1
|
Lav Madsen P, Sejersen C, Nyberg M, Sørensen MH, Hellsten Y, Gaede P, Bojer AS. The cardiovascular changes underlying a low cardiac output with exercise in patients with type 2 diabetes mellitus. Front Physiol 2024; 15:1294369. [PMID: 38571722 PMCID: PMC10987967 DOI: 10.3389/fphys.2024.1294369] [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: 09/14/2023] [Accepted: 02/19/2024] [Indexed: 04/05/2024] Open
Abstract
The significant morbidity and premature mortality of type 2 diabetes mellitus (T2DM) is largely associated with its cardiovascular consequences. Focus has long been on the arterial atheromatosis of DM giving rise to early stroke and myocardial infarctions, whereas less attention has been given to its non-ischemic cardiovascular consequences. Irrespective of ischemic changes, T2DM is associated with heart failure (HF) most commonly with preserved ejection fraction (HFpEF). Largely due to increasing population ages, hypertension, obesity and T2DM, HFpEF is becoming the most prevalent form of heart failure. Unfortunately, randomized controlled trials of HFpEF have largely been futile, and it now seems logical to address the important different phenotypes of HFpEF to understand their underlying pathophysiology. In the early phases, HFpEF is associated with a significantly impaired ability to increase cardiac output with exercise. The lowered cardiac output with exercise results from both cardiac and peripheral causes. T2DM is associated with left ventricular (LV) diastolic dysfunction based on LV hypertrophy with myocardial disperse fibrosis and significantly impaired ability for myocardial blood flow increments with exercise. T2DM is also associated with impaired ability for skeletal muscle vasodilation during exercise, and as is the case in the myocardium, such changes may be related to vascular rarefaction. The present review discusses the underlying phenotypical changes of the heart and peripheral vascular system and their importance for an adequate increase in cardiac output. Since many of the described cardiovascular changes with T2DM must be considered difficult to change if fully developed, it is suggested that patients with T2DM are early evaluated with respect to their cardiovascular compromise.
Collapse
Affiliation(s)
- Per Lav Madsen
- Department Cardiology, Herlev-Gentofte Hospital, Copenhagen University, Copenhagen, Denmark
- Department Clinical Medicine, Copenhagen University, Copenhagen, Denmark
- The August Krogh Section for Human Physiology, Department Nutrition, Exercise and Sports, Copenhagen University, Copenhagen, Denmark
| | - Casper Sejersen
- The August Krogh Section for Human Physiology, Department Nutrition, Exercise and Sports, Copenhagen University, Copenhagen, Denmark
- Department of Anaesthesia, Rigshospitalet, Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Michael Nyberg
- Department Kidney and Vascular Biology, Global Drug Discovery, Novo Nordisk, Copenhagen, Denmark
| | | | - Ylva Hellsten
- The August Krogh Section for Human Physiology, Department Nutrition, Exercise and Sports, Copenhagen University, Copenhagen, Denmark
| | - Peter Gaede
- Department Endocrinology, Slagelse-Næstved Hospital, Copenhagen, Denmark
| | - Annemie Stege Bojer
- Department Cardiology, Herlev-Gentofte Hospital, Copenhagen University, Copenhagen, Denmark
- Department Endocrinology, Slagelse-Næstved Hospital, Copenhagen, Denmark
| |
Collapse
|
2
|
Lu YJ, Chen SY, Lai YC, Chaiyawat P, Chao YH, Chuang LM, Shih TTF, Wang HK. Muscle Microcirculatory Responses to Incremental Exercises Are Correlated with Peak Oxygen Uptake in Individuals With and Without Type 2 Diabetes Mellitus. Metab Syndr Relat Disord 2022; 20:405-413. [PMID: 35594301 DOI: 10.1089/met.2021.0101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Background: The role of impaired oxygen extraction on peak oxygen uptake (V̇O2peak) has been extensively studied using noninvasive and indirect methods in both diabetic patients and healthy participants. Methods: A total of 22 participants with type 2 diabetes mellitus [T2DM; median (range) age: 60 (47-70) years] and 22 controls [58 (52-69) years] with no history of diabetes were recruited (reference no. 201812135RINB). Subjects performed an exhaustive incremental exercise and were evaluated using a gas analyzer and near-infrared spectroscopy (NIRS) to determine V̇O2peak and changes in muscle oxygenation (SmO2) in the vastus lateralis, respectively. Measurements were taken at rest, warm-up, a period during exercise when SmO2 reached a minimum saturation plateau, and recovery. The microcirculatory responses of the vastus lateralis muscle during incremental exercise in patients with T2DM were compared with those in control individuals, and the correlation between changes in SmO2 and V̇O2peak was estimated. Results: The diabetic group demonstrated lower V̇O2peak, peak workload, peak heart rate, peak minute ventilation (all P < 0.05), and lower SmO2 during the rest, warm-up, and recovery phases (all P < 0.05) compared with the control group. A correlation was observed between the change in SmO2 between the warm-up and plateau value and the V̇O2peak (r = 0.608, P = 0.006). Conclusions: The results obtained in this study using NIRS support the feasibility of directly measuring changes in muscle SmO2 magnitudes to estimate the contributions of peripheral active muscle to systemic O2 uptake (V̇O2) during incremental exercise.
Collapse
Affiliation(s)
- Yan-Jhen Lu
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.,Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan
| | - Ssu-Yuan Chen
- Division of Physical Medicine and Rehabilitation, Fu Jen Catholic University Hospital, New Taipei City, Taiwan.,School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.,Department of Physical Medicine and Rehabilitation, College of Medicine, National Taiwan University, Taipei, Taiwan.,Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei, Taiwan
| | - Ying-Chuen Lai
- Division of Metabolism and Endocrinology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.,College of Medicine, National Taiwan University, Taipei, Taiwan
| | | | - Yuan-Hung Chao
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.,Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan
| | - Lee-Ming Chuang
- Division of Metabolism and Endocrinology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.,College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Tiffany Ting-Fang Shih
- Department of Medical Image and Radiology, Medical College and Hospital, National Taiwan University, Taipei, Taiwan
| | - Hsing-Kuo Wang
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.,Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan
| |
Collapse
|
3
|
Nesti L, Pugliese NR, Sciuto P, De Biase N, Mazzola M, Fabiani I, Trico D, Masi S, Natali A. Mechanisms of reduced peak oxygen consumption in subjects with uncomplicated type 2 diabetes. Cardiovasc Diabetol 2021; 20:124. [PMID: 34158062 PMCID: PMC8218418 DOI: 10.1186/s12933-021-01314-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
Background Type 2 diabetes mellitus (T2D) increases the risk of incident heart failure (HF), whose earliest fingerprint is effort intolerance (i.e. impaired peak oxygen consumption, or VO2peak). In the uncomplicated T2D population, however, the prevalence of effort intolerance and the underpinning mechanistic bases are uncertain. Leveraging the multiparametric characterization allowed by imaging-cardiopulmonary exercise testing (iCPET), the aim of this study is to quantify effort intolerance in T2D and to dissect the associated cardiopulmonary alterations. Methods Eighty-eight adults with well-controlled and uncomplicated T2D and no criteria for HF underwent a maximal iCPET with speckle tracking echocardiography, vascular and endothelial function assessment, as well as a comprehensive biohumoral characterization. Effort intolerance was defined by a VO2peak below 80% of maximal predicted oxygen uptake. Results Forty-eight patients (55%) had effort intolerance reaching a lower VO2peak than T2D controls (16.5 ± 3.2 mL/min/kg, vs 21.7 ± 5.4 mL/min/kg, p < 0.0001). Despite a comparable cardiac output, patients with effort intolerance showed reduced peak peripheral oxygen extraction (11.3 ± 3.1 vs 12.7 ± 3.3 mL/dL, p = 0.002), lower VO2/work slope (9.9 ± 1.2 vs 11.2 ± 1.4, p < 0.0001), impaired left ventricle systolic reserve (peak S’ 13.5 ± 2.8 vs 15.2 ± 3.0, p = 0.009) and global longitudinal strain (peak-rest ΔGLS 1.7 ± 1.5 vs 2.5 ± 1.8, p = 0.03) than subjects with VO2peak above 80%. Diastolic function, vascular resistance, endothelial function, biohumoral exams, right heart and pulmonary function indices did not differ between the two groups. Conclusions Effort intolerance and reduced VO2peak is a severe and highly prevalent condition in uncomplicated, otherwise asymptomatic T2D. It results from a major defect in skeletal muscle oxygen extraction coupled with a subtle myocardial systolic dysfunction. Supplementary Information The online version contains supplementary material available at 10.1186/s12933-021-01314-6.
Collapse
Affiliation(s)
- Lorenzo Nesti
- Metabolism, Nutrition, and Atherosclerosis Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Via Savi 10, 56126, Pisa, Italy. .,Cardiopulmonary Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
| | - Nicola Riccardo Pugliese
- Cardiopulmonary Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Paolo Sciuto
- Metabolism, Nutrition, and Atherosclerosis Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Via Savi 10, 56126, Pisa, Italy
| | - Nicolò De Biase
- Cardiopulmonary Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Matteo Mazzola
- Cardiopulmonary Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | | | - Domenico Trico
- Metabolism, Nutrition, and Atherosclerosis Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Via Savi 10, 56126, Pisa, Italy.,Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Stefano Masi
- Cardiopulmonary Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Andrea Natali
- Metabolism, Nutrition, and Atherosclerosis Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Via Savi 10, 56126, Pisa, Italy.,Cardiopulmonary Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| |
Collapse
|
4
|
Grotle AK, Kaur J, Stone AJ, Fadel PJ. Neurovascular Dysregulation During Exercise in Type 2 Diabetes. Front Physiol 2021; 12:628840. [PMID: 33927637 PMCID: PMC8076798 DOI: 10.3389/fphys.2021.628840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/05/2021] [Indexed: 12/12/2022] Open
Abstract
Emerging evidence suggests that type 2 diabetes (T2D) may impair the ability to properly adjust the circulation during exercise with augmented blood pressure (BP) and an attenuated contracting skeletal muscle blood flow (BF) response being reported. This review provides a brief overview of the current understanding of these altered exercise responses in T2D and the potential underlying mechanisms, with an emphasis on the sympathetic nervous system and its regulation during exercise. The research presented support augmented sympathetic activation, heightened BP, reduced skeletal muscle BF, and impairment in the ability to attenuate sympathetically mediated vasoconstriction (i.e., functional sympatholysis) as potential drivers of neurovascular dysregulation during exercise in T2D. Furthermore, emerging evidence supporting a contribution of the exercise pressor reflex and central command is discussed along with proposed future directions for studies in this important area of research.
Collapse
Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - Paul J Fadel
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
| |
Collapse
|
5
|
Reichert KP, Castro MFV, Assmann CE, Bottari NB, Miron VV, Cardoso A, Stefanello N, Morsch VMM, Schetinger MRC. Diabetes and hypertension: Pivotal involvement of purinergic signaling. Biomed Pharmacother 2021; 137:111273. [PMID: 33524787 PMCID: PMC7846467 DOI: 10.1016/j.biopha.2021.111273] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/11/2020] [Accepted: 12/26/2020] [Indexed: 02/07/2023] Open
Abstract
Diabetes mellitus (DM) and hypertension are highly prevalent worldwide health problems and frequently associated with severe clinical complications, such as diabetic cardiomyopathy, nephropathy, retinopathy, neuropathy, stroke, and cardiac arrhythmia, among others. Despite all existing research results and reasonable speculations, knowledge about the role of purinergic system in individuals with DM and hypertension remains restricted. Purinergic signaling accounts for a complex network of receptors and extracellular enzymes responsible for the recognition and degradation of extracellular nucleotides and adenosine. The main components of this system that will be presented in this review are: P1 and P2 receptors and the enzymatic cascade composed by CD39 (NTPDase; with ATP and ADP as a substrate), CD73 (5′-nucleotidase; with AMP as a substrate), and adenosine deaminase (ADA; with adenosine as a substrate). The purinergic system has recently emerged as a central player in several physiopathological conditions, particularly those linked to inflammatory responses such as diabetes and hypertension. Therefore, the present review focuses on changes in both purinergic P1 and P2 receptor expression as well as the activities of CD39, CD73, and ADA in diabetes and hypertension conditions. It can be postulated that the manipulation of the purinergic axis at different levels can prevent or exacerbate the insurgency and evolution of diabetes and hypertension working as a compensatory mechanism.
Collapse
Affiliation(s)
- Karine Paula Reichert
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Milagros Fanny Vera Castro
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Charles Elias Assmann
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Nathieli Bianchin Bottari
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Vanessa Valéria Miron
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Andréia Cardoso
- Academic Coordination, Medicine, Campus Chapecó, Federal University of Fronteira Sul, Chapecó, SC, Brazil
| | - Naiara Stefanello
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Vera Maria Melchiors Morsch
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Maria Rosa Chitolina Schetinger
- Department of Biochemistry and Molecular Biology, Post-Graduation Program of Biological Sciences: Toxicological Biochemistry, CCNE, Federal University of Santa Maria, Santa Maria, RS, Brazil.
| |
Collapse
|
6
|
Matsumoto T, Takayanagi K, Kojima M, Taguchi K, Kobayashi T. Differential Contractile Reactivity to Nucleotides in Femoral Arteries of OLETF and LETO Rats. Biol Pharm Bull 2020; 43:1987-1992. [PMID: 33268721 DOI: 10.1248/bpb.b20-00653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extracellular nucleotides play an important role in the regulation of vascular function, and an abnormal vascular function is an important participant in the development and progression of diabetic vascular complications. The purpose of this study was to determine whether contractile responses induced by extracellular nucleotides and a dinucleotide, uridine adenosine tetraphosphate (Up4A), in femoral arteries would be altered at the chronic stage of type 2 diabetes. We determined the changes in contractile reactivity induced by ATP, uridine triphosphate (UTP), uridine diphosphate (UDP), and Up4A in the femoral arteries of Otsuka Long-Evans Tokushima Fatty (OLETF) rats (aged male type 2 diabetic rats) and, Long-Evans Tokushima Otsuka (LETO) rats (controls for OLETF rats). ATP-induced contractions were greater in OLETF rats than in LETO rats. UTP-induced contractions were lower in OLETF rats than in LETO rats. UDP- and Up4A-induced contractions were similar between OLETF and LETO rats. The femoral artery contractile changes induced by the extracellular nucleotides and dinucleotide were similar when nitric oxide synthase was inhibited. These results suggest that the extent of femoral artery contractile reactivity to nucleotides/dinucleotides differs during long-term duration of type 2 diabetes.
Collapse
Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Keisuke Takayanagi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Mihoka Kojima
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Kumiko Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| |
Collapse
|
7
|
Cruz AM, Beall C. Extracellular ATP Increases Glucose Metabolism in Skeletal Muscle Cells in a P2 Receptor Dependent Manner but Does Not Contribute to Palmitate-Induced Insulin Resistance. Front Physiol 2020; 11:567378. [PMID: 33101053 PMCID: PMC7545032 DOI: 10.3389/fphys.2020.567378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/26/2020] [Indexed: 11/24/2022] Open
Abstract
Saturated fatty acids such as palmitate contribute to the development of Type 2 Diabetes by reducing insulin sensitivity, increasing inflammation and potentially contributing to anabolic resistance. We hypothesized that palmitate-induced ATP release from skeletal muscle cells may increase inflammatory cytokine production and contribute to insulin/anabolic resistance in an autocrine/paracrine manner. In C2C12 myotubes differentiated at physiological glucose concentrations (5.5 mM), palmitate treatment (16 h) at concentrations greater than 250 μM increased release of ATP and inflammatory cytokines IL-6 and MIF, significantly blunted insulin and amino acid-induced signaling and reduced mitochondrial function. In contrast to our hypothesis, degradation of extracellular ATP using apyrase, did not alter palmitate-induced insulin resistance nor alter release of cytokines. Moreover, treatment with ATPγS (16 h), a non-hydrolysable ATP analog, in the absence of palmitate, did not diminish insulin sensitivity. Acute treatment with ATPγS produced insulin mimetic roles; increased phosphorylation of PKB (aka AKT), S6K1 and ERK and enhanced GLUT4-mediated glucose uptake in the absence of exogenous insulin. The increases in PKB and S6K1 phosphorylation were completely prevented by pre-incubation with broad spectrum purinergic receptor (P2R) blockers PPADs and suramin but not by P2 × 4 or P2 × 7 blockers 5-BDBD or A-438079, respectively. Moreover, ATPγS increased IL-6 yet decreased MIF release, similar to the cytokine profile produced by exercise. Acute and chronic treatment with ATPγS increased glycolytic rate in a manner that was differentially inhibited by PPADs and suramin, suggesting heterogeneous P2R activation in the control of cellular metabolism. In summary, our data suggest that the palmitate-induced increase in ATP does not contribute to insulin/anabolic resistance in a cell autonomous manner.
Collapse
Affiliation(s)
- Ana Miguel Cruz
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, United Kingdom
| | - Craig Beall
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, United Kingdom
| |
Collapse
|
8
|
Nesti L, Pugliese NR, Sciuto P, Natali A. Type 2 diabetes and reduced exercise tolerance: a review of the literature through an integrated physiology approach. Cardiovasc Diabetol 2020; 19:134. [PMID: 32891175 PMCID: PMC7487838 DOI: 10.1186/s12933-020-01109-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/29/2020] [Indexed: 12/14/2022] Open
Abstract
The association between type 2 diabetes mellitus (T2DM) and heart failure (HF) is well established. Early in the course of the diabetic disease, some degree of impaired exercise capacity (a powerful marker of health status with prognostic value) can be frequently highlighted in otherwise asymptomatic T2DM subjects. However, the literature is quite heterogeneous, and the underlying pathophysiologic mechanisms are far from clear. Imaging-cardiopulmonary exercise testing (CPET) is a non-invasive, provocative test providing a multi-variable assessment of pulmonary, cardiovascular, muscular, and cellular oxidative systems during exercise, capable of offering unique integrated pathophysiological information. With this review we aimed at defying the cardiorespiratory alterations revealed through imaging-CPET that appear specific of T2DM subjects without overt cardiovascular or pulmonary disease. In synthesis, there is compelling evidence indicating a reduction of peak workload, peak oxygen assumption, oxygen pulse, as well as ventilatory efficiency. On the contrary, evidence remains inconclusive about reduced peripheral oxygen extraction, impaired heart rate adjustment, and lower anaerobic threshold, compared to non-diabetic subjects. Based on the multiparametric evaluation provided by imaging-CPET, a dissection and a hierarchy of the underlying mechanisms can be obtained. Here we propose four possible integrated pathophysiological mechanisms, namely myocardiogenic, myogenic, vasculogenic and neurogenic. While each hypothesis alone can potentially explain the majority of the CPET alterations observed, seemingly different combinations exist in any given subject. Finally, a discussion on the effects -and on the physiological mechanisms-of physical activity and exercise training on oxygen uptake in T2DM subjects is also offered. The understanding of the early alterations in the cardiopulmonary response that are specific of T2DM would allow the early identification of those at a higher risk of developing HF and possibly help to understand the pathophysiological link between T2DM and HF.
Collapse
Affiliation(s)
- Lorenzo Nesti
- Metabolism, Nutrition and Atherosclerosis Lab, Dietologia Universitaria, Pisa, Italy. .,Cardiopulmonary Test Lab, Department of Clinical and Experimental Medicine, University of Pisa, Via Savi 10, 56126, Pisa, Italy.
| | - Nicola Riccardo Pugliese
- Cardiopulmonary Test Lab, Department of Clinical and Experimental Medicine, University of Pisa, Via Savi 10, 56126, Pisa, Italy
| | - Paolo Sciuto
- Metabolism, Nutrition and Atherosclerosis Lab, Dietologia Universitaria, Pisa, Italy
| | - Andrea Natali
- Metabolism, Nutrition and Atherosclerosis Lab, Dietologia Universitaria, Pisa, Italy
| |
Collapse
|
9
|
Gratal P, Lamuedra A, Medina JP, Bermejo-Álvarez I, Largo R, Herrero-Beaumont G, Mediero A. Purinergic System Signaling in Metainflammation-Associated Osteoarthritis. Front Med (Lausanne) 2020; 7:506. [PMID: 32984382 PMCID: PMC7485330 DOI: 10.3389/fmed.2020.00506] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/22/2020] [Indexed: 12/18/2022] Open
Abstract
Inflammation triggered by metabolic imbalance, also called metainflammation, is low-grade inflammation caused by the components involved in metabolic syndrome (MetS), including central obesity and impaired glucose tolerance. This phenomenon is mainly due to excess nutrients and energy, and it contributes to the pathogenesis of osteoarthritis (OA). OA is characterized by the progressive degeneration of articular cartilage, which suffers erosion and progressively becomes thinner. Purinergic signaling is involved in several physiological and pathological processes, such as cell proliferation in development and tissue regeneration, neurotransmission and inflammation. Adenosine and ATP receptors, and other members of the signaling pathway, such as AMP-activated protein kinase (AMPK), are involved in obesity, type 2 diabetes (T2D) and OA progression. In this review, we focus on purinergic regulation in osteoarthritic cartilage and how different components of MetS, such as obesity and T2D, modulate the purinergic system in OA. In that regard, we describe the critical role in this disease of receptors, such as adenosine A2A receptor (A2AR) and ATP P2X7 receptor. Finally, we also assess how nucleotides regulate the inflammasome in OA.
Collapse
Affiliation(s)
- Paula Gratal
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | - Ana Lamuedra
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | - Juan Pablo Medina
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | | | - Raquel Largo
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | | | - Aránzazu Mediero
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| |
Collapse
|
10
|
Zhou R, Dang X, Sprague RS, Mustafa SJ, Zhou Z. Alteration of purinergic signaling in diabetes: Focus on vascular function. J Mol Cell Cardiol 2020; 140:1-9. [PMID: 32057736 DOI: 10.1016/j.yjmcc.2020.02.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 01/02/2020] [Accepted: 02/09/2020] [Indexed: 12/11/2022]
Abstract
Diabetes is an important risk factor for the development of cardiovascular disease including atherosclerosis and ischemic heart disease. Vascular complications including macro- and micro-vascular dysfunction are the leading causes of morbidity and mortality in diabetes. Disease mechanisms at present are unclear and no ideal therapies are available, which urgently calls for the identification of novel therapeutic targets/agents. An altered nucleotide- and nucleoside-mediated purinergic signaling has been implicated to cause diabetes-associated vascular dysfunction in major organs. Alteration of both purinergic P1 and P2 receptor sensitivity rather than the changes in receptor expression accounts for vascular dysfunction in diabetes. Activation of P2X7 receptors plays a crucial role in diabetes-induced retinal microvascular dysfunction. Recent findings have revealed that both ecto-nucleotidase CD39, a key enzyme hydrolyzing ATP, and CD73, an enzyme regulating adenosine turnover, are involved in the renal vascular injury in diabetes. Interestingly, erythrocyte dysfunction in diabetes by decreasing ATP release in response to physiological stimuli may serve as an important trigger to induce vascular dysfunction. Nucleot(s)ide-mediated purinergic activation also exerts long-term actions including inflammatory and atherogenic effects in hyperglycemic and diabetic conditions. This review highlights the current knowledge regarding the altered nucleot(s)ide-mediated purinergic signaling as an important disease mechanism for the diabetes-associated vascular complications. Better understanding the role of key receptor-mediated signaling in diabetes will provide more insights into their potential as targets for the treatment.
Collapse
Affiliation(s)
- Rui Zhou
- Institute of Cardiovascular Research, The Key Laboratory of Medical Electrophysiology of Ministry of Education, Southwest Medical University, Luzhou, PR China
| | - Xitong Dang
- Institute of Cardiovascular Research, The Key Laboratory of Medical Electrophysiology of Ministry of Education, Southwest Medical University, Luzhou, PR China
| | - Randy S Sprague
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - S Jamal Mustafa
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Zhichao Zhou
- Division of Cardiology, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
| |
Collapse
|
11
|
Inhibition of pyruvate dehydrogenase complex activity by 3-bromopyruvate affects blood platelets responses in type 2 diabetes. Pharmacol Rep 2020; 72:225-237. [PMID: 32016856 DOI: 10.1007/s43440-019-00005-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 09/04/2019] [Accepted: 10/11/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND Hyperactivation of blood platelets is an essential factor in the pathomechanism of diabetes-evoked angiopathies. The aim of this work was to investigate whether blood platelets hyperactivation resulting from type 2 diabetic hyperglycaemia-increased pyruvate dehydrogenase complex activity and excessive acetyl-CoA accumulation may be brought to the normal range by the enzyme inhibitors. METHODS Platelets were isolated from the blood of 9 type 2 diabetic patients and 10 healthy donors. Effects of 3-bromopyruvate and 3-nitropropionate on pyruvate dehydrogenase complex (PDHC) and succinate dehydrogenase activities, as well as levels of acetyl-CoA, ATP, thiobarbituric acid reactive species and aggregation were assessed in non-activated and thrombin-activated platelets. RESULTS In type 2 diabetic patients fasting plasma glucose and fructosamine levels were 61 and 64% higher, respectively, than in the healthy group (p < 0.001). In non-activated diabetic platelets PDHC activity, PDHC-E2, acetyl-CoA and ATP levels were 66, 70, 68 and 60%, higher, respectively, than in platelets from healthy controls (p < 0.01). 3-bromopyruvate (0.1 mM) decreased pyruvate dehydrogenase activity in healthy and diabetic platelets by 42% and 59%, respectively. Similar inhibitory effects were observed for acetyl-CoA and ATP levels, aggregation and TBARS accumulation rates. Succinate dehydrogenase activity was inhibited by 3-nitropropionate (10 mM) to 38 and 41% of control values in healthy and diabetic platelets, respectively, but affected neither function nor acetyl-CoA metabolism in platelets of both groups. CONCLUSIONS These data indicate that inhibition of pyruvate dehydrogenase excessive activity in diabetic platelets by 3-bromopyruvate may normalise their functional parameters through adjustment of acetyl-CoA/ATP levels to control values. Platelets from blood of diabetic patients display higher activities of pyruvate dehydrogenase complex (PDHC), higher levels of dihydrolipoate transacetylase (DLAT, E2 subunit of PDHC) as well as higher levels of acetyl-CoA yielding greater ATP/ADP accumulation than in platelets of normoglycemic subjects. Therefore, in diabetic platelets, thrombin caused higher release of ATP/ADP triggering excessive production of reactive oxygen species (ROS) and stronger aggregation compared to control platelets. In diabetic platelets, relative excess of DLAT in PDHC made them highly susceptible to 3-bromopyruvate (3BrP) inhibition. Resulting limitation of acetyl-CoA provision by 3-BrP normalised activity of diabetic platelets.
Collapse
|
12
|
Grotle AK, Stone AJ. Exaggerated exercise pressor reflex in type 2 diabetes: Potential role of oxidative stress. Auton Neurosci 2019; 222:102591. [PMID: 31669797 PMCID: PMC6858935 DOI: 10.1016/j.autneu.2019.102591] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 02/08/2023]
Abstract
Type 2 diabetes mellitus (T2DM) leads to exaggerated cardiovascular responses to exercise, in part due to an exaggerated exercise pressor reflex. Accumulating data suggest excessive oxidative stress contributes to an exaggerated exercise pressor reflex in cardiovascular-related diseases. Excessive oxidative stress is also a primary underlying mechanism for the development and progression of T2DM. However, whether oxidative stress plays a role in mediating the exaggerated exercise pressor reflex in T2DM is not known. Therefore, this review explores the potential role of oxidative stress leading to increased activation of the afferent arm of the exercise pressor reflex. Several lines of evidence support direct and indirect effects of oxidative stress on the exercise pressor reflex. For example, intramuscular ROS may directly and indirectly (by attenuating contracting muscle blood flow) increase group III and IV afferent activity. Oxidative stress is a primary underlying mechanism for the development of neuropathic pain, which in turn is associated with increased group III and IV afferent activity. These are the same type of afferents that evoke muscle pain and the exercise pressor reflex. Furthermore, oxidative stress-induced release of inflammatory mediators may modulate afferent activity. Collectively, these alterations may result in a positive feedback loop that further amplifies the exercise pressor reflex. An exaggerated reflex increases the risk of adverse cardiovascular events. Thus, identifying the contribution of oxidative stress could provide a potential therapeutic target to reduce this risk in T2DM.
Collapse
Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX 78712, United States of America
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX 78712, United States of America.
| |
Collapse
|
13
|
Groen MB, Knudsen TA, Finsen SH, Pedersen BK, Hellsten Y, Mortensen SP. Reduced skeletal-muscle perfusion and impaired ATP release during hypoxia and exercise in individuals with type 2 diabetes. Diabetologia 2019; 62:485-493. [PMID: 30607464 DOI: 10.1007/s00125-018-4790-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/08/2018] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Plasma ATP is a potent vasodilator and is thought to play a role in the local regulation of blood flow. Type 2 diabetes is associated with reduced tissue perfusion. We aimed to examine whether individuals with type 2 diabetes have reduced plasma ATP concentrations compared with healthy control participants (case-control design). METHODS We measured femoral arterial and venous plasma ATP levels with the intravascular microdialysis technique during normoxia, hypoxia and one-legged knee-extensor exercise (10 W and 30 W) in nine participants with type 2 diabetes and eight control participants. In addition, we infused acetylcholine (ACh), sodium nitroprusside (SNP) and ATP into the femoral artery to assess vascular function and ATP signalling. RESULTS Individuals with type 2 diabetes had a lower leg blood flow (LBF; 2.9 ± 0.1 l/min) compared with the control participants (3.2 ± 0.1 l/min) during exercise (p < 0.05), in parallel with lower venous plasma ATP concentration (205 ± 35 vs 431 ± 72 nmol/l; p < 0.05). During systemic hypoxia, LBF increased from 0.35 ± 0.04 to 0.54 ± 0.06 l/min in control individuals, whereas it did not increase (0.25 ± 0.04 vs 0.31 ± 0.03 l/min) in the those with type 2 diabetes and was lower than in the control individuals (p < 0.05). Hypoxia increased venous plasma ATP levels in both groups (p < 0.05), but the increase was higher in control individuals (90 ± 26 nmol/l) compared to those with type 2 diabetes (18 ± 5 nmol/l). LBF and vascular conductance were lower during ATP (0.15 and 0.4 μmol min-1 [kg leg mass]-1) and ACh (100 μg min-1 [kg leg mass]-1) infusion in individuals with type 2 diabetes compared with the control participants (p < 0.05), whereas there was no difference during SNP infusion. CONCLUSIONS/INTERPRETATION These findings demonstrate that individuals with type 2 diabetes have lower plasma ATP concentrations during exercise and hypoxia compared with control individuals, and this occurs in parallel with lower blood flow. Moreover, individuals with type 2 diabetes have a reduced vasodilatory response to infused ATP. These impairments in the ATP system are both likely to contribute to the reduced tissue perfusion associated with type 2 diabetes. TRIAL REGISTRATION ClinicalTrials.gov NCT02001766.
Collapse
Affiliation(s)
- Martin B Groen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21 3, 5000, Odense, Denmark
| | - Trine A Knudsen
- Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Stine H Finsen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21 3, 5000, Odense, Denmark
| | - Bente K Pedersen
- Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Stefan P Mortensen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21 3, 5000, Odense, Denmark.
- Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark.
| |
Collapse
|
14
|
Roberto S, Milia R, Doneddu A, Pinna V, Palazzolo G, Serra S, Orrù A, Hosseini Kakhak SA, Ghiani G, Mulliri G, Pagliaro P, Crisafulli A. Hemodynamic abnormalities during muscle metaboreflex activation in patients with type 2 diabetes mellitus. J Appl Physiol (1985) 2018; 126:444-453. [PMID: 30543497 DOI: 10.1152/japplphysiol.00794.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Metaboreflex is a reflex triggered during exercise or postexercise muscle ischemia (PEMI) by metaboreceptor stimulation. Typical features of metaboreflex are increased cardiac output (CO) and blood pressure. Patients suffering from metabolic syndrome display hemodynamic abnormalities, with an exaggerated systemic vascular resistance (SVR) and reduced CO response during PEMI-induced metaboreflex. Whether patients with type 2 diabetes mellitus (DM2) have similar hemodynamic abnormalities is unknown. Here we contrast the hemodynamic response to PEMI in 14 patients suffering from DM2 (age 62.7 ± 8.3 yr) and in 15 age-matched controls (CTLs). All participants underwent a control exercise recovery reference test and a PEMI test to obtain the metaboreflex response. Central hemodynamics were evaluated by unbiased operator-independent impedance cardiography. Although the blood pressure response to PEMI was not significantly different between the groups, we found that the SVR and CO responses were reversed in patients with DM2 as compared with the CTLs (SVR: 392.5 ± 549.6 and -14.8 ± 258.9 dyn·s-1·cm-5; CO: -0.25 ± 0.63 and 0.46 ± 0.50 l/m, respectively, in DM2 and in CTL groups, respectively; P < 0.05 for both). Of note, stroke volume (SV) increased during PEMI in the CTL group only. Failure to increase SV and CO was the consequence of reduced venous return, impaired cardiac performance, and augmented afterload in patients with DM2. We conclude that patients with DM2 have an exaggerated vasoconstriction in response to metaboreflex activation not accompanied by a concomitant increase in heart performance. Therefore, in these patients, blood pressure response to the metaboreflex relies more on SVR increases rather than on increases in SV and CO. NEW & NOTEWORTHY The main new finding of the present investigation is that subjects with type 2 diabetes mellitus have an exaggerated vasoconstriction in response to metaboreflex activation. In these patients, blood pressure response to the metaboreflex relies more on systemic vascular resistance than on cardiac output increments.
Collapse
Affiliation(s)
- Silvana Roberto
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Raffaele Milia
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Azzurra Doneddu
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Virginia Pinna
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Girolamo Palazzolo
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Stefano Serra
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Andrea Orrù
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | | | - Giovanna Ghiani
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Gabriele Mulliri
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Pasquale Pagliaro
- Cardiovascular Physiology Laboratory, Department of Clinical and Biological Science, University of Torino , Turin , Italy
| | - Antonio Crisafulli
- Sports Physiology Laboratory, Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| |
Collapse
|
15
|
Altered Purinergic Receptor Sensitivity in Type 2 Diabetes-Associated Endothelial Dysfunction and Up₄A-Mediated Vascular Contraction. Int J Mol Sci 2018; 19:ijms19123942. [PMID: 30544633 PMCID: PMC6320923 DOI: 10.3390/ijms19123942] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 02/06/2023] Open
Abstract
Purinergic signaling may be altered in diabetes accounting for endothelial dysfunction. Uridine adenosine tetraphosphate (Up4A), a novel dinucleotide substance, regulates vascular function via both purinergic P1 and P2 receptors (PR). Up4A enhances vascular contraction in isolated arteries of diabetic rats likely through P2R. However, the precise involvement of PRs in endothelial dysfunction and the vasoconstrictor response to Up4A in diabetes has not been fully elucidated. We tested whether inhibition of PRs improved endothelial function and attenuated Up4A-mediated vascular contraction using both aortas and mesenteric arteries of type 2 diabetic (T2D) Goto Kakizaki (GK) rats vs. control Wistar (WT) rats. Endothelium-dependent (EDR) but not endothelium-independent relaxation was significantly impaired in both aortas and mesenteric arteries from GK vs. WT rats. Non-selective inhibition of P1R or P2R significantly improved EDR in aortas but not mesenteric arteries from GK rats. Inhibition of A1R, P2X7R, or P2Y6R significantly improved EDR in aortas. Vasoconstrictor response to Up4A was enhanced in aortas but not mesenteric arteries of GK vs. WT rats via involvement of A1R and P2X7R but not P2Y6R. Depletion of major endothelial component nitric oxide enhanced Up4A-induced aortic contraction to a similar extent between WT and GK rats. No significant differences in protein levels of A1R, P2X7R, and P2Y6R in aortas from GK and WT rats were observed. These data suggest that altered PR sensitivity accounts for endothelial dysfunction in aortas in diabetes. Modulating PRs may represent a potential therapy for improving endothelial function.
Collapse
|
16
|
Poitras VJ, Hudson RW, Tschakovsky ME. Exercise intolerance in Type 2 diabetes: is there a cardiovascular contribution? J Appl Physiol (1985) 2018; 124:1117-1139. [PMID: 29420147 DOI: 10.1152/japplphysiol.00070.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Physical activity is critically important for Type 2 diabetes management, yet adherence levels are poor. This might be partly due to disproportionate exercise intolerance. Submaximal exercise tolerance is highly sensitive to muscle oxygenation; impairments in exercising muscle oxygen delivery may contribute to exercise intolerance in Type 2 diabetes since there is considerable evidence for the existence of both cardiac and peripheral vascular dysfunction. While uncompromised cardiac output during submaximal exercise is consistently observed in Type 2 diabetes, it remains to be determined whether an elevated cardiac sympathetic afferent reflex could sympathetically restrain exercising muscle blood flow. Furthermore, while deficits in endothelial function are common in Type 2 diabetes and are often cited as impairing exercising muscle oxygen delivery, no direct evidence in exercise exists, and there are several other vasoregulatory mechanisms whose dysfunction could contribute. Finally, while there are findings of impaired oxygen delivery, conflicting evidence also exists. A definitive conclusion that Type 2 diabetes compromises exercising muscle oxygen delivery remains premature. We review these potentially dysfunctional mechanisms in terms of how they could impair oxygen delivery in exercise, evaluate the current literature on whether an oxygen delivery deficit is actually manifest, and correspondingly identify key directions for future research.
Collapse
Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada.,Department of Physiology, Queen's University , Kingston, Ontario , Canada.,Children's Hospital of Eastern Ontario, Research Institute , Ottawa, Ontario , Canada
| | - Robert W Hudson
- Department of Medicine, Division of Endocrinology, Queen's University , Kingston, Ontario , Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada
| |
Collapse
|
17
|
Fujii N, Meade RD, McNeely BD, Nishiyasu T, Sigal RJ, Kenny GP. Type 2 diabetes specifically attenuates purinergic skin vasodilatation without affecting muscarinic and nicotinic skin vasodilatation and sweating. Exp Physiol 2018; 103:212-221. [DOI: 10.1113/ep086694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/28/2017] [Indexed: 01/12/2023]
Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sport Sciences; University of Tsukuba; Tsukuba Japan
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
| | - Brendan D. McNeely
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences; University of Tsukuba; Tsukuba Japan
| | - Ronald J. Sigal
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
- Department of Medicine; Cumming School of Medicine, University of Calgary; Calgary Alberta Canada
- Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa Ontario Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
- Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa Ontario Canada
| |
Collapse
|
18
|
Chen HJ, Roy TL, Wright GA. Perfusion measures for symptom severity and differential outcome of revascularization in limb ischemia: Preliminary results with arterial spin labeling reactive hyperemia. J Magn Reson Imaging 2017; 47:1578-1588. [PMID: 29193492 DOI: 10.1002/jmri.25910] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/13/2017] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Previously, a theoretical model based on microvascular physiology was established to facilitate the interpretation of calf perfusion dynamics recorded by arterial spin labeling (ASL). PURPOSE To investigate the clinical relevance of novel perfusion indices by comparing them to the symptoms, response to revascularization, and short-term functional outcome in patients with peripheral arterial disease (PAD). STUDY TYPE Prospective cohort study. POPULATION Nineteen patients with PAD. FIELD STRENGTH/SEQUENCE Pulsed ASL at 3T. ASSESSMENT The mid-calf reactive hyperemia induced by 2 minutes of arterial occlusion was recorded in PAD patients. The perfusion responses were characterized by the peak, time-to-peak, and physiological model-derived indices including the baseline perfusion fr , arterial resistance Ra , and compliance Ca , and sensitivity gATP and response time τATP of downstream microvasculature to metabolic stress. These indices were compared to the disease severity and outcome within 6 months after revascularization assessed by self-reported symptoms and the ankle-brachial index. Disease severity was categorized as asymptomatic, claudication, or critical limb ischemia. The outcome was categorized as symptom resolved or limited improvement. STATISTICAL TESTS Severity and outcome groups were compared using Mann-Whitney and Kruskal-Wallis tests with Holm-Sidak adjustments. RESULTS The peak perfusion decreased and model arterial resistance increased progressively with increasing severity of limb ischemia (P = 0.0402 and 0.0413, respectively). Eleven patients had a successful endovascular procedure, including six patients who had symptoms resolved, four patients who had remaining leg pain, and one patient lost to follow-up. The subjects with limited improvement had significantly lower preintervention microvascular sensitivity gATP than those with symptoms resolved (8.72 ± 1.46 vs. 4.93 ± 0.91, P = 0.0466). DATA CONCLUSION ASL reactive hyperemia reflects multiple aspects of the pathophysiology. Measures of macrovascular arterial disease are related to the manifested symptom severity, whereas preintervention gATP associated with microvascular dysfunction is related to prognosis following revascularization. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1578-1588.
Collapse
Affiliation(s)
- Hou-Jen Chen
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Trisha L Roy
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Division of Vascular Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Graham A Wright
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
| |
Collapse
|
19
|
Zhou Z, Sorop O, de Beer VJ, Heinonen I, Cheng C, Jan Danser AH, Duncker DJ, Merkus D. Altered purinergic signaling in uridine adenosine tetraphosphate-induced coronary relaxation in swine with metabolic derangement. Purinergic Signal 2017; 13:319-329. [PMID: 28540569 PMCID: PMC5563292 DOI: 10.1007/s11302-017-9563-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/24/2017] [Indexed: 12/13/2022] Open
Abstract
We previously demonstrated that uridine adenosine tetraphosphate (Up4A) induces potent and partially endothelium-dependent relaxation in the healthy porcine coronary microvasculature. We subsequently showed that Up4A-induced porcine coronary relaxation was impaired via downregulation of P1 receptors after myocardial infarction. In view of the deleterious effect of metabolic derangement on vascular function, we hypothesized that the coronary vasodilator response to Up4A is impaired in metabolic derangement, and that the involvement of purinergic receptor subtypes and endothelium-derived vasoactive factors (EDVFs) is altered. Coronary small arteries, dissected from the apex of healthy swine and swine 6 months after induction of diabetes with streptozotocin and fed a high-fat diet, were mounted on wire myographs. Up4A (10-9-10-5 M)-induced coronary relaxation was maintained in swine with metabolic derangement compared to normal swine, despite impaired endothelium-dependent relaxation to bradykinin and despite blunted P2X7 receptor and NO-mediated vasodilator influences of Up4A. Moreover, a thromboxane-mediated vasoconstrictor influence was unmasked. In contrast, an increased Up4A-mediated vasodilator influence via P2Y1 receptors was observed, while, in response to Up4A, cytochrome P450 2C9 switched from producing vasoconstrictor to vasodilator metabolites in swine with metabolic derangement. Coronary vascular expression of A2A and P2X7 receptors as well as eNOS, as assessed with real-time PCR, was reduced in swine with metabolic derangement. In conclusion, although the overall coronary vasodilator response to Up4A was maintained in swine with metabolic derangement, the involvement of purinergic receptor subtypes and EDVF was markedly altered, revealing compensatory mechanisms among signaling pathways in Up4A-mediated coronary vasomotor influence in the early phase of metabolic derangement. Future studies are warranted to investigate the effects of severe metabolic derangement on coronary responses to Up4A.
Collapse
Affiliation(s)
- Zhichao Zhou
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
- Unit of Cardiology, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Oana Sorop
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Vincent J de Beer
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Ilkka Heinonen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
- Department of Clinical Physiology and Nuclear Medicine, University of Turku, Turku, Finland
| | - Caroline Cheng
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
- Department of Nephrology & Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - A H Jan Danser
- Division of Pharmacology, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Dirk J Duncker
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
| |
Collapse
|
20
|
Chen HJ, Wright GA. A physiological model for interpretation of arterial spin labeling reactive hyperemia of calf muscles. PLoS One 2017; 12:e0183259. [PMID: 28837695 PMCID: PMC5570335 DOI: 10.1371/journal.pone.0183259] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 08/01/2017] [Indexed: 11/18/2022] Open
Abstract
To characterize and interpret arterial spin labeling (ASL) reactive hyperemia of calf muscles for a better understanding of the microcirculation in peripheral arterial disease (PAD), we present a physiological model incorporating oxygen transport, tissue metabolism, and vascular regulation mechanisms. The model demonstrated distinct effects between arterial stenoses and microvascular dysfunction on reactive hyperemia, and indicated a higher sensitivity of 2-minute thigh cuffing to microvascular dysfunction than 5-minute cuffing. The recorded perfusion responses in PAD patients (n = 9) were better differentiated from the normal subjects (n = 7) using the model-based analysis rather than characterization using the apparent peak and time-to-peak of the responses. The analysis results suggested different amounts of microvascular disease within the patient group. Overall, this work demonstrates a novel analysis method and facilitates understanding of the physiology involved in ASL reactive hyperemia. ASL reactive hyperemia with model-based analysis may be used as a noninvasive microvascular assessment in the presence of arterial stenoses, allowing us to look beyond the macrovascular disease in PAD. A subgroup who will have a poor prognosis after revascularization in the patients with critical limb ischemia may be associated with more severe microvascular diseases, which may potentially be identified using ASL reactive hyperemia.
Collapse
Affiliation(s)
- Hou-Jen Chen
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Physical Sciences Platform and Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
- * E-mail:
| | - Graham A. Wright
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Physical Sciences Platform and Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
| |
Collapse
|
21
|
Boushel R. Linking skeletal muscle blood flow and metabolism to the limits of human performance. Appl Physiol Nutr Metab 2016; 42:111-115. [PMID: 28006435 DOI: 10.1139/apnm-2016-0393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Over the last 50 years, Bengt Saltin's contributions to our understanding of physiology of the circulation, the matching of the circulation to muscle metabolism, and the underlying mechanisms that set the limits for exercise performance were enormous. His research addressed the key questions in the field using sophisticated experimental methods including field expeditions. From the Dallas Bedrest Study to the 1-leg knee model to the physiology of lifelong training, his prodigious body of work was foundational in the field of exercise physiology and his leadership propelled integrative human physiology into the mainstream of biological sciences.
Collapse
Affiliation(s)
- Robert Boushel
- School of Kinesiology, University of British Columbia, 210-6100 University Boulevard, Vancouver, BC V6T 1Z1, Canada.,School of Kinesiology, University of British Columbia, 210-6100 University Boulevard, Vancouver, BC V6T 1Z1, Canada
| |
Collapse
|
22
|
Nassi A, Malorgio F, Tedesco S, Cignarella A, Gaion RM. Upregulation of inducible NO synthase by exogenous adenosine in vascular smooth muscle cells activated by inflammatory stimuli in experimental diabetes. Cardiovasc Diabetol 2016; 15:32. [PMID: 26879172 PMCID: PMC4754884 DOI: 10.1186/s12933-016-0349-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/02/2016] [Indexed: 01/19/2023] Open
Abstract
Background Adenosine has been shown to induce nitric oxide (NO) production via inducible NO synthase (iNOS) activation in vascular smooth muscle cells (VSMCs). Although this is interpreted as a beneficial vasodilating pathway in vaso-occlusive disorders, iNOS is also involved in diabetic vascular dysfunction. Because the turnover of and the potential to modulate iNOS by adenosine in experimental diabetes have not been explored, we hypothesized that both the adenosine system and control of iNOS function are impaired in VSMCs from streptozotocin-diabetic rats. Methods Male Sprague–Dawley rats were injected with streptozotocin once to induce diabetes. Aortic VSMCs from diabetic and nondiabetic rats were isolated, cultured and exposed to lipopolysaccharide (LPS) plus a cytokine mix for 24 h in the presence or absence of (1) exogenous adenosine and related compounds, and/or (2) pharmacological agents affecting adenosine turnover. iNOS functional expression was determined by immunoblotting and NO metabolite assays. Concentrations of adenosine, related compounds and metabolites thereof were assayed by HPLC. Vasomotor responses to adenosine were determined in endothelium-deprived aortic rings. Results Treatment with adenosine-degrading enzymes or receptor antagonists increased iNOS formation in activated VSMCs from nondiabetic and diabetic rats. Following treatment with the adenosine transport inhibitor NBTI, iNOS levels increased in nondiabetic but decreased in diabetic VSMCs. The amount of secreted NO metabolites was uncoupled from iNOS levels in diabetic VSMCs. Addition of high concentrations of adenosine and its precursors or analogues enhanced iNOS formation solely in diabetic VSMCs. Exogenous adenosine and AMP were completely removed from the culture medium and converted into metabolites. A tendency towards elevated inosine generation was observed in diabetic VSMCs, which were also less sensitive to CD73 inhibition, but inosine supplementation did not affect iNOS levels. Pharmacological inhibition of NOS abolished adenosine-induced vasorelaxation in aortic tissues from diabetic but not nondiabetic animals. Conclusions Endogenous adenosine prevented cytokine- and LPS-induced iNOS activation in VSMCs. By contrast, supplementation with adenosine and its precursors or analogues enhanced iNOS levels in diabetic VSMCs. This effect was associated with alterations in exogenous adenosine turnover. Thus, overactivation of the adenosine system may foster iNOS-mediated diabetic vascular dysfunction.
Collapse
Affiliation(s)
- Alberto Nassi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy. .,Transplant Immunology Unit, Padua University Hospital, Padova, Italy.
| | - Francesca Malorgio
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy.
| | - Serena Tedesco
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy.
| | | | - Rosa Maria Gaion
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy.
| |
Collapse
|
23
|
Corrêa APDS, Antunes CF, Figueira FR, de Castro MA, Ribeiro JP, Schaan BD. Effect of acute inspiratory muscle exercise on blood flow of resting and exercising limbs and glucose levels in type 2 diabetes. PLoS One 2015; 10:e0121384. [PMID: 25803283 PMCID: PMC4372446 DOI: 10.1371/journal.pone.0121384] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/31/2015] [Indexed: 11/19/2022] Open
Abstract
To evaluate the effects of inspiratory loading on blood flow of resting and exercising limbs in patients with diabetic autonomic neuropathy. Ten diabetic patients without cardiovascular autonomic neuropathy (DM), 10 patients with cardiovascular autonomic neuropathy (DM-CAN) and 10 healthy controls (C) were randomly assigned to inspiratory muscle load of 60% or 2% of maximal inspiratory pressure (PImax) for approximately 5 min, while resting calf blood flow (CBF) and exercising forearm blood flow (FBF) were measured. Reactive hyperemia was also evaluated. From the 20 diabetic patients initially allocated, 6 wore a continuous glucose monitoring system to evaluate the glucose levels during these two sessions (2%, placebo or 60%, inspiratory muscle metaboreflex). Mean age was 58 ± 8 years, and mean HbA1c, 7.8% (62 mmol/mol) (DM and DM-CAN). A PImax of 60% caused reduction of CBF in DM-CAN and DM (P<0.001), but not in C, whereas calf vascular resistance (CVR) increased in DM-CAN and DM (P<0.001), but not in C. The increase in FBF during forearm exercise was blunted during 60% of PImax in DM-CAN and DM, and augmented in C (P<0.001). Glucose levels decreased by 40 ± 18.8% (P<0.001) at 60%, but not at 2%, of PImax. A negative correlation was observed between reactive hyperemia and changes in CVR (Beta coefficient = -0.44, P = 0.034). Inspiratory muscle loading caused an exacerbation of the inspiratory muscle metaboreflex in patients with diabetes, regardless of the presence of neuropathy, but influenced by endothelial dysfunction. High-intensity exercise that recruits the diaphragm can abruptly reduce glucose levels.
Collapse
Affiliation(s)
- Ana Paula dos Santos Corrêa
- Exercise Pathophysiology Research Laboratory, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brasil
- Faculty of Health Sciences, University of Sydney, Lidcombe, NSW, Australia
| | - Cristiano Fetter Antunes
- Exercise Pathophysiology Research Laboratory, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brasil
| | - Franciele Ramos Figueira
- Exercise Pathophysiology Research Laboratory, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brasil
- Postgraduate Program in Endocrinology and Department of Internal Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brasil
| | - Marina Axmann de Castro
- Postgraduate Program in Pneumology Science, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brasil
| | - Jorge Pinto Ribeiro
- Exercise Pathophysiology Research Laboratory, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brasil
- Postgraduate Program in Cardiology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brasil
| | - Beatriz D’Agord Schaan
- Exercise Pathophysiology Research Laboratory, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brasil
- Postgraduate Program in Endocrinology and Department of Internal Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brasil
- * E-mail:
| |
Collapse
|
24
|
Vianna LC, Deo SH, Jensen AK, Holwerda SW, Zimmerman MC, Fadel PJ. Impaired dynamic cerebral autoregulation at rest and during isometric exercise in type 2 diabetes patients. Am J Physiol Heart Circ Physiol 2015; 308:H681-7. [PMID: 25599569 DOI: 10.1152/ajpheart.00343.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 01/15/2015] [Indexed: 12/21/2022]
Abstract
Type 2 diabetes mellitus patients (T2D) have elevated risk of stroke, suggesting that cerebrovascular function is impaired. Herein, we examined dynamic cerebral autoregulation (CA) at rest and during exercise in T2D patients and determined whether underlying systemic oxidative stress is associated with impairments in CA. Middle cerebral artery blood velocity and arterial blood pressure (BP) were measured at rest and during 2-min bouts of low- and high-intensity isometric handgrip performed at 20% and 40% maximum voluntary contraction, respectively, in seven normotensive and eight hypertensive T2D patients and eight healthy controls. Dynamic CA was estimated using the rate of regulation (RoR). Total reactive oxygen species (ROS) and superoxide levels were measured at rest. There were no differences in RoR at rest or during exercise between normotensive and hypertensive T2D patients. However, when compared with controls, T2D patients exhibited lower RoR at rest and during low-intensity handgrip indicating impaired dynamic CA. Moreover, the RoR was further reduced by 29 ± 4% during high-intensity handgrip in T2D patients (0.307 ± 0.012/s rest vs. 0.220 ± 0.014/s high intensity; P < 0.01), although well maintained in controls. T2D patients demonstrated greater baseline total ROS and superoxide compared with controls, both of which were negatively related to RoR during handgrip (e.g., total ROS: r = -0.71, P < 0.05; 40% maximum voluntary contraction). Collectively, these data demonstrate impaired dynamic CA at rest and during isometric handgrip in T2D patients, which may be, in part, related to greater underlying systemic oxidative stress. Additionally, dynamic CA is blunted further with high intensity isometric contractions potentially placing T2D patients at greater risk for cerebral events during such activities.
Collapse
Affiliation(s)
- Lauro C Vianna
- Faculty of Physical Education, University of Brasília, DF, Brazil; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Shekhar H Deo
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Areum K Jensen
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Seth W Holwerda
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Matthew C Zimmerman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Paul J Fadel
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and
| |
Collapse
|
25
|
Balasubramanian R, Robaye B, Boeynaems JM, Jacobson KA. Enhancement of glucose uptake in mouse skeletal muscle cells and adipocytes by P2Y6 receptor agonists. PLoS One 2014; 9:e116203. [PMID: 25549240 PMCID: PMC4280206 DOI: 10.1371/journal.pone.0116203] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 12/03/2014] [Indexed: 01/04/2023] Open
Abstract
Glucose uptake by peripheral tissues such as skeletal muscles and adipocytes is important in the maintenance of glucose homeostasis. We previously demonstrated that P2Y6 receptor (P2Y6R) agonists protect pancreatic islet cells from apoptosis and stimulate glucose-dependent insulin release. Here, we investigated the effects of P2Y6R activation on glucose uptake in insulin target tissues. An agonist of the P2Y6R, P1-(5′-uridine)-P3-(5′-N4-methoxycytidine)-triphosphate (MRS2957), significantly increased the uptake of [3H]2-deoxyglucose in mouse C2C12 myotubes and 3T3-L1 adipocytes, and this stimulation was significantly decreased by a selective P2Y6R antagonist N,N″-1,4-butanediyl-bis[N′-(3-isothiocyanatophenyl)thiourea] (MRS2578). Pre-incubation with Compound C (an inhibitor of 5′-AMP-activated protein kinase, AMPK), or AMPK siRNA abolished the stimulatory effect of MRS2957 on glucose uptake. Also, MRS2957 (60 min incubation) increased recruitment of the facilitated glucose transporter-4 (GLUT4) to the cell membrane, which was blocked by MRS2578. Treatment of C2C12 myotubes with MRS2957 induced significant phosphorylation of AMPK, which increase GLUT4 expression through histone deacetylase (HDAC)5 signaling. Glucose uptake in primary mouse adipocytes from wild-type mice was stimulated upon P2Y6R activation by either MRS2957 or native agonist UDP, and the P2Y6R effect was antagonized by MRS2578. However, in adipocytes from P2Y6R-knockout mice P2Y6R agonists had no effect on glucose uptake, and there was no change in the glucose uptake by insulin. Our results indicate that the P2Y6R promotes glucose metabolism in peripheral tissues, which may be mediated through AMPK signaling.
Collapse
Affiliation(s)
- Ramachandran Balasubramanian
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bernard Robaye
- Institute of Interdisciplinary Research, IRIBHM, Université Libre de Bruxelles, Gosselies, Belgium
| | | | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| |
Collapse
|
26
|
Kiely C, O'Connor E, O'Shea D, Green S, Egaña M. Hemodynamic responses during graded and constant-load plantar flexion exercise in middle-aged men and women with type 2 diabetes. J Appl Physiol (1985) 2014; 117:755-64. [DOI: 10.1152/japplphysiol.00555.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypotheses that type 2 diabetes (T2D) impairs the 1) leg hemodynamic responses to an incremental intermittent plantar-flexion exercise and 2) dynamic responses of leg vascular conductance (LVC) during low-intensity (30% maximal voluntary contraction, MVC) and high-intensity (70% MVC) constant-load plantar-flexion exercise in the supine posture. Forty-four middle-aged individuals with T2D (14 women), and 35 healthy nondiabetic (ND) individuals (18 women) were tested. Leg blood flow (LBF) was measured between each contraction using venous occlusion plethysmography. During the incremental test peak force (Fpeak) relative to MVC was significantly reduced ( P < 0.05) in men and women with T2D compared with their respective nondiabetic counterparts. Peak LBF and the slope of LBF relative to percentage Fpeak were also reduced ( P < 0.05) in women with T2D compared with healthy women (peak blood flow, 460.6 ± 126.8 vs. 628.3 ± 347.7 ml/min; slope, 3.78 ± 1.74 vs. 5.85 ± 3.14 ml·min−1·%Fpeak−1) and in men with T2D compared with nondiabetic men (peak blood flow, 621.7 ± 241.3 vs. 721.2 ± 359.7 ml/min; slope, 5.75 ± 2.66 vs. 6.33 ± 3.63 ml·min−1·%Fpeak−1). During constant-load contractions at 30% MVC T2D did not affect the dynamic responses of LVC (LBF/MAP). However, at 70% MVC [completed by a subgroup of participants (20 with T2D, 6 women; 13 ND, 6 women)] the time constant of the second growth phase of LVC was longer and the amplitude of the first growth phase was lower ( P < 0.05 for both) in men and women with T2D. The results suggest that the T2D-induced impairments in performance of the leg muscles are related to reductions in blood flow in both men and women.
Collapse
Affiliation(s)
- Catherine Kiely
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Eamonn O'Connor
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Ireland; and
| | - Simon Green
- School of Science and Health and School of Medicine, University of Western Sydney, Sydney, Australia
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| |
Collapse
|
27
|
Mortensen SP, McAllister RM, Yang HT, Hellsten Y, Laughlin MH. The effect of purinergic P2 receptor blockade on skeletal muscle exercise hyperemia in miniature swine. Eur J Appl Physiol 2014; 114:2147-55. [DOI: 10.1007/s00421-014-2932-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 06/03/2014] [Indexed: 10/25/2022]
|
28
|
P2X(7) receptor in the kidneys of diabetic rats submitted to aerobic training or to N-acetylcysteine supplementation [corrected]. PLoS One 2014; 9:e97452. [PMID: 24940871 PMCID: PMC4062402 DOI: 10.1371/journal.pone.0097452] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 04/20/2014] [Indexed: 12/22/2022] Open
Abstract
Previous studies in our laboratory showed that N-acetylcysteine supplementation or aerobic training reduced oxidative stress and the progression of diabetic nephropathy in rats. The P2X7 receptor is up-regulated in pathological conditions, such as diabetes mellitus. This up-regulation is related to oxidative stress and induces tissue apoptosis or necrosis. The aim of the present study is to assess the role of P2X7 receptor in the kidneys of diabetic rats submitted to aerobic training or N-acetylcysteine supplementation. Diabetes was induced in male Wistar rats by streptozotocin (60 mg/kg, i.v.) and the training was done on a treadmill; N-acetylcysteine was given in the drinking water (600 mg/L). By confocal microscopy, as compared to control, the kidneys of diabetic rats showed increased P2×7 receptor expression and a higher activation in response to 2′(3′)-O-(4-benzoylbenzoyl) adenosine5'–triphosphate (specific agonist) and adenosine triphosphate (nonspecific agonist) (all p<0.05). All these alterations were reduced in diabetic rats treated with N-acetylcysteine, exercise or both. We also observed measured proteinuria and albuminuria (early marker of diabetic nephropathy) in DM groups. Lipoperoxidation was strongly correlated with P2X7 receptor expression, which was also correlated to NO•, thus associating this receptor to oxidative stress and kidney lesion. We suggest that P2X7 receptor inhibition associated with the maintenance of redox homeostasis could be useful as coadjuvant treatment to delay the progression of diabetic nephropathy.
Collapse
|
29
|
Burnstock G, Ralevic V. Purinergic signaling and blood vessels in health and disease. Pharmacol Rev 2013; 66:102-92. [PMID: 24335194 DOI: 10.1124/pr.113.008029] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purinergic signaling plays important roles in control of vascular tone and remodeling. There is dual control of vascular tone by ATP released as a cotransmitter with noradrenaline from perivascular sympathetic nerves to cause vasoconstriction via P2X1 receptors, whereas ATP released from endothelial cells in response to changes in blood flow (producing shear stress) or hypoxia acts on P2X and P2Y receptors on endothelial cells to produce nitric oxide and endothelium-derived hyperpolarizing factor, which dilates vessels. ATP is also released from sensory-motor nerves during antidromic reflex activity to produce relaxation of some blood vessels. In this review, we stress the differences in neural and endothelial factors in purinergic control of different blood vessels. The long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides in promoting migration and proliferation of both vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis and vessel remodeling during restenosis after angioplasty are described. The pathophysiology of blood vessels and therapeutic potential of purinergic agents in diseases, including hypertension, atherosclerosis, ischemia, thrombosis and stroke, diabetes, and migraine, is discussed.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK; and Department of Pharmacology, The University of Melbourne, Australia.
| | | |
Collapse
|
30
|
Abstract
The pancreas is an organ with a central role in nutrient breakdown, nutrient sensing and release of hormones regulating whole body nutrient homeostasis. In diabetes mellitus, the balance is broken-cells can be starving in the midst of plenty. There are indications that the incidence of diabetes type 1 and 2, and possibly pancreatogenic diabetes, is rising globally. Events leading to insulin secretion and action are complex, but there is emerging evidence that intracellular nucleotides and nucleotides are not only important as intracellular energy molecules but also as extracellular signalling molecules in purinergic signalling cascades. This signalling takes place at the level of the pancreas, where the close apposition of various cells-endocrine, exocrine, stromal and immune cells-contributes to the integrated function. Following an introduction to diabetes, the pancreas and purinergic signalling, we will focus on the role of purinergic signalling and its changes associated with diabetes in the pancreas and selected tissues/organ systems affected by hyperglycaemia and other stress molecules of diabetes. Since this is the first review of this kind, a comprehensive historical angle is taken, and common and divergent roles of receptors for nucleotides and nucleosides in different organ systems will be given. This integrated picture will aid our understanding of the challenges of the potential and currently used drugs targeted to specific organ/cells or disorders associated with diabetes.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF UK
- Department of Pharmacology, Melbourne University, Melbourne, Australia
| | - Ivana Novak
- Molecular and Integrative Physiology, Department of Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100 Copenhagen Ø, Denmark
| |
Collapse
|
31
|
Saltin B, Mortensen SP. Inefficient functional sympatholysis is an overlooked cause of malperfusion in contracting skeletal muscle. J Physiol 2012; 590:6269-75. [PMID: 22988143 PMCID: PMC3533189 DOI: 10.1113/jphysiol.2012.241026] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 09/03/2012] [Indexed: 11/08/2022] Open
Abstract
Contracting skeletal muscle can overcome sympathetic vasoconstrictor activity (functional sympatholysis), which allows for a blood supply that matches the metabolic demand. This ability is thought to be mediated by locally released substances that modulate the effect of noradrenaline (NA) on the α-receptor. Tyramine induces local NA release and can be used in humans to investigate the underlying mechanisms and physiological importance of functional sympatholysis in the muscles of healthy and diseased individuals as well as the impact of the active muscles' training status. In sedentary elderly men, functional sympatholysis and muscle blood flow are impaired compared to young men, but regular physical activity can prevent these age related impairments. In young subjects, two weeks of leg immobilization causes a reduced ability for functional sympatholysis, whereas the trained leg maintained this function. Patients with essential hypertension have impaired functional sympatholysis in the forearm, and reduced exercise hyperaemia in the leg, but this can be normalized by aerobic exercise training. The effect of physical activity on the local mechanisms that modulate sympathetic vasoconstriction is clear, but it remains uncertain which locally released substance(s) block the effect of NA and how this is accomplished. NO and ATP have been proposed as important inhibitors of NA mediated vasoconstriction and presently an inhibitory effect of ATP on NA signalling via P2 receptors appears most likely.
Collapse
Affiliation(s)
- Bengt Saltin
- The Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen, Denmark.
| | | |
Collapse
|
32
|
Johnson BD, Harvey RE, Barnes JN. Exercise: where the body leads and the heart must follow. J Physiol 2012; 590:4127-8. [DOI: 10.1113/jphysiol.2012.239285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|
33
|
Crecelius AR, Kirby BS, Luckasen GJ, Larson DG, Dinenno FA. ATP-mediated vasodilatation occurs via activation of inwardly rectifying potassium channels in humans. J Physiol 2012; 590:5349-59. [PMID: 22777673 DOI: 10.1113/jphysiol.2012.234245] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Circulating ATP possesses unique vasomotor properties in humans and has been hypothesized to play a role in vascular control under a variety of physiological conditions. However, the primary downstream signalling mechanisms underlying ATP-mediated vasodilatation remain unclear. The purpose of the present experiment was to determine whether ATP-mediated vasodilatation is independent of nitric oxide (NO) and prostaglandin (PG) synthesis and occurs primarily via the activation of Na(+)/K(+)-ATPase and inwardly rectifying potassium (K(IR)) channels in humans. In all protocols, young healthy adults were studied and forearm vascular conductance (FVC) was calculated from forearm blood flow (measured via venous occlusion plethysmography) and intra-arterial blood pressure to quantify local vasodilatation. Vasodilator responses (%FVC) during intra-arterial ATP infusions were unchanged following combined inhibition of NO and PGs (n = 8; P > 0.05) whereas the responses to KCl were greater (P < 0.05). Combined infusion of ouabain (to inhibit Na(+)/K(+)-ATPase) and barium chloride (BaCl(2); to inhibit K(IR) channels) abolished KCl-mediated vasodilatation (n = 6; %FVC = 134 ± 13 vs. 4 ± 5%; P < 0.05), demonstrating effective blockade of direct vascular hyperpolarization. The vasodilator responses to three different doses of ATP were inhibited on average 56 ± 5% (n = 16) following combined ouabain plus BaCl(2) infusion. In follow-up studies, BaCl(2) alone inhibited the vasodilator responses to ATP on average 51 ± 3% (n = 6), which was not different than that observed for combined ouabain plus BaCl(2) administration. Our novel results indicate that the primary mechanism of ATP-mediated vasodilatation is vascular hyperpolarization via activation of K(IR) channels. These observations translate in vitro findings to humans in vivo and may help explain the unique vasomotor properties of intravascular ATP in the human circulation.
Collapse
Affiliation(s)
- Anne R Crecelius
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1582, USA
| | | | | | | | | |
Collapse
|
34
|
Alteration of purinergic neurotransmission in isolated atria of streptozotocin-induced diabetic rats. J Cardiovasc Pharmacol 2012; 59:158-64. [PMID: 21983745 DOI: 10.1097/fjc.0b013e31823a0f31] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cardiac dysfunctions are described in diabetes. However, the role of purinergic neurotransmission in diabetes-related cardiovascular diseases is unknown. The purpose of this study was to evaluate the purinergic neurotransmission in isolated atria from streptozotocin-induced diabetic rats. The animals were grouped as control and diabetic with 30 days (D30) and 60 days (D60) after streptozotocin-induced diabetes. The isolated left and right atria were used in functional experiments. The effects of adenosine triphosphate, uridine diphosphate, and adenosine were evaluated on atrial inotropism and chronotropism. The antagonists 8-cyclopentyl-1,3-dipropylxanthine and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate were also used, as blockers of P1 and P2 receptors, respectively. A negative inotropic effect followed by a positive inotropic effect was induced by adenosine triphosphate in isolated atria. This negative inotropic effect was decreased by 25% in left atria of D30. Additionally, the apparent affinity for adenosine was diminished in left atria of D30, suggesting changes in P1 receptor function. No changes were found in the right atria of D30 stimulated by adenosine. The left atria and right atria stimulated by uridine diphosphate showed an increased inotropic effect of 92% and 17%, respectively. No changes were observed in left and right atria of D30 stimulated by uridine diphosphate. Our data showed the involvement of purinergic neurotransmission in diabetes-related cardiovascular changes.
Collapse
|
35
|
Regulatory mechanisms underlying the modulation of GIRK1/GIRK4 heteromeric channels by P2Y receptors. Pflugers Arch 2012; 463:625-33. [PMID: 22362083 DOI: 10.1007/s00424-012-1082-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 02/05/2012] [Accepted: 02/06/2012] [Indexed: 01/10/2023]
Abstract
The muscarinic K(+) channel (I (K,ACh)) is a heterotetramer composed of GIRK1 (Kir3.1) and GIRK4 (Kir3.4) subunits of a G protein-coupled inwardly rectifying channel, and plays an important role in mediating electrical responses to the vagal stimulation in the heart. I (K,ACh) displays biphasic changes (activation followed by inhibition) through the stimulation of the purinergic P2Y receptors, but the regulatory mechanism involved in these modulation of I (K,ACh) by P2Y receptors remains to be fully elucidated. Various P2Y receptor subtypes and GIRK1/GIRK4 (I (GIRK)) were co-expressed in Chinese hamster ovary cells, and the effect of stimulation of P2Y receptor subtypes on I (GIRK) were examined using the whole-cell patch-clamp method. Extracellular application of 10 μM ATP induced a transient activation of I (GIRK) through the P2Y(1) receptor, which was completely abolished by pretreatment with pertussis toxin. ATP initially caused an additive transient increase in ACh-activated I (GIRK) (via M(2) receptor), which was followed by subsequent inhibition. This inhibition of I (GIRK) by ATP was attenuated by co-expression of regulator of G-protein signaling 2, or phosphatidylinositol-4-phosphate-5-kinase, or intracellular phosphatidylinositol 4,5-bisphosphate loading, but not by the exposure to protein kinase C inhibitors. P2Y(4) stimulation also persistently suppressed the ACh-activated I (GIRK). In addition, I (GIRK) evoked by the stimulation of the P2Y(4) receptor exhibited a transient activation, but that evoked by the stimulation of P2Y(2) or P2Y(12) receptor showed a rather persistent activation. These results reveal (1) that P2Y(1) and P2Y(4) are primarily coupled to the G(q)-phospholipase C-pathway, while being weakly linked to G(i/o), and (2) that P2Y(2) and P2Y(12) involve G(i/o) activation.
Collapse
|
36
|
Bornø A, Ploug T, Bune LT, Rosenmeier JB, Thaning P. Purinergic receptors expressed in human skeletal muscle fibres. Purinergic Signal 2011; 8:255-64. [PMID: 22052557 DOI: 10.1007/s11302-011-9279-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Accepted: 10/17/2011] [Indexed: 12/24/2022] Open
Abstract
Purinergic receptors are present in most tissues and thought to be involved in various signalling pathways, including neural signalling, cell metabolism and local regulation of the microcirculation in skeletal muscles. The present study aims to determine the distribution and intracellular content of purinergic receptors in skeletal muscle fibres in patients with type 2 diabetes and age-matched controls. Muscle biopsies from vastus lateralis were obtained from six type 2 diabetic patients and seven age-matched controls. Purinergic receptors were analysed using light and confocal microscopy in immunolabelled transverse sections of muscle biopsies. The receptors P2Y(4), P2Y(11) and likely P2X(1) were present intracellularly or in the plasma membrane of muscle fibres and were thus selected for further detailed morphological analysis. P2X(1) receptors were expressed in intracellular vesicles and sarcolemma. P2Y(4) receptors were present in sarcolemma. P2Y(11) receptors were abundantly and diffusely expressed intracellularly and were more explicitly expressed in type I than in type II fibres, whereas P2X(1) and P2Y(4) showed no fibre-type specificity. Both diabetic patients and healthy controls showed similar distribution of receptors. The current study demonstrates that purinergic receptors are located intracellularly in human skeletal muscle fibres. The similar cellular localization of receptors in healthy and diabetic subjects suggests that diabetes is not associated with an altered distribution of purinergic receptors in skeletal muscle fibres. We speculate that the intracellular localization of purinergic receptors may reflect a role in regulation of muscle metabolism; further studies are nevertheless needed to determine the function of the purinergic system in skeletal muscle cells.
Collapse
Affiliation(s)
- A Bornø
- Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen N, Denmark
| | | | | | | | | |
Collapse
|
37
|
Ishida K, Matsumoto T, Taguchi K, Kamata K, Kobayashi T. Mechanisms underlying altered extracellular nucleotide-induced contractions in mesenteric arteries from rats in later-stage type 2 diabetes: effect of ANG II type 1 receptor antagonism. Am J Physiol Heart Circ Physiol 2011; 301:H1850-61. [PMID: 21856926 DOI: 10.1152/ajpheart.00502.2011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Little is known about the vascular contractile responsiveness to, and signaling pathways for, extracellular nucleotides in the chronic stage of type 2 diabetes or whether the ANG II type 1 receptor blocker losartan might alter such responses. We hypothesized that nucleotide-induced arterial contractions are augmented in diabetic Goto-Kakizaki (GK) rats and that treatment with losartan would normalize the contractions. Here, we investigated the vasoconstrictor effects of ATP/UTP in superior mesenteric arteries isolated from GK rats (37-42 wk old) that had or had not received 2 wk of losartan (25 mg·kg(-1)·day(-1)). In arteries from GK rats (vs. those from Wistar rats), 1) ATP- and UTP-induced contractions, which were blocked by the nonselective P2 antagonist suramin, were enhanced, and these enhancements were suppressed by endothelial denudation, by cyclooxygenase (COX) inhibitors, or by a cytosolic phospholipase A(2) (cPLA(2)) inhibitor; 2) both nucleotides induced increased release of PGE(2) and PGF(2α); 3) nucleotide-stimulated cPLA(2) phosphorylations were increased; 4) COX-1 and COX-2 expressions were increased; and 5) neither P2Y2 nor P2Y6 receptor expression differed, but P2Y4 receptor expression was decreased. Mesenteric arteries from GK rats treated with losartan exhibited (vs. untreated GK) 1) reduced nucleotide-induced contractions, 2) suppressed UTP-induced release of PGE(2) and PGF(2α), 3) suppressed UTP-stimulated cPLA(2) phosphorylation, 4) normalized expressions of COX-2 and P2Y4 receptors, and 5) reduced superoxide generation. Our data suggest that the diabetes-related enhancement of ATP-mediated vasoconstriction was due to P2Y receptor-mediated activation of the cPLA(2)/COX pathway and, moreover, that losartan normalizes such contractions by a suppressing action within this pathway.
Collapse
Affiliation(s)
- Keiko Ishida
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo, Japan
| | | | | | | | | |
Collapse
|
38
|
Thaning P, Bune LT, Zaar M, Saltin B, Rosenmeier JB. Functional sympatholysis during exercise in patients with type 2 diabetes with intact response to acetylcholine. Diabetes Care 2011; 34:1186-91. [PMID: 21447654 PMCID: PMC3114484 DOI: 10.2337/dc10-2129] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Sympathetic vasoconstriction is blunted in contracting human skeletal muscles (functional sympatholysis). In young subjects, infusion of adenosine and ATP increases blood flow, and the latter compound also attenuates α-adrenergic vasoconstriction. In patients with type 2 diabetes and age-matched healthy subjects, we tested 1) the sympatholytic capacity during one-legged exercise, 2) the vasodilatory capacity of adenosine and ATP, and 3) the ability to blunt α-adrenergic vasoconstriction during ATP infusion. RESEARCH DESIGN AND METHODS In 10 control subjects and 10 patients with diabetes and normal endothelial function, determined by leg blood flow (LBF) response to acetylcholine infusion, we measured LBF and venous NA, with and without tyramine-induced sympathetic vasoconstriction, during adenosine-, ATP-, and exercise-induced hyperemia. RESULTS LBF during acetylcholine did not differ significantly. LBF increased ninefold during exercise and during adenosine- and ATP-induced hyperemia. Infusion of tyramine during exercise did not reduce LBF in either the control or the patient group. During combined ATP and tyramine infusions, LBF decreased by 30% in both groups. Adenosine had no sympatholytic effect. CONCLUSIONS In patients with type 2 diabetes and normal endothelial function, functional sympatholysis was intact during moderate exercise. The vasodilatory response for adenosine and ATP did not differ between the patients with diabetes and the control subjects; however, the vasodilatory effect of adenosine and ATP and the sympatholytic effect of ATP seem to decline with age.
Collapse
Affiliation(s)
- Pia Thaning
- The Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen, Denmark.
| | | | | | | | | |
Collapse
|