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Körei AE, Putz Z, Vági OE, Tordai DZ, Menyhárt A, Istenes I, Horváth VJ, Kempler P. The handgrip test - A historical test for diabetic autonomic neuropathy or a marker of something else? J Diabetes Complications 2024; 38:108668. [PMID: 38241880 DOI: 10.1016/j.jdiacomp.2023.108668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/10/2023] [Accepted: 12/17/2023] [Indexed: 01/21/2024]
Abstract
Cardiovascular autonomic neuropathy (CAN) is a frequent complication of diabetes mellitus and is associated with increased morbidity and mortality in patients with diabetes. Hence, early and correct diagnosis of CAN is crucial. Standard cardiovascular reflex rests (CARTs) have been the gold standard of CAN assessment. Originally, CARTs consisted of five reflex tests, but measuring diastolic blood pressure response to sustained handgrip exercise has no longer been suggested as an established clinical test. Increasing body of evidence suggests that isometric handgrip test should no longer be used for the evaluation of sympathetic dysfunction during cardiovascular autonomic neuropathy assessment in diabetic patients. The associations of isometric handgrip test results with parameters of hypertension and markers of hypertension-related target-organ damage in diabetic and non-diabetic individuals point toward its potential role as a screening tool to identify patients with high cardiovascular risk. The current review summarizes historical view of standard cardiovascular reflex tests and latest data on isometric handgrip test.
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Affiliation(s)
- Anna Erzsébet Körei
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary.
| | - Zsuzsanna Putz
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Orsolya Erzsébet Vági
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Dóra Zsuzsanna Tordai
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Adrienn Menyhárt
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Ildikó Istenes
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Viktor József Horváth
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Péter Kempler
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
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Ratchford SM, Broxterman RM, La Salle DT, Kwon OS, Hopkins PN, Richardson RS, Trinity JD. Obesity does not alter vascular function and handgrip exercise hemodynamics in middle-aged patients with hypertension. Am J Physiol Regul Integr Comp Physiol 2024; 326:R1-R9. [PMID: 37842741 PMCID: PMC11283903 DOI: 10.1152/ajpregu.00105.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/19/2023] [Accepted: 10/09/2023] [Indexed: 10/17/2023]
Abstract
Lifestyle modification including exercise training is often the first line of defense in the treatment of obesity and hypertension (HTN), however, little is known regarding how these potentially compounding disease states impact vasodilatory and hemodynamic responses at baseline and exercise. Therefore, this study sought to compare the impact of obesity on vascular function and hemodynamics at baseline and during handgrip (HG) exercise among individuals with HTN. Non-obese (13M/7F, 56 ± 16 yr, 25 ± 4 kg/m2) and obese (17M/4F, 50 ± 7 yr, 35 ± 4 kg/m2) middle-aged individuals with HTN forwent antihypertensive medication use for ≥2 wk before assessment of vascular function by brachial artery flow-mediated dilation (FMD) and exercise hemodynamics during progressive HG exercise at 15-30-45% maximal voluntary contraction (MVC). FMD was not different between Non-Obese (4.1 ± 1.7%) and Obese (5.2 ± 1.9%, P = 0.11). Systolic blood pressure (SBP) was elevated by ∼15% during the supine baseline and during HG exercise in the obese group. The blood flow response to HG exercise at 30% and 45% MVC was ∼20% greater (P < 0.05) in the obese group but not different after normalizing for the higher, albeit, nonsignificant differences in workloads (MVC: obese: 24 ± 5 kg, non-obese: 21 ± 5 kg, P = 0.11). Vascular conductance and the brachial artery shear-induced vasodilatory response during HG were not different between groups (P > 0.05). Taken together, despite elevated SBP during HG exercise, obesity does not lead to additional impairments in vascular function and peripheral exercising hemodynamics in patients with HTN. Obesity may not be a contraindication when prescribing exercise for the treatment of HTN among middle-aged adults, however, the elevated SBP should be appropriately monitored.NEW & NOTEWORTHY This study examined vascular function and handgrip exercise hemodynamics in obese and nonobese individuals with hypertension. Obesity, when combined with hypertension, was neither associated with additional vascular function impairments at baseline nor peripheral hemodynamics and vasodilation during exercise compared with nonobese hypertension. Interestingly, systolic blood pressure and pulse pressure were greater in the obese group during supine baseline and exercise. These findings should not be ignored and may be particularly important for rehabilitation strategies.
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Affiliation(s)
- Stephen M Ratchford
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veteran Affairs Medical Center, Salt Lake City, Utah, United States
| | - Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veteran Affairs Medical Center, Salt Lake City, Utah, United States
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, United States
| | - D Taylor La Salle
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - Oh Sung Kwon
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, United States
- Department of Kinesiology, University of Connecticut, Storrs, Connecticut, United States
| | - Paul N Hopkins
- Department of Internal Medicine, Division of Cardiovascular Genetics, University of Utah, Salt Lake City, Utah, United States
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veteran Affairs Medical Center, Salt Lake City, Utah, United States
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, United States
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veteran Affairs Medical Center, Salt Lake City, Utah, United States
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, United States
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
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Bock JM, Hanson BE, Miller KA, Seaberg NT, Ueda K, Feider AJ, Hanada S, Lira VA, Casey DP. Eight weeks of inorganic nitrate/nitrite supplementation improves aerobic exercise capacity and the gas exchange threshold in patients with type 2 diabetes. J Appl Physiol (1985) 2022; 133:1407-1414. [PMID: 36326473 PMCID: PMC9762960 DOI: 10.1152/japplphysiol.00478.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 11/06/2022] Open
Abstract
Patients with type 2 diabetes mellitus (T2DM) have reduced exercise capacity, indexed by lower maximal oxygen consumption (V̇o2max) and achievement of the gas exchange threshold (GET) at a lower % V̇o2max. The ubiquitous signaling molecule nitric oxide (NO) plays a multifaceted role during exercise and, as patients with T2DM have poor endogenous NO production, we investigated if inorganic nitrate/nitrite supplementation (an exogenous source of NO) improves exercise capacity in patients with T2DM. Thirty-six patients with T2DM (10F, 59 ± 9 yr, 32.0 ± 5.1 kg/m2, HbA1c = 7.4 ± 1.4%) consumed beetroot juice containing either inorganic nitrate/nitrite (4.03 mmol/0.29 mmol) or a placebo (0.8 mmol/0.00 mmol) for 8 wk. A maximal exercise test was completed before and after both interventions. V̇o2max was determined by averaging 15-s data, whereas the GET was identified using the V-slope method and breath-by-breath data. Inorganic nitrate/nitrite increased both absolute (1.96 ± 0.67 to 2.07 ± 0.75 L/min) and relative (20.7 ± 7.0 to 21.9 ± 7.4 mL/kg/min, P < 0.05 for both) V̇o2max, whereas no changes were observed following placebo (1.94 ± 0.40 to 1.90 ± 0.39 L/min, P = 0.33; 20.0 ± 4.2 to 19.7 ± 4.6 mL/kg/min, P = 0.39). Maximal workload was also increased following inorganic nitrate/nitrite supplementation (134 ± 47 to 140 ± 51 W, P < 0.05) but not placebo (138 ± 32 to 138 ± 32 W, P = 0.98). V̇o2 at the GET (1.11 ± 0.27 to 1.27 ± 0.38L/min) and the %V̇o2max in which GET occurred (56 ± 8 to 61 ± 7%, P < 0.05 for both) increased following inorganic nitrate/nitrite supplementation but not placebo (1.10 ± 0.23 to 1.08 ± 0.21 L/min, P = 0.60; 57 ± 9 to 57 ± 8%, P = 0.90) although the workload at GET did not achieve statistical significance (group-by-time P = 0.06). Combined inorganic nitrate/nitrite consumption improves exercise capacity, maximal workload, and promotes a rightward shift in the GET in patients with T2DM. This manuscript reports data from a registered Clinical Trial at ClinicalTrials.gov ID: NCT02804932.NEW & NOTEWORTHY We report that increasing nitric oxide bioavailability via 8 wk of inorganic nitrate/nitrite supplementation improves maximal aerobic exercise capacity in patients with type 2 diabetes mellitus. Similarly, we observed a rightward shift in the gas exchange threshold. Taken together, these data indicate inorganic nitrate/nitrite may serve as a means to improve fitness in patients with type 2 diabetes mellitus.
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Affiliation(s)
- Joshua M Bock
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
| | - Brady E Hanson
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
| | - Kayla A Miller
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
| | - Nathanael T Seaberg
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
| | - Kenichi Ueda
- Department of Anesthesia, University of Iowa, Iowa City, Iowa
| | - Andrew J Feider
- Department of Anesthesia, University of Iowa, Iowa City, Iowa
| | - Satoshi Hanada
- Department of Anesthesia, University of Iowa, Iowa City, Iowa
| | - Vitor A Lira
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
| | - Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
- Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa
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Weavil JC, Kwon OS, Hughen RW, Zhang J, Light AR, Amann M. Gene and protein expression of dorsal root ganglion sensory receptors in normotensive and hypertensive male rats. Am J Physiol Regul Integr Comp Physiol 2022; 323:R221-R226. [PMID: 35608265 PMCID: PMC9291411 DOI: 10.1152/ajpregu.00007.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The exercise pressor reflex (EPR), a neurocirculatory control mechanism, is exaggerated in hypertensive humans and rats. Disease-related abnormalities within the afferent arm of the reflex loop, including mechano- and metabosensitive receptors located at the terminal end of group III/IV muscle afferents, may contribute to the dysfunctional EPR in hypertension. Using control (WKY) and spontaneous hypertensive (SHR) rats, we examined dorsal root ganglion (DRG) gene and protein expression of molecular receptors recognized as significant determinants of the EPR. Twelve lumbar DRGs (6-left, 6-right) were harvested from each of 10 WKY (arterial blood pressure (MAP): 96±9mmHg) and 10 SHR (MAP: 144±9mmHg). DRGs from the left side were used for protein expression (Western blotting; normalized to GAPDH), whereas right-side DRGs (i.e., parallel structure) were used to determine mRNA levels (RNA-sequencing, normalized to TPM). Analyses focused on metabosensitive (ASIC3, Bradykinin-receptor B2, EP4, P2X3, TRPv1) and mechanosensitive (Piezo1/2) receptors. While Piezo1 was similar in both groups (P=0.75), protein expression for all other receptors was significantly higher in SHR compared to WKY. With the exception of a greater Bradykinin-receptor B2 in SHR (P<0.05), mRNA expression of all other receptors was not different between groups (P>0.18). The higher protein content of these sensory receptors in SHR indirectly supports the previously proposed hypothesis that the exaggerated EPR in hypertension is, in part, due to disease-related abnormalities within the afferent arm of the reflex loop. The upregulated receptor content, combined with normal mRNA levels, insinuates that posttranscriptional regulation of sensory receptor protein expression might be impaired in hypertension.
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Affiliation(s)
- Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, United States.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Oh Sung Kwon
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States.,Department of Kinesiology, University of Connecticut, Storrs, CT, United States
| | - Ronald W Hughen
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, United States
| | - Jie Zhang
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, United States
| | - Alan R Light
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, United States
| | - Markus Amann
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, United States.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, United States
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Grotle AK, Macefield VG, Farquhar WB, O'Leary DS, Stone AJ. Recent advances in exercise pressor reflex function in health and disease. Auton Neurosci 2020; 228:102698. [PMID: 32861944 DOI: 10.1016/j.autneu.2020.102698] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 01/11/2023]
Abstract
Autonomic alterations at the onset of exercise are critical to redistribute cardiac output towards the contracting muscles while preventing a fall in arterial pressure due to excessive vasodilation within the contracting muscles. Neural mechanisms responsible for these adjustments include central command, the exercise pressor reflex, and arterial and cardiopulmonary baroreflexes. The exercise pressor reflex evokes reflex increases in sympathetic activity to the heart and systemic vessels and decreases in parasympathetic activity to the heart, which increases blood pressure (BP), heart rate, and total peripheral resistance through vasoconstriction of systemic vessels. In this review, we discuss recent advancements in our understanding of exercise pressor reflex function in health and disease. Specifically, we discuss emerging evidence suggesting that sympathetic vasoconstrictor drive to the contracting and non-contracting skeletal muscle is differentially controlled by central command and the metaboreflex in healthy conditions. Further, we discuss evidence from animal and human studies showing that cardiovascular diseases, including hypertension, diabetes, and heart failure, lead to an altered exercise pressor reflex function. We also provide an update on the mechanisms thought to underlie this altered exercise pressor reflex function in each of these diseases. Although these mechanisms are complex, multifactorial, and dependent on the etiology of the disease, there is a clear consensus that several mechanisms are involved. Ultimately, approaches targeting these mechanisms are clinically significant as they provide alternative therapeutic strategies to prevent adverse cardiovascular events while also reducing symptoms of exercise intolerance.
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Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States of America
| | | | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, United States of America
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States of America.
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Sidhu SK, Weavil JC, Rossman MJ, Jessop JE, Bledsoe AD, Buys MJ, Supiano MS, Richardson RS, Amann M. Exercise Pressor Reflex Contributes to the Cardiovascular Abnormalities Characterizing: Hypertensive Humans During Exercise. Hypertension 2019; 74:1468-1475. [PMID: 31607174 DOI: 10.1161/hypertensionaha.119.13366] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We investigated the impact of hypertension on circulatory responses to exercise and the role of the exercise pressor reflex in determining the cardiovascular abnormalities characterizing patients with hypertension. After a 7-day drug washout, 8 hypertensive (mean arterial pressure [MAP] 130±4 mm Hg; 65±3 years) and 8 normotensive (MAP 117±2 mm Hg; 65±2 years) individuals performed single-leg knee-extensor exercise (7 W, 15 W, 50%, 80%-Wpeak) under control conditions and with lumbar intrathecal fentanyl impairing feedback from µ-opioid receptor-sensitive leg muscle afferents. Femoral artery blood flow (QL), MAP (femoral artery), leg vascular conductance, and changes in cardiac output were continuously measured. While the increase in MAP from rest to control exercise was significantly greater in hypertension compared with normotension, the exercise-induced increase in cardiac output was comparable between groups, and QL and leg vascular conductance responses were ≈18% and ≈32% lower in the hypertensive patients (P<0.05). The blockade-induced decreases in MAP were significantly larger during exercise in hypertensive (≈11 mm Hg) compared with normotensive (≈6 mm Hg). Afferent blockade attenuated the central hemodynamic response to exercise similarly in both groups resulting in a ≈15% lower cardiac output at each workload. With no effect in normotensive, afferent blockade significantly raised the peripheral hemodynamic response to exercise in hypertensive, resulting in ≈14% and ≈23% higher QL and leg vascular conductance during exercise. Finally, QL and MAP during fentanyl-exercise in hypertensive were comparable to that of normotensive under control conditions (P>0.2). These findings suggest that exercise pressor reflex abnormalities largely account for the exaggerated MAP response and the impaired peripheral hemodynamics during exercise in hypertension.
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Affiliation(s)
- Simranjit K Sidhu
- From the Department of Internal Medicine, Division of Geriatrics (S.K.S., M.J.R., M.S.S., R.S.R., M.A.), University of Utah, Salt Lake City.,Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Australia (S.K.S.)
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, VAMC Salt Lake City, UT (J.C.W., M.S.S., R.S.R., M.A.)
| | - Matthew J Rossman
- From the Department of Internal Medicine, Division of Geriatrics (S.K.S., M.J.R., M.S.S., R.S.R., M.A.), University of Utah, Salt Lake City
| | - Jacob E Jessop
- Department of Anesthesiology (J.E.J., A.D.B., M.J.B., M.A.), University of Utah, Salt Lake City
| | - Amber D Bledsoe
- Department of Anesthesiology (J.E.J., A.D.B., M.J.B., M.A.), University of Utah, Salt Lake City
| | - Michael J Buys
- Department of Anesthesiology (J.E.J., A.D.B., M.J.B., M.A.), University of Utah, Salt Lake City
| | - Mark S Supiano
- From the Department of Internal Medicine, Division of Geriatrics (S.K.S., M.J.R., M.S.S., R.S.R., M.A.), University of Utah, Salt Lake City.,Geriatric Research, Education, and Clinical Center, VAMC Salt Lake City, UT (J.C.W., M.S.S., R.S.R., M.A.)
| | - Russell S Richardson
- From the Department of Internal Medicine, Division of Geriatrics (S.K.S., M.J.R., M.S.S., R.S.R., M.A.), University of Utah, Salt Lake City.,Geriatric Research, Education, and Clinical Center, VAMC Salt Lake City, UT (J.C.W., M.S.S., R.S.R., M.A.)
| | - Markus Amann
- From the Department of Internal Medicine, Division of Geriatrics (S.K.S., M.J.R., M.S.S., R.S.R., M.A.), University of Utah, Salt Lake City.,Department of Anesthesiology (J.E.J., A.D.B., M.J.B., M.A.), University of Utah, Salt Lake City.,Geriatric Research, Education, and Clinical Center, VAMC Salt Lake City, UT (J.C.W., M.S.S., R.S.R., M.A.)
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Vianna LC, Fisher JP. Reflex control of the cardiovascular system during exercise in disease. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Müller PDT, Nogueira JHZ, Augusto TRDL, Chiappa GR. Faster oxygen uptake, heart rate, and ventilatory kinetics in stepping compared with cycle ergometry in patients with COPD during moderate-intensity exercise. Appl Physiol Nutr Metab 2019; 44:879-885. [PMID: 30649910 DOI: 10.1139/apnm-2018-0662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Step tests are a stressful and feasible cost-effective modality to evaluate aerobic performance. However, the eccentric in addition to concentric muscle contractions of the legs on stepping emerge as a potential speeding factor for cardioventilatory and metabolic adjustments towards a steady-state, since eccentric contractions would prompt an earlier and stronger mechanoreceptor activation, as well as higher heart rate/cardiac output adjustments to the same metabolic demand. Moreover, shorter tests are ideal for exercise-limited subjects. Nine subjects with chronic obstructive pulmonary disease were invited to participate in comprehensive lung function tests and constant work tests performed on different days at a 90% gas exchange threshold for 6 min, in single-step tests or cycle ergometry. After careful monoexponential regression modelling, statistically relevant faster phase II time constants for oxygen uptake (45 ± 18 s vs 53 ± 17 s, p = 0.017) and minute ventilation (61 ± 13 s vs 74 ± 17 s, p = 0.027) were observed in the 6-min step tests compared with cycle ergometry, respectively. Despite an absence of heart rate time constant difference (43 ± 20 s vs 69 ± 46 s, p = 0.167), there was a significantly faster rate constant toward a steady state for heart rate (p = 0.02). In addition, 4-min compared with 6-min analysis presented similar results (p > 0.05), providing an appropriate steady-state. We conclude that step tests might elicit faster time constants compared with cycle ergometry, at the same average metabolic level, and 4-min analysis has similar mean errors compared with 6-min analysis within an acceptable range. New studies, comprising mechanisms and detailed physiological backgrounds, are necessary.
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Affiliation(s)
- Paulo de Tarso Müller
- a Laboratory of Respiratory Pathophysiology (LAFIR), Maria Aparecida Pedrossian Universitary Hospital (HUMAP), Campo Grande, MS 79040-630, Brazil
| | - João Henrique Zardetti Nogueira
- a Laboratory of Respiratory Pathophysiology (LAFIR), Maria Aparecida Pedrossian Universitary Hospital (HUMAP), Campo Grande, MS 79040-630, Brazil
| | - Tiago Rodrigues de Lemos Augusto
- a Laboratory of Respiratory Pathophysiology (LAFIR), Maria Aparecida Pedrossian Universitary Hospital (HUMAP), Campo Grande, MS 79040-630, Brazil
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Caldwell JT, Sutterfield SL, Post HK, Craig JC, Baumfalk DR, Copp SW, Ade CJ. Impact of Acute Dietary Nitrate Supplementation during Exercise in Hypertensive Women. Med Sci Sports Exerc 2018; 51:1014-1021. [PMID: 30531488 DOI: 10.1249/mss.0000000000001857] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION the aim of the current investigation was to examine if dietary nitrate supplementation would improve vascular control in hypertensive postmenopausal women (PMW). We tested the hypotheses that acute dietary nitrate supplementation would 1) significantly decrease arterial blood pressure (BP) at rest and during exercise, 2) increase limb blood flow during steady-state (SS) exercise, and 3) improve functional sympatholysis during SS exercise. METHODS Ten hypertensive PMW underwent a randomized, double-blind, placebo-controlled trial with a nitrate-rich (NR) or nitrate-poor (NP) supplement. Beat-by-beat BP and heart rate were recorded throughout the trial on the nonexercising limb. Forearm blood flow was measured via ultrasonography on the brachial artery of the exercising limb. All patients performed a resting cold pressor test (CPT) (2 min) and then 7 min of submaximal handgrip exercise with a CPT applied during minutes 5-7. RESULTS SS systolic (NR, 170 ± 7; NP, 171 ± 37 mm Hg), diastolic (NR, 89 ± 2; NP, 92 ± 2 mm Hg), and mean arterial (NR, 121 ± 4; NP, 123 ± 2 mm Hg) pressures were not different between NP and NR treatment conditions (P > 0.05). During SS exercise, forearm blood flow (NR, 189 ± 8; NP, 218 ± 8 mL·min; P = 0.03) in the NR treatment was significantly lower compared with NP. When the CPT was applied during minutes 6-7 of exercise, forearm vascular conductance was reduced by 15% in the NR condition, but only 7% in the NR condition. CONCLUSIONS In summary, an acute NR supplement improved functional sympatholysis by ~50% versus an NP placebo condition. Improvements in functional sympatholysis may have important implications regarding exercise tolerance in hypertensive PMW.
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Affiliation(s)
- Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, KS
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Mueller PJ, Clifford PS, Crandall CG, Smith SA, Fadel PJ. Integration of Central and Peripheral Regulation of the Circulation during Exercise: Acute and Chronic Adaptations. Compr Physiol 2017; 8:103-151. [DOI: 10.1002/cphy.c160040] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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11
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Wang HJ. Mineralocorticoids: the secret of muscle reflex dysfunction in hypertension? Am J Physiol Heart Circ Physiol 2017; 313:H931-H933. [PMID: 28822968 DOI: 10.1152/ajpheart.00501.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 11/22/2022]
Affiliation(s)
- Han-Jun Wang
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska; and .,Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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12
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Mitchell JH. Abnormal cardiovascular response to exercise in hypertension: contribution of neural factors. Am J Physiol Regul Integr Comp Physiol 2017; 312:R851-R863. [PMID: 28381455 DOI: 10.1152/ajpregu.00042.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/10/2017] [Accepted: 03/22/2017] [Indexed: 02/02/2023]
Abstract
During both dynamic (e.g., endurance) and static (e.g., strength) exercise there are exaggerated cardiovascular responses in hypertension. This includes greater increases in blood pressure, heart rate, and efferent sympathetic nerve activity than in normal controls. Two of the known neural factors that contribute to this abnormal cardiovascular response are the exercise pressor reflex (EPR) and functional sympatholysis. The EPR originates in contracting skeletal muscle and reflexly increases sympathetic efferent nerve activity to the heart and blood vessels as well as decreases parasympathetic efferent nerve activity to the heart. These changes in autonomic nerve activity cause an increase in blood pressure, heart rate, left ventricular contractility, and vasoconstriction in the arterial tree. However, arterial vessels in the contracting skeletal muscle have a markedly diminished vasoconstrictor response. The markedly diminished vasoconstriction in contracting skeletal muscle has been termed functional sympatholysis. It has been shown in hypertension that there is an enhanced EPR, including both its mechanoreflex and metaboreflex components, and an impaired functional sympatholysis. These conditions set up a positive feedback or vicious cycle situation that causes a progressively greater decrease in the blood flow to the exercising muscle. Thus these two neural mechanisms contribute significantly to the abnormal cardiovascular response to exercise in hypertension. In addition, exercise training in hypertension decreases the enhanced EPR, including both mechanoreflex and metaboreflex function, and improves the impaired functional sympatholysis. These two changes, caused by exercise training, improve the muscle blood flow to exercising muscle and cause a more normal cardiovascular response to exercise in hypertension.
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Affiliation(s)
- Jere H Mitchell
- Cardiology Division, University of Texas Southwestern Medical Center, Dallas, Texas
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Barbosa TC, Vianna LC, Fernandes IA, Prodel E, Rocha HNM, Garcia VP, Rocha NG, Secher NH, Nobrega ACL. Intrathecal fentanyl abolishes the exaggerated blood pressure response to cycling in hypertensive men. J Physiol 2016; 594:715-25. [PMID: 26659384 DOI: 10.1113/jp271335] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/07/2015] [Indexed: 01/01/2023] Open
Abstract
KEY POINTS The increase in blood pressure observed during physical activities is exaggerated in patients with hypertension, exposing them to a higher cardiovascular risk. Neural signals from the skeletal muscles appear to be overactive, resulting in this abnormal response in hypertensive patients. In the present study, we tested whether the attenuation of these neural signals in hypertensive patients could normalize their abnormal increase in blood pressure during physical activity. Attenuation of the neural signals from the leg muscles with intrathecal fentanyl injection reduced the blood pressure of hypertensive men during cycling exercise to a level comparable to that of normotensive men. Skeletal muscle afferent overactivity causes the abnormal cardiovascular response to exercise and was reverted in this experimental model, appearing as potential target for treatment. Hypertensive patients present an exaggerated increase in blood pressure and an elevated cardiovascular risk during exercise. Although controversial, human studies suggest that group III and IV skeletal muscle afferents might contribute to this abnormal response. In the present study, we investigated whether attenuation of the group III and IV muscle afferent signal of hypertensive men eliminates the exaggerated increase in blood pressure occurring during exercise. Eight hypertensive men performed two sessions of 5 min of cycling exercise at 40 W. Between sessions, the subjects were provided with a lumbar intrathecal injection of fentanyl, a μ-opioid receptor agonist, aiming to attenuate the central projection of opioid-sensitive group III and IV muscle afferent nerves. The cardiovascular response to exercise of these subjects was compared with that of six normotensive men. During cycling, the hypertensive group demonstrated an exaggerated increase in blood pressure compared to the normotensive group (mean ± SEM: +17 ± 3 vs. +8 ± 1 mmHg, respectively; P < 0.05), whereas the increase in heart rate, stroke volume, cardiac output and vascular conductance was similar (P > 0.05). Fentanyl inhibited the blood pressure response to exercise in the hypertensive group (+11 ± 2 mmHg) to a level comparable to that of the normotensive group (P > 0.05). Moreover, fentanyl increased the responses of vascular conductance and stroke volume to exercise (P < 0.05), whereas the heart rate response was attenuated (P < 0.05) and the cardiac output response was maintained (P > 0.05). The results of the present study show that attenuation of the exercise pressor reflex normalizes the blood pressure response to cycling exercise in hypertensive individuals.
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Affiliation(s)
- Thales C Barbosa
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
| | - Lauro C Vianna
- Faculty of Physical Education, University of Brasilia, DF, Brazil
| | - Igor A Fernandes
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
| | - Eliza Prodel
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
| | - Helena N M Rocha
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
| | - Vinicius P Garcia
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
| | - Natalia G Rocha
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
| | - Niels H Secher
- Copenhagen Muscle Research Centre, Department of Anaesthesiology, University of Copenhagen, Denmark
| | - Antonio C L Nobrega
- Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, RJ, Brazil
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Liang N, Mitchell JH, Smith SA, Mizuno M. Exaggerated sympathetic and cardiovascular responses to stimulation of the mesencephalic locomotor region in spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2016; 310:H123-31. [PMID: 26545711 PMCID: PMC4796463 DOI: 10.1152/ajpheart.00479.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/05/2015] [Indexed: 02/05/2023]
Abstract
The sympathetic and pressor responses to exercise are exaggerated in hypertension. However, the underlying mechanisms causing this abnormality remain to be fully elucidated. Central command, a neural drive originating in higher brain centers, is known to activate cardiovascular and locomotor control circuits concomitantly. As such, it is a viable candidate for the generation of the augmented vascular response to exercise in this disease. We hypothesized that augmentations in central command function contribute to the heightened cardiovascular response to exercise in hypertension. To test this hypothesis, changes in renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) in response to electrical stimulation of mesencephalic locomotor region (MLR; 20-50 μA in 10-μA steps evoking fictive locomotion), a putative component of the central command pathway, were examined in decerebrate, paralyzed normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Tibial nerve discharge during MLR stimulation significantly increased in an intensity-dependent manner in both WKY and SHR but was not different between groups. Stimulation of the MLR evoked significantly larger increases in RSNA and MAP with increasing stimulation intensity in both groups. Importantly, the increases in sympathetic and pressor responses to this fictive locomotion were significantly greater in SHR compared with WKY across all stimulation intensities (e.g., at 50 μA, ΔRSNA: WKY 153 ± 31%, SHR 287 ± 42%; ΔMAP: WKY 87 ± 9 mmHg, SHR 139 ± 7 mmHg). These findings provide the first evidence that central command may be a critical contributor to the exaggerated rise in sympathetic activity and blood pressure during exercise in hypertension.
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Affiliation(s)
- Nan Liang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Jere H Mitchell
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Scott A Smith
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Masaki Mizuno
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; and
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Abstract
Exercise training is the cornerstone in the prevention and management of hypertension and atherosclerotic cardiovascular disease. However, blood pressure (BP) response to exercise is exaggerated in hypertension often to the range that raises the safety concern, which may prohibit patients from regular exercise. This augmented pressor response is shown to be related to excessive sympathetic stimulation caused by overactive muscle reflex. Exaggerated sympathetic-mediated vasoconstriction further contributes to the rise in BP during exercise in hypertension. Exercise training has been shown to reduce both exercise pressor reflex and attenuate the abnormal vasoconstriction. Hypertension also contributes to cognitive impairment, and exercise training has been shown to improve cognitive function through both BP-dependent and BP-independent pathways. Additional studies are still needed to determine if newer modes of exercise training such as high-intensity interval training may offer advantages over traditional continuous moderate training in improving BP and brain health in hypertensive patients.
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Mizuno M, Iwamoto GA, Vongpatanasin W, Mitchell JH, Smith SA. Dynamic exercise training prevents exercise pressor reflex overactivity in spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2015; 309:H762-70. [PMID: 26163445 DOI: 10.1152/ajpheart.00358.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/04/2015] [Indexed: 11/22/2022]
Abstract
Cardiovascular responses to exercise are exaggerated in hypertension. We previously demonstrated that this heightened cardiovascular response to exercise is mediated by an abnormal skeletal muscle exercise pressor reflex (EPR) with important contributions from its mechanically and chemically sensitive components. Exercise training attenuates exercise pressor reflex function in healthy subjects as well as in heart failure rats. However, whether exercise training has similar physiological benefits in hypertension remains to be elucidated. Thus we tested the hypothesis that the EPR overactivity manifest in hypertension is mitigated by exercise training. Changes in mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) in response to muscle contraction, passive muscle stretch, and hindlimb intra-arterial capsaicin administration were examined in untrained normotensive Wistar-Kyoto rats (WKYUT; n = 6), exercise-trained WKY (WKYET; n = 7), untrained spontaneously hypertensive rats (SHRUT; n = 8), and exercise-trained SHR (SHRET; n = 7). Baseline MAP after decerebration was significantly decreased by 3 mo of wheel running in SHRET (104 ± 9 mmHg) compared with SHRUT (125 ± 10 mmHg). As previously reported, the pressor and renal sympathetic responses to muscle contraction, stretch, and capsaicin administration were significantly higher in SHRUT than WKYUT. Exercise training significantly attenuated the enhanced contraction-induced elevations in MAP (SHRUT: 53 ± 11 mmHg; SHRET: 19 ± 3 mmHg) and RSNA (SHRUT: 145 ± 32%; SHRET: 57 ± 11%). Training produced similar attenuating effects in SHR during passive stretch and capsaicin administration. These data demonstrate that the abnormally exaggerated EPR function that develops in hypertensive rats is significantly diminished by exercise training.
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Affiliation(s)
- Masaki Mizuno
- Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas;
| | - Gary A Iwamoto
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Wanpen Vongpatanasin
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Hypertension Section, Cardiology Division, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jere H Mitchell
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Scott A Smith
- Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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