Venous occlusion to the lower limb attenuates vasoconstriction in the nonexercised limb during posthandgrip muscle ischemia

2004 ◽  
Vol 96 (3) ◽  
pp. 981-984 ◽  
Author(s):  
K. Tokizawa ◽  
M. Mizuno ◽  
Y. Nakamura ◽  
I. Muraoka
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Cardiovascular Responses ◽  
Venous Occlusion ◽  
Muscle Ischemia ◽  
Baseline Values ◽  
Exercise Muscle ◽  
Forearm Vascular Resistance ◽  
Muscle Chemoreflex

We investigated the effects of increases in calf volume on cardiovascular responses during handgrip (HG) exercise and post-HG exercise muscle ischemia (PEMI). Seven subjects completed two trials: one control (no occlusion) and one venous occlusion (VO) session. Both trials included a baseline measurement followed by 15 min of rest (REST), 2 min of HG, and 2 min of PEMI. VO was applied at 100 mmHg via cuffs placed around both distal thighs during REST, HG, and PEMI. Mean arterial pressure, heart rate, forearm blood flow (FBF) in the nonexercised arm, and forearm vascular resistance (FVR) in the nonexercised arm (FVR) were measured. During REST and HG, there were no significant differences between trials in all parameters. During PEMI in the control trial, mean arterial pressure and FVR were significantly greater and FBF was significantly lower than baseline values ( P < 0.05 for each). In contrast, in the VO trial, FBF and FVR responses were different from control responses. In the VO trial, FBF was significantly greater than in the control trial (4.7 ± 0.5 vs. 2.5 ± 0.3 ml·100 ml-1·min-1, P < 0.05) and FVR was significantly lower (28.0 ± 4.8 vs. 49.1 ± 4.6 units, respectively, P < 0.05). These results indicate that increases in vascular resistance in the nonexercised limb induced by activation of the muscle chemoreflex can be attenuated by increases in calf volume.

Passive triceps surae stretch inhibits vasoconstriction in the nonexercised limb during posthandgrip muscle ischemia

2004 ◽  
Vol 97 (5) ◽  
pp. 1681-1685 ◽  
Author(s):  
Ken Tokizawa ◽  
Masaki Mizuno ◽  
Yoshio Nakamura ◽  
Isao Muraoka
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Forearm Blood Flow ◽  
Triceps Surae ◽  
Muscle Ischemia ◽  
Forearm Vascular Conductance ◽  
Muscle Mechanoreceptor ◽  
Baseline Values ◽  
Exercise Muscle ◽  
The Right

We investigated whether selective muscle mechanoreceptor activation in the lower limb opposes arm muscle metaboreceptor activation-mediated limb vasoconstriction. Seven subjects completed two trials: one control trial and one stretch trial. Both trials included 2 min of handgrip and 2 min of posthandgrip exercise muscle ischemia (PEMI). In the stretch trial, a 2-min sustained triceps surae stretch, by brief passive dorsiflexion of the right foot, was performed simultaneously during PEMI. Mean arterial pressure, heart rate, and forearm blood flow (FBF) in the nonexercised arm and forearm vascular conductance (FVC) in the nonexercised arm were measured. During PEMI in the control trial, mean arterial pressure was significantly greater and FBF and FVC were significantly lower than baseline values ( P < 0.05 for each). In contrast, FBF and FVC during PEMI in the stretch trial exhibited different responses than in the control trial. FBF and FVC were significantly greater in the stretch trial than in the control trial (FBF, 5.5 ± 0.4 vs. 3.8 ± 0.4 ml·100 ml−1·min−1; FVC, 0.048 ± 0.004 vs. 0.033 ± 0.003 unit, respectively; P < 0.05). These results indicate that passive triceps surae stretch can inhibit vasoconstriction in the nonexercised forearm mediated via muscle metaboreceptor activation in the exercised arm.

Cardiovascular and Valsalva responses during parabolic flight

1998 ◽  
Vol 85 (5) ◽  
pp. 1957-1965 ◽  
Author(s):  
Todd T. Schlegel ◽  
Edgar W. Benavides ◽  
Donald C. Barker ◽  
Troy E. Brown ◽  
Deborah L. Harm ◽  
...  
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Human Subjects ◽  
Parabolic Flight ◽  
Cardiovascular Responses ◽  
Systematic Evaluation ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Flight Measurements

We investigated the integrated cardiovascular responses of 15 human subjects to the acute gravitational changes (micro- and hypergravity portions) of parabolic flight. Measurements were made with subjects quietly seated and while subjects performed controlled Valsalva maneuvers. During quiet, seated, parabolic flight, mean arterial pressure increased during the transition into microgravity but decreased as microgravity was sustained. The decrease in mean arterial pressure was accompanied by immediate reflexive increases in heart rate but by absent (or later-than-expected) reflexive increases in total vascular resistance. Mean arterial pressure responses in Valsalva phases IIl, III, and IV were accentuated in hypergravity relative to microgravity ( P < 0.01, P < 0.01, and P < 0.05, respectively), but accentuations differed qualitatively and quantitatively from those induced by a supine-to-seated postural change in 1 G. This study is the first systematic evaluation of temporal and Valsalva-related changes in cardiovascular parameters during parabolic flight. Results suggest that arterial baroreflex control of vascular resistance may be modified by alterations of cardiopulmonary, vestibular, and/or other receptor activity.

Hemodynamic and sympathoadrenal responses to mental stress during nitric oxide synthesis inhibition

2004 ◽  
Vol 287 (5) ◽  
pp. H2309-H2315 ◽  
Author(s):  
Madeleine Lindqvist ◽  
Anders Melcher ◽  
Paul Hjemdahl
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Mental Stress ◽  
Stress Test ◽  
Arterial Plasma ◽  
Forearm Vascular Resistance

Cardiovascular and sympathoadrenal responses to a reproducible mental stress test were investigated in eight healthy young men before and during intravenous infusion of the nitric oxide (NO) synthesis inhibitor N-monomethyl-l-arginine (l-NMMA). Before l-NMMA, stress responses included significant increases in heart rate, mean arterial pressure, and cardiac output (CO) and decreases in systemic and forearm vascular resistance. Arterial plasma norepinephrine (NE) increased. At rest after 30 min of infusion of l-NMMA (0.3 mg·kg−1·min−1 iv), mean arterial pressure increased from 98 ± 4 to 108 ± 3 mmHg ( P < 0.001) because of an increase in systemic vascular resistance from 12.9 ± 0.5 to 18.5 ± 0.9 units ( P < 0.001). CO decreased from 7.7 ± 0.4 to 5.9 ± 0.3 l/min ( P < 0.01). Arterial plasma NE decreased from 2.08 ± 0.16 to 1.47 ± 0.14 nmol/l. Repeated mental stress during continued infusion of l-NMMA (0.15 mg·kg−1·min−1) induced qualitatively similar cardiovascular responses, but there was a marked attenuation of the increase in mean arterial blood pressure, resulting in similar “steady-state” blood pressures during mental stress without and with NO blockade. Increases in heart rate and CO were attenuated, but stress-induced decreases in systemic and forearm vascular resistance were essentially unchanged. Arterial plasma NE increased less than during the first stress test. Thus the increased arterial tone at rest during l-NMMA infusion is compensated for by attenuated increases in blood pressure during mental stress, mainly through a markedly attenuated CO response and suppressed sympathetic nerve activity.

scholarly journals Sustained increases in blood pressure elicited by prolonged face cooling in humans

2016 ◽  
Vol 311 (4) ◽  
pp. R643-R648 ◽  
Author(s):  
Zachary J. Schlader ◽  
Gregory L. Coleman ◽  
James R. Sackett ◽  
Suman Sarker ◽  
Blair D. Johnson
Keyword(s):  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Dependent Variables ◽  
The Face ◽  
Cardiac Parasympathetic Activity ◽  
Ice Water ◽  
Face Cooling ◽  
Forearm Vascular Resistance

We tested the hypothesis that increases in blood pressure are sustained throughout 15 min of face cooling. Two independent trials were carried out. In the Face-Cooling Trial, 10 healthy adults underwent 15 min of face cooling where a 2.5-liter bag of ice water (0 ± 0°C) was placed over their cheeks, eyes, and forehead. The Sham Trial was identical except that the temperature of the water was 34 ± 1°C. Primary dependent variables were forehead temperature, mean arterial pressure, and forearm vascular resistance. The square root of the mean of successive differences in R-R interval (RMSSD) provided an index of cardiac parasympathetic activity. In the Face Cooling Trial, forehead temperature fell from 34.1 ± 0.9°C at baseline to 12.9 ± 3.3°C at the end of face cooling ( P < 0.01). Mean arterial pressure increased from 83 ± 9 mmHg at baseline to 106 ± 13 mmHg at the end of face cooling ( P < 0.01). RMSSD increased from 61 ± 40 ms at baseline to 165 ± 97 ms during the first 2 min of face cooling ( P ≤ 0.05), but returned to baseline levels thereafter (65 ± 49 ms, P ≥ 0.46). Forearm vascular resistance increased from 18.3 ± 4.4 mmHg·ml−1·100 g tissue−1·min at baseline to 26.6 ± 4.0 mmHg·ml−1·100 g tissue−1·min at the end of face cooling ( P < 0.01). There were no changes in the Sham Trial. These data indicate that increases in blood pressure are sustained throughout 15 min of face cooling, and face cooling elicits differential time-dependent parasympathetic and likely sympathetic activation.

Rodent cardiovascular responses to baroreceptor unloading: Effect of plane of anaesthesia

2011 ◽  
Vol 36 (3) ◽  
pp. 376-381 ◽  
Author(s):  
Charlotte W. Usselman ◽  
Louis Mattar ◽  
Jasna Twynstra ◽  
Ian Welch ◽  
J. Kevin Shoemaker
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Cardiovascular Responses ◽  
Cardiovascular Control ◽  
Noxious Stimulation ◽  
Lower Body

The objective of this study was to determine whether a plane of urethane–α-chloralose anaesthesia that suppresses motor reflexes would affect baroreflex cardiovascular control relative to a plane of anaesthesia that leaves motor reflexes intact. Adult male Sprague–Dawley rats were anaesthetized to either a light (motor reflexes intact) or deep (motor reflexes suppressed) plane of anaesthesia. Animals were exposed to graded (–2 to –10 mm Hg) lower body negative pressure while heart rate, vascular resistance, and mean arterial pressure were assessed. No between-group differences were observed in baseline hemodynamics. Graded lower body negative pressure progressively increased heart rate (p < 0.01) and vascular resistance (p < 0.001) and reduced mean arterial pressure (p < 0.001) similarly in light and deep planes of anaesthesia. Therefore, the deep plane of anaesthesia was not associated with a degradation of the autonomic response to baroreceptor unloading beyond that observed at the light plane. These data support the use of urethane–α-chloralose anaesthesia in studies examining reflex cardiovascular control concomitant with some degree of noxious stimulation.

scholarly journals Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance

2002 ◽  
Vol 92 (2) ◽  
pp. 586-594 ◽  
Author(s):  
Wendy W. Waters ◽  
Michael G. Ziegler ◽  
Janice V. Meck
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Orthostatic Hypotension ◽  
Vascular Resistance ◽  
Plasma Volume ◽  
Strong Dependence ◽  
Cardiovascular Responses ◽  
Volume Status ◽  
Men And Women

About 20% of astronauts suffer postspaceflight presyncope. We studied pre- to postflight (5- to 16-day missions) cardiovascular responses to standing in 35 astronauts to determine differences between 1) men and women and 2) presyncopal and nonpresyncopal groups. The groups were presyncopal women, presyncopal men, and nonpresyncopal men based on their ability to stand for 10 min postflight. Preflight, women and presyncopal men had low vascular resistance, with the women having the lowest. Postflight, women experienced higher rates of presyncope (100 vs. 20%; P = 0.001) and greater losses of plasma volume (20 vs. 7%; P < 0.05) than men. Also, presyncopal subjects had lower standing mean arterial pressure (P ≤ 0.001) and vascular resistance ( P < 0.05), smaller increases in norepinephrine ( P ≤ 0.058) and greater increases in epinephrine ( P ≤ 0.058) than nonpresyncopal subjects. Presyncopal subjects had a strong dependence on plasma volume to maintain standing stroke volume. These findings suggest that postflight presyncope is greatest in women, and this can be ascribed to a combination of inherently low-resistance responses, a strong dependence on volume status, and relative hypoadrenergic responses. Conversely, high vascular resistance and postflight hyperadrenergic responses prevent presyncope.

scholarly journals Plasticity in breathing and arterial blood pressure following acute intermittent hypercapnic hypoxia in infant rat pups with a partial loss of 5-HT neurons

2015 ◽  
Vol 309 (10) ◽  
pp. R1273-R1284 ◽  
Author(s):  
Jennifer Magnusson ◽  
Kevin J. Cummings
Keyword(s):  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Arterial Blood Pressure ◽  
Cardiovascular Responses ◽  
Partial Loss ◽  
Rat Pups ◽  
Arterial Blood ◽  
Hypercapnic Hypoxia ◽  
Long Term Facilitation

The role of serotonin (5-HT) neurons in cardiovascular responses to acute intermittent hypoxia (AIH) has not been studied in the neonatal period. We hypothesized that a partial loss of 5-HT neurons would reduce arterial blood pressure (BP) at rest, increase the fall in BP during hypoxia, and reduce the long-term facilitation of breathing (vLTF) and BP following AIH. We exposed 2-wk-old, 5,7-dihydroxytryptamine-treated and controls to AIH (10% O2; n = 13 control, 14 treated), acute intermittent hypercapnia (5% CO2; n = 12 and 11), or acute intermittent hypercapnic hypoxia (AIHH; 10% O2, 5% CO2; n = 15 and 17). We gave five 5-min challenges of AIH and acute intermittent hypercapnia, and twenty ∼20-s challenges of AIHH to mimic sleep apnea. Systolic BP (sBP), diastolic BP, mean arterial pressure, heart rate (HR), ventilation (V̇e), and metabolic rate (V̇o2) were continuously monitored. 5,7-Dihydroxytryptamine induced an ∼35% loss of 5-HT neurons from the medullary raphe. Compared with controls, pups deficient in 5-HT neurons had reduced resting sBP (∼6 mmHg), mean arterial pressure (∼5 mmHg), and HR (56 beats/min), and experienced a reduced drop in BP during hypoxia. AIHH induced vLTF in both groups, reflected in increased V̇e and V̇e/V̇o2, and decreased arterial Pco2. The sBP of pups deficient in 5-HT neurons, but not controls, was increased 1 h following AIHH. Our data suggest that a relatively small loss of 5-HT neurons compromises resting BP and HR, but has no influence on ventilatory plasticity induced by AIHH. AIHH may be useful for reversing cardiorespiratory defects related to partial 5-HT system dysfunction.

Hypotensive and Regional Haemodynamic Effects of Exercise, Fasted and after Food, in Human Sympathetic Denervation

1998 ◽  
Vol 94 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Sharmini Puvi-Rajasingham ◽  
Gareth D. P. Smith ◽  
Adeola Akinola ◽  
Christopher J. Mathias
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Superior Mesenteric Artery ◽  
Vascular Resistance ◽  
Mesenteric Artery ◽  
Autonomic Failure ◽  
Sympathetic Denervation ◽  
Stroke Distance

1. In human sympathetic denervation due to primary autonomic failure, food and exercise in combination may produce a cumulative blood pressure lowering effect due to simultaneous splanchnic and skeletal muscle dilatation unopposed by corrective cardiovascular reflexes. We studied 12 patients with autonomic failure during and after 9 min of supine exercise, when fasted and after a liquid meal. Standing blood pressure was also measured before and after exercise. 2. When fasted, blood pressure fell during exercise from 162 ± 7/92 ± 4 to 129 ± 9/70 ± 5 mmHg (mean arterial pressure by 22 ± 5%), P < 0.0005. After the meal, blood pressure fell from 159 ± 8/88 ± 6 to 129 ± 6/70 ± 4 mmHg (mean arterial pressure by 22 ± 3%), P < 0.0001, and further during exercise to 123 ± 6/61 ± 3 mmHg (mean arterial pressure by 9 ± 3%), P < 0.01. The stroke distance—heart rate product, an index of cardiac output, did not change after the meal. During exercise, changes in the stroke distance—heart rate product were greater when fasted. 3. Resting forearm and calf vascular resistance were higher when fasted. Calf vascular resistance fell further after exercise when fasted. Resting superior mesenteric artery vascular resistance was lower when fed; 0.19 ± 0.02 compared with 032 ± 0.06, P < 0.05. After exercise, superior mesenteric artery vascular resistance had risen by 82%, to 0.53 ± 0.12, P < 0.05 (fasted) and by 47%, to 0.29 ± 0.05, P < 0.05 (fed). 4. On standing, absolute levels of blood pressure were higher when fasted [83 ± 7/52 ± 7 compared with 71 ± 2/41 ± 3 (fed), each P < 0.05]. Subjects were more symptomatic on standing post-exercise when fed. 5. In human sympathetic denervation, exercise in the fed state lowered blood pressure further than when fasted and worsened symptoms of postural hypotension.

Enhanced vasodilation to acetylcholine in athletes is associated with lower plasma cholesterol

1996 ◽  
Vol 270 (6) ◽  
pp. H2008-H2013 ◽  
Author(s):  
B. A. Kingwell ◽  
B. Tran ◽  
J. D. Cameron ◽  
G. L. Jennings ◽  
A. M. Dart
Keyword(s):  
Sodium Nitroprusside ◽  
Vascular Resistance ◽  
Repeated Measures ◽  
Vascular Reactivity ◽  
Plasma Cholesterol ◽  
Total Cholesterol Level ◽  
Venous Occlusion ◽  
Ang Ii ◽  
Elevated Cholesterol ◽  
Forearm Vascular Resistance

We investigated a change in vascular reactivity as a potential adaptive mechanism to chronic exercise. The study consisted of 2 separate protocols with 10 male athletes and 10 age-matched sedentary male control subjects participating in each. Protocol 1 investigated forearm blood flow responses to intra-arterial infusions of acetylcholine and sodium nitroprusside by use of venous occlusion plethysmography. Protocol 2 used identical techniques to study responses to norepinephrine, angiotensin II (ANG II), and NG-monomethyl-L-arginine (L-NMMA). The percent reduction in forearm vascular resistance to acetylcholine was significantly greater in the athletic compared with the sedentary group (multivariate analysis of variance for repeated measures, P = 0.03). Covariance analysis suggested that the lower total cholesterol level of the athletic group (P = 0.03) may contribute to their enhanced responsiveness to acetylcholine. There were no differences between athletic and sedentary groups in the forearm vascular resistance responses to norepinephrine, ANG II, sodium nitroprusside, or L-NMMA. These data support the hypothesis that long-term endurance training is associated with enhanced endothelium-dependent dilator reserve due to altered lipoprotein levels in athletes. This finding may have therapeutic application in conditions of elevated cholesterol and impaired vasodilator capacity including hypertension, hypercholesterolemia, atherosclerosis, and cardiac failure.

Increased vascular resistance in paralyzed legs after spinal cord injury is reversible by training

2002 ◽  
Vol 93 (6) ◽  
pp. 1966-1972 ◽  
Author(s):  
Maria T. E. Hopman ◽  
Jan T. Groothuis ◽  
Marcel Flendrie ◽  
Karin H. L. Gerrits ◽  
Sibrand Houtman
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Cord Injury

The purpose of the present study was to determine the effect of a spinal cord injury (SCI) on resting vascular resistance in paralyzed legs in humans. To accomplish this goal, we measured blood pressure and resting flow above and below the lesion (by using venous occlusion plethysmography) in 11 patients with SCI and in 10 healthy controls (C). Relative vascular resistance was calculated as mean arterial pressure in millimeters of mercury divided by the arterial blood flow in milliliters per minute per 100 milliliters of tissue. Arterial blood flow in the sympathetically deprived and paralyzed legs of SCI was significantly lower than leg blood flow in C. Because mean arterial pressure showed no differences between both groups, leg vascular resistance in SCI was significantly higher than in C. Within the SCI group, arterial blood flow was significantly higher and vascular resistance significantly lower in the arms than in the legs. To distinguish between the effect of loss of central neural control vs. deconditioning, a group of nine SCI patients was trained for 6 wk and showed a 30% increase in leg blood flow with unchanged blood pressure levels, indicating a marked reduction in vascular resistance. In conclusion, vascular resistance is increased in the paralyzed legs of individuals with SCI and is reversible by training.

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