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Hamaoka T, Leuenberger UA, Drew RC, Murray M, Blaha C, Luck JC, Sinoway LI, Cui J. Glucose metabolism and autonomic function in healthy individuals and patients with type 2 diabetes mellitus at rest and during exercise. Exp Physiol 2024; 109:214-226. [PMID: 38050866 PMCID: PMC10841625 DOI: 10.1113/ep091444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/31/2023] [Indexed: 12/07/2023]
Abstract
Autonomic dysfunction is a common complication of type 2 diabetes mellitus (T2DM). However, the character of dysfunction varies in different reports. Differences in measurement methodology and complications might have influenced the inconsistent results. We sought to evaluate comprehensively the relationship between abnormal glucose metabolism and autonomic function at rest and the response to exercise in healthy individuals and T2DM patients. We hypothesized that both sympathetic and parasympathetic indices would decrease with the progression of abnormal glucose metabolism in individuals with few complications related to high sympathetic tone. Twenty healthy individuals and 11 T2DM patients without clinically evident cardiovascular disease other than controlled hypertension were examined. Resting muscle sympathetic nerve activity (MSNA), heart rate variability, spontaneous cardiovagal baroreflex sensitivity (CBRS), sympathetic baroreflex sensitivity and the MSNA response to handgrip exercise were measured. Resting MSNA was lower in patients with T2DM than in healthy control subjects (P = 0.011). Resting MSNA was negatively correlated with haemoglobin A1c in all subjects (R = -0.45, P = 0.024). The parasympathetic components of heart rate variability and CBRS were negatively correlated with glycaemic/insulin indices in all subjects and even in the control group only (all, P < 0.05). In all subjects, the MSNA response to exercise was positively correlated with fasting blood glucose (R = 0.69, P < 0.001). Resting sympathetic activity and parasympathetic modulation of heart rate were decreased in relationship to abnormal glucose metabolism. Meanwhile, the sympathetic responses to handgrip were preserved in diabetics. The responses were correlated with glucose/insulin parameters throughout diabetic and control subjects. These results suggest the importance of a comprehensive assessment of autonomic function in T2DM.
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Affiliation(s)
- Takuto Hamaoka
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Urs A. Leuenberger
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Rachel C. Drew
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
- Department of Exercise and Health SciencesUniversity of Massachusetts BostonBostonMassachusettsUSA
| | - Matthew Murray
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Cheryl Blaha
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Jonathan Carter Luck
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Lawrence I. Sinoway
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Jian Cui
- Penn State Heart and Vascular InstitutePennsylvania State University College of MedicineHersheyPennsylvaniaUSA
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Mizrak I, Lund MAV, Landgrebe AV, Asserhøj LL, Holstein-Rathlou NH, Greisen G, Clausen TD, Main KM, Vejlstrup NG, Jensen RB, Pinborg A, Madsen PL. Cardiovascular autonomic nervous function in children conceived by assisted reproductive technology with frozen or fresh embryo transfer. Am J Physiol Heart Circ Physiol 2024; 326:H216-H222. [PMID: 37999646 DOI: 10.1152/ajpheart.00680.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/17/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023]
Abstract
As a result of epigenetic changes, children conceived by assisted reproduction may be at risk of premature cardiovascular aging with notably increased blood pressures. Their cardiovascular autonomic nervous function is unknown. Therefore, this study investigated the cardiovascular autonomic nervous function in 8-12-yr-old children (51% girls) conceived naturally (n = 33) or by assisted reproduction with frozen (n = 34) or fresh (n = 38) embryo transfer by evaluating heart rate variability, during rest; from provocation maneuvers; and from baroreflex function. Heart rate and blood pressure response to provocation maneuvers and baroreflex function were comparable between children conceived naturally or by assisted reproduction. The mean RR-interval and high-frequency component of heart rate variability were lower in children conceived by assisted reproduction than in children conceived naturally. Children conceived by fresh embryo transfer had ∼17% lower heart rate-corrected standard deviation of normal-to-normal R-R intervals; ∼22% lower heart rate-corrected square root of the mean of the squared difference between successive R-R intervals; and ∼37% higher low-frequency/high-frequency ratio than naturally conceived children. Children conceived by assisted reproduction still had lower heart rate variability and vagal modulation than naturally conceived children after adjustment for confounders. Thus, these results raise the possibility of sympathetic predominance in children conceived by assisted reproduction. Therefore, it is important to reproduce these results in larger and older cohorts as sympathetic predominance relates with cardiovascular and metabolic diseases.NEW & NOTEWORTHY We observed that children conceived by assisted reproductive technology (both frozen and fresh embryo transfer) had lowered heart rate variability during rest as compared with children conceived naturally. During physiological stress maneuvers, however, the cardiovascular autonomic nervous regulation was comparable between children conceived by assisted reproductive technologies and naturally. Our findings highlight the potential that lowered heart rate variability during rest in children conceived by assisted reproductive technologies may precede premature hypertension.
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Affiliation(s)
- Ikram Mizrak
- Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Copenhagen, Denmark
- Fertility Department, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Morten A V Lund
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ann V Landgrebe
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Louise L Asserhøj
- Fertility Department, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Niels-Henrik Holstein-Rathlou
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gorm Greisen
- Department of Neonatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Tine D Clausen
- Department of Gynecology and Obstetrics, North Zealand Hospital, Copenhagen University Hospital, Hillerød, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Katharina M Main
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels G Vejlstrup
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rikke B Jensen
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anja Pinborg
- Fertility Department, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per L Madsen
- Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Pruter WW, Klassen SA, Dominelli PB, Wiggins CC, Senefeld JW, Roy TK, Joyner MJ, Baker SE. Attenuated cardiac autonomic function in humans with high-affinity hemoglobin and compensatory polycythemia. Am J Physiol Regul Integr Comp Physiol 2023; 324:R625-R634. [PMID: 36878486 PMCID: PMC10085552 DOI: 10.1152/ajpregu.00113.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023]
Abstract
During hypoxic exposure, humans with high-affinity hemoglobin (and compensatory polycythemia) have blunted increases in heart rate compared with healthy humans with typical oxyhemoglobin dissociation curves. This response may be associated with altered autonomic control of heart rate. Our hypothesis-generating study aimed to investigate cardiac baroreflex sensitivity and heart rate variability among nine humans with high-affinity hemoglobin [6 females, O2 partial pressure at 50% [Formula: see text] (P50) = 16 ± 1 mmHg] compared with 12 humans with typical affinity hemoglobin (6 F, P50 = 26 ± 1 mmHg). Participants breathed normal room air for a 10-min baseline, followed by 20 min of isocapnic hypoxic exposure, designed to lower the arterial partial pressure O2 ([Formula: see text]) to ∼50 mmHg. Beat-by-beat heart rate and arterial blood pressure were recorded. Data were averaged in 5-min periods throughout the hypoxia exposure, beginning with the last 5 min of baseline in normoxia. Spontaneous cardiac baroreflex sensitivity and heart rate variability were determined using the sequence method and the time and frequency domain analyses, respectively. Cardiac baroreflex sensitivity was lower in humans with high-affinity hemoglobin than controls at baseline and during isocapnic hypoxic exposure (normoxia: 7 ± 4 vs. 16 ± 10 ms/mmHg, hypoxia minutes 15-20: 4 ± 3 vs. 14 ± 11 ms/mmHg; group effect: P = 0.02, high-affinity hemoglobin vs. control, respectively). Heart rate variability calculated in both the time (standard deviation of the N-N interval) and frequency (low frequency) domains was lower in humans with high-affinity hemoglobin than in controls (all P < 0.05). Our data suggest that humans with high-affinity hemoglobin may have attenuated cardiac autonomic function.
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Affiliation(s)
- Wyatt W Pruter
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Stephen A Klassen
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Jonathon W Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Tuhin K Roy
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
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Mattos S, Rabello da Cunha M, Barreto Silva MI, Serfaty F, Tarvainen MP, Klein MRST, Neves MF. Effects of weight loss through lifestyle changes on heart rate variability in overweight and obese patients: A systematic review. Clin Nutr 2022; 41:2577-2586. [PMID: 36228570 DOI: 10.1016/j.clnu.2022.09.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/27/2022] [Accepted: 09/16/2022] [Indexed: 12/27/2022]
Abstract
BACKGROUND & AIMS The effects of calorie restriction and physical activity on autonomic regulation and cardiac vagal control in overweight and obese individuals remain inconsistent. Thus, this systematic review aimed to evaluate the weight loss effects through lifestyle changes on heart rate variability (HRV) markers in overweight and obese subjects. METHODS A systematic search for studies published up to November 2021 was conducted in MEDLINE, Embase, EBSCO host and VHL REGIONAL/LILACS. The main outcomes were changes in HRV indices from pre- and post-nutritional intervention and exercise in overweight and obese individuals. This review was registered in PROSPERO: CRD42021274467. RESULTS The literature search retrieved 959 articles, of which 12 were included in this review. The intervention in nine studies was diet only, in two studies was diet and exercise, and in one study diet was compared to diet and exercise. The weight loss was greater than 10% in four studies and between 5 and 10% in three studies. Most of the studies revealed that weight loss through lifestyle changes seems to promote beneficial effects on HRV, restoring sympathovagal balance by increasing parasympathetic activity and reducing sympathetic activation. CONCLUSION This systematic review exhibited the beneficial effects of weight loss through lifestyle changes on cardiac autonomic control in overweight and obese individuals. Future investigations need standardization of HRV indices for better interpretation of autonomic function in different clinical situations.
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Affiliation(s)
- Samanta Mattos
- Department of Clinical Medicine, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Maria Inês Barreto Silva
- Department of Applied Nutrition, Nutrition Institute, State University of Rio de Janeiro, Rio de Janeiro, Brazil; Department of Applied Nutrition, Nutrition School, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabiano Serfaty
- Department of Clinical Medicine, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mika P Tarvainen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland
| | | | - Mario Fritsch Neves
- Department of Clinical Medicine, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
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Abe T, Song JS, Bell ZW, Wong V, Spitz RW, Yamada Y, Loenneke JP. Comparisons of calorie restriction and structured exercise on reductions in visceral and abdominal subcutaneous adipose tissue: a systematic review. Eur J Clin Nutr 2022; 76:184-195. [PMID: 34040197 DOI: 10.1038/s41430-021-00942-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 05/02/2021] [Accepted: 05/12/2021] [Indexed: 01/06/2023]
Abstract
Exercise and low-calorie diets are common approaches taken to produce an energy deficit for weight loss in obesity. Changes in visceral and abdominal subcutaneous fat associated with weight loss are important questions but have not yet been concluded. We investigated the relationship between changes in visceral (VAT) and subcutaneous adipose tissue (SAT) areas obtained by abdominal imaging with the change in total body fat. The relevant databases were searched through January 2021 according to the PRISMA guidelines. Sixty-five studies were included. We found that the change in total body fat was associated with changes in both VAT and abdominal SAT areas, but the relationship between total body fat and the abdominal SAT area appeared stronger. Baseline values of VAT and abdominal SAT area were similar in the three treatment groups (calorie restriction, calorie restriction plus exercise, and exercise alone). The reduction in abdominal SAT area for a loss of 1 kg of total body fat was about 10 cm2, which was similar among all the treatments. The change in VAT area (-26.3 cm2) was a similar level as the change in abdominal SAT area (-31.5 cm2) in the exercise, whereas in the calorie restriction with and without exercise, the change in VAT area (-33.6 and -51.6 cm2, respectively) was approximately half of the reduction of SAT area (-65.1 and -87.2 cm2, respectively). Absolute changes in VAT and abdominal SAT areas might differ between interventions for the exercise and calorie restriction with and without exercise.
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Affiliation(s)
- Takashi Abe
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA. .,Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba, Japan.
| | - Jun Seob Song
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA
| | - Zachary W Bell
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA
| | - Vickie Wong
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA
| | - Robert W Spitz
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA
| | - Yujiro Yamada
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA
| | - Jeremy P Loenneke
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, MS, USA
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Subramanian SK, Sharma VK, Arunachalam V, Rajendran R, Gaur A. Comparison of Baroreflex Sensitivity and Cardiac Autonomic Function Between Adolescent Athlete and Non-athlete Boys - A Cross-Sectional Study. Front Physiol 2019; 10:1043. [PMID: 31507430 PMCID: PMC6713997 DOI: 10.3389/fphys.2019.01043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/30/2019] [Indexed: 01/24/2023] Open
Abstract
Introduction: It is well known that regular physical activity improves cardiovascular health, and higher baroreflex sensitivity and heart rate variability are associated with cardiovascular health. Adolescence is the age when an individual's behavior is easily modified; early intervention at this stage in terms of physical conditioning or training prevents future cardiovascular risk. Hence, we conceived the present study to assess and compare the baroreflex sensitivity and autonomic function between adolescent athletes and non-athletes. Methods: We recruited school going athletes (n = 30) and non-athlete boys (n = 30) in the 10-19 age group after obtaining their assent and consent from their parents. We assessed height, weight, heart rate, blood pressure, baroreflex sensitivity, and cardiac autonomic function. Comparison between groups was made using the unpaired t-test for height, weight, body mass index, heart rate, blood pressure, and baroreflex sensitivity and using Mann-Whitney U test for cardiac autonomic function parameters. Results: There was a trend for higher baroreflex sensitivity in athletes. Heart rate variability (total power and SDNN) was higher in athletes. The parasympathetic tone was higher in terms of higher RMSSD, and higher HF power. Parasympathetic reactivity was higher in athletes in terms of higher 30:15 ratio and EI ratio. Conclusion: Athletic level physical conditioning has a positive influence on baroreflex function and autonomic function that may prove beneficial to the adolescents' cardiovascular health.
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Affiliation(s)
- Senthil Kumar Subramanian
- Department of Physiology, All India Institute of Medical Sciences (AIIMS), Mangalagiri, Vijayawada, India
| | - Vivek Kumar Sharma
- Department of Physiology, Government Institute of Medical Sciences, Greater Noida, India
| | | | - Rajathi Rajendran
- Department of Physiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India
| | - Archana Gaur
- Department of Physiology, Chengalpattu Medical College, Chengalpattu, India
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Costa J, Moreira A, Moreira P, Delgado L, Silva D. Effects of weight changes in the autonomic nervous system: A systematic review and meta-analysis. Clin Nutr 2018; 38:110-126. [PMID: 29395374 DOI: 10.1016/j.clnu.2018.01.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/28/2017] [Accepted: 01/02/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND Obesity has been linked to autonomic dysfunction, which is thought to be one of the main contributors for hypertension, cardiac remodelling and death. Exercise and diet-based weight loss are the mainstay therapy for obesity, but there is a paucity of data regarding the effect of weight changes in autonomic nervous system (ANS) activity. OBJECTIVE To describe the impact of weight changes in autonomic nervous system. METHODS A systematic literature search of four biomedical databases was performed evaluating effects of weight changes, thorough diet and/or exercise-based interventions, in the following ANS outcomes: heart rate variability, namely low frequency (LF)/high frequency (HF) ratio (LF/HF ratio), normalized units of LF (LFnu) and HF (HFnu), muscle sympathetic nerve activity (MSNA), noradrenaline spillover rate (NA-SR), standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), baroreflex sensitivity and pupillometry. Quality appraisal was performed using the GRADE methodology and, where fitting, studies with comparable outcomes were pooled for meta-analysis. RESULTS Twenty-seven studies - 7 controlled clinical trials and 20 observational studies - were included. Weight gain was reported in 4 studies and weight loss in all the other studies. Interventions inducing weight changes included: hypocaloric or hypercaloric diets, exercise (strength, endurance or aerobic training) and hypocaloric diet coupled with exercise programs. Most studies which resulted in weight loss reported decreases in LF/HF ratio, LFnu, MSNA burst frequency and incidence, NA-SR, and an increase of baroreflex sensitivity, HF, HFnu and RMSSD, pointing to a parasympathetic nervous system activation. Meta-analysis regarding weight loss interventions showed a significant pooled effect size (95% CI) with a decreased of MSNA burst frequency -5.09 (-8.42, -1.75), MSNA incidence -6.66 (-12.40, -0.62), however this was not significant for SDNN 14.32 (-4.31, 32.96). Weight gain was associated with an increase in LF/HF, LFnu, MSNA burst frequency and incidence. The weight loss effects were potentiated by the association of hypocaloric diet with exercise. Nevertheless, weight changes effects in these outcomes were based in low or very low quality of evidence. CONCLUSIONS Diet and exercise based weight loss appears to increase parasympathetic and decrease sympathetic activity, the opposing effects being observed with weight gain. These findings are not uniformly reported in the literature, possibly due to differences in study design, methodology, characteristics of the participants and techniques used to estimate autonomic nervous activity.
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Affiliation(s)
- João Costa
- Faculty of Medicine, University of Porto, Porto, Portugal.
| | - André Moreira
- Basic and Clinical Immunology, Department of Pathology, Faculty of Medicine, University of Porto, Portugal; Serviço de Imunoalergologia, Centro Hospitalar São João, Porto, Portugal
| | - Pedro Moreira
- Faculty of Nutrition and Food Sciences, Universidade do Porto, Porto, Portugal
| | - Luís Delgado
- Basic and Clinical Immunology, Department of Pathology, Faculty of Medicine, University of Porto, Portugal; Serviço de Imunoalergologia, Centro Hospitalar São João, Porto, Portugal
| | - Diana Silva
- Basic and Clinical Immunology, Department of Pathology, Faculty of Medicine, University of Porto, Portugal; Serviço de Imunoalergologia, Centro Hospitalar São João, Porto, Portugal
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Diabetic status and grade of nonalcoholic fatty liver disease are associated with lower baroreceptor sensitivity in patients with nonalcoholic fatty liver disease. Eur J Gastroenterol Hepatol 2017; 29:956-961. [PMID: 28471821 DOI: 10.1097/meg.0000000000000898] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVES Baroreceptor sensitivity (BRS), a functional consequence of vascular stiffness, may be affected by the presence of diabetes mellitus (DM) and nonalcoholic fatty liver disease (NAFLD). The present study was designed to assess the effect of diabetic status and NAFLD grade on the BRS in patients with NAFLD. METHODS Seventy-five individuals (25 NAFLD without DM, 25 NAFLD with DM and 25 controls) were recruited for the study who underwent anthropometric and body composition analysis along with estimation of plasma glucose, serum insulin and serum lipids. BRS and blood pressure variability (BPV) analysis was carried out in both time and frequency domains. Carotid-radial and carotid-dorsalis pedis artery pulse wave velocity, and radial artery augmentation index were computed as measures of arterial stiffness. RESULTS BRS was found to be lower in the NAFLD with DM group as well those with grade II NAFLD compared with the controls. Correlation analysis showed a negative correlation of BRS with postprandial blood glucose level (r=-0.39) and BMI (r=-0.467). The diabetic status and grade of NAFLD were associated independently with a decrease in BRS as well as the low-frequency component of diastolic BPV. The augmentation index and carotid-distal pulse wave velocity were higher in the NAFLD with DM group compared with controls. CONCLUSION Both the diabetic status and grade of NAFLD were shown to have an independent effect on the decrease in the BRS with a consequent effect on BPV, with a greater influence of diabetic status rather than NAFLD grade on arterial stiffness.
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Christou GA, Kiortsis DN. The effects of body weight status on orthostatic intolerance and predisposition to noncardiac syncope. Obes Rev 2017; 18:370-379. [PMID: 28112481 DOI: 10.1111/obr.12501] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/07/2016] [Accepted: 11/24/2016] [Indexed: 12/16/2022]
Abstract
Orthostatic intolerance (OI) is frequently the mechanism underlying the occurrence of noncardiac syncope (NCS) and is associated with substantial risk for injury. Body weight status appears to be a modifier of orthostatic responses and possibly influences the propensity to NCS. The majority of cross-sectional studies have found that the lower the body mass index (BMI) the greater the predisposition to OI is, accompanied with both down-regulation of sympathetic nervous system activity and up-regulation of parasympathetic nervous system activity. These changes appear to occur across the whole spectrum of BMI values from underweight to obesity, while they may be associated more strongly with central body fat than total body fat. Weight loss following bariatric surgery has been consistently found to increase OI, attributed first to the effects of weight loss per se, second to the specific type of surgical procedure and third to the potential postoperative autonomic neuropathy due to vitamin deficiency. The increased OI following bariatric surgery renders this intervention not easily tolerable for the affected individuals, mandating increased fluid and salt intake, pharmacological measures or surgical adjustments to attenuate OI. All future studies investigating orthostatic responses and NCS should implement a matching of the population arms for BMI and ideally for body fat.
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Affiliation(s)
- G A Christou
- Laboratory of Physiology, Medical School, University of Ioannina, Ioannina, Greece
| | - D N Kiortsis
- Laboratory of Physiology, Medical School, University of Ioannina, Ioannina, Greece
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Merlotti C, Ceriani V, Morabito A, Pontiroli AE. Subcutaneous fat loss is greater than visceral fat loss with diet and exercise, weight-loss promoting drugs and bariatric surgery: a critical review and meta-analysis. Int J Obes (Lond) 2017; 41:672-682. [DOI: 10.1038/ijo.2017.31] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 12/30/2016] [Accepted: 01/20/2017] [Indexed: 02/07/2023]
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van Brussel PM, van den Bogaard B, de Weijer BA, Truijen J, Krediet CTP, Janssen IM, van de Laar A, Kaasjager K, Fliers E, van Lieshout JJ, Serlie MJ, van den Born BJH. Blood pressure reduction after gastric bypass surgery is explained by a decrease in cardiac output. J Appl Physiol (1985) 2016; 122:223-229. [PMID: 27765843 DOI: 10.1152/japplphysiol.00362.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 10/03/2016] [Accepted: 10/10/2016] [Indexed: 01/31/2023] Open
Abstract
Blood pressure (BP) decreases in the first weeks after Roux-and-Y gastric bypass surgery. Yet the pathophysiology of the BP-lowering effects observed after gastric bypass surgery is incompletely understood. We evaluated BP, systemic hemodynamics, and baroreflex sensitivity in 15 obese women[mean age 42 ± 7 standard deviation (SD) yr, body mass index 45 ± 6 kg/m2] 2 wk before and 6 wk following Roux-and-Y gastric bypass surgery. Six weeks after gastric bypass surgery, mean body weight decreased by 13 ± 5 kg (10%, P < 0.001). Office BP decreased from 137 ± 10/86 ± 6 to 128 ± 12/81 ± 9 mmHg (P < 0.001, P < 0.01), while daytime ambulatory BP decreased from 128 ± 14/80 ± 9 to 114 ± 10/73 ± 6 mmHg (P = 0.01, P = 0.05), whereas nighttime BP decreased from 111 ± 13/66 ± 7 to 102 ± 9/62 ± 7 mmHg (P = 0.04, P < 0.01). The decrease in BP was associated with a 1.6 ± 1.2 l/min (20%, P < 0.01) decrease in cardiac output (CO), while systemic vascular resistance increased (153 ± 189 dyn·s·cm-5, 15%, P < 0.01). The maximal ascending slope in systolic blood pressure decreased (192 mmHg/s, 19%, P = 0.01), suggesting a reduction in left ventricular contractility. Baroreflex sensitivity increased from 9.0 [6.4-14.3] to 13.8 [8.5-19.0] ms/mmHg (median [interquartile range]; P < 0.01) and was inversely correlated with the reductions in heart rate (R = -0.64, P = 0.02) and CO (R = -0.61, P = 0.03). In contrast, changes in body weight were not correlated with changes in either BP or CO. The BP reduction following Roux-and-Y gastric bypass surgery is correlated with a decrease in CO independent of changes in body weight. The contribution of heart rate to the reduction in CO together with enhanced baroreflex sensitivity suggests a shift toward increased parasympathetic cardiovascular control. NEW & NOTEWORTHY The reason for the decrease in blood pressure (BP) in the first weeks after gastric bypass surgery remains to be elucidated. We show that the reduction in BP following surgery is caused by a decrease in cardiac output. In addition, the maximal ascending slope in systolic blood pressure decreased suggesting a reduction in left ventricular contractility and cardiac workload. These findings help to understand the physiological changes following gastric bypass surgery and are relevant in light of the increased risk of heart failure in these patients.
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Affiliation(s)
- Peter M van Brussel
- Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Bas van den Bogaard
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Barbara A de Weijer
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jasper Truijen
- Laboratory for Clinical Cardiovascular Physiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - C T Paul Krediet
- Department of Nephrology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Ignace M Janssen
- Department of Surgery, Rijnstate Hospital, Arnhem, The Netherlands
| | | | - Karin Kaasjager
- Department of Internal Medicine, University Medical Center, Utrecht, The Netherlands; and
| | - Eric Fliers
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Johannes J van Lieshout
- Laboratory for Clinical Cardiovascular Physiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Center, Nottingham, United Kingdom
| | - Mireille J Serlie
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Bert-Jan H van den Born
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands;
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12
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Holwerda SW, Vianna LC, Restaino RM, Chaudhary K, Young CN, Fadel PJ. Arterial baroreflex control of sympathetic nerve activity and heart rate in patients with type 2 diabetes. Am J Physiol Heart Circ Physiol 2016; 311:H1170-H1179. [PMID: 27591221 DOI: 10.1152/ajpheart.00384.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/24/2016] [Indexed: 02/08/2023]
Abstract
Despite greater blood pressure reactivity to acute cardiovascular stressors and a higher prevalence of hypertension in type 2 diabetes (T2D) patients, limited information is available regarding arterial baroreflex (ABR) control in T2D. We hypothesized that ABR control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) are attenuated in T2D patients. Seventeen T2D patients (50 ± 2 yr; 31 ± 1 kg/m2), 9 weight-matched controls (WM-CON, 46 ± 2 yr; 32 ± 2 kg/m2) and 10 lean controls (Lean-CON, 49 ± 3 yr; 23 ± 1 kg/m2), underwent bolus infusions of sodium nitroprusside (100 μg) followed 60 s later by phenylephrine (150 μg) and weighted linear regression performed. No group differences in overall sympathetic baroreflex gain were observed (T2D: -2.5 ± 0.3 vs. WM-CON: -2.6 ± 0.2 vs. Lean-CON: -2.7 ± 0.4 arbitrary units·beat·mmHg-1, P > 0.05) or in sympathetic baroreflex gain when derived separately during blood pressure (BP) falls (nitroprusside) and BP rises (phenylephrine). In contrast, overall cardiac baroreflex gain was reduced in T2D patients compared with Lean-CON (T2D: 8.2 ± 1.5 vs. Lean-CON: 15.6 ± 2.9 ms·mmHg-1, P < 0.05) and also tended to be reduced in WM-CON (9.3 ± 1.9 ms·mmHg-1) compared with Lean-CON (P = 0.059). Likewise, during BP rises, cardiac baroreflex gain was reduced in T2D patients and weight-matched controls compared with lean controls (P < 0.05), whereas no group differences were found during BP falls (P > 0.05). Sympathetic and cardiac ABR gains were comparable between normotensive and hypertensive T2D patients (P > 0.05). These findings suggest preserved ABR control of MSNA in T2D patients compared with both obese and lean age-matched counterparts, with a selective impairment in ABR HR control in T2D that may be related to obesity.
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Affiliation(s)
- Seth W Holwerda
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
| | - Lauro C Vianna
- Faculty of Physical Education, University of Brasilia, Distrito Federal, Brazil
| | - Robert M Restaino
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Kunal Chaudhary
- Department of Internal Medicine, University of Missouri, Columbia, Missouri
| | - Colin N Young
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia; and
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
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13
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Verheggen RJHM, Maessen MFH, Green DJ, Hermus ARMM, Hopman MTE, Thijssen DHT. A systematic review and meta-analysis on the effects of exercise training versus hypocaloric diet: distinct effects on body weight and visceral adipose tissue. Obes Rev 2016; 17:664-90. [PMID: 27213481 DOI: 10.1111/obr.12406] [Citation(s) in RCA: 193] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/25/2016] [Accepted: 02/12/2016] [Indexed: 12/12/2022]
Abstract
Exercise training ('exercise') and hypocaloric diet ('diet') are frequently prescribed for weight loss in obesity. Whilst body weight changes are commonly used to evaluate lifestyle interventions, visceral adiposity (VAT) is a more relevant and stronger predictor for morbidity and mortality. A meta-analysis was performed to assess the effects of exercise or diet on VAT (quantified by radiographic imaging). Relevant databases were searched through May 2014. One hundred seventeen studies (n = 4,815) were included. We found that both exercise and diet cause VAT loss (P < 0.0001). When comparing diet versus training, diet caused a larger weight loss (P = 0.04). In contrast, a trend was observed towards a larger VAT decrease in exercise (P = 0.08). Changes in weight and VAT showed a strong correlation after diet (R(2) = 0.737, P < 0.001), and a modest correlation after exercise (R(2) = 0.451, P < 0.001). In the absence of weight loss, exercise is related to 6.1% decrease in VAT, whilst diet showed virtually no change (1.1%). In conclusion, both exercise and diet reduce VAT. Despite a larger effect of diet on total body weight loss, exercise tends to have superior effects in reducing VAT. Finally, total body weight loss does not necessarily reflect changes in VAT and may represent a poor marker when evaluating benefits of lifestyle-interventions.
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Affiliation(s)
- R J H M Verheggen
- Department of Physiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - M F H Maessen
- Department of Physiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - D J Green
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.,School of Sport Science, Exercise and Health, the University of Western Australia, Crawley, Western Australia, Australia
| | - A R M M Hermus
- Department of Internal Medicine, Division of Endocrinology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - M T E Hopman
- Department of Physiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - D H T Thijssen
- Department of Physiology, Radboud University Medical Centre, Nijmegen, The Netherlands.,Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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14
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Tian Y, Huang C, He Z, Hong P, Zhao J. Autonomic function responses to training: Correlation with body composition changes. Physiol Behav 2015; 151:308-13. [PMID: 26253213 DOI: 10.1016/j.physbeh.2015.07.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 07/19/2015] [Accepted: 07/30/2015] [Indexed: 11/30/2022]
Abstract
AIM The causal relation between autonomic function and adiposity is an unresolved issue. Thus, we studied whether resting heart rate variability (HRV) changes could be used to predict changes in body composition after 16 weeks of individualized exercise training. METHODS A total of 117 sedentary overweight/obese adults volunteered to join an intervention group (IN, n=82) or a control group (CON, n=35). The intervention group trained for 30-40 min three times a week with an intensity of 85-100% of individual ventilatory threshold (Thvent). At baseline and after a 16-week training period, resting HRV variables, body composition and peak oxygen uptake (VO2peak) were assessed. RESULTS Compared with CON, exercise training significantly improved HRV and body composition and increased VO2peak (P<0.05). Significant correlations were observed between changes of HRV variables and body composition indices and VO2peak (P<0.05). Greater individual changes in HRV in response to exercise training were observed for those with greater total and central fat loss. CONCLUSION Individual aerobic-based exercise training was for improving autonomic function and resting HRV responses to aerobic training is a potential indicator for adaptations to exercise training.
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Affiliation(s)
- Ye Tian
- China Institute of Sport Science, Beijing, China.
| | - Chuanye Huang
- Department of Sports Science, Shandong University of Sport, Shandong, China
| | - Zihong He
- China Institute of Sport Science, Beijing, China
| | - Ping Hong
- China Institute of Sport Science, Beijing, China
| | - Jiexiu Zhao
- China Institute of Sport Science, Beijing, China
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15
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Vinik AI, Nevoret ML, Casellini C. The New Age of Sudomotor Function Testing: A Sensitive and Specific Biomarker for Diagnosis, Estimation of Severity, Monitoring Progression, and Regression in Response to Intervention. Front Endocrinol (Lausanne) 2015; 6:94. [PMID: 26124748 PMCID: PMC4463960 DOI: 10.3389/fendo.2015.00094] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/23/2015] [Indexed: 12/27/2022] Open
Abstract
Sudorimetry technology has evolved dramatically, as a rapid, non-invasive, robust, and accurate biomarker for small fibers that can easily be integrated into clinical practice. Though skin biopsy with quantitation of intraepidermal nerve fiber density is still currently recognized as the gold standard, sudorimetry may yield diagnostic information not only on autonomic dysfunction but also enhance the assessment of the small somatosensory nerves, disease detection, progression, and response to therapy. Sudorimetry can be assessed using Sudoscan™, which measures electrochemical skin conductance (ESC) of hands and feet. It is based on different electrochemical principles (reverse iontophoresis and chronoamperometry) to measure sudomotor function than prior technologies, affording it a much more practical and precise performance profile for routine clinical use with potential as a research tool. Small nerve fiber dysfunction has been found to occur early in metabolic syndrome and diabetes and may also be the only neurological manifestation in small fiber neuropathies, beneath the detection limits of traditional nerve function tests. Test results are robust, accomplished within minutes, require little technical training and no calculations, since established norms have been provided for the effects of age, gender, and ethnicity. Sudomotor testing has been greatly under-utilized in the past, restricted to specialized centers capable of handling the technically demanding and expensive technology. Yet, evaluation of autonomic and somatic nerve function has been shown to be one of the best estimates of cardiovascular risk. Evaluation of sweating has the appeal of quantifiable non-invasive determination of the integrity of the peripheral autonomic nervous system, and can now be accomplished rapidly at point of care clinics with the determination of ESC, allowing intervention for morbid complications prior to permanent structural nerve damage. We review here sudomotor function testing technology, the research evidence accumulated supporting the clinical utility of measuring ESC, the medical applications of sudorimetry now available to physicians with this device, and clinical vignettes illustrating its use in the clinical decision-making process.
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Affiliation(s)
- Aaron I. Vinik
- Division of Endocrinology and Metabolism, Department of Medicine, Strelitz Diabetes and Neuroendocrine Center, Eastern Virginia Medical School, Norfolk, VA, USA
| | | | - Carolina Casellini
- Division of Endocrinology and Metabolism, Department of Medicine, Strelitz Diabetes and Neuroendocrine Center, Eastern Virginia Medical School, Norfolk, VA, USA
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16
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Caloric restriction decreases orthostatic tolerance independently from 6° head-down bedrest. PLoS One 2015; 10:e0118812. [PMID: 25915488 PMCID: PMC4411149 DOI: 10.1371/journal.pone.0118812] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 01/09/2015] [Indexed: 11/19/2022] Open
Abstract
Astronauts consume fewer calories during spaceflight and return to earth with an increased risk of orthostatic intolerance. Whether a caloric deficiency modifies orthostatic responses is not understood. Thus, we determined the effects of a hypocaloric diet (25% caloric restriction) during 6° head down bedrest (an analog of spaceflight) on autonomic neural control during lower body negative pressure (LBNP). Nine healthy young men completed a randomized crossover bedrest study, consisting of four (2 weeks each) interventions (normocaloric bedrest, normocaloric ambulatory, hypocaloric bedrest, hypocaloric ambulatory), each separated by 5 months. Muscle sympathetic nerve activity (MSNA) was recorded at baseline following normocaloric and hypocaloric interventions. Heart rate (HR) and arterial pressure were recorded before, during, and after 3 consecutive stages (7 min each) of LBNP (-15, -30, -45 mmHg). Caloric and posture effects during LBNP were compared using two-way ANOVA with repeated measures. There was a strong trend toward reduced basal MSNA following caloric restriction alone (normcaloric vs. hypocaloric: 22±3 vs. 14±4 burst/min, p = 0.06). Compared to the normocaloric ambulatory, both bedrest and caloric restriction were associated with lower systolic blood pressure during LBNP (p<0.01); however, HR responses were directionally opposite (i.e., increase with bedrest, decrease with caloric restriction). Survival analysis revealed a significant reduction in orthostatic tolerance following caloric restriction (normocaloric finishers: 12/16; hypocaloric finishers: 6/16; χ2, p = 0.03). Caloric restriction modifies autonomic responses to LBNP, which may decrease orthostatic tolerance after spaceflight.
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17
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A body shape index and heart rate variability in healthy indians with low body mass index. J Nutr Metab 2014; 2014:865313. [PMID: 25371818 PMCID: PMC4202247 DOI: 10.1155/2014/865313] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/12/2014] [Indexed: 02/07/2023] Open
Abstract
Background. One third of Indian population is said to be suffering from chronic energy deficiency (CED), with increased risk of developing chronic diseases. A new anthropometric measure called A Body Shape Index (ABSI) is said to be a better index in predicting risks for premature mortality. ABSI is also in part said to be a surrogate of visceral fat. Objective. The present study aimed to explore the association between indices of HRV (heart rate variability), BMI, WC, and ABSI in healthy Indian males with low BMI (BMI < 18.5 kg/m2) and to compare with normal BMI group (BMI 18.5 to 24.9 kg/m2). Methodology. ABSI and BMI were derived from anthropometric parameters, namely, height, weight, and waist circumference in 178 males aged 18 to 78 years. Subjects were categorized into two groups based on their BMI. Results and Conclusions. Power spectral analysis of HRV demonstrated a significant negative correlation between Log HF (high frequency) and ABSI in both low BMI [−24.2 (9.4), P < 0.05] and normal BMI group [−23.41 (10.1), P < 0.05] even after controlling for age. Thus even with slight increase in BMI among low BMI individuals, there could be a greater risk of cardiovascular morbidity and mortality.
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18
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Iliescu R, Tudorancea I, Irwin ED, Lohmeier TE. Chronic baroreflex activation restores spontaneous baroreflex control and variability of heart rate in obesity-induced hypertension. Am J Physiol Heart Circ Physiol 2013; 305:H1080-8. [PMID: 23913707 PMCID: PMC3798752 DOI: 10.1152/ajpheart.00464.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/27/2013] [Indexed: 12/21/2022]
Abstract
The sensitivity of baroreflex control of heart rate is depressed in subjects with obesity hypertension, which increases the risk for cardiac arrhythmias. The mechanisms are not fully known, and there are no therapies to improve this dysfunction. To determine the cardiovascular dynamic effects of progressive increases in body weight leading to obesity and hypertension in dogs fed a high-fat diet, 24-h continuous recordings of spontaneous fluctuations in blood pressure and heart rate were analyzed in the time and frequency domains. Furthermore, we investigated whether autonomic mechanisms stimulated by chronic baroreflex activation and renal denervation-current therapies in patients with resistant hypertension, who are commonly obese-restore cardiovascular dynamic control. Increases in body weight to ∼150% of control led to a gradual increase in mean arterial pressure to 17 ± 3 mmHg above control (100 ± 2 mmHg) after 4 wk on the high-fat diet. In contrast to the gradual increase in arterial pressure, tachycardia, attenuated chronotropic baroreflex responses, and reduced heart rate variability were manifest within 1-4 days on high-fat intake, reaching 130 ± 4 beats per minute (bpm) (control = 86 ± 3 bpm) and ∼45% and <20%, respectively, of control levels. Subsequently, both baroreflex activation and renal denervation abolished the hypertension. However, only baroreflex activation effectively attenuated the tachycardia and restored cardiac baroreflex sensitivity and heart rate variability. These findings suggest that baroreflex activation therapy may reduce the risk factors for cardiac arrhythmias as well as lower arterial pressure.
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Affiliation(s)
- Radu Iliescu
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
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19
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Improvement in cardiovascular indices after Roux-en-Y gastric bypass or sleeve gastrectomy for morbid obesity. Obes Surg 2013; 23:31-8. [PMID: 22923313 DOI: 10.1007/s11695-012-0743-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Morbidly obese patients display cardiac abnormalities which are partially reversed after weight loss. The aim of the present study was to assess the potential difference in cardiovascular disease indices between patients who underwent either gastric bypass surgery or sleeve gastrectomy. METHODS Thirty-seven morbidly obese patients who underwent either Roux-en-Y gastric bypass (RYGB) (n = 14) or SG (n = 23) were examined before, 3 and 6 months after surgery. Indices of cardiac autonomic nervous system activity were evaluated, namely baroreflex sensitivity (BRS) and heart rate variability (HRV). A complete echocardiographic study was performed in a subgroup of 17 patients (RYGB 8, SG 9) preoperatively and 6 months after surgery, evaluating epicardial fat thickness, aortic distensibility, left ventricular (LV) Tei index, left atrium diameter, ejection fraction, and LV mass. RESULTS All subjects experienced significant (p < 0.001) and similar weight loss independently of the type of operation. BRS and HRV indices improved significantly and to the same degree after surgery in both groups. In the echocardiographic study, all parameters improved significantly at 6 months in comparison with the baseline values. In addition, the RYGB group displayed significantly greater reduction in epicardial fat thickness (p = 0.007) and also tended to have a better LV performance as expressed by the lower values of the Tei index (p = 0.06) compared to the SG group 6 months after surgery. CONCLUSIONS Both RYGB and SG exert comparable effects on weight loss and improvement of cardiovascular parameters. RYGB displays a more beneficial influence on epicardial fat thickness and left ventricular performance than SG.
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Abstract
Excess body weight is a major risk factor for cardiovascular disease, increasing the risk of hypertension, hyperglycaemia and dyslipidaemia, recognized as the metabolic syndrome. Adipose tissue acts as an endocrine organ by producing various signalling cytokines called adipokines (including leptin, free fatty acids, tumour necrosis factor-α, interleukin-6, C-reactive protein, angiotensinogen and adiponectin). A chronic dysregulation of certain adipokines can have deleterious effects on insulin signalling. Chronic sympathetic overactivity is also known to be present in central obesity, and recent findings demonstrate the consequence of an elevated sympathetic outflow to organs such as the heart, kidneys and blood vessels. Chronic sympathetic nervous system overactivity can also contribute to a further decline of insulin sensitivity, creating a vicious cycle that may contribute to the development of the metabolic syndrome and hypertension. The cause of this overactivity is not clear, but may be driven by certain adipokines. The purpose of this review is to summarize how obesity, notably central or visceral as observed in the metabolic syndrome, leads to adipokine expression contributing to changes in insulin sensitivity and overactivity of the sympathetic nervous system.
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Affiliation(s)
- Michael M Smith
- Department of Human Physiology, University of Oregon, Eugene, OR 97403-1240, USA
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21
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Weinheimer EM, Sands LP, Campbell WW. A systematic review of the separate and combined effects of energy restriction and exercise on fat-free mass in middle-aged and older adults: implications for sarcopenic obesity. Nutr Rev 2010; 68:375-88. [DOI: 10.1111/j.1753-4887.2010.00298.x] [Citation(s) in RCA: 243] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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22
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Chen JS, Wang HJ, Chang WC, Jao CC, Wu BT, Shyu WC, Lee SD. Altered nitroxidergic and NMDA receptor-mediated modulation of baroreflex-mediated heart rate in obese Zucker rats. Hypertens Res 2010; 33:932-6. [DOI: 10.1038/hr.2010.109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
BACKGROUND The dysfunction of baroreflex plays an important role in the pathogenesis of essential hypertension. Recent studies suggest that approximately 40% of the variation in baroreflex sensitivity (BRS) may be accounted for by genetic factors. However, only a few such genetic polymorphisms have been explicitly identified. METHODS A total of 182 normotensive young men were included in the study. They were tested for the occurrence of genotypes involving nine polymorphisms in six genes that have a role in the regulation of the cardiovascular system. BRS was calculated from the spontaneous fluctuation of systolic blood pressure (SBP) and heart interval, using a sequence method. RESULTS BRS was negatively correlated with body mass index (BMI), SBP, and family history of hypertension. Univariate analysis revealed that BRS is significantly associated with three of the polymorphisms studied. At the polymorphism T-786C in the endothelial nitric oxide (NO) synthase (eNOS) gene, the subjects with TT genotype had lower BRS than subjects carrying either the TC or the CC genotype. At the polymorphism of C-344T in the aldosterone synthase gene (CYP11B2), subjects with the TT genotype had higher BRS as compared to those with CC. At the polymorphism of T-58C in the bradykinin B2 receptor (B2R) gene, subjects with CC genotype had lower BRS as compared to subjects with TT. A multivariable linear regression analysis indicated that 16% of the BRS variation could be explained by these three polymorphisms. CONCLUSIONS Baroreflex function plays an important role in regulating blood pressure, both in the short term and in the long term. Three polymorphisms that are associated with the variation in BRS were identified in the eNOS, CYP11B2, and B2R genes, respectively; overall, they accounted for 16% of the BRS variation.
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24
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Straznicky NE, Lambert GW, Lambert EA. Neuroadrenergic dysfunction in obesity: an overview of the effects of weight loss. Curr Opin Lipidol 2010; 21:21-30. [PMID: 19809312 DOI: 10.1097/mol.0b013e3283329c62] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PURPOSE OF REVIEW The prevalence of obesity is rising to epidemic proportions worldwide, and in tandem so is that of type 2 diabetes. Neuroadrenergic abnormalities, comprising increased resting sympathetic nervous system activity and blunted sympathetic neural responsiveness are recognized features of metabolic syndrome obesity, which contribute importantly to both the pathophysiology and adverse clinical prognosis of this high-risk population. Weight loss is recommended as first-line treatment for obesity. This review examines the effects of nonpharmacological weight loss on sympathetic nervous system function under basal and stimulated conditions. RECENT FINDINGS Human weight loss trials show that even moderate weight reduction is accompanied by significant attenuation in resting whole-body norepinephrine spillover rate and muscle sympathetic nerve activity, an improvement in cardiac autonomic modulation, and a reversal of blunted sympathetic responsiveness at both peripheral and central nervous system levels. Recent findings underscore the relevance of insulin resistance in mediating blunted sympathetic responsiveness to endogenous hyperinsulinemia induced by glucose ingestion. Impaired insulin transport across the blood-brain barrier may be one mechanism mediating these effects. Weight loss reverses blunted sympathetic responsiveness to glucose, which has implications for postprandial energy expenditure and body weight homeostasis. SUMMARY The autonomic dysfunction of obesity is reversible with weight loss, highlighting the importance of lifestyle intervention as a key therapeutic modality.
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Affiliation(s)
- Nora E Straznicky
- Human Neurotransmitters Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia.
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25
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Ramos PS, Araújo CGS. Lower cardiac vagal tone in non-obese healthy men with unfavorable anthropometric characteristics. Clinics (Sao Paulo) 2010; 65:45-51. [PMID: 20126345 PMCID: PMC2815282 DOI: 10.1590/s1807-59322010000100008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 10/19/2009] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVES to determine if there are differences in cardiac vagal tone values in non-obese healthy, adult men with and without unfavorable anthropometric characteristics. INTRODUCTION It is well established that obesity reduces cardiac vagal tone. However, it remains unknown if decreases in cardiac vagal tone can be observed early in non-obese healthy, adult men presenting unfavorable anthropometric characteristics. METHODS Among 1688 individuals assessed between 2004 and 2008, we selected 118 non-obese (BMI <30 kg/m(2)), healthy men (no known disease conditions or regular use of relevant medications), aged between 20 and 77 years old (42 +/- 12-years-old). Their evaluation included clinical examination, anthropometric assessment (body height and weight, sum of six skinfolds, waist circumference and somatotype), a 4-second exercise test to estimate cardiac vagal tone and a maximal cardiopulmonary exercise test to exclude individuals with myocardial ischemia. The same physician performed all procedures. RESULTS A lower cardiac vagal tone was found for the individuals in the higher quintiles - unfavorable anthropometric characteristics - of BMI (p=0.005), sum of six skinfolds (p=0.037) and waist circumference (p<0.001). In addition, the more endomorphic individuals also presented a lower cardiac vagal tone (p=0.023), while an ectomorphic build was related to higher cardiac vagal tone values as estimated by the 4-second exercise test (r=0.23; p=0.017). CONCLUSIONS Non-obese and healthy adult men with unfavorable anthropometric characteristics tend to present lower cardiac vagal tone levels. Early identification of this trend by simple protocols that are non-invasive and risk-free, using select anthropometric characteristics, may be clinically useful in a global strategy to prevent cardiovascular disease.
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Affiliation(s)
- Plínio S. Ramos
- Programa de Pós-Graduação em Educação Física, Universidade Gama Filho - Rio de Janeiro/RJ, Brasil
| | - Claudio Gil S. Araújo
- Programa de Pós-Graduação em Educação Física, Universidade Gama Filho - Rio de Janeiro/RJ, Brasil
- Clínica de Medicina do Exercício (CLINIMEX) - Rio de Janeiro/RJ,Brasil
- , Tel: 55 21 2256.7183
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Straznicky NE, Lambert EA, Nestel PJ, McGrane MT, Dawood T, Schlaich MP, Masuo K, Eikelis N, de Courten B, Mariani JA, Esler MD, Socratous F, Chopra R, Sari CI, Paul E, Lambert GW. Sympathetic neural adaptation to hypocaloric diet with or without exercise training in obese metabolic syndrome subjects. Diabetes 2010; 59:71-9. [PMID: 19833893 PMCID: PMC2797947 DOI: 10.2337/db09-0934] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Sympathetic nervous system (SNS) overactivity contributes to the pathogenesis and target organ complications of obesity. This study was conducted to examine the effects of lifestyle interventions (weight loss alone or together with exercise) on SNS function. RESEARCH DESIGN AND METHODS Untreated men and women (mean age 55 +/- 1 year; BMI 32.3 +/- 0.5 kg/m(2)) who fulfilled Adult Treatment Panel III metabolic syndrome criteria were randomly allocated to either dietary weight loss (WL, n = 20), dietary weight loss and moderate-intensity aerobic exercise (WL+EX, n = 20), or no treatment (control, n = 19). Whole-body norepinephrine kinetics, muscle sympathetic nerve activity by microneurography, baroreflex sensitivity, fitness (maximal oxygen consumption), metabolic, and anthropometric measurements were made at baseline and 12 weeks. RESULTS Body weight decreased by -7.1 +/- 0.6 and -8.4 +/- 1.0 kg in the WL and WL+EX groups, respectively (both P < 0.001). Fitness increased by 19 +/- 4% (P < 0.001) in the WL+EX group only. Resting SNS activity decreased similarly in the WL and WL+EX groups: norepinephrine spillover by -96 +/- 30 and -101 +/- 34 ng/min (both P < 0.01) and muscle sympathetic nerve activity by -12 +/- 6 and -19 +/- 4 bursts/100 heart beats, respectively (both P < 0.01), but remained unchanged in control subjects. Blood pressure, baroreflex sensitivity, and metabolic parameters improved significantly and similarly in the two lifestyle intervention groups. CONCLUSIONS The addition of moderate-intensity aerobic exercise training to a weight loss program does not confer additional benefits on resting SNS activity. This suggests that weight loss is the prime mover in sympathetic neural adaptation to a hypocaloric diet.
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Affiliation(s)
- Nora E Straznicky
- Human Neurotransmitters Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia.
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Fujibayashi M, Hamada T, Matsumoto T, Kiyohara N, Tanaka S, Kotani K, Egawa K, Kitagawa Y, Kiso Y, Sakane N, Moritani T. Thermoregulatory sympathetic nervous system activity and diet-induced waist-circumference reduction in obese Japanese women. Am J Hum Biol 2009; 21:828-35. [DOI: 10.1002/ajhb.20899] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Deley G, Picard G, Taylor JA. Arterial baroreflex control of cardiac vagal outflow in older individuals can be enhanced by aerobic exercise training. Hypertension 2009; 53:826-32. [PMID: 19332656 DOI: 10.1161/hypertensionaha.109.130039] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Maintained cardiac vagal function is critical to cardiovascular health in human aging. Aerobic exercise training has been considered an attractive intervention to increase cardiovagal baroreflex function; however, the data are equivocal. Moreover, if regular exercise does reverse the age-related decline in cardiovagal baroreflex function, it is unknown how this might be achieved. Therefore, we assessed the effects of a 6-month aerobic training program on baroreflex gain and its mechanical and neural components in older individuals (5 women and 7 men, aged 55 to 71 years). We assessed baroreflex function using pharmacological pressure changes (bolus nitroprusside followed by bolus phenylephrine) and estimated the integrated gain (Delta R-R interval/Delta systolic blood pressure) and mechanical (Delta diameter/Delta pressure) and neural (Delta R-R interval/Delta diameter) components via measurements of carotid artery diameter in previously sedentary older individuals before and after 6 months of aerobic training. There was a significant 26% increase in baroreflex gain that was directly related to the amount of exercise performed and that was derived mainly from an increase in the neural component of the arterial baroreflex (P<0.05). We did find changes in the mechanical component, but unlike integrated gain and the neural component, these were not related to the magnitude of the exercise stimulus. These results suggest that exercise training can have a powerful effect on cardiovagal baroreflex function, but a sufficient stimulus is necessary to produce the effect. Moreover, adaptations in the afferent-efferent baroreflex control of cardiac vagal outflow may be crucial for the improvement in arterial baroreflex function in older humans.
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Affiliation(s)
- Gaelle Deley
- Cardiovascular Research Laboratory, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA 02114, USA
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El-Wazir YM, Li SG, Smith R, Silcox DL, Brown DR, Randall DC. Parasympathetic response to acute stress is attenuated in young Zucker obese rats. Auton Neurosci 2008; 143:33-9. [PMID: 18722824 DOI: 10.1016/j.autneu.2008.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 07/11/2008] [Accepted: 07/14/2008] [Indexed: 10/21/2022]
Abstract
We compared arterial blood pressure (BP) and heart rate (HR) control in 9- to 11-week old obese Zucker rats (n=10; weight=452+/-45 g, average+/-SD) to age-matched, lean Zucker animals (n=13; weight=280+/-46 g). BP was measured by indwelling catheter. Baseline pressure was 113.1+/-7.0 mm Hg in the lean vs. 111.7+/-5.6 in the obese rats (NS). Baseline HR was 413+/-43 in the lean vs. 422+/-22 bpm in the obese animals (NS). Rats were classically conditioned by following a 15-second tone (CS+) with a 0.5-second tail shock. There were no between-group differences in the BP response to CS+. Conversely, heart rate (HR) decreased significantly (p<0.05) more during the last 10 s of the tone in the lean group (-46.0+/-21.5 bpm) vs. the obese (-17.8+/-21.7 bpm). This bradycardia was blocked by atropine. Finally, the change in HR divided by the change in arterial BP (DeltaHR/DeltaBP) following an intravenous bolus of phenylephrine (PE; 5 microg/kg) and following sodium nitroprusside (NP; 5 microg/kg) was determined. The DeltaHR/DeltaBP following PE was smaller in the obese (n=6; -1.36+/-0.60) vs. lean (n=5; -2.80+/-0.92); there was no difference in the response following NP. These data indicate that the BP response to a behavioral challenge did not differ in the obese rat vs. the lean animal, but that the obese subjects had an attenuated parasympathetic response to the stress, probably secondary to alterations in baroreflex function.
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Affiliation(s)
- Yasser M El-Wazir
- Department of Physiology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
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Factors associated with percent change in visceral versus subcutaneous abdominal fat during weight loss: findings from a systematic review. Int J Obes (Lond) 2008; 32:619-28. [PMID: 18180786 DOI: 10.1038/sj.ijo.0803761] [Citation(s) in RCA: 201] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Visceral adipose tissue (VAT) is associated with greater obesity-related metabolic disturbance. Many studies have reported preferential loss of VAT with weight loss. OBJECTIVE This systematic review looks for factors associated with preferential loss of VAT relative to subcutaneous abdominal fat (SAT) during weight loss. DESIGN Medline and Embase were searched for imaging-based measurements of VAT and subcutaneous abdominal adipose tissue (SAT) before and after weight loss interventions. We examine for factors that influences the percentage change in VAT versus SAT (%deltaV/%deltaS) with weight loss. Linear regression analyses were performed on the complete data set and on subgroups of studies. Factors examined included percentage weight loss, degree of caloric restriction, exercise, initial body mass index (BMI), gender, time of follow-up and baseline VAT/SAT. RESULTS There were 61 studies with a total of 98 cohort time points extracted. Percentage weight loss was the only variable that influenced %deltaV/%deltaS (r=-0.29, P=0.005). Modest weight loss generated preferential loss of VAT, but with greater weight loss this effect was attenuated. The method of weight loss was not an influence with one exception. Very-low-calorie diets (VLCDs) provided exceptional short-term (<4 weeks) preferential VAT loss. But this effect was lost by 12-14 weeks. CONCLUSIONS Visceral adipose tissue is lost preferentially with modest weight loss, but the effect is attenuated with greater weight loss. Acute caloric restriction, using VLCD, produces early preferential loss of VAT. These observations may help to explain the metabolic benefits of modest weight loss.
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Figueroa A, Baynard T, Fernhall B, Carhart R, Kanaley JA. Endurance training improves post-exercise cardiac autonomic modulation in obese women with and without type 2 diabetes. Eur J Appl Physiol 2007; 100:437-44. [PMID: 17406886 DOI: 10.1007/s00421-007-0446-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2007] [Indexed: 12/22/2022]
Abstract
Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function and increased risk for cardiac complications, especially after exercise. Since improvements at rest are not always observed after training, we investigated changes in resting and post-exercise autonomic function in obese women with and without T2D after16-week of walking training. Heart rate (HR) variability (HRV) and baroreflex sensitivity (BRS) were measured at rest and 20 min after a 20 min bout of treadmill exercise at 65% VO(2) peak in obese women with (n = 8) and without T2D (n = 12) before and after training. HRV was analyzed by frequency-domain [high- (HF) power and low-frequency (LF)] and BRS by the sequence method. Exercise training induced similar significant changes in VO(2) peak, resting systolic blood pressure (SBP) and post-exercise autonomic function in both groups. Training increased VO(2 )peak (6%; P < 0.01) and decreased resting SBP (8%; P < 0.001). Increased post-exercise HR recovery (5%; P < 0.001), HF power (14%; P < 0.05), LF power (14%; P < 0.05) and BRS (86%; P < 0.001) were also observed. Resting autonomic function and post-exercise SBP were not altered after training. In conclusion, endurance training reduced blood pressure without changes in HRV and BRS at rest, but training increased HRV and BRS during the recovery of acute endurance exercise indicating an improved post-exercise autonomic modulation of HR, which was similar in obese women with and without T2D.
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Affiliation(s)
- Arturo Figueroa
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
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Bechtold AG, Scheuer DA. Glucocorticoids act in the dorsal hindbrain to modulate baroreflex control of heart rate. Am J Physiol Regul Integr Comp Physiol 2005; 290:R1003-11. [PMID: 16269575 PMCID: PMC5730876 DOI: 10.1152/ajpregu.00345.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Systemic corticosterone (Cort) modulates arterial baroreflex control of both heart rate and renal sympathetic nerve activity. Because baroreceptor afferents terminate in the dorsal hindbrain (DHB), an area with dense corticosteroid receptor expression, we tested the hypothesis that prolonged activation of DHB Cort receptors increases the midpoint and reduces the gain of arterial baroreflex control of heart rate in conscious rats. Small (3-4 mg) pellets of Cort (DHB Cort) or Silastic (DHB Sham) were placed on the surface of the DHB, or Cort was administered systemically by placing a Cort pellet on the surface of the dura (Dura Cort). Baroreflex control of heart rate was determined in conscious male Sprague Dawley rats on each of 4 days after initiation of treatment. Plots of arterial pressure vs. heart rate were analyzed using a four-parameter logistic function. After 3 days of treatment, the arterial pressure midpoint for baroreflex control of heart rate was increased in DHB Cort rats (123 +/- 2 mmHg) relative to both DHB Sham (108 +/- 3 mmHg) and Dura Cort rats (109 +/- 2 mmHg, P < 0.05). On day 4, baseline arterial pressure was greater in DHB Cort (112 +/- 2 mmHg) compared with DHB Sham (105 +/- 2 mmHg) and Dura Cort animals (106 +/- 2 mmHg, P < 0.05), and the arterial pressure midpoint was significantly greater than mean arterial pressure in the DHB Cort group only. Also on day 4, maximum baroreflex gain was reduced in DHB Cort (2.72 +/- 0.12 beats x min(-1) x mmHg(-1)) relative to DHB Sham and Dura Cort rats (3.51 +/- 0.28 and 3.37 +/- 0.27 beats x min(-1) x mmHg(-1), P < 0.05). We conclude that Cort acts in the DHB to increase the midpoint and reduce the gain of the heart rate baroreflex function.
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Affiliation(s)
- Andrea G Bechtold
- Division of Pharmacology, University of Missouri-Kansas City, Kansas City, Missouri 64108, USA
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