scholarly journals Local adenosine receptor blockade accentuates the sympathetic responses to fatiguing exercise

2010 ◽  
Vol 298 (6) ◽  
pp. H2130-H2137 ◽  
Author(s):  
Jian Cui ◽  
Urs A. Leuenberger ◽  
Cheryl Blaha ◽  
Jonathan Yoder ◽  
Zhaohui Gao ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Adenosine Receptor ◽  
Muscle Sympathetic Nerve Activity ◽  
Receptor Blockade ◽  
Isometric Handgrip ◽  
Before And After ◽  
Fatiguing Exercise ◽  
Blood Pressure Responses ◽  
Bier Block ◽  
Passive Stretch

The role adenosine plays in evoking the exercise pressor reflex in humans remains controversial. We hypothesized that localized forearm adenosine receptor blockade would attenuate muscle sympathetic nerve activity (MSNA) responses to fatiguing handgrip exercise in humans. Blood pressure (Finometer), heart rate, and MSNA from the peroneal nerve were assessed in 11 healthy young volunteers during fatiguing isometric handgrip, postexercise circulatory occlusion (PECO), and passive muscle stretch during PECO. The protocol was performed before and after adenosine receptor blockade by local infusion of 40 mg aminophylline in saline via forearm Bier block (regional intravenous anesthesia). In the second experiment, the same amount of saline was infused via the Bier block. After aminophylline, the MSNA and blood pressure responses to fatiguing handgrip, PECO, and passive stretch (all P < 0.05) were significantly greater than during the control condition. Saline Bier block had no similar effects on the MSNA and blood pressure responses. These data suggest that adenosine receptor antagonism in the exercising muscles may accentuate sympathetic activation during fatiguing exercise.

scholarly journals Resistance and aerobic exercise protects against acute endothelial impairment induced by a single exposure to hypertension during exertion

2011 ◽  
Vol 110 (4) ◽  
pp. 1013-1020 ◽  
Author(s):  
Shane A. Phillips ◽  
Emon Das ◽  
Jingli Wang ◽  
Kirkwood Pritchard ◽  
David D. Gutterman
Keyword(s):  
Blood Pressure ◽  
Resistance Exercise ◽  
Aerobic Exercise ◽  
Vascular Function ◽  
Cardiovascular Health ◽  
Weight Lifting ◽  
Acute Hypertension ◽  
Before And After ◽  
Weight Lifters ◽  
Blood Pressure Responses

Resistance and aerobic exercise is recommended for cardiovascular health and disease prevention. However, the accompanying increase in arterial pressure during resistance exercise may be detrimental to vascular health. This study tests the vascular benefits of aerobic compared with resistance exercise on preventing impaired vascular function induced by a single weight lifting session that is associated with acute hypertension. Healthy, lean sedentary (SED) subjects, weight lifters, runners (>15 miles/wk), and cross trainers (chronic aerobic and resistance exercisers), underwent a single progressive leg press weight lifting session with blood pressure measurements. Brachial artery flow-mediated vasodilation (FMD; an index of arterial endothelial function) was determined using ultrasonography immediately before and after weight lifting. Sublingual nitroglycerin (0.4 mg) was used to determine endothelium-independent dilation after weight lifting. All subjects were normotensive with similar blood pressure responses during exercise. Baseline FMD was lower in runners (5.4 ± 0.5%; n = 13) and cross trainers (4.44 ± 0.3%; n = 13) vs. SED (8.5 ± 0.8%; n = 13; P = 0.037). Brachial FMD improved in conditioned weight lifters (to 8.8 ± 0.9%; P = 0.007) and runners (to 7.6 ± 0.6%; P < 0.001) but not cross trainers (to 5.3 ± 0.6%; P = NS) after acute hypertension. FMD was decreased in SED (to 5.7 ± 0.4%; P = 0.019). Dilation to nitroglycerin was similar among groups. These data suggest that endothelial responses are maintained after exposure to a single bout of weight lifting in resistance and aerobic athletes. Resistance and aerobic exercise may confer similar protection against acute vascular insults such as exertional hypertension.

scholarly journals Sympathetic and cardiovascular responses to venous distension in an occluded limb

2011 ◽  
Vol 301 (6) ◽  
pp. R1831-R1837 ◽  
Author(s):  
Jian Cui ◽  
Urs A. Leuenberger ◽  
Zhaohui Gao ◽  
Lawrence I. Sinoway
Keyword(s):  
Blood Pressure ◽  
Sympathetic Nerve Activity ◽  
Present Report ◽  
Muscle Sympathetic Nerve Activity ◽  
Cardiovascular Responses ◽  
Saline Infusion ◽  
Nerve Activity ◽  
Sympathetic Response ◽  
Venous Circulation ◽  
Blood Pressure Responses

We recently showed that a fixed volume (i.e., 40 ml) of saline infused into the venous circulation of an arterially occluded vascular bed increases muscle sympathetic nerve activity (MSNA) and blood pressure. In the present report, we hypothesized that the volume and rate of infusion would influence the magnitude of the sympathetic response. Blood pressure, heart rate, and MSNA were assessed in 13 young healthy subjects during forearm saline infusions (arrested circulation). The effects of different volumes of saline (i.e., 2%, 3%, 4%, or 5% forearm volume at 30 ml/min) and different rates of infusion (i.e., 5% forearm volume at 10, 20, or 30 ml/min) were evaluated. MSNA and blood pressure responses were linked with the infusion volume. Infusion of 5% of forearm volume evoked greater MSNA responses than did infusion of 2% of forearm volume (Δ11.6 ± 1.9 vs. Δ3.1 ± 1.8 bursts/min and Δ332 ± 105 vs. Δ38 ± 32 units/min, all P < 0.05). Moreover, greater MSNA responses were evoked by saline infusion at 30 ml/min than 10 ml/min ( P < 0.05). Sonographic measurements confirmed that the saline infusions induced forearm venous distension. The results suggest that volume and rate of saline infusion are important factors in evoking sympathetic activation. We postulate that venous distension contributes to cardiovascular autonomic adjustment in humans.

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.

scholarly journals Limb venous distension evokes sympathetic activation via stimulation of the limb afferents in humans

2012 ◽  
Vol 303 (4) ◽  
pp. H457-H463 ◽  
Author(s):  
Jian Cui ◽  
Patrick M. McQuillan ◽  
Cheryl Blaha ◽  
Allen R. Kunselman ◽  
Lawrence I. Sinoway
Keyword(s):  
Blood Pressure ◽  
Normal Saline ◽  
Sympathetic Nerve Activity ◽  
Human Subjects ◽  
Muscle Sympathetic Nerve Activity ◽  
Saline Infusion ◽  
Afferent Nerves ◽  
Postural Stress ◽  
Human Forearm ◽  
Blood Pressure Responses

We have recently shown that a saline infusion in the veins of an arterially occluded human forearm evokes a systemic response with increases in muscle sympathetic nerve activity (MSNA) and blood pressure. In this report, we examined whether this response was a reflex that was due to venous distension. Blood pressure (Finometer), heart rate, and MSNA (microneurography) were assessed in 14 young healthy subjects. In the saline trial ( n = 14), 5% forearm volume normal saline was infused in an arterially occluded arm. To block afferents in the limb, 90 mg of lidocaine were added to the same volume of saline in six subjects during a separate visit. To examine whether interstitial perfusion of normal saline alone induced the responses, the same volume of albumin solution (5% concentration) was infused in 11 subjects in separate studies. Lidocaine abolished the MSNA and blood pressure responses seen with saline infusion. Moreover, compared with the saline infusion, an albumin infusion induced a larger (MSNA: Δ14.3 ± 2.7 vs. Δ8.5 ± 1.3 bursts/min, P < 0.01) and more sustained MSNA and blood pressure responses. These data suggest that venous distension activates afferent nerves and evokes a powerful systemic sympathoexcitatory reflex. We posit that the venous distension plays an important role in evoking the autonomic adjustments seen with postural stress in human subjects.

Effects of combined histamine H1 and H2 receptor blockade on hemodynamic responses to dynamic exercise in males with high-normal blood pressure

2020 ◽  
Vol 45 (7) ◽  
pp. 769-776
Author(s):  
Ashley Naylor ◽  
Brian Shariffi ◽  
Trevor L. Gillum ◽  
Boyer William ◽  
Sean Sullivan ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Dynamic Exercise ◽  
Histamine Receptors ◽  
Normal Group ◽  
Receptor Blockade ◽  
Peripheral Vasoconstriction ◽  
Before And After ◽  
Group A ◽  
Postexercise Hypotension ◽  
Response To Exercise

While postexercise hypotension is associated with histamine H1 and H2 receptor-mediated postexercise vasodilation, effects of histaminergic vasodilation on blood pressure (BP) in response to dynamic exercise are not known. Thus, in 20 recreationally active male participants (10 normotensive and 10 with high-normal BP) we examined the effects of histamine H1 and H2 receptor blockade on cardiac output (CO), mean atrial pressure (MAP), aortic stiffness (AoStiff), and total vascular conductance (TVC) at rest and during progressive cycling exercise. Compared with the normotensive group, MAP, CO, and AoStiff were higher in the high-normal group before and after the blockade at rest, while TVC was similar. At the 40% workload, the blockade significantly increased MAP in both groups, while no difference was found in the TVC. CO was higher in the high-normal group than the normotensive group in both conditions. At the 60% workload, the blockade substantially increased MAP and decreased TVC in the normotensive group, while there were no changes in the high-normal group. A similar CO response pattern was observed at the 60% workload. These findings suggest that the mechanism eliciting an exaggerated BP response to exercise in the high-normal group may be partially due to the inability of histamine receptors. Novelty Males with high-normal BP had an exaggerated BP response to exercise. The overactive BP response is known due to an increase in peripheral vasoconstriction. Increase in peripheral vasoconstriction is partially due to inability of histamine receptors.

Effects of ganglionic blockade by hexamethonium on blood pressure responses to histamine

1960 ◽  
Vol 199 (5) ◽  
pp. 745-747 ◽  
Author(s):  
James G. Hilton
Keyword(s):  
Blood Pressure ◽  
Nervous Activity ◽  
Blocking Agent ◽  
Sodium Pentobarbital ◽  
Autonomic Nervous Activity ◽  
Control Blood Pressure ◽  
Acid Phosphate ◽  
Before And After ◽  
Blood Pressure Responses ◽  
Ganglionic Blocking

The effects of blockade of the autonomic ganglia by administration of hexamethonium on blood pressure responses to histamine were studied in the dog anesthetized with sodium pentobarbital. A series of graded doses of histamine acid phosphate were administered before and after the blockade of the ganglia, and blood pressure responses elicited by these doses of histamine were analyzed for minimum attained blood pressure and actual fall and duration of fall in blood pressure. In all cases the minimum attained blood pressure was lower after administration of the ganglionic blocking agent than before. The amount of lowering of the minimum attainable blood pressure was about the same as that of lowering of the control blood pressure produced by the ganglionic blocking agent. Actual fall in blood pressure was unaffected by administration of the ganglionic blocking agent but duration of the fall following all the larger doses of histamine was markedly prolonged by this same procedure. Prolongation of depressor response and lowering of minimum attained blood pressure seem to be more related to the presence or absence of autonomic nervous activity than to the level of control blood pressure.

Chemoreflex and metaboreflex control during static hypoxic exercise

2005 ◽  
Vol 288 (4) ◽  
pp. H1724-H1729 ◽  
Author(s):  
Anne Houssiere ◽  
Boutaina Najem ◽  
Agniezka Ciarka ◽  
Sonia Velez-Roa ◽  
Robert Naeije ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Circulatory Arrest ◽  
Handgrip Exercise ◽  
Isometric Handgrip ◽  
Isometric Handgrip Exercise ◽  
Baseline Values ◽  
Hypoxic Exercise

To investigate the effects of muscle metaboreceptor activation during hypoxic static exercise, we recorded muscle sympathetic nerve activity (MSNA), heart rate, blood pressure, ventilation, and blood lactate in 13 healthy subjects (22 ± 2 yr) during 3 min of three randomized interventions: isocapnic hypoxia (10% O2) (chemoreflex activation), isometric handgrip exercise in normoxia (metaboreflex activation), and isometric handgrip exercise during isocapnic hypoxia (concomitant metaboreflex and chemoreflex activation). Each intervention was followed by a forearm circulatory arrest to allow persistent metaboreflex activation in the absence of exercise and chemoreflex activation. Handgrip increased blood pressure, MSNA, heart rate, ventilation, and lactate (all P < 0.001). Hypoxia without handgrip increased MSNA, heart rate, and ventilation (all P < 0.001), but it did not change blood pressure and lactate. Handgrip enhanced blood pressure, heart rate, MSNA, and ventilation responses to hypoxia (all P < 0.05). During circulatory arrest after handgrip in hypoxia, heart rate returned promptly to baseline values, whereas ventilation decreased but remained elevated ( P < 0.05). In contrast, MSNA, blood pressure, and lactate returned to baseline values during circulatory arrest after hypoxia without exercise but remained markedly increased after handgrip in hypoxia ( P < 0.05). We conclude that metaboreceptors and chemoreceptors exert differential effects on the cardiorespiratory and sympathetic responses during exercise in hypoxia.

scholarly journals Acute blood pressure responses after different isometric handgrip protocols in hypertensive patients

Clinics ◽  
2018 ◽  
Vol 73 ◽  
Author(s):  
GO Silva ◽  
BQ Farah ◽  
AH Germano-Soares ◽  
A Andrade-Lima ◽  
FS Santana ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Isometric Handgrip ◽  
Hypertensive Patients ◽  
Blood Pressure Responses

Attenuated responses to sympathoexcitation in individuals with Down syndrome

2003 ◽  
Vol 94 (6) ◽  
pp. 2158-2165 ◽  
Author(s):  
Bo Fernhall ◽  
Mari Otterstetter
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Down Syndrome ◽  
Autonomic Dysfunction ◽  
Treadmill Exercise ◽  
Cold Pressor ◽  
Normal Weight ◽  
Maximal Heart Rate ◽  
Isometric Handgrip ◽  
Blood Pressure Responses

This study evaluated blood pressure and heart rate responses to exercise and nonexercise tasks as indexes of autonomic function in subjects with and without Down syndrome (DS). Twenty-four subjects (12 with and 12 without DS) completed maximal treadmill exercise, isometric handgrip (30% of maximum), and cold pressor tests, with heart rate and blood pressure measurements. Maximal heart rate and heart rate and blood pressure responses to the isometric handgrip and cold pressor tests were reduced in subjects with DS ( P < 0.05). Both early (first 30 s) and late (last 30 s) responses were reduced. Obesity did not appear to influence the results, as both obese and normal-weight subjects with DS exhibited similar responses, and controlling for body mass index did not alter the results between controls and subjects with DS. Individuals with DS, without congenital heart disease, exhibit reduced heart rate and blood pressure responses to isometric handgrip exercise and cold pressor testing, consistent with autonomic dysfunction. Autonomic dysfunction may partially explain chronotropic incompetence observed during maximal treadmill exercise in individuals with DS.

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