardiology, 6431 Fannin Street, MSB 1.246, Houston, TX 77030, USA
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15
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Hutchinson DS, Summers RJ, Gibbs ME. Energy metabolism and memory processing: role of glucose transport and glycogen in responses to adrenoceptor activation in the chicken. Brain Res Bull 2008; 76:224-34. [PMID: 18498935 DOI: 10.1016/j.brainresbull.2008.02.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 01/22/2008] [Accepted: 02/11/2008] [Indexed: 11/28/2022]
Abstract
From experiments using a discriminated bead task in young chicks, we have defined when and where adrenoceptors (ARs) are involved in memory modulation. All three ARs subtypes (alpha(1)-, alpha(2)- and beta-ARs) are found in the chick brain and in regions associated with memory. Glucose and glycogen are important in the role of memory consolidation in the chick since increasing glucose levels improves memory consolidation while inhibiting glucose transporters (GLUTs) or glycogen breakdown inhibits memory consolidation. The selective beta(3)-AR agonist CL316243 enhances memory consolidation by a glucose-dependent mechanism and the administration of the non-metabolized glucose analogue 2-deoxyglucose reduces the ability of CL316243 to enhance memory. Agents that reduce glucose uptake by GLUTs and its incorporation into the glycolytic pathway also reduce the effectiveness of CL316243, but do not alter the dose-response relationship to the beta(2)-AR agonist zinterol. However, beta(2)-ARs do have a role in memory related to glycogen breakdown and inhibition of glycogenolysis reduces the ability of zinterol to enhance memory. Both beta(2)- and beta(3)-ARs are found on astrocytes from chick forebrain, and the actions of beta(3)-ARs on glucose uptake, and beta(2)-ARs on the breakdown of glycogen is consistent with an effect on astrocytic metabolism at the time of memory consolidation 30 min after training. We have shown that both beta(2)- and beta(3)-ARs can increase glucose uptake in chick astrocytes but do so by different mechanisms. This review will focus on the role of ARs on memory consolidation and specifically the role of energy metabolism on AR modulation of memory.
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Affiliation(s)
- Dana S Hutchinson
- Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia.
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16
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Angeloni C, Maraldi T, Ghelli A, Rugolo M, Leoncini E, Hakim G, Hrelia S. Green tea modulates alpha(1)-adrenergic stimulated glucose transport in cultured rat cardiomyocytes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:7553-8. [PMID: 17676868 DOI: 10.1021/jf071188+] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
alpha1-Adrenergic stimulation triggers glucose transport in the heart through the translocation of glucose transporter (GLUT) 1 and GLUT4 to plasma membranes, mediated by protein kinase C (PKC) isoforms. Evidence is emerging that dietary polyphenolic compounds may act not only as antioxidants but also by modulating PKC-mediated signaling. This study evaluated the ability of a green tea extract (GTE) to modulate alpha1-adrenoceptor-mediated glucose transport in rat cardiomyocytes. GTE supplementation decreased phenylephrine (PhE)-stimulated glucose uptake and GLUT4 recruitment. PhE stimulation activated PKC alpha, beta, delta, and epsilon, while GTE supplementation decreased the translocation of beta and delta isoforms, but not alpha and epsilon, supporting the notion that GTE directly affects PKC activation and is a beta and delta isoform-selective PKC inhibitor. Due to reactive oxygen species (ROS) involvement in pathological heart alterations, the observation that GTE is able to both inhibit effects originated by some PKC isoforms and counteract ROS deleterious effects could be important in the prevention/counteraction of these diseases.
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Affiliation(s)
- Cristina Angeloni
- Department of Biochemistry G.Moruzzi, Via Irnerio 48, University of Bologna, 40126 Bologna, Italy
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Wu Q, Kazantzis M, Doege H, Ortegon AM, Tsang B, Falcon A, Stahl A. Fatty acid transport protein 1 is required for nonshivering thermogenesis in brown adipose tissue. Diabetes 2006; 55:3229-37. [PMID: 17130465 DOI: 10.2337/db06-0749] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Nonshivering thermogenesis in brown adipose tissue (BAT) generates heat through the uncoupling of mitochondrial beta-oxidation from ATP production. The principal energy source for this process is fatty acids that are either synthesized de novo in BAT or are imported from circulation. How uptake of fatty acids is mediated and regulated has remained unclear. Here, we show that fatty acid transport protein (FATP)1 is expressed on the plasma membrane of BAT and is upregulated in response to cold stimuli, concomitant with an increase in the rate of fatty acid uptake. In FATP1-null animals, basal fatty acid uptake is reduced and remains unchanged following cold exposure. As a consequence, FATP1 knockout (KO) animals display smaller lipid droplets in BAT and fail to defend their core body temperature at 4 degrees C, despite elevated serum free fatty acid levels. Similarly, FATP1 is expressed by the BAT-derived cell line HIB-1B upon differentiation, and both fatty acid uptake and FATP1 protein levels are rapidly elevated following isoproterenol stimulation. Stimulation of fatty uptake by isoproterenol required both protein kinase A and mitogen-activated kinase signaling and is completely dependent on FATP1 expression, as small-hairpin RNA-mediated knock down of FATP1 abrogated the effect.
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Affiliation(s)
- Qiwei Wu
- Palo Alto Medical Foundation, Research Institute, Ames Building, 795 El Camino Real, Palo Alto, CA 94301, USA
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Hutchinson DS, Bengtsson T. alpha1A-adrenoceptors activate glucose uptake in L6 muscle cells through a phospholipase C-, phosphatidylinositol-3 kinase-, and atypical protein kinase C-dependent pathway. Endocrinology 2005; 146:901-12. [PMID: 15550506 DOI: 10.1210/en.2004-1083] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of alpha1-adrenoceptor activation on glucose uptake in L6 cells was investigated. The alpha1-adrenoceptor agonist phenylephrine [pEC50 (-log10 EC50), 5.27 +/- 0.30] or cirazoline (pEC50, 5.00 +/- 0.23) increased glucose uptake in a concentration-dependent manner, as did insulin (pEC50, 7.16 +/- 0.21). The alpha2-adrenoceptor agonist clonidine was without any stimulatory effect on glucose uptake. The stimulatory effect of cirazoline was inhibited by the alpha1-adrenoceptor antagonist prazosin, but not by the beta-adrenoceptor antagonist propranolol. RT-PCR showed that the alpha1A-adrenoceptor was the sole alpha1-adrenoceptor subtype expressed in L6 cells. Cirazoline- or insulin-mediated glucose uptake was inhibited by the phosphatidylinositol-3 kinase inhibitor LY294002, suggesting a possible interaction between the alpha1-adrenoceptor and insulin pathways. Cirazoline or insulin stimulated phosphatidylinositol-3 kinase activity, but alpha1-adrenoceptor activation did not phosphorylate Akt. Both cirazoline- and insulin-mediated glucose uptake were inhibited by protein kinase C (PKC), phospholipase C, and p38 kinase inhibitors, but not by Erk1/2 inhibitors (despite both treatments being able to phosphorylate Erk1/2). Insulin and cirazoline were able to activate and phosphorylate p38 kinase. The phorbol ester 12-O-tetradecanoylphorbol-13-acetate and the calcium ionophore A23187 produced significant increases in glucose uptake, indicating roles for PKC and calcium in glucose uptake. Down-regulation of conventional PKC isoforms inhibited glucose uptake mediated by 12-O-tetradecanoylphorbol-13-acetate, but not by insulin or cirazoline. This study demonstrates that alpha1-adrenoceptors mediate increases in glucose uptake in L6 muscle cells. This effect appears to be related to activation of phospholipase C, phosphatidylinositol-3 kinase, p38 kinase, and PKC.
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Affiliation(s)
- Dana S Hutchinson
- Department of Physiology, The Wenner-Gren Institute, Arrhenius Laboratory F3, Stockholm University, SE 10691 Stockholm, Sweden
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Flechtner-Mors M, Jenkinson CP, Alt A, Biesalski HK, Adler G, Ditschuneit HH. Sympathetic regulation of glucose uptake by the alpha1-adrenoceptor in human obesity. ACTA ACUST UNITED AC 2004; 12:612-20. [PMID: 15090628 DOI: 10.1038/oby.2004.70] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To investigate the involvement of alpha1-adrenoceptors in the sympathetic regulation of glucose uptake in human adipocytes. RESEARCH METHODS AND PROCEDURES Twenty-four severely obese subjects participated in this study. The microdialysis technique was used to determine interstitial glucose concentration after stimulation of abdominal subcutaneous adipose tissue with the alpha1-agonist norfenefrine, the alpha1,2beta-agonist norepinephrine, and both agents in combination with the alpha1-antagonist urapidil. The effect of beta-adrenoceptor stimulation was assessed by orciprenaline. Changes in local blood flow were determined using the ethanol escape technique. RESULTS Both norfenefrine and norepinephrine induced a concentration-dependent decrease of interstitial glucose concentration, with a greater decrease observed with norepinephrine. Preperfusion of adipose tissue with urapidil inhibited glucose decrease. The inhibition was overcome with high concentrations of norfenefrine and norepinephrine, respectively. Both adrenergic agents induced tachyphylaxia. Urapidil enhanced extracellular glucose level at high concentration. Blood flow decreased in the presence of norfenefrine and norepinephrine but increased in response to urapidil. The accelerated blood flow due to urapidil was counteracted by norepinephrine and norfenefrine. Orciprenaline decreased interstitial glucose concentration and increased nutritive blood flow. The observed changes in blood flow induced by adrenergic agents were not related to glucose uptake. DISCUSSION The stimulatory effect of the sympathetic nerves on glucose uptake in subcutaneous adipose tissue appears to be mediated by the alpha1-adrenoceptor. Norepinephrine enhances glucose entry into adipocytes independently of insulin action. In obese subjects with insulin resistance, the alpha1-adrenergic receptor may provide an important alternative pathway for glucose uptake.
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Fischer-Rasokat U, Doenst T. Insulin-induced improvement of postischemic recovery is abolished by inhibition of protein kinase C in rat heart. J Thorac Cardiovasc Surg 2003; 126:1806-12. [PMID: 14688691 DOI: 10.1016/s0022-5223(03)01229-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We demonstrated earlier that postischemic addition of insulin improves recovery of function in isolated rat heart by phosphatidylinositol 3-kinase. Activation of phosphatidylinositol 3-kinase before ischemia improves recovery of the heart after ischemia through protein kinase C. We tested whether protein kinase C activation is required for the positive inotropic effect of insulin during reperfusion. METHODS Isolated working rat hearts were perfused with Krebs-Henseleit buffer containing [2-(3)H]glucose (5 mmol/L, 0.05 microCi/mL) plus oleate (0.4 mmol/L) and were subjected to 15 minutes of global ischemia followed by 35 minutes of reperfusion with or without insulin (1 mU/mL). We measured cardiac power, glucose uptake, and tissue metabolites. The protein kinase C inhibitor chelerythrine (5 micromol/L) was added either at the beginning of the experiment or together with insulin. Experiments were repeated under normoxic conditions. RESULTS Cardiac power before ischemia was 9.63 to 12.4 mW. Insulin improved recovery of power after ischemia (96.3% +/- 10.8% versus 65.7% +/- 3.79%, P <.05). This effect was abolished by chelerythrine (55.3% +/- 6.49%). However, chelerythrine given at reperfusion did not block insulin's effect on recovery (101.0% +/- 4.25%, P <.05). Postischemic glucose uptake was not increased by insulin (3.07 +/- 0.32 before, 3.45 +/- 0.34 micromol/min/gdw after ischemia, not significant) and was not affected by chelerythrine (3.01 +/- 0.26 before, 3.29 +/- 0.32 micromol/min/gdw after ischemia, not significant). Under normoxic conditions, chelerythrine did not influence insulin's effects on glucose uptake or power. CONCLUSION The results suggest that (1) insulin's effect on recovery is dependent on ischemia-induced protein kinase C activation, (2) the activity of protein kinase C during reperfusion may not be important for this effect of insulin, and (3) protein kinase C plays no role in insulin's effect on glucose uptake under normoxic or postischemic conditions.
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Soto PF, Herrero P, Kates AM, Dence CS, Ehsani AA, Dávila-Román V, Schechtman KB, Gropler RJ. Impact of aging on myocardial metabolic response to dobutamine. Am J Physiol Heart Circ Physiol 2003; 285:H2158-64. [PMID: 12881222 DOI: 10.1152/ajpheart.00086.2003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In humans, under resting conditions there is an age-related decrease in myocardial fatty acid utilization (MFAU) and oxidation (MFAO) and a relative increase in myocardial glucose utilization (MGU). The impact of age on an individual's myocardial metabolic response to catecholamines is not well defined. Sixteen younger (mean age, 26 +/- 5 yr) and 14 older (mean age, 69 +/- 4 yr) volunteers underwent positron emission tomography to measure myocardial blood flow, myocardial oxygen consumption (M.VO2), MFAU, MFAO, and MGU both under resting conditions and during dobutamine infusion. In response to dobutamine administration, the rate-pressure product, myocardial blood flow, and M.VO2 measurements increased by similar amounts in both groups. No age-related differences were noted in the responses of plasma insulin, glucose, fatty acid, or lactate levels to dobutamine. With dobutamine infusion, MFAU and MFAO increased by a similar extent in both younger and older volunteers (age/dobutamine interactions, P = 0.62 and 0.75, respectively). In contrast, MGU increased with dobutamine administration in the younger (from 149 +/- 71 to 209 +/- 78 nmol.g(-1).min(-1); P = 0.04) but not in the older (from 235 +/- 147 to 176 +/- 84 nmol.g(-1).min(-1); P = 0.23; age/dobutamine interaction, P = 0.03) group. With dobutamine infusion, hearts in both younger and older volunteers responded by increasing their MFAU and MFAO values. Whereas younger hearts also responded with an increase in MGU, older hearts did not. Although the clinical significance of these findings awaits further study, these results may partially explain the impaired contractile reserve and the increased incidence of cardiovascular disease in older individuals.
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Affiliation(s)
- Pablo F Soto
- Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110, USA
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Coven DL, Hu X, Cong L, Bergeron R, Shulman GI, Hardie DG, Young LH. Physiological role of AMP-activated protein kinase in the heart: graded activation during exercise. Am J Physiol Endocrinol Metab 2003; 285:E629-36. [PMID: 12759223 DOI: 10.1152/ajpendo.00171.2003] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
AMP-activated protein kinase (AMPK) is emerging as a key signaling pathway that modulates cellular metabolic processes. In skeletal muscle, AMPK is activated during exercise. Increased myocardial substrate metabolism during exercise could be explained by AMPK activation. Although AMPK is known to be activated during myocardial ischemia, it remains uncertain whether AMPK is activated in response to the physiological increases in cardiac work associated with exercise. Therefore, we evaluated cardiac AMPK activity in rats at rest and after 10 min of treadmill running at moderate (15% grade, 16 m/min) or high (15% grade, 32 m/min) intensity. Total AMPK activity in the heart increased in proportion to exercise intensity (P < 0.05). AMPK activity associated with the alpha2-catalytic subunit increased 2.8 +/- 0.4-fold (P < 0.02 vs. rest) and 4.5 +/- 0.6-fold (P < 0.001 vs. rest) with moderate- and high-intensity exercise, respectively. AMPK activity associated with the alpha1-subunit increased to a lesser extent. Phosphorylation of the Thr172-regulatory site on AMPK alpha-catalytic subunits increased during exercise (P < 0.001). There was no increase in Akt phosphorylation during exercise. The changes in AMPK activity during exercise were associated with physiological AMPK effects (GLUT4 translocation to the sarcolemma and ACC phosphorylation). Thus cardiac AMPK activity increases progressively with exercise intensity, supporting the hypothesis that AMPK has a physiological role in the heart.
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Affiliation(s)
- David L Coven
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510, USA
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Véga C, Pellerin L, Dantzer R, Magistretti PJ. Long-term modulation of glucose utilization by IL-1 alpha and TNF-alpha in astrocytes: Na+ pump activity as a potential target via distinct signaling mechanisms. Glia 2002; 39:10-8. [PMID: 12112371 DOI: 10.1002/glia.10080] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) markedly stimulate glucose utilization in primary cultures of mouse cortical astrocytes. The mechanism that gives rise to this effect, which takes place several hours after application of cytokine, has remained unclear. Experiments were conducted to identify the major signaling cascades involved in the metabolic action of cytokine. First, the selective IL-1 receptor antagonist (IL-1ra) prevents the effect of IL-1alpha on glucose utilization in a concentration-dependent manner, whereas it has no effect on the action of TNF-alpha. Then, using inhibitors of three classical signaling cascades known to be activated by cytokines, it appears that the PI3 kinase is essential for the effect of both IL-1alpha and TNF-alpha, whereas the action of IL-1alpha also requires activation of the MAP kinase pathway. Participation of a phospholipase C-dependent pathway does not appear critical for both IL-1alpha and TNF-alpha. Inhibition of NO synthase by L-NAME did not prevent the metabolic response to both IL-1alpha and TNF-alpha, indicating that nitric oxide is probably not involved. In contrast, the Na(+)/K(+) ATPase inhibitor ouabain prevents the IL-1alpha- and TNF-alpha-stimulated 2-deoxyglucose (2DG) uptake. When treatment of astrocytes with a cytokine was followed 24 h later by an acute application of glutamate, a synergistic enhancement in glucose utilization was observed. This effect was greatly reduced by ouabain. These data suggest that Na(+) pump activity is a common target for both the long-term metabolic action of cytokines promoted by the activation of distinct signaling pathways and the enhanced metabolic response to glutamate.
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Affiliation(s)
- Céline Véga
- Institut de Physiologie, Lausanne, Switzerland
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Sidell RJ, Cole MA, Draper NJ, Desrois M, Buckingham RE, Clarke K. Thiazolidinedione treatment normalizes insulin resistance and ischemic injury in the zucker Fatty rat heart. Diabetes 2002; 51:1110-7. [PMID: 11916933 DOI: 10.2337/diabetes.51.4.1110] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Obesity is associated with risk factors for cardiovascular disease, including insulin resistance, and can lead to cardiac hypertrophy and congestive heart failure. Here, we used the insulin-sensitizing agent rosiglitazone to investigate the cellular mechanisms linking insulin resistance in the obese Zucker rat heart with increased susceptibility to ischemic injury. Rats were treated for 7 or 14 days with 3 mg/kg per os rosiglitazone. Hearts were isolated and perfused before and during insulin stimulation or during 32 min low-flow ischemia at 0.3 ml small middle dot min(-1) small middle dot grams wet wt(-1) and reperfusion. D[2-(3)H]glucose was used as a tracer of glucose uptake, and phosphorus-31 nuclear magnetic resonance spectroscopy was used to follow energetics during ischemia. At 12 months of age, obese rat hearts were insulin resistant with decreased GLUT4 protein expression. During ischemia, glucose uptake was lower and depletion of ATP was greater in obese rat hearts, thereby significantly impairing recovery of contractile function during reperfusion. Rosiglitazone treatment normalized the insulin resistance and restored GLUT4 protein levels in obese rat hearts. Glucose uptake during ischemia was also normalized by rosiglitazone treatment, thereby preventing the greater loss of ATP and restoring recovery of contractile function to that of lean rat hearts. We conclude that rosiglitazone treatment, by normalizing glucose uptake, protected obese rat hearts from ischemic injury.
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Affiliation(s)
- Robert J Sidell
- Department of Biochemistry, University of Oxford, Oxford, U.K. GlaxoSmithKline, Harlow, Essex, U.K
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Zechner C, Beyersdorf F, Doenst T. The role of calcium in the regulation of glucose uptake in isolated working rat heart. Mol Cell Biochem 2002; 232:75-80. [PMID: 12030382 DOI: 10.1023/a:1014897304124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Catecholamines or ischemia may increase myocardial glucose uptake by an increase in intracellular calcium. We tested the hypothesis that increasing or decreasing extracellular calcium supply would change glucose uptake. Hearts were perfused for 60 min at a physiological workload with Krebs-Henseleit buffer containing glucose (5 mM) and oleate (0.4 mM; bound to 1% BSA). Calcium concentration was 2.5 mM. In group A (control; n = 12), insulin (1 mU/ml) was added at 30 min. In Group B (n = 7), the calcium concentration was increased to 5.0 and 7.5 mM at 20 min and 40 min, respectively. In Group C (n = 7), verapamil was added at 20 min (0.25 microM) and 40 min (1.0 microM) to decrease calcium influx. In group D (n = 7), EDTA was added at 20 min (0.5 mM) and at 40 min (1.5 mM) to decrease the free extracellular calcium. Glucose uptake was measured by 3H2O production from [2-3H]glucose and cardiac work was measured simultaneously. Cardiac power in group B was 8.24 +/- 0.60 mW at 2.5 mM calcium, 9.45 +/- 0.50 mW at 5 mM calcium and 7.99 +/- 0.99 mW at 7.5 mM calcium (n.s.). The addition of verapamil decreased contractile function in a dose-dependent manner (8.50 +/- 0.74 vs. 3.11 +/- 0.84 vs. 1.48 +/- 0.39 mW, p < 0.01) suggesting that verapamil decreased cytosolic calcium concentration. A similar dose-dependent reduction in contractile performance was observed in the EDTA group (8.44 +/- 0.81 vs. 7.42 +/- 0.96 vs. 4.03 +/- 1.32 mW, p < 0.01). Glucose uptake was 1.35 +/- 0.11 micromol/min/g dry weight under control conditions. Glucose uptake increased threefold with the addition of insulin. Increasing extracellular [Ca2+] did not affect glucose uptake. Decreasing Ca2+ availability showed a trend towards a decrease in glucose uptake (n.s.), which was minor compared to the decrease in contractile function. We conclude that extracellular calcium does not regulate glucose uptake in the isolated working rat heart in the presence of glucose and fatty acids as substrates. The trend of decreased glucose uptake when calcium supply was limited may be due to dramatically reduced energy demand and not directly due to changes in calcium.
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Affiliation(s)
- Christoph Zechner
- Department of Cardiovascular Surgery, University of Freiburg, Germany
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27
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Yoshioka J, Kusuoka H, Imahashi K, Hashimoto K, Hori M, Terakawa T, Nishimura T. Troglitazone enhances glucose uptake induced by alpha-adrenoceptor stimulation via phosphatidylinositol 3-kinase in rat heart. Clin Exp Pharmacol Physiol 2001; 28:752-7. [PMID: 11553036 DOI: 10.1046/j.1440-1681.2001.03515.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Thiazolidinedione-derived agents have been reported to act as insulin sensitizers by augmenting insulin-dependent stimulation of phosphatidylinositol 3-kinase (PI3K) activity in a specific manner. It has been suggested that alpha-adrenoceptor stimulation mediates glucose uptake through PI3K in the heart. 2. To elucidate whether the thiazolidinedione-derived agent troglitazone (TRO) affects glucose uptake induced by alpha-adrenoceptor stimulation through PI3K, the rate of glucose uptake was quantified from the rate of accumulation of sugar phosphate (d[SP]/dt) using [(31)P] nuclear magnetic resonance spectroscopy after substitution of glucose with 2-deoxyglucose in rat perfused heart. Hearts were stimulated with 100 micromol/L phenylephrine plus 10 micromol/L propranolol (alpha-adrenoceptor stimulation), or 1 micromol/L isoproterenol plus 10 micromol/L phentolamine (beta-adrenoceptor stimulation). 3. The d[SP]/dt in the alpha- and beta-adrenoceptor-stimulated groups (0.45 +/- 0.06 and 0.42 +/- 0.04 micromol/min per g, respectively) was higher than that of the control group (0.27 +/- 0.02 micromol/min per g; P < 0.01). The addition of 2 microg/mL troglitazone to alpha-adrenoceptor stimulation augmented d[SP]/dt (0.72 +/- 0.08 micromol/min per g; P < 0.05 vs the alpha-adrenoceptor-stimulated group), which was effectively blocked by 3 micromol/L wortmannin (0.35 +/- 0.06 micromol/min per g; P < 0.01 vs troglitazone + alpha-adrenoceptor stimulation group). However, addition of troglitazone to beta-adrenoceptor stimulation did not alter d[SP]/dt (0.33 +/- 0.02 micromol/min per g; P = NS vs the beta-adrenoceptor-stimulated group). 4. These results indicate that troglitazone acutely enhances alpha-adrenoceptor stimulation on glucose uptake through a PI3K-dependent pathway, thus possibly improving glucose utilization in a catecholamine-released state.
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Affiliation(s)
- J Yoshioka
- Division of Tracer Kinetics, Osaka University Graduate School of Medicine, Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-ku, Osaka 540-0006, Japan
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Huisamen B, van Zyl M, Keyser A, Lochner A. The effects of insulin and beta-adrenergic stimulation on glucose transport, glut 4 and PKB activation in the myocardium of lean and obese non-insulin dependent diabetes mellitus rats. Mol Cell Biochem 2001; 223:15-25. [PMID: 11681717 DOI: 10.1023/a:1017528402205] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glucose uptake, glut 4 translocation and activation of protein kinase B were measured in Langendorff perfused hearts from (i) Wistar control, (ii) lean, neonatal Streptozotocin induced (Stz) and (iii) Zucker (fa/fa) obese diabetic rats of 10-12 weeks old. Hearts were subjected to stimulation with insulin, isoproterenol (beta-adrenergic agonist) or a combination of insulin and isoproterenol, during the perfusion protocol. Basal myocardial glucose uptake was impaired in both diabetic models, but could be stimulated significantly by insulin. In the Zucker rats, the time-course of insulin action was delayed. Insulin and beta-stimulation of glucose uptake were not additive. Evaluation of sarcolemmal membranes from these hearts showed that the affinity of glut 4 was significantly lower in the Zucker but not in the Stz hearts while a reduced affinity found with a combination of insulin and beta-stimulation in control hearts, was absent in both diabetic models. Total membrane lysates were analyzed for glut 4 expression while an intracellular component was generated to quantify translocation on stimulation as well as activity of protein kinase B (PKB). At this age, the neonatal Streptozotocin induced diabetic animals presented with more faulty regulation concerning adrenergic stimulated effects on elements of this signal transduction pathway while the Zucker fa/fa animals showed larger deviations in insulin stimulated effects. The overall response of the Zucker myocardium was poorer than that of the Stz group. No significant modulation of beta-adrenergic signaling on insulin stimulated glucose uptake was found. The PI-3-kinase inhibitor wortmannin, could abolish glucose uptake as well as PKB activation elicited by both insulin and isoproterenol.
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Affiliation(s)
- B Huisamen
- Department of Medical Physiology and Biochemistry, Faculty of Medicine, University of Stellenbosch, Tygerberg, Republic of South Africa
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Salvi S. Protecting the myocardium from ischemic injury: a critical role for alpha(1)-adrenoreceptors? Chest 2001; 119:1242-9. [PMID: 11296192 DOI: 10.1378/chest.119.4.1242] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Ischemic preconditioning (IPC) refers to the ability of short periods of ischemia to make the myocardium more resistant to a subsequent ischemic insult. It is the most powerful form of endogenous protection against myocardial infarction and has been demonstrated in all species evaluated to date. However, the cellular mechanisms that drive IPC remain poorly understood. This hypothesis describes an important role for alpha(1)-adrenoreceptors in mediating IPC and discusses the underlying mechanisms by which this is likely achieved. alpha(1)-Adrenoreceptors are present in the myocardium of all mammalian species, and several lines of evidence suggest that they play an important role in mediating IPC. During periods of myocardial hypoxia/ischemia, cardiomyocytes have to rely solely on anaerobic glycolysis for energy production; for this, the cells have to depend on increased glucose entry inside the cell as well as increased glycolysis. Stimulation of alpha(1)-adrenoreceptors increases glucose transport inside the cardiomyocytes by translocating glucose transporter (GLUT)-1 and GLUT-4 from the cytoplasm to the plasma membrane, enhances glycogenolysis by activating phosphorylase kinase, increases the rate of glycolysis by activating the enzyme phosphofructokinase, reduces intracellular acidity produced during excessive glycolysis by activating the Na(+)/H(+) exchanger, and inhibits apoptosis by increasing the levels of the antiapoptotic protein Bcl-2. Myocardial ischemia produces an increase in the expression of alpha(1)-adrenoreceptors in cardiomyocytes, as well as increases the levels of its agonist norepinephrine by several fold. During ischemic states, upregulation of alpha(1)-adrenoreceptors and increase in norepinephrine release could be a powerful adaptive mechanism that drives IPC. An understanding into the role of alpha(1)-adrenoreceptors in mediating IPC could not only point to newer treatments for limiting myocardial damage during myocardial infarction or heart surgery, but could also help in avoiding the use of alpha(1)-antagonists in patients with ischemic heart disease.
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Affiliation(s)
- S Salvi
- Department of Medicine, Southampton General Hospital, Southampton, UK.
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Doenst T, Cedars AM, Taegtmeyer H. Insulin-stimulated glucose transport is dependent on Golgi function in isolated working rat heart. J Mol Cell Cardiol 2000; 32:1481-8. [PMID: 10900174 DOI: 10.1006/jmcc.2000.1181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
UNLABELLED Insulin and epinephrine stimulate glucose uptake through distinct mechanisms. We tested the hypothesis that the golgi apparatus is involved in insulin-stimulated but not epinephrine-stimulated glucose transport and phosphorylation. METHODS We perfused isolated working rat hearts with Krebs-Henseleit buffer containing [2-(3)H]glucose (5 mmol/l, 0.05 microCi/ml) and Na-oleate (0.4 mmol/l). In the absence or presence of the inhibitor of golgi function, brefeldin A (30 micromol/l), either insulin (1 mU/ml), epinephrine (1 micromol/l), or phenylephrine (100 micromol/l) plus propranolol (10 micromol/l, selective alpha -adrenergic stimulation) were added to the perfusate. RESULTS Cardiac power was stable in all groups (between 8.56+/-0.61 and 10.4+/-1.11 mW) and increased (34%) with addition of epinephrine, but not with selective alpha -adrenergic stimulation. Insulin, epinephrine, and selective alpha -receptor stimulation increased glucose transport and phosphorylation (micromol/min/g dry wt, basal: 1.19+/-0.13, insulin: 3.89+/-0.36, epinephrine: 3.46+/-0.27, alpha -stimulation: 4.08+/-0.40). Brefeldin A increased basal glucose transport and phosphorylation and blunted insulin-stimulated but not epinephrine-stimulated glucose transport and phosphorylation. Selective alpha -stimulated glucose transport and phosphorylation was also blunted by brefeldin A. CONCLUSIONS Both insulin and alpha -adrenergic stimulation result in glucose transporter translocation from a pool that requires golgi function. Stimulation with epinephrine results in glucose transporter translocation from a pool that does not require golgi function. The stimulating effects of the alpha -adrenergic pathway on glucose transport and phosphorylation are independent of changes in cardiac performance.
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Affiliation(s)
- T Doenst
- Department of Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA
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Tong H, Chen W, London RE, Murphy E, Steenbergen C. Preconditioning enhanced glucose uptake is mediated by p38 MAP kinase not by phosphatidylinositol 3-kinase. J Biol Chem 2000; 275:11981-6. [PMID: 10766828 DOI: 10.1074/jbc.275.16.11981] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ischemia is reported to stimulate glucose uptake, but the signaling pathways involved are poorly understood. Modulation of glucose transport could be important for the cardioprotective effects of brief intermittent periods of ischemia and reperfusion, termed ischemic preconditioning. Previous work indicates that preconditioning reduces production of acid and lactate during subsequent sustained ischemia, consistent with decreased glucose utilization. However, there are also data that preconditioning enhances glucose uptake. The present study examines whether preconditioning alters glucose transport and whether this is mediated by either phosphatidylinositol 3-kinase (PI3K) or p38 MAP kinase. Langendorff-perfused rat hearts were preconditioned with 4 cycles of 5 min of ischemia and 5 min of reperfusion, with glucose as substrate. During the last reflow, glucose was replaced with 5 mM acetate and 5 mM 2-deoxyglucose (2DG), and hexose transport was measured from the rate of production of 2-deoxyglucose 6-phosphate (2DG6P), using (31)P nuclear magnetic resonance. Preconditioning stimulated 2DG uptake; after 15 min of perfusion with 2DG, 2DG6P levels were 165% of initial ATP in preconditioned hearts compared with 96% in control hearts (p < 0.05). Wortmannin, an inhibitor of PI3K, did not block the preconditioning induced stimulation of 2DG6P production, but perfusion with SB202190, an inhibitor of p38 MAP kinase, did attenuate 2DG6P accumulation (111% of initial ATP, p < 0. 05 compared with preconditioned hearts). SB202190 had no effect on 2DG6P accumulation in nonpreconditioned hearts. Preconditioning stimulation of translocation of GLUT4 to the plasma membrane was not inhibited by wortmannin. The data demonstrate that ischemic preconditioning increases hexose transport and that this is mediated by p38 MAP kinase and is PI3K-independent.
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Affiliation(s)
- H Tong
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Morisco C, Condorelli G, Orzi F, Vigliotta G, Di Grezia R, Beguinot F, Trimarco B, Lembo G. Insulin-stimulated cardiac glucose uptake is impaired in spontaneously hypertensive rats: role of early steps of insulin signalling. J Hypertens 2000; 18:465-73. [PMID: 10779099 DOI: 10.1097/00004872-200018040-00017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Although the heart is one of the target organs of insulin, it is still unknown whether the effect of insulin on cardiac muscle is preserved in essential hypertension, where insulin resistance has been observed in skeletal muscle. METHODS We evaluated cardiac glucose uptake and the early steps of insulin signalling in spontaneously hypertensive (SHR, 10-12 weeks old) and in age-matched normotensive Wistar-Kyoto (WKY) rats. Cardiac glucose uptake (micromol/100 g per min) was assessed by 2-[14C]deoxyglucose method. After an overnight fast, 16 WKY rats and 17 SHR underwent a hyperinsulinemic euglycemic clamp. In particular, 2-h intravenous (i.v.) infusion of insulin (10 mU/kg per min) or saline (NaCl 0.9%) was administered, followed by an i.v. bolus injection of 2-[14C]deoxyglucose (100 microCi/kg) to measure cardiac glucose uptake. RESULTS During saline infusion, cardiac glucose uptake was significantly higher in SHR compared to WKY rats (85 +/- 18 versus 8 +/- 3 mg/kg per min, P < 0.01). Furthermore, insulin was able to markedly increase cardiac glucose uptake in WKY rats whereas this insulin action was entirely abolished in SHR; thus, the cardiac glucose uptake became similar in the two rat strains (76 +/- 16 versus 82 +/- 16 mg/kg per min, not significant). More importantly, during saline infusion SHR showed a significantly higher phosphorylation of insulin receptor substance-1 (IRS-1) coupled to enhanced association of the p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase) to IRS-1 and to an increased PI 3-kinase activity compared to WKY rats. As expected, insulin exposure evoked an activation of its signalling cascade in WKY rats. In contrast, in SHR, the hormone failed to activate post-receptor molecular events. CONCLUSIONS Our data indicate that the heart of SHR shows an overactivity of the proximal steps of insulin signalling which cannot be further increased by the exposure to the hormone. This abnormality may account for the marked increase of basal cardiac glucose uptake and the loss of insulin-stimulated glucose uptake observed in SHR.
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Affiliation(s)
- C Morisco
- Department of Neurocardiology, IRCCS INM Neuromed, Pozzilli (IS), Italy
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