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Caturano A, Galiero R, Vetrano E, Sardu C, Rinaldi L, Russo V, Monda M, Marfella R, Sasso FC. Insulin-Heart Axis: Bridging Physiology to Insulin Resistance. Int J Mol Sci 2024; 25:8369. [PMID: 39125938 PMCID: PMC11313400 DOI: 10.3390/ijms25158369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2024] [Revised: 07/26/2024] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
Insulin signaling is vital for regulating cellular metabolism, growth, and survival pathways, particularly in tissues such as adipose, skeletal muscle, liver, and brain. Its role in the heart, however, is less well-explored. The heart, requiring significant ATP to fuel its contractile machinery, relies on insulin signaling to manage myocardial substrate supply and directly affect cardiac muscle metabolism. This review investigates the insulin-heart axis, focusing on insulin's multifaceted influence on cardiac function, from metabolic regulation to the development of physiological cardiac hypertrophy. A central theme of this review is the pathophysiology of insulin resistance and its profound implications for cardiac health. We discuss the intricate molecular mechanisms by which insulin signaling modulates glucose and fatty acid metabolism in cardiomyocytes, emphasizing its pivotal role in maintaining cardiac energy homeostasis. Insulin resistance disrupts these processes, leading to significant cardiac metabolic disturbances, autonomic dysfunction, subcellular signaling abnormalities, and activation of the renin-angiotensin-aldosterone system. These factors collectively contribute to the progression of diabetic cardiomyopathy and other cardiovascular diseases. Insulin resistance is linked to hypertrophy, fibrosis, diastolic dysfunction, and systolic heart failure, exacerbating the risk of coronary artery disease and heart failure. Understanding the insulin-heart axis is crucial for developing therapeutic strategies to mitigate the cardiovascular complications associated with insulin resistance and diabetes.
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Affiliation(s)
- Alfredo Caturano
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy; (A.C.); (R.G.); (E.V.); (C.S.); (R.M.)
- Department of Experimental Medicine, University of Campania Luigi Vanvitelli, 80138 Naples, Italy;
| | - Raffaele Galiero
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy; (A.C.); (R.G.); (E.V.); (C.S.); (R.M.)
| | - Erica Vetrano
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy; (A.C.); (R.G.); (E.V.); (C.S.); (R.M.)
| | - Celestino Sardu
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy; (A.C.); (R.G.); (E.V.); (C.S.); (R.M.)
| | - Luca Rinaldi
- Department of Medicine and Health Sciences “Vincenzo Tiberio”, Università degli Studi del Molise, 86100 Campobasso, Italy;
| | - Vincenzo Russo
- Department of Biology, College of Science and Technology, Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA 19122, USA;
- Division of Cardiology, Department of Medical Translational Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy
| | - Marcellino Monda
- Department of Experimental Medicine, University of Campania Luigi Vanvitelli, 80138 Naples, Italy;
| | - Raffaele Marfella
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy; (A.C.); (R.G.); (E.V.); (C.S.); (R.M.)
| | - Ferdinando Carlo Sasso
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy; (A.C.); (R.G.); (E.V.); (C.S.); (R.M.)
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2
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Geng X, Ji J, Liu Y, Li X, Chen Y, Su L, Zhao L. Cyanidin-3-O-Glucoside Supplementation Ameliorates Metabolic Insulin Resistance via Restoration of Nitric Oxide-Mediated Endothelial Insulin Transport. Mol Nutr Food Res 2021; 66:e2100742. [PMID: 34841692 DOI: 10.1002/mnfr.202100742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/18/2021] [Indexed: 11/06/2022]
Abstract
SCOPE Anthocyanin cyanidin-3-O-glucoside (Cy3G) possesses a great potential in prevention of diabetes and its vascular complications while the underlying mechanisms are still far from clear. Accumulating evidence suggests that endothelial insulin transport plays a critical role in regulating metabolic insulin sensitivity. Whether Cy3G can modulate metabolic insulin resistance via regulating endothelial insulin transport is not reported yet. METHODS AND RESULTS Palmitic acid (PA)-treated mouse aortic endothelial cells (MAECs) model and high-fat diet (HFD) fed mice model are used. Compared with HFD mice, Cy3G supplementation decrease exogenous insulin content in skeletal muscle and ameliorate metabolic insulin resistance. In culture, Cy3G can directly ameliorate PA-induced impairment on FITC-insulin uptake in MAECs. Mechanistically, Cy3G can effectively decrease inflammatory cytokines and toll-like receptor 4 (TLR4)/nuclear factor-kappa-B inhibitor alpha (IκBα) activation, and restore the attenuated Akt/eNOS signaling pathway. Blunted nitric oxide (NO) synthase with N-nitro-l-arginine methyl ester (L-NAME) can effectively abolish the protective role of Cy3G on endothelial insulin transport and insulin-stimulated glucose utilization in HFD-fed mice. CONCLUSIONS These findings suggest that Cy3G supplementation can directly restore the attenuated nitic oxide-mediated endothelial insulin transport and thereby ameliorate metabolic insulin resistance. Our finding can provide a novel explanation for the anti-diabetic effects of Cy3G.
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Affiliation(s)
- Xiuwen Geng
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
| | - Jiajun Ji
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
| | - Yuanhua Liu
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
| | - Xueyan Li
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
| | - Yunan Chen
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
| | - Lei Su
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
| | - Lina Zhao
- Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, Guangdong Province, 510080, P.R. China.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Guangzhou, Guangdong Province, 510080, P.R. China
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3
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Jeon YK, Shin MJ, Saini SK, Custodero C, Aggarwal M, Anton SD, Leeuwenburgh C, Mankowski RT. Vascular dysfunction as a potential culprit of sarcopenia. Exp Gerontol 2020; 145:111220. [PMID: 33373710 DOI: 10.1016/j.exger.2020.111220] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 02/08/2023]
Abstract
Aging-related changes to biological structures such as cardiovascular and musculoskeletal systems contribute to the development of comorbid conditions including cardiovascular disease and frailty, and ultimately lead to premature death. Although, frail older adults often demonstrate both cardiovascular and musculoskeletal comorbidities, the etiology of sarcopenia, and especially the contribution of cardiovascular aging is unclear. Aging-related vascular calcification is prevalent in older adults and is a known risk factor for cardiovascular disease and death. The effect vascular calcification has on function during aging is not well understood. Emerging findings suggest vascular calcification can impact skeletal muscle perfusion, negatively affecting nutrient and oxygen delivery to skeletal muscle, ultimately accelerating muscle loss and functional decline. The present review summarizes existing evidence on the biological mechanisms linking vascular calcification with sarcopenia during aging.
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Affiliation(s)
- Yun Kyung Jeon
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA; Division of Endocrinology and Metabolism, Department of Internal Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Myung Jun Shin
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA; Department of Rehabilitation Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Sunil Kumar Saini
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - Carlo Custodero
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA; Dipartimento Interdisciplinare di Medicina, Clinica Medica Cesare Frugoni, University of Bari Aldo Moro, Bari, Italy
| | - Monica Aggarwal
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, FL, USA
| | - Stephen D Anton
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | | | - Robert T Mankowski
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA.
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4
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Turaihi AH, Serné EH, Molthoff CFM, Koning JJ, Knol J, Niessen HW, Goumans MJTH, van Poelgeest EM, Yudkin JS, Smulders YM, Jimenez CR, van Hinsbergh VWM, Eringa EC. Perivascular Adipose Tissue Controls Insulin-Stimulated Perfusion, Mitochondrial Protein Expression, and Glucose Uptake in Muscle Through Adipomuscular Arterioles. Diabetes 2020; 69:603-613. [PMID: 32005705 DOI: 10.2337/db18-1066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/24/2020] [Indexed: 11/13/2022]
Abstract
Insulin-mediated microvascular recruitment (IMVR) regulates delivery of insulin and glucose to insulin-sensitive tissues. We have previously proposed that perivascular adipose tissue (PVAT) controls vascular function through outside-to-inside communication and through vessel-to-vessel, or "vasocrine," signaling. However, direct experimental evidence supporting a role of local PVAT in regulating IMVR and insulin sensitivity in vivo is lacking. Here, we studied muscles with and without PVAT in mice using combined contrast-enhanced ultrasonography and intravital microscopy to measure IMVR and gracilis artery diameter at baseline and during the hyperinsulinemic-euglycemic clamp. We show, using microsurgical removal of PVAT from the muscle microcirculation, that local PVAT depots regulate insulin-stimulated muscle perfusion and glucose uptake in vivo. We discovered direct microvascular connections between PVAT and the distal muscle microcirculation, or adipomuscular arterioles, the removal of which abolished IMVR. Local removal of intramuscular PVAT altered protein clusters in the connected muscle, including upregulation of a cluster featuring Hsp90ab1 and Hsp70 and downregulation of a cluster of mitochondrial protein components of complexes III, IV, and V. These data highlight the importance of PVAT in vascular and metabolic physiology and are likely relevant for obesity and diabetes.
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Affiliation(s)
- Alexander H Turaihi
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Erik H Serné
- Department of Internal Medicine, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Carla F M Molthoff
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Jasper J Koning
- Department of Molecular Cell Biology and Immunology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Jaco Knol
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Hans W Niessen
- Department of Pathology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Marie Jose T H Goumans
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Erik M van Poelgeest
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - John S Yudkin
- Institute of Cardiovascular Science, Division of Medicine, University College London, London, U.K
| | - Yvo M Smulders
- Department of Internal Medicine, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Connie R Jimenez
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Victor W M van Hinsbergh
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Etto C Eringa
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
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5
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Roberts-Thomson KM, Betik AC, Premilovac D, Rattigan S, Richards SM, Ross RM, Russell RD, Kaur G, Parker L, Keske MA. Postprandial microvascular blood flow in skeletal muscle: Similarities and disparities to the hyperinsulinaemic-euglycaemic clamp. Clin Exp Pharmacol Physiol 2019; 47:725-737. [PMID: 31868941 DOI: 10.1111/1440-1681.13237] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 12/12/2019] [Accepted: 12/18/2019] [Indexed: 12/22/2022]
Abstract
Skeletal muscle contributes to ~40% of total body mass and has numerous important mechanical and metabolic roles in the body. Skeletal muscle is a major site for glucose disposal following a meal. Consequently, skeletal muscle plays an important role in postprandial blood glucose homeostasis. Over the past number of decades, research has demonstrated that insulin has an important role in vasodilating the vasculature in skeletal muscle in response to an insulin infusion (hyperinsulinaemic-euglycaemic clamp) or following the ingestion of a meal. This vascular action of insulin is pivotal for glucose disposal in skeletal muscle, as insulin-stimulated vasodilation increases the delivery of both glucose and insulin to the myocyte. Notably, in insulin-resistant states such as obesity and type 2 diabetes, this vascular response of insulin in skeletal muscle is significantly impaired. Whereas the majority of work in this field has focussed on the action of insulin alone on skeletal muscle microvascular blood flow and myocyte glucose metabolism, there is less understanding of how the consumption of a meal may affect skeletal muscle blood flow. This is in part due to complex variations in glucose and insulin dynamics that occurs postprandially-with changes in humoral concentrations of glucose, insulin, amino acids, gut and pancreatic peptides-compared to the hyperinsulinaemic-euglycaemic clamp. This review will address the emerging body of evidence to suggest that postprandial blood flow responses in skeletal muscle may be a function of the nutritional composition of a meal.
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Affiliation(s)
- Katherine M Roberts-Thomson
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Andrew C Betik
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Dino Premilovac
- School of Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Stephen Rattigan
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | | | - Renee M Ross
- School of Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Ryan D Russell
- Department of Health and Human Performance, College of Health Professions, University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Gunveen Kaur
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Lewan Parker
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Michelle A Keske
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia.,Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
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6
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Akerstrom T, Goldman D, Nilsson F, Milkovich SL, Fraser GM, Brand CL, Hellsten Y, Ellis CG. Hyperinsulinemia does not cause de novo capillary recruitment in rat skeletal muscle. Microcirculation 2019; 27:e12593. [PMID: 31605649 PMCID: PMC7064932 DOI: 10.1111/micc.12593] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 09/05/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022]
Abstract
Objective The effect of insulin on blood flow distribution within muscle microvasculature has been suggested to be important for glucose metabolism. However, the “capillary recruitment” hypothesis is still controversial and relies on studies using indirect contrast‐enhanced ultrasound (CEU) methods. Methods We studied how hyperinsulinemia effects capillary blood flow in rat extensor digitorum longus (EDL) muscle during euglycemic hyperinsulinemic clamp using intravital video microscopy (IVVM). Additionally, we modeled blood flow and microbubble distribution within the vascular tree under conditions observed during euglycemic hyperinsulinemic clamp experiments. Results Euglycemic hyperinsulinemia caused an increase in erythrocyte (80 ± 25%, P < .01) and plasma (53 ± 12%, P < .01) flow in rat EDL microvasculature. We found no evidence of de novo capillary recruitment within, or among, capillary networks supplied by different terminal arterioles; however, erythrocyte flow became slightly more homogenous. Our computational model predicts that a decrease in asymmetry at arteriolar bifurcations causes redistribution of microbubble flow among capillaries already perfused with erythrocytes and plasma, resulting in 25% more microbubbles flowing through capillaries. Conclusions Our model suggests increase in CEU signal during hyperinsulinemia reflects a redistribution of arteriolar flow and not de novo capillary recruitment. IVVM experiments support this prediction showing increases in erythrocyte and plasma flow and not capillary recruitment.
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Affiliation(s)
- Thorbjorn Akerstrom
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
| | - Franciska Nilsson
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Stephanie L Milkovich
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
| | - Graham M Fraser
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | | | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Christopher G Ellis
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
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7
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Zhao P, Tian D, Song G, Ming Q, Liu J, Shen J, Liu QH, Yang X. Neferine Promotes GLUT4 Expression and Fusion With the Plasma Membrane to Induce Glucose Uptake in L6 Cells. Front Pharmacol 2019; 10:999. [PMID: 31551792 PMCID: PMC6737894 DOI: 10.3389/fphar.2019.00999] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 08/06/2019] [Indexed: 11/21/2022] Open
Abstract
Glucose transporter 4 (GLUT4) is involved in regulating glucose uptake in striated muscle, liver, and adipose tissue. Neferine is a dibenzyl isoquinoline alkaloid derived from dietary lotus seeds and has multiple pharmacological effects. Therefore, this study investigated neferine’s role in glucose translocation to cell surface, glucose uptake, and GLUT4 expression. In our study, neferine upregulated GLUT4 expression, induced GLUT4 plasma membrane fusion, increased intracellular Ca2+, promoted glucose uptake, and alleviated insulin resistance in L6 cells. Furthermore, neferine significantly activated phosphorylation of AMP-activated protein kinase (AMPK) and protein kinase C (PKC). AMPK and PKC inhibitors blocked neferine-induced GLUT4 expression and increased intracellular Ca2+. While neferine-induced GLUT4 expression and intracellular Ca2+ were inhibited by G protein and PLC inhibitors, only intracellular Ca2+ was inhibited by inositol trisphosphate receptor (IP3R) inhibitors. Thus, neferine promoted GLUT4 expression via the G protein-PLC-PKC and AMPK pathways, inducing GLUT4 plasma membrane fusion and subsequent glucose uptake and increasing intracellular Ca2+ through the G protein-PLC-IP3-IP3R pathway. Treatment with 0 mM extracellular Ca2+ + Ca2+ chelator did not inhibit neferine-induced GLUT4 expression but blocked neferine-induced GLUT4 plasma membrane fusion and glucose uptake, suggesting the latter two are Ca2+-dependent. Therefore, we conclude that neferine is a potential treatment for type 2 diabetes.
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Affiliation(s)
- Ping Zhao
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China.,National Demonstration Center for Experimental Ethnopharmacology Education, South-Central University for Nationalities, Wuhan, China.,Hubei Medical Biology International Science and Technology Cooperation Base, Wuhan, China
| | - Di Tian
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Guanjun Song
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Qian Ming
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Jia Liu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Jinhua Shen
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China.,Hubei Medical Biology International Science and Technology Cooperation Base, Wuhan, China
| | - Qing-Hua Liu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China.,Hubei Medical Biology International Science and Technology Cooperation Base, Wuhan, China
| | - Xinzhou Yang
- National Demonstration Center for Experimental Ethnopharmacology Education, South-Central University for Nationalities, Wuhan, China.,School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China
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8
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Valdivieso P, Franchi MV, Gerber C, Flück M. Does a Better Perfusion of Deconditioned Muscle Tissue Release Chronic Low Back Pain? Front Med (Lausanne) 2018; 5:77. [PMID: 29616222 PMCID: PMC5869187 DOI: 10.3389/fmed.2018.00077] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/07/2018] [Indexed: 12/19/2022] Open
Abstract
Non-specific chronic low back pain (nsCLBP) is a multifactorial condition of unknown etiology and pathogenesis. Physical and genetic factors may influence the predisposition of individuals to CLBP, which in many instances share a musculoskeletal origin. A reduced pain level in low back pain patients that participate in exercise therapy highlights that disuse-related muscle deconditioning may predispose individuals to nsCLBP. In this context, musculoskeletal pain may be the consequence of capillary rarefaction in inactive muscle as this would lower local tissue drainage and washing out of toxic waste. Muscle activity is translated into an angio-adaptative process, which implicates angiogenic-gene expression and individual response differences due to heritable modifications of such genes (gene polymorphisms). The pathophysiologic mechanism underlying nsCLBP is still largely unaddressed. We hypothesize that capillary rarefaction due to a deconditioning of dorsal muscle groups exacerbates nsCLBP by increasing noxious sensation, reducing muscle strength and fatigue resistance by initiating a downward spiral of local deconditioning of back muscles which diminishes their load-bearing capacity. We address the idea that specific factors such as angiotensin-converting enzyme and Tenascin-C might play an important role in altering susceptibility to nsCLBP via their effects on microvascular perfusion and vascular remodeling of skeletal muscle, inflammation, and pain sensation. The genetic profile may help to explain the individual predisposition to nsCLBP, thus identifying subgroups of patients, which could benefit from ad hoc treatment types. Future therapeutic approaches aimed at relieving the pain associated with nsCLBP should be based on the verification of mechanistic processes of activity-induced angio-adaptation and muscle-perfusion.
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Affiliation(s)
- Paola Valdivieso
- Laboratory for Muscle Plasticity, Department of Orthopedics, University of Zurich, Zürich, Switzerland.,Interdisciplinary Spinal Research, Department of Chiropractic Medicine, Balgrist University Hospital, Zürich, Switzerland
| | - Martino V Franchi
- Laboratory for Muscle Plasticity, Department of Orthopedics, University of Zurich, Zürich, Switzerland
| | - Christian Gerber
- Orthopedics Department, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Martin Flück
- Laboratory for Muscle Plasticity, Department of Orthopedics, University of Zurich, Zürich, Switzerland
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9
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Concomitant external pneumatic compression treatment with consecutive days of high intensity interval training reduces markers of proteolysis. Eur J Appl Physiol 2017; 117:2587-2600. [PMID: 29075862 DOI: 10.1007/s00421-017-3746-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 10/18/2017] [Indexed: 12/19/2022]
Abstract
PURPOSE To compare the effects of external pneumatic compression (EPC) and sham when used concurrently with high intensity interval training (HIIT) on performance-related outcomes and recovery-related molecular measures. METHODS Eighteen recreationally endurance-trained male participants (age: 21.6 ± 2.4 years, BMI: 25.7 ± 0.5 kg/m2, VO2peak: 51.3 ± 0.9 mL/kg/min) were randomized to balanced sham and EPC treatment groups. Three consecutive days of HIIT followed by EPC/sham treatment (Days 2-4) and 3 consecutive days of recovery (Days 5-7) with EPC/sham only on Days 5-6 were employed. Venipuncture, flexibility and pressure-to-pain threshold (PPT) measurements were made throughout. Vastus lateralis muscle was biopsied at PRE (i.e., Day 1), 1-h post-EPC/sham treatment on Day 2 (POST1), and 24-h post-EPC/sham treatment on Day 7 (POST2). 6-km run time trial performance was tested at PRE and POST2. RESULTS No group × time interaction was observed for flexibility, PPT, or serum measures of creatine kinase (CK), hsCRP, and 8-isoprostane. However, there was a main effect of time for serum CK (p = 0.005). Change from PRE in 6-km run times at POST2 were not significantly different between groups. Significant between-groups differences existed for change from PRE in atrogin-1 mRNA (p = 0.018) at the POST1 time point (EPC: - 19.7 ± 8.1%, sham: + 7.7 ± 5.9%) and atrogin-1 protein concentration (p = 0.013) at the POST2 time point (EPC: - 31.8 ± 7.5%, sham: + 96.0 ± 34.7%). In addition, change from PRE in poly-Ub proteins was significantly different between groups at both the POST1 (EPC: - 26.0 ± 10.3%, sham: + 34.8 ± 28.5%; p = 0.046) and POST2 (EPC: - 33.7 ± 17.2%, sham: + 21.4 ± 14.9%; p = 0.037) time points. CONCLUSIONS EPC when used concurrently with HIIT and in subsequent recovery days reduces skeletal muscle markers of proteolysis.
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10
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Turaihi AH, van Poelgeest EM, van Hinsbergh VWM, Serné EH, Smulders YM, Eringa EC. Combined Intravital Microscopy and Contrast-enhanced Ultrasonography of the Mouse Hindlimb to Study Insulin-induced Vasodilation and Muscle Perfusion. J Vis Exp 2017. [PMID: 28362362 PMCID: PMC5407697 DOI: 10.3791/54912] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
It has been demonstrated that insulin's vascular actions contribute to regulation of insulin sensitivity. Insulin's effects on muscle perfusion regulate postprandial delivery of nutrients and hormones to insulin-sensitive tissues. We here describe a technique for combining intravital microscopy (IVM) and contrast-enhanced ultrasonography (CEUS) of the adductor compartment of the mouse hindlimb to simultaneously visualize muscle resistance arteries and perfusion of the microcirculation in vivo. Simultaneously assessing insulin's effect at multiple levels of the vascular tree is important to study relationships between insulin's multiple vasoactive effects and muscle perfusion. Experiments in this study were performed in mice. First, the tail vein cannula is inserted for the infusion of anesthesia, vasoactive compounds and ultrasound contrast agent (lipid-encapsulated microbubbles). Second, a small incision is made in the groin area to expose the arterial tree of the adductor muscle compartment. The ultrasound probe is then positioned at the contralateral upper hindlimb to view the muscles in cross-section. To assess baseline parameters, the arterial diameter is assessed and microbubbles are subsequently infused at a constant rate to estimate muscle blood flow and microvascular blood volume (MBV). When applied before and during a hyperinsulinemic-euglycemic clamp, combined IVM and CEUS allow assessment of insulin-induced changes of arterial diameter, microvascular muscle perfusion and whole-body insulin sensitivity. Moreover, the temporal relationship between responses of the microcirculation and the resistance arteries to insulin can be quantified. It is also possible to follow-up the mice longitudinally in time, making it a valuable tool to study changes in vascular and whole-body insulin sensitivity.
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Affiliation(s)
- Alexander H Turaihi
- Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center;
| | - Erik M van Poelgeest
- Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center
| | - Victor W M van Hinsbergh
- Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center
| | - Erik H Serné
- Department of Internal Medicine, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center
| | - Yvo M Smulders
- Department of Internal Medicine, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center
| | - Etto C Eringa
- Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center
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11
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Keske MA, Dwyer RM, Russell RD, Blackwood SJ, Brown AA, Hu D, Premilovac D, Richards SM, Rattigan S. Regulation of microvascular flow and metabolism: An overview. Clin Exp Pharmacol Physiol 2016; 44:143-149. [DOI: 10.1111/1440-1681.12688] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/07/2016] [Accepted: 10/21/2016] [Indexed: 01/12/2023]
Affiliation(s)
- Michelle A Keske
- Menzies Institute for Medical Research University of Tasmania Hobart Tas. Australia
| | - Renee M Dwyer
- School of Medicine University of Tasmania Hobart Tas. Australia
| | - Ryan D Russell
- Menzies Institute for Medical Research University of Tasmania Hobart Tas. Australia
| | - Sarah J Blackwood
- Menzies Institute for Medical Research University of Tasmania Hobart Tas. Australia
| | - Aascha A Brown
- Menzies Institute for Medical Research University of Tasmania Hobart Tas. Australia
| | - Donghua Hu
- Menzies Institute for Medical Research University of Tasmania Hobart Tas. Australia
| | - Dino Premilovac
- School of Medicine University of Tasmania Hobart Tas. Australia
| | | | - Stephen Rattigan
- Menzies Institute for Medical Research University of Tasmania Hobart Tas. Australia
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12
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Tanigaki K, Chambliss KL, Yuhanna IS, Sacharidou A, Ahmed M, Atochin DN, Huang PL, Shaul PW, Mineo C. Endothelial Fcγ Receptor IIB Activation Blunts Insulin Delivery to Skeletal Muscle to Cause Insulin Resistance in Mice. Diabetes 2016; 65:1996-2005. [PMID: 27207525 PMCID: PMC4915578 DOI: 10.2337/db15-1605] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 04/09/2016] [Indexed: 12/12/2022]
Abstract
Modest elevations in C-reactive protein (CRP) are associated with type 2 diabetes. We previously revealed in mice that increased CRP causes insulin resistance and mice globally deficient in the CRP receptor Fcγ receptor IIB (FcγRIIB) were protected from the disorder. FcγRIIB is expressed in numerous cell types including endothelium and B lymphocytes. Here we investigated how endothelial FcγRIIB influences glucose homeostasis, using mice with elevated CRP expressing or lacking endothelial FcγRIIB. Whereas increased CRP caused insulin resistance in mice expressing endothelial FcγRIIB, mice deficient in the endothelial receptor were protected. The insulin resistance with endothelial FcγRIIB activation was due to impaired skeletal muscle glucose uptake caused by attenuated insulin delivery, and it was associated with blunted endothelial nitric oxide synthase (eNOS) activation in skeletal muscle. In culture, CRP suppressed endothelial cell insulin transcytosis via FcγRIIB activation and eNOS antagonism. Furthermore, in knock-in mice harboring constitutively active eNOS, elevated CRP did not invoke insulin resistance. Collectively these findings reveal that by inhibiting eNOS, endothelial FcγRIIB activation by CRP blunts insulin delivery to skeletal muscle to cause insulin resistance. Thus, a series of mechanisms in endothelium that impairs insulin movement has been identified that may contribute to type 2 diabetes pathogenesis.
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Affiliation(s)
- Keiji Tanigaki
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ken L Chambliss
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ivan S Yuhanna
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Anastasia Sacharidou
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Mohamed Ahmed
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Dmitriy N Atochin
- Cardiovascular Research Center and Cardiology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Paul L Huang
- Cardiovascular Research Center and Cardiology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Philip W Shaul
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Chieko Mineo
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
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13
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Mahmoud AM, Brown MD, Phillips SA, Haus JM. Skeletal Muscle Vascular Function: A Counterbalance of Insulin Action. Microcirculation 2016; 22:327-47. [PMID: 25904196 DOI: 10.1111/micc.12205] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/20/2015] [Indexed: 12/11/2022]
Abstract
Insulin is a vasoactive hormone that regulates vascular homeostasis by maintaining balance of endothelial-derived NO and ET-1. Although there is general agreement that insulin resistance and the associated hyperinsulinemia disturb this balance, the vascular consequences for hyperinsulinemia in isolation from insulin resistance are still unclear. Presently, there is no simple answer for this question, especially in a background of mixed reports examining the effects of experimental hyperinsulinemia on endothelial-mediated vasodilation. Understanding the mechanisms by which hyperinsulinemia induces vascular dysfunction is essential in advancing treatment and prevention of insulin resistance-related vascular complications. Thus, we review literature addressing the effects of hyperinsulinemia on vascular function. Furthermore, we give special attention to the vasoregulatory effects of hyperinsulinemia on skeletal muscle, the largest insulin-dependent organ in the body. This review also characterizes the differential vascular effects of hyperinsulinemia on large conduit vessels versus small resistance microvessels and the effects of metabolic variables in an effort to unravel potential sources of discrepancies in the literature. At the cellular level, we provide an overview of insulin signaling events governing vascular tone. Finally, we hypothesize a role for hyperinsulinemia and insulin resistance in the development of CVD.
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Affiliation(s)
- Abeer M Mahmoud
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.,Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Michael D Brown
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.,Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Shane A Phillips
- Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.,Department of Physical Therapy, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Jacob M Haus
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.,Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
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14
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Brook MS, Wilkinson DJ, Phillips BE, Perez-Schindler J, Philp A, Smith K, Atherton PJ. Skeletal muscle homeostasis and plasticity in youth and ageing: impact of nutrition and exercise. Acta Physiol (Oxf) 2016; 216:15-41. [PMID: 26010896 PMCID: PMC4843955 DOI: 10.1111/apha.12532] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/10/2014] [Accepted: 05/18/2015] [Indexed: 12/18/2022]
Abstract
Skeletal muscles comprise a substantial portion of whole body mass and are integral for locomotion and metabolic health. Increasing age is associated with declines in both muscle mass and function (e.g. strength‐related performance, power) with declines in muscle function quantitatively outweighing those in muscle volume. The mechanisms behind these declines are multi‐faceted involving both intrinsic age‐related metabolic dysregulation and environmental influences such as nutritional and physical activity. Ageing is associated with a degree of ‘anabolic resistance’ to these key environmental inputs, which likely accelerates the intrinsic processes driving ageing. On this basis, strategies to sensitize and/or promote anabolic responses to nutrition and physical activity are likely to be imperative in alleviating the progression and trajectory of sarcopenia. Both resistance‐ and aerobic‐type exercises are likely to confer functional and health benefits in older age, and a clutch of research suggests that enhancement of anabolic responsiveness to exercise and/or nutrition may be achieved by optimizing modifications of muscle‐loading paradigms (workload, volume, blood flow restriction) or nutritional support (e.g. essential amino acid/leucine) patterns. Nonetheless, more work is needed in which a more holistic view in ageing studies is taken into account. This should include improved characterization of older study recruits, that is physical activity/nutritional behaviours, to limit confounding variables influencing whether findings are attributable to age, or other environmental influences. Nonetheless, on balance, ageing is associated with declines in muscle mass and function and a partially related decline in aerobic capacity. There is also good evidence that metabolic flexibility is impaired in older age.
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Affiliation(s)
- M. S. Brook
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical Metabolic and Molecular Physiology; University of Nottingham; Royal Derby Hospital Centre; Derby UK
| | - D. J. Wilkinson
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical Metabolic and Molecular Physiology; University of Nottingham; Royal Derby Hospital Centre; Derby UK
| | - B. E. Phillips
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical Metabolic and Molecular Physiology; University of Nottingham; Royal Derby Hospital Centre; Derby UK
| | - J. Perez-Schindler
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; Birmingham UK
| | - A. Philp
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; Birmingham UK
| | - K. Smith
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical Metabolic and Molecular Physiology; University of Nottingham; Royal Derby Hospital Centre; Derby UK
| | - P. J. Atherton
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical Metabolic and Molecular Physiology; University of Nottingham; Royal Derby Hospital Centre; Derby UK
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15
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Bodenlenz M, Ellmerer M, Schaupp L, Jacobsen LV, Plank J, Brunner GA, Wutte A, Aigner B, Mautner SI, Pieber TR. Bioavailability of insulin detemir and human insulin at the level of peripheral interstitial fluid in humans, assessed by open-flow microperfusion. Diabetes Obes Metab 2015; 17:1166-72. [PMID: 26260082 DOI: 10.1111/dom.12551] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 07/30/2015] [Accepted: 08/06/2015] [Indexed: 11/28/2022]
Abstract
AIMS To find an explanation for the lower potency of insulin detemir observed in humans compared with unmodified human insulin by investigating insulin detemir and human insulin concentrations directly at the level of peripheral insulin-sensitive tissues in humans in vivo. METHODS Euglycaemic-hyperinsulinaemic clamp experiments were performed in healthy volunteers. Human insulin was administered i.v. at 6 pmol/kg/min and insulin detemir at 60 pmol/kg/min, achieving a comparable steady-state pharmacodynamic action. In addition, insulin detemir was doubled to 120 pmol/kg/min. Minimally invasive open-flow microperfusion (OFM) sampling methodology was combined with inulin calibration to quantify human insulin and insulin detemir in the interstitial fluid (ISF) of subcutaneous adipose and skeletal muscle tissue. RESULTS The human insulin concentration in the ISF was ∼115 pmol/l or ∼30% of the serum concentration, whereas the insulin detemir concentration in the ISF was ∼680 pmol/l or ∼2% of the serum concentration. The molar insulin detemir interstitial concentration was five to six times higher than the human insulin interstitial concentration and metabolic clearance of insulin detemir from serum was substantially reduced compared with human insulin. CONCLUSIONS OFM proved useful for target tissue measurements of human insulin and the analogue insulin detemir. Our tissue data confirm a highly effective retention of insulin detemir in the vascular compartment. The higher insulin detemir relative to human insulin tissue concentrations at comparable pharmacodynamics, however, indicate that the lower potency of insulin detemir in humans is attributable to a reduced effect in peripheral insulin-sensitive tissues and is consistent with the reduced in vitro receptor affinity.
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MESH Headings
- Adult
- Biological Availability
- Calibration
- Cross-Over Studies
- Dose-Response Relationship, Drug
- Extracellular Fluid/metabolism
- Glucose Clamp Technique
- Humans
- Hypoglycemic Agents/administration & dosage
- Hypoglycemic Agents/blood
- Hypoglycemic Agents/metabolism
- Hypoglycemic Agents/pharmacokinetics
- Infusions, Intravenous
- Insulin Detemir/administration & dosage
- Insulin Detemir/blood
- Insulin Detemir/metabolism
- Insulin Detemir/pharmacokinetics
- Insulin, Regular, Human/administration & dosage
- Insulin, Regular, Human/blood
- Insulin, Regular, Human/metabolism
- Insulin, Regular, Human/pharmacokinetics
- Inulin/administration & dosage
- Inulin/blood
- Inulin/metabolism
- Inulin/pharmacokinetics
- Lipoylation
- Male
- Metabolic Clearance Rate
- Muscle, Skeletal/metabolism
- Subcutaneous Fat/metabolism
- Tissue Distribution
- Young Adult
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Affiliation(s)
- M Bodenlenz
- HEALTH, Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Graz, Austria
| | - M Ellmerer
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - L Schaupp
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | | | - J Plank
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - G A Brunner
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - A Wutte
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - B Aigner
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
- Division of General Dermatology, Department of Dermatology and Venereology, Medical University of Graz, Graz, Austria
| | - S I Mautner
- HEALTH, Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Graz, Austria
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - T R Pieber
- HEALTH, Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Graz, Austria
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria
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16
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Acute enzymatic glycocalyx degradation results in reduced insulin sensitivity but normal glucose tolerance in conscious rats. Cardiovasc Endocrinol 2014. [DOI: 10.1097/xce.0000000000000017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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17
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Phillips BE, Atherton PJ, Varadhan K, Wilkinson DJ, Limb M, Selby AL, Rennie MJ, Smith K, Williams JP. Pharmacological enhancement of leg and muscle microvascular blood flow does not augment anabolic responses in skeletal muscle of young men under fed conditions. Am J Physiol Endocrinol Metab 2014; 306:E168-76. [PMID: 24280127 DOI: 10.1152/ajpendo.00440.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Skeletal muscle anabolism associated with postprandial plasma aminoacidemia and insulinemia is contingent upon amino acids (AA) and insulin crossing the microcirculation-myocyte interface. In this study, we hypothesized that increasing muscle microvascular blood volume (flow) would enhance fed-state anabolic responses in muscle protein turnover. We studied 10 young men (23.2 ± 2.1 yr) under postabsorptive and fed [iv Glamin (∼10 g AA), glucose ∼7.5 mmol/l] conditions. Methacholine was infused into the femoral artery of one leg to determine, via bilateral comparison, the effects of feeding alone vs. feeding plus pharmacological vasodilation. We measured leg blood flow (LBF; femoral artery) by Doppler ultrasound, muscle microvascular blood volume (MBV) by contrast-enhanced ultrasound (CEUS), muscle protein synthesis (MPS) and breakdown (MPB; a-v balance modeling), and net protein balance (NPB) using [1,2-(13)C2]leucine and [(2)H5]phenylalanine tracers via gas chromatography-mass spectrometry (GC-MS). Indexes of anabolic signaling/endothelial activation (e.g., Akt/mTORC1/NOS) were assessed using immunoblotting techniques. Under fed conditions, LBF (+12 ± 5%, P < 0.05), MBV (+25 ± 10%, P < 0.05), and MPS (+129 ± 33%, P < 0.05) increased. Infusion of methacholine further enhanced LBF (+126 ± 12%, P < 0.05) and MBV (+79 ± 30%, P < 0.05). Despite these radically different blood flow conditions, neither increases in MPS in response to feeding (0.04 ± 0.004 vs. 0.08 ± 0.01%/h, P < 0.05) nor improvements in NPB (-4.4 ± 2.4 vs. 16.4 ± 5.7 nmol Phe·100 ml leg(-1)·min(-1), P < 0.05) were affected by methacholine infusion (MPS 0.07 ± 0.01%/h; NPB 24.0 ± 7.7 nmol Phe·100 ml leg(-1)·min(-1)), whereas MPB was unaltered by either feeding or infusion of methacholine. Thus, enhancing LBF/MBV above that occurring naturally with feeding alone does not improve muscle anabolism.
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Affiliation(s)
- Bethan E Phillips
- Division of Medical Science and Graduate Entry Medicine, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom; and
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18
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Ko J, Kim K. Effects of exercise and diet composition on expression of MCP-1 and oxidative stress-related mRNA of adipose tissue in diet-induced obese mice. J Exerc Nutrition Biochem 2013; 17:181-8. [PMID: 25566429 PMCID: PMC4241907 DOI: 10.5717/jenb.2013.17.4.181] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 11/20/2013] [Accepted: 11/23/2013] [Indexed: 11/04/2022] Open
Abstract
The aim of the study was to analyze how the expression of MCP-1, HIF-1α, NOX2, ERK1, ERK2, and Mn-SOD mRNA, which are related to inflammation and oxidative stress and which can influence the accumulation of macrophage in obese adipose tissue, differed according to a high-fat diet, change of diet composition, and exercise. Obesity was induced using a high-fat diet (45% fat) for five weeks. This investigation analyzed how the change of diet composition for eight weeks and long-term exercise training affected the expression of mRNA in epididymal white adipose tissue. For the experiment, 56 four-week-old C57BL/6 mice were used. Their epididymal white adipose tissue was extracted and used in RT-PCR analysis to find the expression level of mRNA. A high-fat diet for 13 weeks showed a significant increase in the expression of MCP-1, HIF-1α, NOX2, and ERK1 mRNA in epididymal adipose tissue. Change in diet composition and exercise decreased the expression of MCP-1, HIF-1α, NOX2, and ERK1 mRNA. Particularly, the group combining a high-fat diet and exercise had a significant increase in the expression of Mn-SOD mRNA in epididymal adipose tissue; however, it showed a significant decrease in MCP-1, HIF-1α, and NOX2. These results suggest that the antioxidant effect and weight loss by exercise decreased inflammation and oxidative stress.
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Affiliation(s)
- Jinho Ko
- Department of Physical Education, Keimyung University, Daegu, Korea
| | - Kijin Kim
- Department of Physical Education, Keimyung University, Daegu, Korea
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19
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Grassi D, Desideri G, Ferri C. Protective effects of dark chocolate on endothelial function and diabetes. Curr Opin Clin Nutr Metab Care 2013; 16:662-8. [PMID: 24100673 DOI: 10.1097/mco.0b013e3283659a51] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE OF REVIEW Relationship between cocoa consumption and cardiovascular disease, particularly focusing on clinical implications resulting from the beneficial effects of cocoa consumption on endothelial function and insulin resistance. This could be of clinical relevance and may suggest the mechanistic explanation for the reduced risk of cardiovascular events reported in the different studies after cocoa intake. RECENT FINDINGS Increasing evidence supports a protective effect of cocoa consumption against cardiovascular disease. Cocoa and flavonoids from cocoa have been described to improve endothelial function and insulin resistance. A proposed mechanism could be considered in the improvement of the endothelium-derived vasodilator nitric oxide by enhancing nitric oxide synthesis or by decreasing nitric oxide breakdown. SUMMARY The endothelium plays a pivotal role in the arterial homeostasis, and insulin resistance is the most important pathophysiological feature in various prediabetic and diabetic states. Reduced nitric oxide bioavailability with endothelial dysfunction is considered the earliest step in the pathogenesis of atherosclerosis. Further, insulin resistance could account, at least in part, for the endothelial dysfunction. Endothelial dysfunction has been considered an important and independent predictor of future development of cardiovascular risk and events. Cocoa and flavonoids from cocoa might positively modulate these mechanisms with a putative role in cardiovascular protection.
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Affiliation(s)
- Davide Grassi
- Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy
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20
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Kubota T, Kubota N, Kadowaki T. The role of endothelial insulin signaling in the regulation of glucose metabolism. Rev Endocr Metab Disord 2013; 14:207-16. [PMID: 23589150 DOI: 10.1007/s11154-013-9242-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The skeletal muscle is one of the major target organs of insulin and plays an essential role in insulin-induced glucose uptake. Some evidence indicates that insulin delivery to skeletal muscle interstitium through the endothelial cells is the rate-limiting step in insulin-stimulated glucose uptake. Researchers have also found that this process is impaired by insulin resistance in type 2 diabetes and obesity. A recent study of ours demonstrated that insulin signaling in the endothelial cells plays a pivotal role in the regulation of glucose uptake by the skeletal muscle. Specifically, impaired insulin signaling in the endothelial cells, with reduction of insulin-induced eNOS phosphorylation, causes attenuation of the insulin-induced capillary recruitment and insulin delivery, which, in turn reduces glucose uptake by the skeletal muscle in high-fat diet-fed mice. Moreover, restoration of the insulin-induced eNOS phosphorylation in the endothelial cells completely reverses the reduction in the capillary recruitment and insulin delivery, and as a result, significantly restores glucose uptake by the skeletal muscle. In the present review, we describe the recent progress in research on the physiological and pathophysiological roles of endothelial insulin signaling in the regulation of insulin-induced glucose uptake by the skeletal muscle.
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Affiliation(s)
- Tetsuya Kubota
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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21
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Rajapakse NW, Chong AL, Zhang WZ, Kaye DM. Insulin-mediated activation of the L-arginine nitric oxide pathway in man, and its impairment in diabetes. PLoS One 2013; 8:e61840. [PMID: 23658699 PMCID: PMC3642141 DOI: 10.1371/journal.pone.0061840] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 03/14/2013] [Indexed: 01/04/2023] Open
Abstract
Aims/Hypothesis Impaired L-arginine transport has been reported in cardiovascular diseases, providing a possible mechanism for reduced nitric oxide (NO) production. Given that cardiovascular diseases are also associated with insulin resistance, and insulin is known to induce vasodilation via a NO-dependent pathway, we hypothesised that abnormal insulin modulation of L-arginine transport may contribute to vascular dysfunction in diabetes. Methods Forearm blood flow (FBF) responses to insulin and sodium nitroprusside (SNP) were measured in control and type 2 diabetic volunteers using venous occlusion plethysmography. Effects of intra-arterial insulin on the forearm veno-arterial flux of arginine and related amino acids were determined by HPLC. The effect of locally delivered insulin on arginine transport was assessed during an intra-arterial infusion of [4,5-3H] L-arginine. Results In controls, intrabrachial infusion of 5 mUnits/min insulin lead to a progressive rise in FBF (p<0.001) while this was not evident in diabetics. In support of this observation, we observed a concomitant, significant increase in the flux of N-hydroxy-L-arginine (the NO precursor) in controls (baseline vs. 60 mins insulin: 16.2±12.2 vs. 33.0±13.1 nmol/100 ml tissue/min; p<0.01), whilst no increase was observed in diabetics. Moreover, insulin augmented the clearance of [3H]L-arginine from the forearm circulation in controls (baseline vs insulin: 123±22 vs. 150±28 ml/min; p<0.05) but not in diabetics. Conclusion These findings suggest that insulin resistance may contribute substantially to the onset and development of cardiovascular disease in type 2 diabetics via abnormal insulin-mediated regulation of L-arginine transport.
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Affiliation(s)
- Niwanthi W. Rajapakse
- Heart Failure Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
- Department of Physiology, Monash University, Melbourne, Australia
| | - Abigail L. Chong
- Heart Failure Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Wei-Zheng Zhang
- Heart Failure Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - David M. Kaye
- Heart Failure Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
- Department of Medicine, Monash University, Melbourne, Australia
- * E-mail:
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Abstract
Insulin resistance affects the vascular endothelium, and contributes to systemic insulin resistance by directly impairing the actions of insulin to redistribute blood flow as part of its normal actions driving muscle glucose uptake. Impaired vascular function is a component of the insulin resistance syndrome, and is a feature of type 2 diabetes. On this basis, the vascular endothelium has emerged as a therapeutic target where the intent is to improve systemic metabolic state by improving vascular function. We review the available literature presenting studies in humans, evaluating the effects of metabolically targeted and vascular targeted therapies on insulin action and systemic metabolism. Therapies that improve systemic insulin resistance exert strong concurrent effects to improve vascular function and vascular insulin action. RAS-acting agents and statins have widely recognized beneficial effects on vascular function but have not uniformly produced the hoped-for metabolic benefits. These observations support the notion that systemic metabolic benefits can arise from therapies targeted at the endothelium, but improving vascular insulin action does not result from all treatments that improve endothelium-dependent vasodilation. A better understanding of the mechanisms of insulin's actions in the vascular wall will advance our understanding of the specificity of these responses, and allow us to better target the vasculature for metabolic benefits.
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Affiliation(s)
- Kieren J Mather
- Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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23
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Muris DMJ, Houben AJHM, Schram MT, Stehouwer CDA. Microvascular dysfunction: an emerging pathway in the pathogenesis of obesity-related insulin resistance. Rev Endocr Metab Disord 2013; 14:29-38. [PMID: 23299657 DOI: 10.1007/s11154-012-9231-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The prevalence of type 2 diabetes mellitus (T2DM) and its major risk factor, obesity, has reached epidemic proportions in Western society. How obesity leads to insulin resistance and subsequent T2DM is incompletely understood. It has been established that insulin can redirect blood flow in skeletal muscle from non-nutritive to nutritive capillary networks, without increasing total blood flow. This results in a net increase of the overall number of perfused nutritive capillary networks and thereby increases insulin-mediated glucose uptake by skeletal muscle. This process, referred to as functional (nutritive) capillary recruitment, has been shown to be endothelium-dependent and to require activation of the phosphatidylinositol-kinase (PI3K) pathway in the endothelial cell. Several studies have demonstrated that these processes are impaired in states of microvascular dysfunction. In obesity, changes in several adipokines are likely candidates to influence insulin signaling pathways in endothelial cells, thereby causing microvascular dysfunction. Microvascular dysfunction, in turn, impairs the timely access of glucose and insulin to their target tissues, and may therefore be an additional cause of insulin resistance. Thus, microvascular dysfunction may be a key feature in the development of obesity-related insulin resistance. In the present review, we will discuss the evidence for this emerging role for the microcirculation as a possible link between obesity and insulin resistance.
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Affiliation(s)
- Dennis M J Muris
- Department of Internal Medicine, Maastricht University Medical Centre (MUMC+), P.O. Box 5800, 6202 AZ, Maastricht, the Netherlands
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24
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Eskens BJM, Mooij HL, Cleutjens JPM, Roos JMA, Cobelens JE, Vink H, Vanteeffelen JWGE. Rapid insulin-mediated increase in microvascular glycocalyx accessibility in skeletal muscle may contribute to insulin-mediated glucose disposal in rats. PLoS One 2013; 8:e55399. [PMID: 23383178 PMCID: PMC3561231 DOI: 10.1371/journal.pone.0055399] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 12/24/2012] [Indexed: 11/29/2022] Open
Abstract
It has been demonstrated that insulin-mediated recruitment of microvascular blood volume is associated with insulin sensitivity. We hypothesize that insulin rapidly stimulates penetration of red blood cells (RBC) and plasma into the glycocalyx and thereby promotes insulin-mediated glucose uptake by increasing intracapillary blood volume. Experiments were performed in rats; the role of the glycocalyx was assessed by enzymatic degradation using a bolus of hyaluronidase. First, the effect of insulin on glycocalyx accessibility was assessed by measuring the depth of penetration of RBCs into the glycocalyx in microvessels of the gastrocnemius muscle with Sidestream Dark-field imaging. Secondly, peripheral insulin sensitivity was determined using intravenous insulin tolerance tests (IVITT). In addition, in a smaller set of experiments, intravital microscopy of capillary hemodynamics in cremaster muscle and histological analysis of the distribution of fluorescently labeled 40 kDa dextrans (D40) in hindlimb muscle was used to evaluate insulin-mediated increases in capillary blood volume. Insulin increased glycocalyx penetration of RBCs by 0.34±0.44 µm (P<0.05) within 10 minutes, and this effect of insulin was greatly impaired in hyaluronidase treated rats. Further, hyaluronidase treated rats showed a 35±25% reduction in whole-body insulin-mediated glucose disposal compared to control rats. Insulin-mediated increases in capillary blood volume were reflected by a rapid increase in capillary tube hematocrit from 21.1±10.1% to 29.0±9.8% (P<0.05), and an increase in D40 intensity in individual capillaries of 134±138% compared to baseline at the end of the IVITT. These effects of insulin were virtually abolished in hyaluronidase treated animals. In conclusion, insulin rapidly increases glycocalyx accessibility for circulating blood in muscle, and this is associated with an increased blood volume in individual capillaries. Hyaluronidase treatment of the glycocalyx abolishes the effects of insulin on capillary blood volume and impairs insulin-mediated glucose disposal.
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Affiliation(s)
- Bart J M Eskens
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
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25
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Premilovac D, Bradley EA, Ng HL, Richards SM, Rattigan S, Keske MA. Muscle insulin resistance resulting from impaired microvascular insulin sensitivity in Sprague Dawley rats. Cardiovasc Res 2013; 98:28-36. [DOI: 10.1093/cvr/cvt015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Kolka CM, Bergman RN. The barrier within: endothelial transport of hormones. Physiology (Bethesda) 2012; 27:237-47. [PMID: 22875454 DOI: 10.1152/physiol.00012.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hormones are involved in a plethora of processes including development and growth, metabolism, mood, and immune responses. These essential functions are dependent on the ability of the hormone to access its target tissue. In the case of endocrine hormones that are transported through the blood, this often means that the endothelium must be crossed. Many studies have shown that the concentrations of hormones and nutrients in blood can be very different from those surrounding the cells on the tissue side of the blood vessel endothelium, suggesting that transport across this barrier can be rate limiting for hormone action. This transport can be regulated by altering the surface area of the blood vessel available for diffusion through to the underlying tissue or by the permeability of the endothelium. Many hormones are known to directly or indirectly affect the endothelial barrier, thus affecting their own distribution to their target tissues. Dysfunction of the endothelial barrier is found in many diseases, particularly those associated with the metabolic syndrome. The interrelatedness of hormones may help to explain why the cluster of diseases in the metabolic syndrome occur together so frequently and suggests that treating the endothelium may ameliorate defects in more than one disease. Here, we review the structure and function of the endothelium, its contribution to the function of hormones, and its involvement in disease.
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Affiliation(s)
- Cathryn M Kolka
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA.
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27
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Abstract
CONTEXT Recent studies on mediators of inflammation, experimental models of atherosclerosis, and acute ischemia have identified novel mechanisms through which insulin may exert cardiovascular protective effects. This review aims to summarize current knowledge regarding the cardiovascular, antiinflammatory, and antiatherogenic effects of insulin, and the effect of intensive glycemic control in acute cardiovascular disease. EVIDENCE ACQUISITION Publications of interest were identified using preselected MeSH terminology and keywords to search online databases such as PubMed and OVID for the period January 1988 to February 2012. Relevant publications were obtained and reviewed by two independent observers, then evaluated a priori against the following criteria: study quality, main clinical outcomes, and applicability to clinical practice. EVIDENCE SYNTHESIS Insulin has been shown to exert vasodilatory, antiinflammatory, and antiatherogenic effects in experimental models, independent of its glucose-lowering effects. Additionally, glucose is known to exert potent proinflammatory, prothrombotic, and proapoptotic effects during myocardial infarct, indicative that hyperglycemia is likely to be injurious to the heart. In this context, through its nonmetabolic and metabolic (glucose-lowering) effects, insulin is likely to be cardioprotective and to improve clinical outcomes in acute myocardial infarction. CONCLUSIONS Despite promising experimental data and evidence of benefit from single-center randomized clinical trials, clinical evidence supporting the cardioprotective effects of insulin from a multicenter randomized clinical trial is still lacking. Future prospective studies with insulin infused at adequate concentrations, individually titrated to achieve and maintain euglycemia (blood glucose < 140 mg/dl) and minimize hypoglycemia, are required to investigate the role of insulin in the management of patients with acute cardiovascular disease.
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Affiliation(s)
- Ajay Chaudhuri
- Diabetes-Endocrinology Center of Western New York, Division of Endocrinology, Kaleida Health/Millard Fillmore Hospital, Buffalo, New York, USA
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28
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De Boer MP, Meijer RI, Wijnstok NJ, Jonk AM, Houben AJ, Stehouwer CD, Smulders YM, Eringa EC, Serné EH. Microvascular dysfunction: a potential mechanism in the pathogenesis of obesity-associated insulin resistance and hypertension. Microcirculation 2012; 19:5-18. [PMID: 21883642 DOI: 10.1111/j.1549-8719.2011.00130.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The intertwined epidemics of obesity and related disorders such as hypertension, insulin resistance, type 2 diabetes, and subsequent cardiovascular disease pose a major public health challenge. To meet this challenge, we must understand the interplay between adipose tissue and the vasculature. Microvascular dysfunction is important not only in the development of obesity-related target-organ damage but also in the development of cardiovascular risk factors such as hypertension and insulin resistance. The present review examines the role of microvascular dysfunction as an explanation for the associations among obesity, hypertension, and impaired insulin-mediated glucose disposal. We also discuss communicative pathways from adipose tissue to the microcirculation.
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Affiliation(s)
- Michiel P De Boer
- Department of Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands
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29
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Sonne MP, Højbjerre L, Alibegovic AC, Nielsen LB, Stallknecht B, Vaag AA, Dela F. Endothelial function after 10 days of bed rest in individuals at risk for type 2 diabetes and cardiovascular disease. Exp Physiol 2011; 96:1000-9. [PMID: 21724735 DOI: 10.1113/expphysiol.2011.058511] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Physical inactivity is considered to be deleterious to vascular health, and in particular in first-degree relatives to patients with type 2 diabetes (FDR) and persons born with low birth weight (LBW), who may later in life develop cardiovascular disease. A period of imposed physical inactivity could unmask this risk. We hypothesized that the impact of physical inactivity on endothelial function would be more marked in subjects at increased risk for type 2 diabetes and cardiovascular disease (LBW and FDR) compared with a matched control group (CON), all of whom were recruited via advertisements and via the Danish Birth Registry. Twenty LBW, 20 CON and 13 FDR were studied before and after 10 days of bed rest. Forearm blood flow (FBF) was measured by venous occlusion plethysmography during brachial intra-arterial infusion of acetylcholine or adenosine at baseline and with superimposed hyperinsulinaemia. Markers of endothelial activation and inflammation were measured in plasma. Bed rest did not change the vasodilator responses to adenosine or acetylcholine alone in any group, but reduced vasodilator responses to adenosine or acetylcholine during hyperinsulinaemia in LBW. Bed rest impaired insulin-mediated vasodilatation in CON and LBW and increased endothelial activation markers in FDR and LBW but not in CON. Vasodilator responses were very low in FDR prior to bed rest, and did not decrease further during bed rest. Physical inactivity does not impair endothelium-dependent vasodilatation per se, but the vascular vasodilator effect of insulin diminished in CON and LBW after bed rest. In FDR, a further deterioration of FBF with inactivity is not possible.
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Affiliation(s)
- Mette P Sonne
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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30
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Sjøberg KA, Rattigan S, Hiscock N, Richter EA, Kiens B. A new method to study changes in microvascular blood volume in muscle and adipose tissue: real-time imaging in humans and rat. Am J Physiol Heart Circ Physiol 2011; 301:H450-8. [PMID: 21622816 DOI: 10.1152/ajpheart.01174.2010] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We employed and evaluated a new application of contrast-enhanced ultrasound for real-time imaging of changes in microvascular blood volume (MBV) in tissues in females, males, and rat. Continuous real-time imaging was performed using contrast-enhanced ultrasound to quantify infused gas-filled microbubbles in the microcirculation. It was necessary to infuse microbubbles for a minimum of 5-7 min to obtain steady-state bubble concentration, a prerequisite for making comparisons between different physiological states. Insulin clamped at a submaximal concentration (∼75 μU/ml) increased MBV by 27 and 39% in females and males, respectively, and by 30% in female subcutaneous adipose tissue. There was no difference in the ability of insulin to increase muscle MBV in females and males, and microvascular perfusion rate was not increased significantly by insulin. However, perfusion rate of the microvascular space was higher in females compared with males. In rats, insulin clamped at a maximal concentration increased muscle MBV by 60%. Large increases in microvascular volume and perfusion rate were detected during electrical stimulation of muscle in rats and immediately after exercise in humans. We have demonstrated that real-time imaging of changes in MBV is possible in human and rat muscle and in subcutaneous adipose tissue and that the method is sensitive enough to pick up relatively small changes in MBV when performed with due consideration of steady-state microbubble concentration. Because of real-time imaging, the method has wide applications for determining MBV in different organs during various physiological or pathophysiological conditions.
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Affiliation(s)
- Kim A Sjøberg
- Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
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31
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Kubota T, Kubota N, Kumagai H, Yamaguchi S, Kozono H, Takahashi T, Inoue M, Itoh S, Takamoto I, Sasako T, Kumagai K, Kawai T, Hashimoto S, Kobayashi T, Sato M, Tokuyama K, Nishimura S, Tsunoda M, Ide T, Murakami K, Yamazaki T, Ezaki O, Kawamura K, Masuda H, Moroi M, Sugi K, Oike Y, Shimokawa H, Yanagihara N, Tsutsui M, Terauchi Y, Tobe K, Nagai R, Kamata K, Inoue K, Kodama T, Ueki K, Kadowaki T. Impaired insulin signaling in endothelial cells reduces insulin-induced glucose uptake by skeletal muscle. Cell Metab 2011; 13:294-307. [PMID: 21356519 DOI: 10.1016/j.cmet.2011.01.018] [Citation(s) in RCA: 320] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 08/13/2010] [Accepted: 01/24/2011] [Indexed: 02/08/2023]
Abstract
In obese patients with type 2 diabetes, insulin delivery to and insulin-dependent glucose uptake by skeletal muscle are delayed and impaired. The mechanisms underlying the delay and impairment are unclear. We demonstrate that impaired insulin signaling in endothelial cells, due to reduced Irs2 expression and insulin-induced eNOS phosphorylation, causes attenuation of insulin-induced capillary recruitment and insulin delivery, which in turn reduces glucose uptake by skeletal muscle. Moreover, restoration of insulin-induced eNOS phosphorylation in endothelial cells completely reverses the reduction in capillary recruitment and insulin delivery in tissue-specific knockout mice lacking Irs2 in endothelial cells and fed a high-fat diet. As a result, glucose uptake by skeletal muscle is restored in these mice. Taken together, our results show that insulin signaling in endothelial cells plays a pivotal role in the regulation of glucose uptake by skeletal muscle. Furthermore, improving endothelial insulin signaling may serve as a therapeutic strategy for ameliorating skeletal muscle insulin resistance.
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Affiliation(s)
- Tetsuya Kubota
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan
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32
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Abstract
The aim of this article is to briefly review available data regarding changes in the structure of microvessels observed in patients with diabetes mellitus, and possible correction by effective treatment. The development of structural changes in the systemic vasculature is the end result of established hypertension. In essential hypertension, small arteries of smooth muscle cells are restructured around a smaller lumen and there is no net growth of the vascular wall, although in some secondary forms of hypertension, a hypertrophic remodelling may be detected. Moreover, in non-insulin-dependent diabetes mellitus a hypertrophic remodelling of subcutaneous small arteries is present. Indices of small resistance artery structure, such as the tunica media to internal lumen ratio, may have a strong prognostic significance in hypertensive and diabetic patients, over and above all other known cardiovascular risk factors. Therefore, regression of vascular alterations is an appealing goal of antihypertensive treatment. Different antihypertensive drugs seem to have different effect on vascular structure. In diabetic hypertensive patients, a significant regression of structural alterations of small resistance arteries with drugs blocking the renin–angiotensin system (angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers) was demonstrated. Alterations in the microcirculation represent a common pathological finding, and microangiopathy is one of the most important mechanisms involved in the development of organ damage as well as of clinical events in patients with diabetes mellitus. Renin–angiotensin system blockade seems to be effective in preventing/regressing alterations in microvascular structure.
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Affiliation(s)
- Enrico Agabiti Rosei
- Department of Medical and Surgical Sciences, University of Brescia, Clinica Medica, Brescia, Italy
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33
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de Kloet AD, Krause EG, Woods SC. The renin angiotensin system and the metabolic syndrome. Physiol Behav 2010; 100:525-34. [PMID: 20381510 DOI: 10.1016/j.physbeh.2010.03.018] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 03/18/2010] [Accepted: 03/26/2010] [Indexed: 01/01/2023]
Abstract
The renin angiotensin system (RAS; most well-known for its critical roles in the regulation of cardiovascular function and hydromineral balance) has regained the spotlight for its potential roles in various aspects of the metabolic syndrome. It may serve as a causal link among obesity and several co-morbidities. Drugs that reduce the synthesis or action of angiotensin-II (A-II; the primary effector peptide of the RAS) have been used to treat hypertension for decades and, more recently, clinical trials have determined the utility of these pharmacological agents to prevent insulin resistance. Moreover, there is evidence that the RAS contributes to body weight regulation by acting in various tissues. This review summarizes what is known of the actions of the RAS in the brain and throughout the body to influence various metabolic disorders. Special emphasis is given to the role of the RAS in body weight regulation. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.
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Affiliation(s)
- Annette D de Kloet
- Program in Neuroscience University of Cincinnati, Cincinnati, OH 45237, United States.
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34
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Wiernsperger N, Bouskela E. Microvascular haemodynamic reactions to insulin. J Physiol 2010; 587:5289; author reply 5291-2. [PMID: 19880878 DOI: 10.1113/jphysiol.2009.179911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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35
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Newman J, Dwyer R, St-Pierre P, Richards S, Clark M, Rattigan S. Reply from J. Newman, R. Dwyer, P. St-Pierre, S. Richards, M. Clark and S. Rattigan. J Physiol 2009. [DOI: 10.1113/jphysiol.2009.181370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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36
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Rizzoni D, Rosei EA. Small artery remodeling in diabetes mellitus. Nutr Metab Cardiovasc Dis 2009; 19:587-592. [PMID: 19481431 DOI: 10.1016/j.numecd.2009.03.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 02/09/2009] [Accepted: 03/10/2009] [Indexed: 11/29/2022]
Abstract
AIMS To briefly review available data regarding changes in the structure of microvessels observed in patients with diabetes mellitus, and possible correction by effective treatment. DATA SYNTHESIS The development of structural changes in the systemic vasculature is the end result of established hypertension. In essential hypertension, small arteries' smooth muscle cells are restructured around a smaller lumen and there is no net growth of the vascular wall, while in some secondary forms of hypertension, hypertrophic remodeling may be detected. Moreover, in non-insulin-dependent diabetes mellitus hypertrophic remodeling of subcutaneous small arteries is present. Indices of small resistance artery structure, such as the tunica media to internal lumen ratio, may have a strong prognostic significance in hypertensive and diabetic patients, over and above all other known cardiovascular risk factors. Therefore, regression of vascular alterations is an appealing goal of antihypertensive treatment. Different antihypertensive drugs seem to have different effects on vascular structure. In diabetic hypertensive patients, a significant regression of structural alterations to the small resistance arteries with drugs blocking the renin-angiotensin system (ACE inhibitors, angiotensin II receptor blockers) was demonstrated. CONCLUSION Alterations in the microcirculation represent a common pathological finding, and microangiopathy is one of the most important mechanisms involved in the development of organ damage as well as of clinical events in patients with diabetes mellitus. Renin-angiotensin system blockade seems to be effective in preventing and/or regressing alterations in the microvascular structure.
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Affiliation(s)
- D Rizzoni
- Clinica Medica, Department of Medical and Surgical Sciences, University of Brescia, Italy.
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37
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Høeg L, Roepstorff C, Thiele M, Richter EA, Wojtaszewski JFP, Kiens B. Higher intramuscular triacylglycerol in women does not impair insulin sensitivity and proximal insulin signaling. J Appl Physiol (1985) 2009; 107:824-31. [DOI: 10.1152/japplphysiol.91382.2008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Women have been shown to have higher muscle triacylglycerol (IMTG) levels than men and could therefore be expected to have lower insulin sensitivity than men, since previous studies have linked high IMTG to decreased insulin sensitivity. Therefore, insulin sensitivity of whole body and leg glucose uptake was studied in 9 women in the follicular phase and 8 men on a controlled diet and matched for maximal oxygen uptake per kilogram of lean body mass and habitual activity level. A 47% higher ( P < 0.05) IMTG level was found in women than in men, and, at the same time, women also displayed 22% higher whole body insulin sensitivity ( P < 0.05) and 29% higher insulin-stimulated leg glucose uptake ( P = 0.05) during an euglycemic-hyperinsulinemic (≈70 μU/ml) clamp compared with matched male subjects. The higher insulin sensitivity in women could not be explained by higher expression of muscle glucose transporter GLUT4, insulin receptor, or Akt expression or by the ability of insulin to stimulate Akt Thr308 or Akt Ser473 phosphorylation. However, a 30% higher ( P < 0.05) capillary density and 31% more type 1 muscle fiber expressed per area in the vastus lateralis muscle were noted in women than in matched men. It is concluded that despite 47% higher IMTG levels in women in the follicular phase, whole body as well as leg insulin sensitivity are higher than in matched men. This was not explained by sex differences in proximal insulin signaling in women. In women, it seems that a high capillary density and type 1 muscle fiber expression may be important for insulin action.
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38
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Barrett EJ, Eggleston EM, Inyard AC, Wang H, Li G, Chai W, Liu Z. The vascular actions of insulin control its delivery to muscle and regulate the rate-limiting step in skeletal muscle insulin action. Diabetologia 2009; 52:752-64. [PMID: 19283361 PMCID: PMC2704146 DOI: 10.1007/s00125-009-1313-z] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Accepted: 01/30/2009] [Indexed: 12/22/2022]
Abstract
Evidence suggests that insulin delivery to skeletal muscle interstitium is the rate-limiting step in insulin-stimulated muscle glucose uptake and that this process is impaired by insulin resistance. In this review we examine the basis for the hypothesis that insulin acts on the vasculature at three discrete steps to enhance its own delivery to muscle: (1) relaxation of resistance vessels to increase total blood flow; (2) relaxation of pre-capillary arterioles to increase the microvascular exchange surface perfused within skeletal muscle (microvascular recruitment); and (3) the trans-endothelial transport (TET) of insulin. Insulin can relax resistance vessels and increase blood flow to skeletal muscle. However, there is controversy as to whether this occurs at physiological concentrations of, and exposure times to, insulin. The microvasculature is recruited more quickly and at lower insulin concentrations than are needed to increase total blood flow, a finding consistent with a physiological role for insulin in muscle insulin delivery. Microvascular recruitment is impaired by obesity, diabetes and nitric oxide synthase inhibitors. Insulin TET is a third potential site for regulating insulin delivery. This is underscored by the consistent finding that steady-state insulin concentrations in plasma are approximately twice those in muscle interstitium. Recent in vivo and in vitro findings suggest that insulin traverses the vascular endothelium via a trans-cellular, receptor-mediated pathway, and emerging data indicate that insulin acts on the endothelium to facilitate its own TET. Thus, muscle insulin delivery, which is rate-limiting for its metabolic action, is itself regulated by insulin at multiple steps. These findings highlight the need to further understand the role of the vascular actions of insulin in metabolic regulation.
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Affiliation(s)
- E J Barrett
- University of Virginia Health System, Charlottesville, VA 22908, USA.
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39
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Muniyappa R, Hall G, Kolodziej TL, Karne RJ, Crandon SK, Quon MJ. Cocoa consumption for 2 wk enhances insulin-mediated vasodilatation without improving blood pressure or insulin resistance in essential hypertension. Am J Clin Nutr 2008; 88:1685-96. [PMID: 19064532 PMCID: PMC2969165 DOI: 10.3945/ajcn.2008.26457] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Essential hypertension is characterized by reciprocal relations between endothelial dysfunction and insulin resistance. Cocoa flavanols stimulate production of the vasodilator nitric oxide from vascular endothelium. OBJECTIVE The objective was to test the hypothesis that consumption of cocoa may simultaneously lower blood pressure, improve endothelial dysfunction, and ameliorate insulin resistance in subjects with essential hypertension. DESIGN We conducted a randomized, placebo-controlled, double-blind, crossover trial of a flavanol-rich cocoa drink (150 mL twice a day, approximately 900 mg flavanols/d) in individuals with essential hypertension (n = 20). Antihypertensive medications were discontinued before study enrollment. After a 7-d cocoa-free run-in period, cocoa or flavanol-poor placebo (approximately 28 mg flavanols/d) treatment for 2 wk was followed by a 1-wk washout and then crossover to the other treatment arm. Blood pressure was measured thrice weekly. At baseline and after each treatment period, we assessed insulin sensitivity (hyperinsulinemic-isoglycemic glucose clamp) and insulin-stimulated changes in brachial artery diameter and forearm skeletal muscle capillary recruitment (Doppler ultrasound with or without microbubble contrast). RESULTS Cocoa treatment for 2 wk increased insulin-stimulated changes in brachial artery diameter when compared with placebo [median percentage increase from baseline (25th-75th percentile): 8.3 (4.2-11.3) compared with 5.9 (-0.3 to 9.6); P < 0.04]. Nevertheless, cocoa treatment did not significantly reduce blood pressure or improve insulin resistance and had no significant effects on skeletal muscle capillary recruitment, circulating plasma concentrations of adipocytokines, or endothelial adhesion molecules. CONCLUSIONS Daily consumption of flavanol-rich cocoa for 2 wk is not sufficient to reduce blood pressure or improve insulin resistance in human subjects with essential hypertension. This trial was registered at clinicaltrials.gov as NCT00099476.
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Affiliation(s)
- Ranganath Muniyappa
- Diabetes Unit, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, MD, USA
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40
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Chiu JD, Richey JM, Harrison LN, Zuniga E, Kolka CM, Kirkman E, Ellmerer M, Bergman RN. Direct administration of insulin into skeletal muscle reveals that the transport of insulin across the capillary endothelium limits the time course of insulin to activate glucose disposal. Diabetes 2008; 57:828-35. [PMID: 18223011 DOI: 10.2337/db07-1444] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Intravenous insulin infusion rapidly increases plasma insulin, yet glucose disposal occurs at a much slower rate. This delay in insulin's action may be related to the protracted time for insulin to traverse the capillary endothelium. An increased delay may be associated with the development of insulin resistance. The purpose of the present study was to investigate whether bypassing the transendothelial insulin transport step and injecting insulin directly into the interstitial space would moderate the delay in glucose uptake observed with intravenous administration of the hormone. RESEARCH DESIGN AND METHODS Intramuscular injections of saline (n = 3) or insulin (n = 10) were administered directly into the vastus medialis of anesthetized dogs. Injections of 0.3, 0.5, 0.7, 1.0, and 3.0 units insulin were administered hourly during a basal insulin euglycemic glucose clamp (0.2mU x min(-1) x kg(-1)). RESULTS Unlike the saline group, each incremental insulin injection caused interstitial (lymph) insulin to rise within 10 min, indicating rapid diffusion of the hormone within the interstitial matrix. Delay in insulin action was virtually eliminated, indicated by immediate dose-dependent increments in hindlimb glucose uptake. Additionally, bypassing insulin transport by direct injection into muscle revealed a fourfold greater sensitivity to insulin of in vivo muscle tissue than previously reported from intravenous insulin administration. CONCLUSIONS Our results indicate that the transport of insulin to skeletal muscle is a rate-limiting step for insulin to activate glucose disposal. Based on these results, we speculate that defects in insulin transport across the endothelial layer of skeletal muscle will contribute to insulin resistance.
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Affiliation(s)
- Jenny D Chiu
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, 1333 San Pablo St., MMR 626, Los Angeles, CA 90033, USA
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41
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Ye J, Gao Z, Yin J, He Q. Hypoxia is a potential risk factor for chronic inflammation and adiponectin reduction in adipose tissue of ob/ob and dietary obese mice. Am J Physiol Endocrinol Metab 2007; 293:E1118-28. [PMID: 17666485 DOI: 10.1152/ajpendo.00435.2007] [Citation(s) in RCA: 612] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic inflammation and reduced adiponectin are widely observed in the white adipose tissue in obesity. However, the cause of the changes remains to be identified. In this study, we provide experimental evidence that hypoxia occurs in adipose tissue in obese mice and that adipose hypoxia may contribute to the endocrine alterations. The adipose hypoxia was demonstrated by a reduction in the interstitial partial oxygen pressure (Po(2)), an increase in the hypoxia probe signal, and an elevation in expression of the hypoxia response genes in ob/ob mice. The adipose hypoxia was confirmed in dietary obese mice by expression of hypoxia response genes. In the adipose tissue, hypoxia was associated with an increased expression of inflammatory genes and decreased expression of adiponectin. In dietary obese mice, reduction in body weight by calorie restriction was associated with an improvement of oxygenation and a reduction in inflammation. In cell culture, inflammatory cytokines were induced by hypoxia in primary adipocytes and primary macrophages of lean mice. The transcription factor NF-kappaB and the TNF-alpha gene promoter were activated by hypoxia in 3T3-L1 adipocytes and NIH3T3 fibroblasts. In addition, adiponectin expression was reduced by hypoxia, and the reduction was observed in the gene promoter in adipocytes. These data suggest a potential role of hypoxia in the induction of chronic inflammation and inhibition of adiponectin in the adipose tissue in obesity.
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Affiliation(s)
- Jianping Ye
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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42
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Newman JMB, Ross RM, Richards SM, Clark MG, Rattigan S. Insulin and contraction increase nutritive blood flow in rat muscle in vivo determined by microdialysis of L-[14C]glucose. J Physiol 2007; 585:217-29. [PMID: 17884927 PMCID: PMC2375457 DOI: 10.1113/jphysiol.2007.138818] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In the present study, a mathematical model using the microdialysis outflow: inflow (O/I) ratio of the novel analogue L-[14C]glucose has been developed which allows the calculation of the nutritive (and non-nutritive) flow in muscle as a proportion of total blood flow. Anaesthetized rats had microdialysis probes carrying L-[14C]glucose inserted through a calf muscle group (tibialis/plantaris/gastrocnemius). The nutritive fraction of total blood flow was determined under basal conditions and in response to contraction (electrical field stimulation), insulin (hyperinsulinaemic euglycaemic clamp with 10 mU min(-1) kg(-1) insulin) or saline control from limb blood flow and the microdialysis O/I ratio of L-[14C]glucose. Both contraction and insulin infusion decreased the O/I ratio of L-[14C]glucose and increased total limb blood flow. Calculations based on mathematical models using L-[14C]glucose O/I and limb blood flow revealed that during basal conditions, the nutritive fraction of total flow was 0.38 +/- 0.06, indicating that basal flow was predominantly non-nutritive. Contraction and insulin increased the nutritive fraction to 0.82 +/- 0.24 (P < 0.05) and 0.52 +/- 0.12 (P < 0.05). Thus the increase in limb blood flow from insulin was fully accommodated by nutritive flow, while contraction increased nutritive flow at the expense of non-nutritive flow. This novel method using microdialysis and the O/I ratio of L-[14C]glucose allows the determination of the nutritive fraction of total flow in muscle as well as the proportion of total flow that may be redistributed in response to contraction and insulin.
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Affiliation(s)
- John M B Newman
- Biochemistry, Medical School, University of Tasmania, Private Bag 58, Hobart 7001, Tasmania, Australia.
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43
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Stepp DW. Impact of obesity and insulin resistance on vasomotor tone: nitric oxide and beyond. Clin Exp Pharmacol Physiol 2007; 33:407-14. [PMID: 16700872 DOI: 10.1111/j.1440-1681.2006.04381.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
1. Obesity is rapidly increasing in Western populations, driving a parallel increase in hypertension, diabetes and vascular disease. Prior to the development of overt diabetes or hypertension, obese patients spend years in a state of progressive insulin resistance and metabolic disease. Mounting evidence suggests that this insulin-resistant state has deleterious effects on the control of blood flow, thus placing organ systems at a higher risk for end-organ damage and increasing cardiovascular mortality. 2. The purpose of the present review is to examine the current literature on the effects of obesity and insulin resistance on the acute control of vascular tone. Effects on nitric oxide (NO)-mediated control of vascular tone are particularly examined with regard to proximal causes and distal mechanisms of the impaired NO-mediation of vasodilation. 3. Finally, novel pathways of impaired control of perfusion are summarized from the recent literature to identify new avenues of exploring impaired vascular function in patients with metabolic disease.
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Affiliation(s)
- David W Stepp
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia 30912-2500, USA.
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44
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Townsend RR, Kapoor S, McFadden CB. Salt intake and insulin sensitivity in healthy human volunteers. Clin Sci (Lond) 2007; 113:141-8. [PMID: 17425514 DOI: 10.1042/cs20060361] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The literature on salt intake and insulin sensitivity presents a mixed picture, as some studies have shown an increase, whereas others have shown a decrease, in insulin action as sodium intake is enhanced. In some cases, this may relate to the study of salt intake in patients with co-morbidities such as hypertension or diabetes. In the present study, we selected healthy normotensive lean volunteers who underwent a euglycaemic clamp following 6 days of a low-salt diet (20 mmol sodium daily) and, subsequently, 6 days of a high-salt diet (200 mmol sodium daily). Our results show an increase in insulin-mediated glucose disposal during euglycaemic clamp conditions that was significantly higher following the high-salt diet compared with the low-salt diet (7.41+/-0.41 compared with 6.11+/-0.40 mg x kg(-1) of body weight x min(-1) respectively; P=0.03). We measured calf blood flow before and during insulin infusion (no significant change after the two dietary salt interventions was detected) and plasma non-esterified fatty acids (also no significant differences were detected). We observed the expected increases in renin concentration and aldosterone activity in subjects on the low-salt diet, and also observed a significantly less increase in plasma noradrenaline concentration during euglycaemic insulin infusion following the high-salt compared with the low-salt diet. We propose that the 4-5-fold increase in serum aldosterone and the greater increase in plasma noradrenaline concentration following the low-salt intervention compared with the high-salt period may have contributed to the differences in insulin sensitivity following the adjustment in dietary sodium intake.
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Affiliation(s)
- Raymond R Townsend
- Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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45
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de Jongh RT, Ijzerman RG, Serné EH, van Weissenbruch MM, Voordouw JJ, Delemarre-van de Waal HA, Stehouwer CDA. Urinary cortisol is inversely associated with capillary recruitment in women: a potential explanation for the cortisol–blood pressure relationship. Clin Sci (Lond) 2007; 113:83-91. [PMID: 17295610 DOI: 10.1042/cs20060357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The relationships of cortisol with elevated blood pressure and insulin resistance are likely to be the result of a complex interplay of different mechanisms. We hypothesize that cortisol is associated with impaired microvascular function and that this contributes to cortisol-associated high blood pressure and insulin resistance. We examined 24 h urinary free cortisol excretion in 56 healthy adults (26 women). Blood pressure was assessed by 24 h ambulatory measurements. Insulin sensitivity was determined using the hyperinsulinaemic euglycaemic clamp technique. Skin capillary recruitment after arterial occlusion was visualized with videomicroscopy and endothelium-(in)dependent vasodilation was evaluated with iontophoresis of acetylcholine and sodium nitroprusside combined with laser Doppler fluxmetry. Men were characterized by higher urinary cortisol excretion [median (interquartile range), 162 (130–194) compared with 118 (99–156) nmol/24 h, P<0.05]. In women, but not in men, urinary cortisol excretion was associated with impaired capillary recruitment (r=−0.66, P<0.001), higher systolic blood pressure (r=0.64, P<0.001) and lower insulin sensitivity (r=−0.43, P<0.05). Urinary cortisol excretion was not associated with endothelium-(in)dependent vasodilation in men or women. Regression analysis demonstrated that capillary recruitment statistically explained 37% of the association between urinary cortisol and blood pressure in women. Capillary recruitment did not explain part of the association between urinary cortisol and insulin sensitivity. In conclusion, urinary cortisol excretion is inversely associated with capillary recruitment in women, but not in men, and capillary recruitment explains part of the cortisol–blood pressure relationship. These data suggest that, in women, impairment of capillary function mediates some of the adverse effects of cortisol and thus may provide a target to prevent such adverse effects.
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Affiliation(s)
- Renate T de Jongh
- Department of Internal Medicine, Institute for Cardiovascular Research-Vrije Universiteit, VU University Medical Center, De Boelelaan, Amsterdam, The Netherlands.
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46
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Affiliation(s)
- Richard N Bergman
- Department of Physiology and Biophysics, Keck School of Medicine, Los Angeles, CA 90033, USA.
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47
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Serné EH, de Jongh RT, Eringa EC, IJzerman RG, Stehouwer CDA. Microvascular dysfunction: a potential pathophysiological role in the metabolic syndrome. Hypertension 2007; 50:204-11. [PMID: 17470716 DOI: 10.1161/hypertensionaha.107.089680] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Erik H Serné
- Department of Internal Medicine, VU Medical Center, Amsterdam, The Netherlands.
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48
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Serné EH, de Jongh RT, Eringa EC, Ijzerman RG, de Boer MP, Stehouwer CDA. Microvascular dysfunction: causative role in the association between hypertension, insulin resistance and the metabolic syndrome? Essays Biochem 2006; 42:163-76. [PMID: 17144887 DOI: 10.1042/bse0420163] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The metabolic syndrome defines a clustering of metabolic risk factors that confers an increased risk for type 2 diabetes and cardiovascular disease. The metabolic syndrome seems to have multiple etiological factors and microvascular dysfunction may be one potential factor explaining the clustering of multiple metabolic risk factors including hypertension, obesity, insulin resistance and glucose intolerance. Microvascular dysfunction may increase not only peripheral vascular resistance and blood pressure, but may also decrease insulin-mediated glucose uptake in muscle. The present article summarizes some of the data concerning the role of microvascular dysfunction in the metabolic syndrome.
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Affiliation(s)
- Erik H Serné
- Department of Internal Medicine, VU Medical Center, PO Box 7057, 1007MB Amsterdam, The Netherlands.
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49
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Wang H, Liu Z, Li G, Barrett EJ. The vascular endothelial cell mediates insulin transport into skeletal muscle. Am J Physiol Endocrinol Metab 2006; 291:E323-32. [PMID: 16569759 DOI: 10.1152/ajpendo.00047.2006] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pathways by which insulin exits the vasculature to muscle interstitium have not been characterized. In the present study, we infused FITC-labeled insulin to trace morphologically (using confocal immunohistochemical methods) insulin transport into rat skeletal muscle. We biopsied rectus muscle at 0, 10, 30, and 60 min after beginning a continuous (10 mU x min(-1) x kg(-1)), intravenous FITC-insulin infusion (with euglycemia maintained). The FITC-insulin distribution was compared with that of insulin receptors (IR), IGF-I receptors (IGF-IR), and caveolin-1 (a protein marker for caveolae) in skeletal muscle vasculature. We observed that muscle endothelium stained strongly for FITC-insulin within 10 min, and this persisted to 60 min. Endothelium stained more strongly for FITC-insulin than any other cellular elements in muscle. IR, IGF-IR, and caveolin-1 were also detected immunohistochemically in muscle endothelial cells. We further compared their intracellular distribution with that of FITC-insulin in cultured bovine aortic endothelial cells (bAECs). Considerable colocalization of IR or IGF-IR with FITC-insulin was noted. There was some but less overlap of IR or IGF-IR or FITC-insulin with caveolin-1. Immunoprecipitation of IR coprecipitated caveolin-1, and conversely the precipitation of caveolin-1 brought down IR. Furthermore, insulin increased the tyrosine phosphorylation of caveolin-1, and filipin (which inhibits caveolae formation) blocked insulin uptake. Finally, the ability of insulin, IGF-I, and IGF-I-blocking antibody to diminish insulin transport across bAECs grown on transwell plates suggested that IGF-IR, in addition to IR, can also mediate transendothelial insulin transit. We conclude that in vivo endothelial cells rapidly take up and concentrate insulin relative to plasma and muscle interstitium and that IGF-IR, like IR, may mediate insulin transit through endothelial cells in a process involving caveolae.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology and Metabolism, Departmetn of Internal Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
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50
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Kim JA, Montagnani M, Koh KK, Quon MJ. Reciprocal relationships between insulin resistance and endothelial dysfunction: molecular and pathophysiological mechanisms. Circulation 2006; 113:1888-904. [PMID: 16618833 DOI: 10.1161/circulationaha.105.563213] [Citation(s) in RCA: 1121] [Impact Index Per Article: 62.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Endothelial dysfunction contributes to cardiovascular diseases, including hypertension, atherosclerosis, and coronary artery disease, which are also characterized by insulin resistance. Insulin resistance is a hallmark of metabolic disorders, including type 2 diabetes mellitus and obesity, which are also characterized by endothelial dysfunction. Metabolic actions of insulin to promote glucose disposal are augmented by vascular actions of insulin in endothelium to stimulate production of the vasodilator nitric oxide (NO). Indeed, NO-dependent increases in blood flow to skeletal muscle account for 25% to 40% of the increase in glucose uptake in response to insulin stimulation. Phosphatidylinositol 3-kinase-dependent insulin-signaling pathways in endothelium related to production of NO share striking similarities with metabolic pathways in skeletal muscle that promote glucose uptake. Other distinct nonmetabolic branches of insulin-signaling pathways regulate secretion of the vasoconstrictor endothelin-1 in endothelium. Metabolic insulin resistance is characterized by pathway-specific impairment in phosphatidylinositol 3-kinase-dependent signaling, which in endothelium may cause imbalance between production of NO and secretion of endothelin-1, leading to decreased blood flow, which worsens insulin resistance. Therapeutic interventions in animal models and human studies have demonstrated that improving endothelial function ameliorates insulin resistance, whereas improving insulin sensitivity ameliorates endothelial dysfunction. Taken together, cellular, physiological, clinical, and epidemiological studies strongly support a reciprocal relationship between endothelial dysfunction and insulin resistance that helps to link cardiovascular and metabolic diseases. In the present review, we discuss pathophysiological mechanisms, including inflammatory processes, that couple endothelial dysfunction with insulin resistance and emphasize important therapeutic implications.
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Affiliation(s)
- Jeong-a Kim
- Diabetes Unit, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, MD 20892-1632, USA
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