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Šorli J, Lenasi H. The Effect of Acute Hyperglycaemia Induced by Oral Glucose Load on Heart Rate Variability and Skin Microvascular Reactivity in Young Adults. Life (Basel) 2023; 14:56. [PMID: 38255671 PMCID: PMC10817604 DOI: 10.3390/life14010056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/24/2024] Open
Abstract
We aimed to elucidate the effects of acute hyperglycaemia, induced by an oral glucose tolerance test (OGTT), on the autonomic nervous system (ANS) and skin microvascular reactivity at the time point of peak plasma glucose concentration (cglc) in 20 young, healthy participants. We assessed their heart rate variability (HRV) as a measure of the ANS activity and the parameters of post-occlusive reactive hyperaemia (PORH) to estimate skin microvascular reactivity as measured by laser Doppler (LD) fluxmetry. The tests were repeated 30 min after a standard OGTT (75 g glucose dissolved in 250 mL water) and, in a separate control experiment, after drinking the same amount of water. Participants had their cglc and serum insulin measured at three consecutive time-points according to the testing protocol. The low-frequency (LF) spectral power, the LF to high-frequency (LF/HF) ratio, and the diastolic blood pressure increased significantly more after water than after OGTT, and there was a trend of the peak LD flux of PORH decreasing more after OGTT than after water. Significant correlations between some PORH and all the HRV parameters and cglc increase after OGTT were found, implying diminished vascular reactivity evoked by hyperglycaemia in healthy subjects with lower glucose tolerance.
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Affiliation(s)
- Jernej Šorli
- General Hospital Dr. Franc Derganc, 5290 Šempeter pri Gorici, Slovenia
| | - Helena Lenasi
- Institute of Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
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2
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Soares RN, Reimer RA, Doyle-Baker PK, Murias JM. Mild obesity does not affect the forearm muscle microvascular responses to hyperglycemia. Microcirculation 2020; 28:e12669. [PMID: 33150675 DOI: 10.1111/micc.12669] [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: 06/20/2020] [Accepted: 10/29/2020] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Mild obesity has been associated with postprandial brachial artery vascular dysfunction. However, direct assessment of these effects within the forearm skeletal muscle microcirculation remains unclear. Thus, this study aimed to investigate the effects of mild obesity on the arm micro- and macrovascular responses to glucose ingestion. METHODS This cross-sectional study combined NIRS assessments of forearm skeletal muscle (FDS) reactivity (reperfusion slope) with %FMD of conduit artery function (brachial artery) before (Pre), as well as 60 and 120 min after glucose ingestion in 10 lean (BMI 23.9 ± 1.8) and 10 obese (BMI 32.9 ± 1.9) individuals. RESULTS Both groups showed a significant increase in the reperfusion slope at 60 and 120 min after glucose ingestion compared with the pre-glucose ingestion measurements. Obese individuals showed a significant (p < .05) reduction in %FMD at 60 min after glucose ingestion, while no significant changes in postprandial %FMD were observed in lean participants. CONCLUSION Even though obese individuals showed impaired postprandial brachial artery function, the current findings suggest that mild obesity does not affect the forearm skeletal muscle responses to glucose ingestion.
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Affiliation(s)
| | - Raylene A Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Patricia K Doyle-Baker
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Faculty of Environmental Design, University of Calgary, Calgary, AB, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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3
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A Protein/Lipid Preload Attenuates Glucose-Induced Endothelial Dysfunction in Individuals with Abnormal Glucose Tolerance. Nutrients 2020; 12:nu12072053. [PMID: 32664350 PMCID: PMC7400934 DOI: 10.3390/nu12072053] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/24/2020] [Accepted: 07/08/2020] [Indexed: 12/24/2022] Open
Abstract
Postprandial hyperglycemia interferes with vascular reactivity and is a strong predictor of cardiovascular disease. Macronutrient preloads reduce postprandial hyperglycemia in subjects with impaired glucose tolerance (IGT) or type 2 diabetes (T2D), but the effect on endothelial function is unknown. Therefore, we examined whether a protein/lipid preload can attenuate postprandial endothelial dysfunction by lowering plasma glucose responses in subjects with IGT/T2D. Endothelial function was assessed by the reactive hyperemia index (RHI) at fasting, 60 min and 120 min during two 75 g oral glucose tolerance tests (OGTTs) preceded by either water or a macronutrient preload (i.e., egg and parmesan cheese) in 22 volunteers with IGT/T2D. Plasma glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), glucagon, free fatty acids, and amino acids were measured through each test. RHI negatively correlated with fasting plasma glucose. During the control OGTT, RHI decreased by 9% and its deterioration was associated with the rise in plasma glucose. The macronutrient preload attenuated the decline in RHI and markedly reduced postprandial glycemia. The beneficial effect of the macronutrient preload on RHI was proportional to the improvement in glucose tolerance and was associated with the increase in plasma GLP-1 and arginine levels. In conclusion, a protein/lipid macronutrient preload attenuates glucose-induced endothelial dysfunction in individuals with IGT/T2D by lowering plasma glucose excursions and by increasing GLP-1 and arginine levels, which are known regulators of the nitric oxide vasodilator system.
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Loader J, Khouri C, Taylor F, Stewart S, Lorenzen C, Cracowski JL, Walther G, Roustit M. The continuums of impairment in vascular reactivity across the spectrum of cardiometabolic health: A systematic review and network meta-analysis. Obes Rev 2019; 20:906-920. [PMID: 30887713 DOI: 10.1111/obr.12831] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/03/2019] [Accepted: 01/03/2019] [Indexed: 12/12/2022]
Abstract
This study aimed to assess, for the first time, the change in vascular reactivity across the full spectrum of cardiometabolic health. Systematic searches were conducted in MEDLINE and EMBASE databases from their inception to March 13, 2017, including studies that assessed basal vascular reactivity in two or more of the following health groups (aged ≥18 years old): healthy, overweight, obesity, impaired glucose tolerance, metabolic syndrome, or type 2 diabetes with or without complications. Direct and indirect comparisons of vascular reactivity were combined using a network meta-analysis. Comparing data from 193 articles (7226 healthy subjects and 19344 patients), the network meta-analyses revealed a progressive impairment in vascular reactivity (flow-mediated dilation data) from the clinical onset of an overweight status (-0.41%, 95% CI, -0.98 to 0.15) through to the development of vascular complications in those with type 2 diabetes (-4.26%, 95% CI, -4.97 to -3.54). Meta-regressions revealed that for every 1 mmol/l increase in fasting blood glucose concentration, flow-mediated dilation decreased by 0.52%. Acknowledging that the time course of disease may vary between patients, this study demonstrates multiple continuums of vascular dysfunction where the severity of impairment in vascular reactivity progressively increases throughout the pathogenesis of obesity and/or insulin resistance, providing information that is important to enhancing the timing and effectiveness of strategies that aim to improve cardiovascular outcomes.
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Affiliation(s)
- Jordan Loader
- Department of Medicine, Austin Health, The University of Melbourne, Melbourne, Australia.,Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia.,LAPEC EA4278, Avignon Université, Avignon, France
| | - Charles Khouri
- Inserm U1042, Université Grenoble Alpes, Grenoble, France.,Clinical Pharmacology, Grenoble Alpes University Hospital, Grenoble, France
| | - Frances Taylor
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia
| | - Simon Stewart
- Hatter Institute for Reducing Cardiovascular Disease in Africa, The University of Cape Town, Cape Town, South Africa
| | - Christian Lorenzen
- School of Exercise Science, Australian Catholic University, Melbourne, Australia
| | - Jean-Luc Cracowski
- Inserm U1042, Université Grenoble Alpes, Grenoble, France.,Clinical Pharmacology, Grenoble Alpes University Hospital, Grenoble, France
| | - Guillaume Walther
- LAPEC EA4278, Avignon Université, Avignon, France.,School of Exercise Science, Australian Catholic University, Melbourne, Australia
| | - Matthieu Roustit
- Inserm U1042, Université Grenoble Alpes, Grenoble, France.,Clinical Pharmacology, Grenoble Alpes University Hospital, Grenoble, France
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Loader J, Montero D, Lorenzen C, Watts R, Méziat C, Reboul C, Stewart S, Walther G. Acute Hyperglycemia Impairs Vascular Function in Healthy and Cardiometabolic Diseased Subjects. Arterioscler Thromb Vasc Biol 2015; 35:2060-72. [DOI: 10.1161/atvbaha.115.305530] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/16/2015] [Indexed: 02/04/2023]
Abstract
Objectives—
Controversy exists over the effect of acute hyperglycemia on vascular function. In this systematic review, we compared the effect of acute hyperglycemia on endothelial and vascular smooth muscle functions across healthy and cardiometabolic diseased subjects.
Approach and Results—
A systematic search of MEDLINE, EMBASE, and Web of Science from inception until July 2014 identified articles evaluating endothelial or vascular smooth muscle function during acute hyperglycemia and normoglycemia. Meta-analyses compared the standardized mean difference (SMD) in endothelial and vascular smooth muscle functions between acute hyperglycemia and normoglycemia. Subgroup analyses and metaregression identified sources of heterogeneity. Thirty-nine articles (525 healthy and 540 cardiometabolic subjects) were analyzed. Endothelial function was decreased (39 studies; n=1065; SMD, −1.25; 95% confidence interval, −1.52 to −0.98;
P
<0.01), whereas vascular smooth muscle function was preserved (6 studies; n=144; SMD, −0.07; 95% confidence interval, −0.30 to 0.16;
P
=0.55) during acute hyperglycemia compared with normoglycemia. Significant heterogeneity was detected among endothelial function studies (
P
<0.01). A subgroup analysis revealed that endothelial function was decreased in the macrocirculation (30 studies; n=884; SMD, −1.40; 95% confidence interval, −1.68 to −1.12;
P
<0.01) but not in the microcirculation (9 studies; n=181; SMD, −0.63; 95% confidence interval, −1.36 to 0.11;
P
=0.09). Similar results were observed according to health status. Macrovascular endothelial function was inversely associated with age, blood pressure, and low-density lipoprotein cholesterol and was positively associated with the postocclusion interval of vascular assessment.
Conclusions—
To our knowledge, this is the first systematic review and meta-analysis of its kind. In healthy and diseased subjects, we found evidence for macrovascular but not microvascular endothelial dysfunction during acute hyperglycemia.
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Affiliation(s)
- Jordan Loader
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - David Montero
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - Christian Lorenzen
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - Rani Watts
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - Cindy Méziat
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - Cyril Reboul
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - Simon Stewart
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
| | - Guillaume Walther
- From the Avignon University, LAPEC EA4278, Avignon, France (J.L., C.M., C.R., G.W.); School of Exercise Science (J.L., C.L., R.W., G.W.) and The Mary MacKillop Institute for Health Research (S.S.), Australian Catholic University, Melbourne, Victoria, Australia; and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland (D.M.)
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Kanaya AM, Dobrosielski DA, Ganz P, Creasman J, Gupta R, Nelacanti V, Vogel-Claussen J, Herrington D. Glycemic associations with endothelial function and biomarkers among 5 ethnic groups: the Multi-Ethnic Study of Atherosclerosis and the Mediators of Atherosclerosis in South Asians Living in America studies. J Am Heart Assoc 2013; 2:e004283. [PMID: 23525433 PMCID: PMC3603246 DOI: 10.1161/jaha.112.004283] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Background The association of prediabetic states with endothelial dysfunction measured by flow‐mediated dilation (FMD) or endothelial biomarker levels remains controversial. We examined data from 5 ethnic groups to determine the association between glucose categories and FMD or endothelial biomarkers. We determined whether these associations vary by ethnic group or body mass index. Methods and Results We used data from 3516 participants from 5 race/ethnic groups with brachial FMD, endothelial biomarkers, and glucose category (normal, impaired fasting glucose [IFG], and diabetes) measures. There were significant ethnic differences in FMD, biomarker levels, and the prevalence of IFG and diabetes. However, all 5 ethnic groups showed similar patterns of higher FMD for the IFG group compared with the normal glucose and diabetes groups, which was most significant among whites and Asian Indians. Associations between glucose categories and endothelial biomarkers were more uniform, with the IFG and diabetes groups having higher biomarker levels than the normal glucose group. These associations did not change with further adjustment for fasting insulin levels. Whites with normal BMI had higher FMD values with higher glucose levels, but those with BMI in the overweight or obese categories had the inverse association (P for interaction=0.01). Conclusions The discordance of IFG being associated with higher FMD but more abnormal endothelial biomarker levels is a novel finding. This higher FMD for the IFG group was most notable in whites of normal BMI. The higher FMD among those with impaired fasting glucose may reflect differences in insulin signaling pathways between the endothelium and skeletal muscle.
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Affiliation(s)
- Alka M Kanaya
- University of California, San Francisco, CA 94143-0320, USA.
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Gosmanov AR, Smiley DD, Peng L, Siquiera J, Robalino G, Newton C, Umpierrez GE. Vascular effects of intravenous intralipid and dextrose infusions in obese subjects. Metabolism 2012; 61:1370-6. [PMID: 22483976 PMCID: PMC3738183 DOI: 10.1016/j.metabol.2012.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Revised: 03/08/2012] [Accepted: 03/09/2012] [Indexed: 01/22/2023]
Abstract
Hyperglycemia and elevated free fatty acids (FFA) are implicated in the development of endothelial dysfunction. Infusion of soy-bean oil-based lipid emulsion (Intralipid®) increases FFA levels and results in elevation of blood pressure (BP) and endothelial dysfunction in obese healthy subjects. The effects of combined hyperglycemia and high FFA on BP, endothelial function and carbohydrate metabolism are not known. Twelve obese healthy subjects received four random, 8-h IV infusions of saline, Intralipid 40 mL/h, Dextrose 10% 40 mL/h, or combined Intralipid and dextrose. Plasma levels of FFA increased by 1.03±0.34 mmol/L (p=0.009) after Intralipid, but FFAs remained unchanged during saline, dextrose, and combined Intralipid and dextrose infusion. Plasma glucose and insulin concentrations significantly increased after dextrose and combined Intralipid and dextrose (all, p<0.05) and were not different from baseline during saline and lipid infusion. Intralipid increased systolic BP by 12±9 mmHg (p<0.001) and diastolic BP by 5±6 mmHg (p=0.022),and decreased flow-mediated dilatation (FMD) from baseline by 3.2%±1.4% (p<0.001). Saline and dextrose infusion had neutral effects on BP and FMD. The co-administration of lipid and dextrose decreased FMD by 2.4%±2.1% (p=0.002) from baseline, but did not significantly increase systolic or diastolic BP. Short-term Intralipid infusion significantly increased FFA and BP; in contrast, FFA and BP were unchanged during combined infusion of Intralipid and dextrose. Combined Intralipid and dextrose infusion resulted in endothelial dysfunction similar to Intralipid alone.
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Affiliation(s)
- Aidar R. Gosmanov
- Department of Medicine, Division of Endocrinology University of Tennessee Health Science Center, Memphis, TN
| | - Dawn D. Smiley
- Department of Medicine, Division of Endocrinology, Emory University, Atlanta, GA
| | - Limin Peng
- Rollins School of Public Health, Emory University, Atlanta, GA
| | - Joselita Siquiera
- Department of Medicine, Division of Endocrinology, Emory University, Atlanta, GA
| | - Gonzalo Robalino
- Department of Medicine, Division of Endocrinology, Emory University, Atlanta, GA
| | - Christopher Newton
- Department of Medicine, Division of Endocrinology, Emory University, Atlanta, GA
| | - Guillermo E. Umpierrez
- Department of Medicine, Division of Endocrinology, Emory University, Atlanta, GA
- Corresponding author. Emory University School of Medicine, 49 Jesse Hill Jr. Drive, Atlanta, Georgia 30303. Tel.: +1 404 778 1665; fax: +1 404 778 1661. (G.E. Umpierrez)
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Liang Y, Roede JR, Dikalov S, Miller NG, Dudley SC, Quyyumi A, Jones DP. Determination of ebselen-sensitive reactive oxygen metabolites (ebROM) in human serum based upon N,N'-diethyl-1,4-phenylenediamine oxidation. Clin Chim Acta 2012; 414:1-6. [PMID: 22687643 DOI: 10.1016/j.cca.2012.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 05/25/2012] [Accepted: 06/01/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Oxidative stress occurs through free radical- and non-radical-mediated oxidative mechanisms, but these are poorly discriminated by most assays. A convenient assay for oxidants in human serum is based upon the Fe(2+)-dependent decomposition of peroxides to oxidize N,N'-diethyl-1,4-phenylenediamine (DEPPD) to a stable radical cation which can be measured spectrophotometrically. METHODS We investigated modification of the DEPPD oxidation assay to discriminate color formation due to non-radical oxidants, including hydroperoxides and endoperoxides, which are sensitive to ebselen. RESULTS Use of serum, which has been pretreated with ebselen as a reference, provides a quantitative assay for non-radical, reactive oxidant species in serum, including hydroperoxides, endoperoxides and epoxides. In a set of 35 human serum samples, non-radical oxidants largely accounted for DEPPD oxidation in 86% of the samples while the remaining 14% had considerable contribution from other redox-active chemicals. CONCLUSIONS The simple modification in which ebselen-pretreated sample is used as a reference provides means to quantify non-radical oxidants in human serum. Application of this approach could enhance understanding of the contribution of different types of oxidative stress to disease.
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Affiliation(s)
- Yongliang Liang
- Clinical Biomarkers Laboratory, Allergy and Critical Care Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, United States
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Han KA, Patel Y, Lteif AA, Chisholm R, Mather KJ. Contributions of dysglycaemia, obesity, and insulin resistance to impaired endothelium-dependent vasodilation in humans. Diabetes Metab Res Rev 2011; 27:354-61. [PMID: 21309061 PMCID: PMC3090665 DOI: 10.1002/dmrr.1183] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Individual effects of hyperglycaemia and obesity to impair vascular health are recognized. However, the relative contributions of dysglycaemia versus other obesity-related traits to vascular dysfunction have not been systematically evaluated. METHODS We undertook a cross-sectional evaluation of factors contributing to vascular function in 271 consecutive subjects, categorized as non-obese normal glucose tolerant (n = 115), non-obese dysglycaemic (n = 32), obese normal glucose tolerant (n = 57), obese dysglycaemic (n = 38), or type 2 diabetic (n = 29). Vascular function was measured invasively as leg blood flow responses to methacholine chloride, an endothelium-dependent vasodilator. Categorical and continuous analyses were carried out to assess the contributions of hyperglycaemia to vascular dysfunction. RESULTS Even among normoglycaemic subjects, obese subjects had impaired vascular function compared to non-obese subjects (p = 0.004). Vascular function was also impaired in non-obese dysglycaemic subjects (p = 0.04 versus non-obese normoglycaemic subjects), to a level comparable to normoglycaemic obese subjects. Within obese subject groups, gradations of dysglycaemia including the presence of diabetes were not associated with further worsening of these vascular responses beyond the effect of obesity alone (p = not significant comparing all obese groups, p < 0.001 versus lean normoglycaemic subjects). After univariate and multivariable modelling analyses we found that effects of glycaemia were less powerful than effects of insulin resistance and obesity on vascular dysfunction. CONCLUSIONS Dysglycaemia contributes to impaired vascular function in non-obese subjects, but obesity and insulin resistance are more important determinants of vascular function in obese and diabetic subjects.
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Affiliation(s)
- K A Han
- Division of Endocrinology & Metabolism, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Sanchez OA, Louie EA, Copenhaver EA, Damon BM. Repeatability of a dual gradient-recalled echo MRI method for monitoring post-isometric contraction blood volume and oxygenation changes. NMR IN BIOMEDICINE 2009; 22:753-761. [PMID: 19382156 PMCID: PMC4440456 DOI: 10.1002/nbm.1388] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The purpose of this study was to assess the repeatability of a dual gradient-recalled echo (GRE) muscle functional MRI technique. On 2 days, subjects (n = 8) performed 10 s isometric dorsiflexion contractions under conditions of: (1) maximal voluntary contraction (MVC), (2) 50% MVC (50% MVC), or (3) 50% MVC with concurrent proximal arterial cuff occlusion (50% MVC(cuff)). Functional MRI data were acquired using single-slice dual GRE (TR/TE = 1000/6, 46 ms)-echo planar imaging for 20 s before, during, and for 180 s after each contraction. The mean signal intensity (SI) time courses at each TE (SI(6) and SI(46), reflecting variations in blood volume and %HbO(2), respectively) from the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles were characterized with the post-contraction change in SI and the time-to-peak SI (DeltaSI and TTP, respectively). DeltaSI(6) following an MVC was 36% higher than that obtained after a 50% MVC (p = 0.048). For DeltaSI(6), the highest intraclass correlation coefficients (ICCs) were observed for the TA muscle in the 50% MVC and MVC conditions, with values of 0.83 (p = 0.01) and 0.88 (p = 0.005), respectively. Bland-Altman plots revealed repeatability coefficients (RCs) for the 50% MVC and MVC conditions in the TA muscle of 1.9 and 1.4, respectively. The most repeatable measures for DeltaSI(46) were obtained for the 50% MVC and MVC conditions in the EDL muscle (p = 0.01 and p = 0.04, respectively). Bland-Altman plots revealed RC's for 50% MVC and MVC conditions in the EDL muscle of 3.9 and 5.7, respectively. DeltaSI(6) and DeltaSI(46) increased as a function of the contraction intensity. The repeatability of the method depends on the muscle and contraction condition being evaluated, and in general, is higher following an MVC.
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Affiliation(s)
- O A Sanchez
- Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA.
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