Abstract 266: Neural Circulatory Responses to Isolated Muscle Metaboreflex Activation in Postmenopausal Women

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Jody L Greaney ◽  
Evan L Matthews ◽  
Paul J Fadel ◽  
William B Farquhar ◽  
Megan M Wenner
Keyword(s):  
Blood Pressure ◽  
Postmenopausal Women ◽  
Young Women ◽  
Blood Pressure Response ◽  
Muscle Sympathetic Nerve Activity ◽  
Feedback Mechanism ◽  
Voluntary Contraction ◽  
Pressure Response ◽  
Isometric Handgrip ◽  
Muscle Metaboreflex

Understanding the neural circulatory responses to exercise in postmenopausal women (PMW) is important given their greater risk for developing hypertension. During exercise, blood pressure is controlled, in part, by the exercise pressor reflex, which is a feedback mechanism originating in skeletal muscle and compromised of mechanically and metabolically sensitive afferents. A recent study reported an enhanced blood pressure response during exercise in normotensive PMW due to greater muscle metaboreflex activation, but the mechanism(s) underlying these responses are unknown. Herein, we tested the hypothesis that metaboreflex activation elicits exaggerated sympathetic nervous system responses in PMW compared to young women, contributing to the enhanced blood pressure response during exercise. Methods: Blood pressure (BP, Finometer) and muscle sympathetic nerve activity (MSNA, peroneal microneurography) were continuously measured in 7 PMW (age 59±2 years; BMI 24±1 kg/m 2 ) and 7 young women (age 23±2 years; BMI 22±2 kg/m 2 ) during 2-minutes of isometric handgrip exercise performed at 30% of maximal voluntary contraction followed by 3-minutes of forearm ischemia (post-exercise ischemia, PEI) to isolate muscle metaboreflex activation. Results: Resting mean arterial pressure (MAP) was similar between PMW (85±3 mmHg) and young women (82±2 mmHg; P>0.05). During exercise, the increase in MAP was greater in PMW (Δ18±2mmHg) compared to young women (Δ 12±2 mmHg; P<0.05), and this was maintained during PEI (Δ13±1 mmHg PMW vs. Δ 6±1 mmHg young women; P<0.05). Resting MSNA was higher in PMW (24±4 bursts/min) compared to young women (9±3 bursts/min; P<0.05). Interestingly, the increase in MSNA during exercise was comparable between groups (P>0.05), whereas during PEI, the increase in MSNA was approximately 50% greater in PMW compared to young women (Δ13±2 burst/min PMW vs. 7±2 bursts/min young women; P<0.05). Conclusions: These preliminary data suggest that compared to young women, PMW exhibit an exaggerated MSNA response to isolated muscle metaboreflex activation.

Blunted blood pressure response to exercise and isolated muscle metaboreflex activation in patients with cirrhosis

2020 ◽  
Author(s):  
Pedro Augusto Carvalho Mira ◽  
Maria Fernanda Almeida Falci ◽  
Janaína Becari Moreira ◽  
Rosa Virginia Diaz Guerrero ◽  
Tarsila Campanha da Rocha Ribeiro ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Pressure Response ◽  
Pressor Response ◽  
Cardiovascular Responses ◽  
Pressure Response ◽  
Isometric Handgrip ◽  
Muscle Metaboreflex ◽  
Cirrhotic Patients ◽  
Response To Exercise

We sought to test the hypothesis that the cardiovascular responses to isolated muscle metaboreflex activation would be blunted in patients with cirrhosis. Eleven patients with cirrhosis and 15 healthy controls were evaluated. Blood pressure (BP, oscillometric method), contralateral forearm blood flow (FBF, venous occlusion plethysmography) and heart rate (HR, electrocardiogram) were measured during baseline, isometric handgrip at 30% of maximal voluntary contraction followed by post-exercise ischemia (PEI). Forearm vascular conductance (FVC) was calculated as follows: (FBF/mean BP) x 100. Changes in HR during handgrip were similar between groups, but tended to be different during PEI (controls: ∆0.5 ± 1.1 bpm vs. cirrhotic patients: ∆3.6 ± 1.0 bpm, P = 0.057). Mean BP response to handgrip (controls: ∆20.9 ± 2.7 mmHg vs. cirrhotic patients: ∆10.6 ± 1.5 mmHg, P = 0.006) and PEI was attenuated in cirrhotic patients (controls: ∆16.1 ± 1.9 mmHg vs. cirrhotic patients: ∆7.2 ± 1.4 mmHg, P = 0.001). In contrast, FBF and FVC increased during handgrip and decreased during PEI similarly between groups. These results indicate that an abnormal muscle metaboreflex activation explained, at least partially, the blunted pressor response to exercise exhibited by cirrhotic patients. Novelty bullets: • Patients with cirrhosis present abnormal muscle metaboreflex activation • Blood pressure response was blunted, but forearm vascular response was preserved • Heart rate response was slightly elevated

scholarly journals Interindividual variability in muscle sympathetic responses to static handgrip in young men: evidence for sympathetic responder types?

2018 ◽  
Vol 314 (1) ◽  
pp. R114-R121 ◽  
Author(s):  
Anthony V. Incognito ◽  
Connor J. Doherty ◽  
Jordan B. Lee ◽  
Matthew J. Burns ◽  
Philip J. Millar
Keyword(s):  
Blood Pressure ◽  
Diastolic Blood Pressure ◽  
Interindividual Variability ◽  
Muscle Sympathetic Nerve Activity ◽  
Voluntary Contraction ◽  
Response Patterns ◽  
Arterial Baroreflex ◽  
Muscle Metaboreflex ◽  
Time To Peak ◽  
Pressure Time

Negative and positive muscle sympathetic nerve activity (MSNA) responders have been observed during mental stress. We hypothesized that similar MSNA response patterns could be identified during the first minute of static handgrip and contribute to the interindividual variability throughout exercise. Supine measurements of multiunit MSNA (microneurography) and continuous blood pressure (Finometer) were recorded in 29 young healthy men during the first (HG1) and second (HG2) minute of static handgrip (30% maximal voluntary contraction) and subsequent postexercise circulatory occlusion (PECO). Responders were identified on the basis of differences from the typical error of baseline total MSNA: 7 negative, 12 positive, and 10 nonresponse patterns. Positive responders demonstrated larger total MSNA responses during HG1 ( P < 0.01) and HG2 ( P < 0.0001); however, the increases in blood pressure throughout handgrip exercise were similar between all groups, as were the changes in heart rate, stroke volume, cardiac output, total vascular conductance, and respiration (all P > 0.05). Comparing negative and positive responders, total MSNA responses were similar during PECO ( P = 0.17) but opposite from HG2 to PECO (∆40 ± 46 vs. ∆-21 ± 62%, P = 0.04). Negative responders also had a shorter time-to-peak diastolic blood pressure during HG1 (20 ± 20 vs. 44 ± 14 s, P < 0.001). Total MSNA responses during HG1 were associated with responses to PECO ( r = 0.39, P < 0.05), the change from HG2 to PECO ( r = −0.49, P < 0.01), and diastolic blood pressure time to peak ( r = 0.50, P < 0.01). Overall, MSNA response patterns during the first minute of static handgrip contribute to interindividual variability and appear to be influenced by differences in central command, muscle metaboreflex activation, and rate of loading of the arterial baroreflex.

scholarly journals BLOOD PRESSURE RESPONSE TO ISOMETRIC HANDGRIP EXERCISE IN DIABETIC PATIENTS WITHOUT ESTABLISHED CVD

2019 ◽  
Vol 37 ◽  
pp. e141
Author(s):  
A. Triantafyllou ◽  
K. Dipla ◽  
N. Koletsos ◽  
S. Papadopoulos ◽  
I. Zografou ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Pressure Response ◽  
Pressure Response ◽  
Diabetic Patients ◽  
Handgrip Exercise ◽  
Isometric Handgrip ◽  
Isometric Handgrip Exercise

Blood pressure response during normocapnic hyperpnoea is blunted in young women compared to men

2018 ◽  
Vol 247 ◽  
pp. 52-56 ◽  
Author(s):  
Kaori Shimizu ◽  
Kanako Goto ◽  
Koji Ishida ◽  
Mitsuru Saito ◽  
Hiroshi Akima ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Young Women ◽  
Blood Pressure Response ◽  
Pressure Response

Exaggerated pressor response to blood flow restriction resistance exercise is associated with a muscle metaboreflex-induced increase in blood pressure in young, healthy humans

2020 ◽  
Author(s):  
Amane Hori ◽  
Daisuke Hasegawa ◽  
Kenichi Suijo ◽  
Keita Nishigaki ◽  
Koji Ishida ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Blood Pressure Response ◽  
Pressure Response ◽  
Blood Flow Restriction ◽  
Post Exercise ◽  
Muscle Metaboreflex ◽  
Flow Restriction ◽  
Muscle Ischemia ◽  
Exercise Muscle

Some researchers are concerned that exercise training with the blood flow restriction (BFR) technique induces an exaggeration in blood pressure response and potentiates adverse cardiovascular events. In the present study, we demonstrate that the blood pressure response to arm-curl exercise was intensified by the BFR technique, and the degree of intensification was associated with a blood pressure response to post-exercise muscle ischemia of the elbow flexors, which elicit a muscle metaboreflex. Novelty bullet Blood flow restriction technique intensifies blood pressure response to exercise, which was associated with a blood pressure response in post-exercise muscle ischemia-induced muscle metaboreflex.

scholarly journals Sex-specific impact of aging on the blood pressure response to exercise

2018 ◽  
Vol 314 (1) ◽  
pp. H95-H104 ◽  
Author(s):  
Joel D. Trinity ◽  
Gwenael Layec ◽  
Corey R. Hart ◽  
Russell S. Richardson
Keyword(s):  
Blood Pressure ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Young Women ◽  
Blood Pressure Response ◽  
Plantar Flexion ◽  
Pressure Response ◽  
Old Men ◽  
Response To Exercise ◽  
Plantar Flexion Exercise

An exaggerated blood pressure (BP) response to exercise has been linked to cardiovascular disease, but little is known about the impact of age and sex on this response. Therefore, this study examined the hemodynamic and skeletal muscle metabolic response to dynamic plantar flexion exercise, at 40% of maximum plantar flexion work rate, in 40 physical activity-matched young (23 ± 1 yr, n = 20) and old (73 ± 2 yr, n = 20), equally distributed, male and female subjects. Central hemodynamics and BP (finometer), popliteal artery blood flow (Doppler ultrasound), and skeletal muscle metabolism (31P-magnetic resonance spectroscopy) were measured during 5 min of plantar flexion exercise. Popliteal artery blood flow and high-energy phosphate responses to exercise were not affected by age or sex, whereas aging, independent of sex, attenuated stroke volume and cardiac output responses. Systolic BP and mean arterial pressure responses were exaggerated in old women (Δ42 ± 4 and Δ28 ± 3 mmHg, respectively), with all other groups exhibiting similar increases in systolic BP (old men: Δ27 ± 8 mmHg, young men: Δ27 ± 3 mmHg, and young women: Δ22 ± 3 mmHg) and mean arterial pressure (old men: Δ15 ± 4 mmHg, young men: Δ19 ± 2 mmHg, and young women: Δ17 ± 2 mmHg). Interestingly, the exercise-induced change in systemic vascular resistance in old women (∆0.8 ± 1.0 mmHg·l−1·min−1) was augmented compared with young women and young and old men (∆−2.8 ± 0.5, ∆−1.6 ± 0.6, and ∆−3.18 ± 1.4 mmHg·l−1·min−1, respectively, P < 0.05). Thus, in combination, advancing age and female sex results in an exaggerated BP response to exercise, likely the result of a failure to reduce systemic vascular resistance. NEW & NOTEWORTHY An exaggerated blood pressure response to exercise has been linked to cardiovascular disease; however, little is known about how age and sex impact this response in healthy individuals. During dynamic exercise, older women exhibited an exaggerated blood pressure response driven by an inability to lower systemic vascular resistance.

scholarly journals Transfer function characteristics of the neural and peripheral arterial baroreflex arcs at rest and during postexercise muscle ischemia in humans

2009 ◽  
Vol 296 (5) ◽  
pp. H1416-H1424 ◽  
Author(s):  
Shigehiko Ogoh ◽  
James P. Fisher ◽  
Colin N. Young ◽  
Peter B. Raven ◽  
Paul J. Fadel
Keyword(s):  
Transfer Function ◽  
Muscle Sympathetic Nerve Activity ◽  
Voluntary Contraction ◽  
Arterial Baroreflex ◽  
Isometric Handgrip ◽  
Vascular Conductance ◽  
Muscle Metaboreflex ◽  
Arterial Blood ◽  
Muscle Ischemia ◽  
Transfer Function Gain

Previous studies have demonstrated an increase in the arterial baroreflex (ABR) control of muscle sympathetic nerve activity (MSNA) during isolated activation of the muscle metaboreflex with postexercise muscle ischemia (PEMI). However, the increased ABR-MSNA control does not appear to manifest in an enhancement in the ABR control of arterial blood pressure (BP), suggesting alterations in the transduction of MSNA into a peripheral vascular response and a subsequent ABR-mediated change in BP. Thus we examined the operating gains of the neural and peripheral arcs of the ABR and their interactive relationship at rest and during muscle metaboreflex activation. In nine healthy subjects, graded isolation of the muscle metaboreflex was achieved by PEMI following isometric handgrip performed at 15% and 30% maximal voluntary contraction (MVC). To obtain the sensitivities of the ABR neural and peripheral arcs, the transfer function gain from BP to MSNA and MSNA to femoral vascular conductance, respectively, was analyzed. No changes from rest were observed in the ABR neural or peripheral arcs during PEMI after 15% MVC handgrip. However, PEMI following 30% MVC handgrip increased the low frequency (LF) transfer function gain between BP and MSNA (ABR neural arc; +58 ± 28%, P = 0.036), whereas the LF gain between MSNA and femoral vascular conductance (ABR peripheral arc) was decreased from rest (−36 ± 8%, P = 0.017). These findings suggest that during high-intensity muscle metaboreflex activation an increased ABR gain of the neural arc appears to offset an attenuation of the peripheral arc gain to help maintain the overall ABR control of systemic BP.

Forearm elevation augments sympathetic activation during handgrip exercise in humans

2002 ◽  
Vol 103 (3) ◽  
pp. 295-301 ◽  
Author(s):  
Daisaku MICHIKAMI ◽  
Atsunori KAMIYA ◽  
Qi FU ◽  
Yuki NIIMI ◽  
Satoshi IWASE ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Muscle Sympathetic Nerve Activity ◽  
Voluntary Contraction ◽  
Sympathetic Activation ◽  
Handgrip Exercise ◽  
Excitatory Effect ◽  
Muscle Metaboreflex ◽  
Forearm Exercise ◽  
Exercise In Humans

Although angina pectoris in patients with coronary heart disease often occurs when their forearms are in an elevated position for a prolonged period, and sympathetic activation is a major cause of this condition, little is known about the physiological effects of forearm elevation on sympathetic activity during forearm exercise. We hypothesized that forearm elevation augments sympathetic activation during the static handgrip exercise in humans. A total of 10 healthy male volunteers performed 2min of static handgrip exercise at 30% of maximal voluntary contraction followed by 2min of post-exercise muscle ischaemia (PEMI; specific activation of the muscle metaboreflex) with two forearm positions: the exercising forearm was elevated 50cm above the heart (forearm-elevated trial) or fixed at the level of the heart (heart-level trial). Muscle sympathetic nerve activity (MSNA), blood pressure and heart rate were monitored. MSNA increased during handgrip exercise in both forearm positions (P<0.001); the increase was 51% greater in the forearm-elevated trial (516±99 arbitrary units) than in the heart-level trial (346±44units; P<0.05). The increase in mean blood pressure was 8.4mmHg greater during exercise in the forearm-elevated trial (P<0.05), while changes in heart rate were similar in both forearm positions. The increase in MSNA during PEMI was 71% greater in the forearm-elevated trial (393±71 arbitrary units/min) than in the heart-level trial (229±29units/min; P<0.05). These results support the hypothesis that forearm elevation augments sympathetic activation during handgrip exercise. The excitatory effect of forearm elevation on exercising MSNA may be mediated primarily by increased activation of the muscle metaboreflex.

Effect of muscle metaboreflex activation on carotid-cardiac baroreflex function in humans

2008 ◽  
Vol 294 (5) ◽  
pp. H2296-H2304 ◽  
Author(s):  
James P. Fisher ◽  
Colin N. Young ◽  
Paul J. Fadel
Keyword(s):  
Blood Pressure ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Isometric Handgrip ◽  
Response Curves ◽  
Baroreflex Control ◽  
Muscle Metaboreflex ◽  
Baroreflex Function ◽  
Carotid Baroreflex ◽  
Neck Pressure

Whether the activation of metabolically sensitive skeletal muscle afferents (i.e., muscle metaboreflex) influences cardiac baroreflex responsiveness remains incompletely understood. A potential explanation for contrasting findings of previous reports may be related to differences in the magnitude of muscle metaboreflex activation utilized. Therefore, the present study was designed to investigate the influence of graded intensities of muscle metaboreflex activation on cardiac baroreflex function. In eight healthy subjects (24 ± 1 yr), the graded isolation of the muscle metaboreflex was achieved by post-exercise ischemia (PEI) following moderate- (PEI-M) and high- (PEI-H) intensity isometric handgrip performed at 35% and 45% maximum voluntary contraction, respectively. Beat-to-beat heart rate (HR) and blood pressure were measured continuously. Rapid pulse trains of neck pressure and neck suction (+40 to −80 Torr) were applied to derive carotid baroreflex stimulus-response curves. Mean blood pressure increased significantly from rest during PEI-M (+13 ± 3 mmHg) and was further augmented during PEI-H (+26 ± 4 mmHg), indicating graded metaboreflex activation. However, the operating point gain and maximal gain (−0.51 ± 0.09, −0.48 ± 0.13, and −0.49 ± 0.12 beats·min−1·mmHg−1 for rest; PEI-M and PEI-H) of the carotid-cardiac baroreflex function curve were unchanged from rest during PEI-M and PEI-H ( P > 0.05 vs. rest). Furthermore, the carotid-cardiac baroreflex function curve was progressively reset rightward from rest to PEI-M to PEI-H, with no upward resetting. These findings suggest that the muscle metaboreflex contributes to the resetting of the carotid baroreflex control of HR; however, it would appear not to influence carotid-cardiac baroreflex responsiveness in humans, even with high-intensity activation during PEI.

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