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Mikel Egaña - One of the best experts on this subject based on the ideXlab platform.

  • Lack of age-specific influence on Leg Blood Flow during incremental calf plantar-flexion exercise in men and women.
    European journal of applied physiology, 2018
    Co-Authors: Heather Reilly, Louise M. Lane, Mikel Egaña
    Abstract:

    Purpose Age-related exercising Leg Blood Flow (LBF) responses during dynamic knee-extension exercise and forearm Blood Flow responses during handgrip exercise are preserved in normally active men but attenuated in activity-matched women. We explored whether these age- and sex-specific effects are also apparent during isometric calf plantar-flexion incremental exercise.

  • Venous occlusion plethysmography vs. Doppler ultrasound in the assessment of Leg Blood Flow kinetics during different intensities of calf exercise
    European Journal of Applied Physiology, 2018
    Co-Authors: Elaine Murphy, Simon Green, Joel Rocha, Norita Gildea, Mikel Egaña
    Abstract:

    Purpose It has recently been shown that venous occlusion plethysmography (VOP) can successfully assess the rate of increase in Leg Blood Flow (LBF) (LBF kinetics) responses during calf exercise, but there is lack of data supporting its validity. Methods Using Doppler ultrasound (DU) as a criterion standard technique, we tested the hypothesis that VOP would provide similar estimates of LBF kinetics responses as DU during calf plantar-flexion exercise at a range of different intensities. Ten healthy men performed repeated intermittent calf plantar-flexion contractions (3 s duty cycles, 1 s contraction/2 s relaxation) at 30, 50 and 70% maximum voluntary contraction (MVC) on different days. Results Resting LBF values were significantly ( P   0.05) between DU and VOP (30% MVC: 330 ± 78 vs. 313 ± 92 ml/min; 50% MVC: 515 ± 145 vs. 483 ± 164 ml/min; 70% MVC: 733 ± 218 vs. 616 ± 229 ml/min). LBF kinetics analyses revealed that the end-amplitude at the highest intensity (70% MVC) was significantly higher when measured by DU compared with VOP, but all other kinetics parameters were not different between VOP and DU. Conclusions Given that these slight differences in amplitude observed during exercise can be explained by differences in vascular regions which the two techniques assess, our results suggest that VOP can accurately assess LBF kinetics responses during calf plantar-flexion exercise at intensities between 30 and 70% MVC.

  • Venous occlusion plethysmography vs. Doppler ultrasound in the assessment of Leg Blood Flow kinetics during different intensities of calf exercise.
    European journal of applied physiology, 2017
    Co-Authors: Elaine Murphy, Simon Green, Joel Rocha, Norita Gildea, Mikel Egaña
    Abstract:

    Purpose It has recently been shown that venous occlusion plethysmography (VOP) can successfully assess the rate of increase in Leg Blood Flow (LBF) (LBF kinetics) responses during calf exercise, but there is lack of data supporting its validity.

  • Effect of elastic-band-based resistance training on Leg Blood Flow in elderly women.
    Applied physiology nutrition and metabolism = Physiologie appliquee nutrition et metabolisme, 2010
    Co-Authors: Mikel Egaña, Heather Reilly, Simon Green
    Abstract:

    The age-related decline in basal limb Blood Flow appears to be related to the pathogenesis of metabolic syn- drome, noninsulin-dependent diabetes, and cardiovascular disease. Resistance training improves basal limb Blood Flow and vascular conductance in middle-aged men and women, but it is unknown whether similar vascular effects of training occur in the elderly. This study aimed to examine the effects of a 12-week progressive resistance training program using elastic bands on basal Leg Blood Flow, vascular conductance, and functional performance in postmenopausal elderly women. Six- teen healthy postmenopausal females (age, 67 ± 5 years) were randomly assigned to a control (n = 8) or resistance training (n = 8) group, where they underwent 2 supervised strength sessions per week for 12 weeks. Prior to and at completion of this 12-week period, functional and strength performance and Leg haemodynamic responses were measured. The training intervention produced significant increases in basal Leg Blood Flow (31%), vascular conductance (34%), and a significant reduction in cardiac work (i.e., rate pressure product) at rest, as well as significant improvements in the 3 functional ability tests performed (30-s bicep curl, 30-s sit to stand, and back scratch). Haemodynamic or functional performance responses were not altered after the 12 weeks in the control group. This study demonstrates that a resistance training program using elastic bands elicits significant improvements in basal Leg Blood Flow in postmenopausal elderly women.

Maria Te Hopman - One of the best experts on this subject based on the ideXlab platform.

  • Leg Blood Flow measurements using venous occlusion plethysmography during head-up tilt.
    Clinical autonomic research : official journal of the Clinical Autonomic Research Society, 2007
    Co-Authors: Miriam Kooijman, Fleur Poelkens, Gerard A. Rongen, Paul Smits, Maria Te Hopman
    Abstract:

    We tested whether venous occlusion plethysmography (VOP) is an appropriate method to measure calf Blood Flow (CBF) during head-up tilt (HUT). CBF measured with VOP was compared with superficial femoral artery Blood Flow as measured by Doppler ultrasound during incremental tilt angles. Measurements of both methods correlated well (r = 0.86). Reproducibility of VOP was fair in supine position and 30° HUT (CV: 11%–15%). This indicates that VOP is an applicable tool to measure Leg Blood Flow during HUT, especially up to 30° HUT.

  • Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances Leg Blood Flow
    Clinical science (London England : 1979), 2007
    Co-Authors: Jan T Groothuis, Nynke Van Dijk, Wouter Wieling, Walter Ter Woerds, Maria Te Hopman
    Abstract:

    In patients with orthostatic intolerance, the mechanisms to maintain BP (Blood pressure) fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is Leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. Therefore the purpose of the present study was to examine the peripheral haemodynamic effects of Leg crossing combined with muscle tensing during 70 degrees head-up tilt. Healthy subjects (n=13) were monitored for 10 min in the supine position followed by 10 min in 70 degrees head-up tilt and, finally, for 2 min of Leg crossing with muscle tensing in 70 degrees head-up tilt. MAP (mean arterial BP), heart rate, stroke volume, cardiac output and total peripheral resistance were measured continuously by Portapres. Leg Blood Flow was measured using Doppler ultrasound. Leg vascular conductance was calculated as Leg Blood Flow/MAP. A significant increase in MAP (13 mmHg), stroke volume (27%) and cardiac output (18%), a significant decrease in heart rate (-5 beats/min) and no change in total peripheral resistance during the physical counter-manoeuvre were observed when compared with baseline 70 degrees head-up tilt. A significant increase in Leg Blood Flow (325 ml/min) and Leg vascular conductance (2.9 arbitrary units) were seen during the physical counter-manoeuvre when compared with baseline 70 degrees head-up tilt. In conclusion, the present study indicates that the physical counter-manoeuvre of Leg crossing combined with muscle tensing clearly enhances Leg Blood Flow and, at the same time, elevates MAP.

  • Does passive cycling induce changes in peripheral Blood Flow in persons with spinal cord injury
    Archives of physical medicine and rehabilitation, 2007
    Co-Authors: Jan T Groothuis, Maria Te Hopman
    Abstract:

    persons with spinal cord injury (SCI). Ballaz concluded that passive Leg cycling increases Blood Flow velocity in the common femoral artery (CFA) of people with SCI. We read this article with great interest, because we recently published a study on the effect of passive movements on Blood Flow and found opposite results, that is, no effect of passive Leg cycling on Blood Flow. 2 Unfortunately, very few studies have addressed the interesting and clinically relevant question whether passive cycling can improve Leg Blood Flow. However, when reading the current study, we had some methodologic concerns, which relate to the timing of and posture in which the measurements of red Blood cell velocity after ceasing the passive Leg cycling were performed. Within 7 seconds of ceasing passive Leg cycling, the measurements of Blood Flow velocity in the CFA were performed. Within this already short time frame, the back of a standardized wheelchair was bent backward (150°). People with SCI, when performing passive Leg cycling in a sitting position, are brought to an intermediate position, between sitting and supine, within the same 7 seconds. A change in body position, from upright to supine, causes a change in Blood distribution, which leads to an instantaneous rise, within 10 seconds, in venous return, stroke volume, cardiac output, and Blood pressure. 3 Consequently, Leg Blood Flow will increase, assuming no change in peripheral vascular resistance. The latter cannot be calculated because no Blood pressure measurements were taken. The observed increase in red Blood cell velocity found in the Ballaz study could be explained by the change in body position rather than by passive Leg cycling itself. Moreover, from a physiologic standpoint, it is hard to explain why and how Leg Blood Flow would increase when there is no increase in oxygen demand, as is the case with paralyzed Leg muscles during passive cycling. The conclusion that passive Leg cycling exercise leads to an increase in Blood Flow velocity in the CFA of people with SCI cannot, in our opinion, be drawn. We believe that this is a particularly relevant point, considering the clinical implications: patients with SCI who have a poor Leg Blood Flow, and consequently clinical problems such as edema and poor wound healing, can gain no Leg Blood Flow benefit from passive cycling but need to exercise their paralyzed Legs using electric

  • Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances Leg Blood Flow
    Clinical Science, 2006
    Co-Authors: Jan T Groothuis, Nynke Van Dijk, Walter Ter Woerds, Wouter Wieling, Maria Te Hopman
    Abstract:

    In patients with orthostatic intolerance the mechanisms to maintain Blood pressure fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is Leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. Therefore, the purpose of the present study was to examine the peripheral haemodynamic effects of Leg crossing combined with muscle tensing during 70 o} head-up tilt (HUT). Thirteen healthy subjects were monitored for 10 minutes in the supine position followed by 10 minutes in 70 0}HUT and, finally, 2 minutes of Leg crossing with muscle tensing in 70 o} HUT. Mean arterial Blood pressure (MAP), heart rate, stroke volume, cardiac output and total peripheral resistance were measured continuously by Portapres. Leg Blood Flow was measured using Doppler ultrasound. Leg vascular conductance was calculated as Leg Blood Flow divided by MAP. Results show a significant increase in MAP (13 mmHg), stroke volume (27%) and cardiac output (18%), a significant decrease in heart rate (-5 bpm) and no change in total peripheral resistance during the physical counter-manoeuvre when compared to baseline 70 o} HUT. A significant increase in Leg Blood Flow (325 ml/min) and Leg vascular conductance (2.9 AU) were seen during the physical counter-manoeuvre when compared to baseline 70 o} HUT. The present study indicates that the physical counter-manoeuvre of Leg crossing combined with muscle tensing clearly enhances Leg Blood Flow and at the same time elevates mean arterial Blood pressure.

  • Passive Leg movements and passive cycling do not alter arterial Leg Blood Flow in subjects with spinal cord injury.
    Physical therapy, 2006
    Co-Authors: Walter Ter Woerds, Patricia C. E. De Groot, Dirk H J M Van Kuppevelt, Maria Te Hopman
    Abstract:

    BACKGROUND AND PURPOSE: Subjects with a spinal cord injury (SCI) are at increased risk for cardiovascular disease-related secondary complications, such as pressure ulcers and attenuated wound healing. It has been suggested that passive exercise enhances Blood Flow via mechanical pump effects or reflex activation. The purpose of this study was to assess the effects of passive Leg movements and passive cycling on the arterial circulation in subjects with SCI. SUBJECTS: Eight men with motor complete SCI and 8 male control subjects participated. METHODS: Echo Doppler measurements were obtained to measure Leg Blood Flow at rest, during and after 10 minutes of standardized passive Leg movements, and during and after 20 minutes of passive Leg cycling. Blood pressure was measured continuously, and total vascular resistance and Leg vascular resistance were calculated. RESULTS: In both groups, no changes in Leg Blood Flow, vascular resistance, or Blood pressure were observed during or after the 2 interventions. DISCUSSION AND CONCLUSION: The results of the study demonstrate that passive Leg movements and passive cycling do not alter the arterial peripheral circulation in subjects with SCI or control subjects. Although the results do not support the use of passive movements or exercise for the prevention of cardiovascular disease-related secondary complications, physical therapists should not be dissuaded from using these techniques to address musculoskeletal concerns.

Simon Green - One of the best experts on this subject based on the ideXlab platform.

  • Venous occlusion plethysmography vs. Doppler ultrasound in the assessment of Leg Blood Flow kinetics during different intensities of calf exercise
    European Journal of Applied Physiology, 2018
    Co-Authors: Elaine Murphy, Simon Green, Joel Rocha, Norita Gildea, Mikel Egaña
    Abstract:

    Purpose It has recently been shown that venous occlusion plethysmography (VOP) can successfully assess the rate of increase in Leg Blood Flow (LBF) (LBF kinetics) responses during calf exercise, but there is lack of data supporting its validity. Methods Using Doppler ultrasound (DU) as a criterion standard technique, we tested the hypothesis that VOP would provide similar estimates of LBF kinetics responses as DU during calf plantar-flexion exercise at a range of different intensities. Ten healthy men performed repeated intermittent calf plantar-flexion contractions (3 s duty cycles, 1 s contraction/2 s relaxation) at 30, 50 and 70% maximum voluntary contraction (MVC) on different days. Results Resting LBF values were significantly ( P   0.05) between DU and VOP (30% MVC: 330 ± 78 vs. 313 ± 92 ml/min; 50% MVC: 515 ± 145 vs. 483 ± 164 ml/min; 70% MVC: 733 ± 218 vs. 616 ± 229 ml/min). LBF kinetics analyses revealed that the end-amplitude at the highest intensity (70% MVC) was significantly higher when measured by DU compared with VOP, but all other kinetics parameters were not different between VOP and DU. Conclusions Given that these slight differences in amplitude observed during exercise can be explained by differences in vascular regions which the two techniques assess, our results suggest that VOP can accurately assess LBF kinetics responses during calf plantar-flexion exercise at intensities between 30 and 70% MVC.

  • Venous occlusion plethysmography vs. Doppler ultrasound in the assessment of Leg Blood Flow kinetics during different intensities of calf exercise.
    European journal of applied physiology, 2017
    Co-Authors: Elaine Murphy, Simon Green, Joel Rocha, Norita Gildea, Mikel Egaña
    Abstract:

    Purpose It has recently been shown that venous occlusion plethysmography (VOP) can successfully assess the rate of increase in Leg Blood Flow (LBF) (LBF kinetics) responses during calf exercise, but there is lack of data supporting its validity.

  • Venous occlusion plethysmography versus Doppler ultrasound in the assessment of Leg Blood Flow during calf exercise
    European journal of applied physiology, 2011
    Co-Authors: Simon Green, R. Thorp, E. J. Reeder, Joseph Donnelly, G. Fordy
    Abstract:

    This study explored the accuracy with which venous occlusion plethysmography (VOP) assesses the hyperaemic response during calf exercise. Using Doppler ultrasound (DU) as a criterion standard technique, we tested the hypotheses that Leg Blood Flow during contraction is not greater than at rest and that VOP provides similar estimates of the hyperaemic response between contractions as DU. Eleven subjects performed several bouts of calf exercise across a wide range of forces (50–400 N ≅ 6–45%MVC). Each bout consisted of 2 min of intermittent contractions preceded and immediately followed by sustained (40 s) contractions. DU estimates of Leg Blood Flow during the sustained contractions were never significantly greater (P > 0.05) than those measured at rest. Paired (DU and VOP) estimates of Leg Blood Flow (n = 488) were obtained between intermittent contractions and ranged between ~50–900 ml min−1. There was a strong correlation between these DU and VOP estimates (Pearson r = 0.91; P < 0.05). Ordinary least products regression analysis, with VOP as the y variable, showed a relatively small proportional bias (slope = 0.942; CI = 0.938–0.946) and fixed bias (y intercept = −13.3 ml min−1; CI = −14.4 to −12.2 ml min−1) between the two measurement techniques. Since these small biases can be explained by the slight differences in vascular regions which the two techniques assess, these data suggest that VOP can accurately assess the hyperaemic response to exercise.

  • Effect of elastic-band-based resistance training on Leg Blood Flow in elderly women.
    Applied physiology nutrition and metabolism = Physiologie appliquee nutrition et metabolisme, 2010
    Co-Authors: Mikel Egaña, Heather Reilly, Simon Green
    Abstract:

    The age-related decline in basal limb Blood Flow appears to be related to the pathogenesis of metabolic syn- drome, noninsulin-dependent diabetes, and cardiovascular disease. Resistance training improves basal limb Blood Flow and vascular conductance in middle-aged men and women, but it is unknown whether similar vascular effects of training occur in the elderly. This study aimed to examine the effects of a 12-week progressive resistance training program using elastic bands on basal Leg Blood Flow, vascular conductance, and functional performance in postmenopausal elderly women. Six- teen healthy postmenopausal females (age, 67 ± 5 years) were randomly assigned to a control (n = 8) or resistance training (n = 8) group, where they underwent 2 supervised strength sessions per week for 12 weeks. Prior to and at completion of this 12-week period, functional and strength performance and Leg haemodynamic responses were measured. The training intervention produced significant increases in basal Leg Blood Flow (31%), vascular conductance (34%), and a significant reduction in cardiac work (i.e., rate pressure product) at rest, as well as significant improvements in the 3 functional ability tests performed (30-s bicep curl, 30-s sit to stand, and back scratch). Haemodynamic or functional performance responses were not altered after the 12 weeks in the control group. This study demonstrates that a resistance training program using elastic bands elicits significant improvements in basal Leg Blood Flow in postmenopausal elderly women.

  • Muscle mitochondrial function, Leg Blood Flow and walking performance in people with peripheral arterial disease
    1999
    Co-Authors: J. Zhou, Simon Green, Christopher D. Askew, Philip J. Walker, Anita Green
    Abstract:

    It has often been reported that the impaired walking performance in people with peripheral arterial disease (PAD) is not correlated to the Leg Blood Flow, despite the importance of Blood Flow to exercise performance. In contrast, some aspects of muscle oxidative metabolism have been related to walking performance in PAD. The purpose of this study was to further explore these relationships in PAD with a particular focus on skeletal muscle mitochondrial function. In 15 PAD patients (age=64.6± 8.5 y; weight=76.7± 16.3 kg), walking performance was tested on the treadmill using an incremental walking test, Leg Blood Flow was tested at rest and after maximal calf exercise using venous occlusion plethysmography, and the mitochondrial ATP production rate (MAPR) using pyruvate, palmitoyl-carnitine, alpha-ketoglutarate and malate (PPKM) as substrates was measured on biopsy samples taken from the medial gastrocnemius muscle in the Leg with the lowest ankle-brachial index (i.e.worst Leg). The data are expressed as mean ± standard deviation. Semi-partial correlation analysis was used to assess the unique contribution of independent variables to the variation in walking performance. The pain-free walking time (3.12± 2.59 min) was positively correlated (P less than 0.05) with MAPR when expressed per mmol ATP/min/g protein (0.3902± 0.2145, r=0.583) and per mmol ATP/min/kg muscle (4.7703± 2.3081, r=0.519), negatively correlated with body weight (r= -0.493), but not correlated with calf Blood Flows. However, the pain-free walking time divided by body weight was positively correlated with resting calf Blood Flow in the best (3.607± 1.83 ml/100ml tissue/min; r=0.577) and worst Leg (3.261± 1.103 ml/100ml tissue/min; r=0.613). The total walking time was not correlated with any of these variables. MAPR and body weight accounted for 29 % and 6 % of the variation in the pain-free walking time respectively. The resting Blood Flow in the worst Leg accounted for 7 % of the variation in the pain-free walking time divided by the body weight. Therefore, of the variables measured, skeletal muscle mitochondrial function is the most important contributor to the difference in walking performance in people with PAD. This study was funded by the QUT and University of Queensland.

Douglas R Seals - One of the best experts on this subject based on the ideXlab platform.

  • high dose ascorbic acid infusion abolishes chronic vasoconstriction and restores resting Leg Blood Flow in healthy older men
    Journal of Applied Physiology, 2007
    Co-Authors: Kristen L Jablonski, Douglas R Seals, Iratxe Eskurza, Kevin D Monahan, Anthony J Donato
    Abstract:

    Resting whole Leg Blood Flow and vascular conductance decrease linearly with advancing age in healthy adult men. The potential role of age-related increases in oxidative stress in these changes is unknown. Resting Leg Blood Flow during saline and ascorbic acid infusion was studied in 10 young (25 +/- 1 yr) and 11 older (63 +/- 2 yr) healthy normotensive men. Plasma oxidized LDL, a marker of oxidative stress, was greater in the older men (P /= 0.70). As a result, the lower baseline femoral artery Blood Flow in the older men was mediated solely by a 32% lower femoral artery vascular conductance (P < 0.05). Baseline femoral vascular conductance also was inversely related to plasma oxidized LDL (r = -0.65, P < 0.01). Ascorbic acid increased femoral vascular conductance by 36% in the older men (P < 0.05) but not in the young men (P = 0.31). In conclusion, ascorbic acid infused at concentrations known to scavenge reactive oxygen species restores resting femoral artery Blood Flow in healthy older adult men by increasing vascular conductance. These results support the hypothesis that oxidative stress plays a major role in the reduced resting whole Leg Blood Flow and increased Leg vasoconstriction observed with aging in men.

  • High-dose ascorbic acid infusion abolishes chronic vasoconstriction and restores resting Leg Blood Flow in healthy older men
    Journal of applied physiology (Bethesda Md. : 1985), 2007
    Co-Authors: Kristen L Jablonski, Douglas R Seals, Iratxe Eskurza, Kevin D Monahan, Anthony J Donato
    Abstract:

    Resting whole Leg Blood Flow and vascular conductance decrease linearly with advancing age in healthy adult men. The potential role of age-related increases in oxidative stress in these changes is ...

  • Oxidative stress contributes to chronic Leg vasoconstriction in estrogen-deficient postmenopausal women
    Journal of applied physiology (Bethesda Md. : 1985), 2006
    Co-Authors: Kerrie L Moreau, Ashley R. Depaulis, Kathleen M. Gavin, Douglas R Seals
    Abstract:

    Basal whole Leg Blood Flow and vascular conductance are reduced in estrogen-deficient postmenopausal compared with premenopausal women. The underlying mechanisms are unknown, but oxidative stress c...

  • Basal Leg Blood Flow in healthy women is related to age and hormone replacement therapy status.
    The Journal of physiology, 2002
    Co-Authors: Kerrie L Moreau, Anthony J Donato, Hirofumi Tanaka, Pamela Parker Jones, Phillip E Gates, Douglas R Seals
    Abstract:

    Basal Leg Blood Flow declines with age in healthy men, an effect that is mediated by augmented sympathetic vasoconstriction. However, in women the presence or absence of oestrogen and selective use of hormone replacement therapy (HRT) may alter these relationships with ageing. We studied 103 healthy women: 73 postmenopausal (41 HRT, mean +/- S.E.M. 61 +/- 1 years; 32 no-HRT, 63 +/- 2 years) and 30 premenopausal (29 +/- 1 years). Compared with the premenopausal controls, absolute femoral artery Blood Flow (duplex ultrasound) was 23 % lower (P < 0.001) in the postmenopausal no-HRT group, but only 13 % lower in the HRT group (P < 0.01). The age and HRT group differences in Leg Blood Flow were consistently associated with differences in Leg vascular conductance, but not with femoral artery lumen diameter, Leg muscle sympathetic nerve activity or cardiac output (systemic arterial Blood Flow). Leg fat-free mass was smaller in the postmenopausal groups (P < 0.05). Femoral Blood Flow normalized for Leg fat-free mass was 17 % lower (P < 0.01) in the postmenopausal no-HRT compared with the premenopausal women, but was not different in the postmenopausal HRT and premenopausal groups. Femoral artery shear stress was similar in the postmenopausal HRT and premenopausal women, but was lower in the postmenopausal no-HRT group (P < 0.01). Basal whole-Leg Blood Flow declines with age in healthy, oestrogen-deficient women, a phenomenon that is mediated primarily by reductions in Leg vascular conductance. Among postmenopausal women, chronic HRT use is associated with augmented basal Leg Blood Flow and vascular conductance. Leg Blood Flow normalized for Leg fat-free mass is preserved with age in women taking chronic HRT. In contrast to men, differences in Leg sympathetic vasoconstrictor nerve activity do not explain group differences in Leg Blood Flow and vascular conductance with ageing in women.

  • Basal Leg Blood Flow in healthy women is related to age and hormone replacement therapy status
    The Journal of Physiology, 2002
    Co-Authors: Kerrie L Moreau, Anthony J Donato, Hirofumi Tanaka, Pamela Parker Jones, Phillip E Gates, Douglas R Seals
    Abstract:

    Reduced basal limb Blood Flow and vascular conductance have important implications for both disease risk and physical function in humans. Recently we demonstrated that basal whole-Leg Blood Flow is 25–30 % lower in healthy older men compared with young men (Dinenno et al. 1999, 2001a). Age-related changes in lower-Leg Blood Flow are mediated by a reduction in Leg vascular conductance (increase in Leg vascular resistance) (Dinenno et al. 1999, 2001a), which is, in turn, associated with elevated Leg muscle sympathetic nerve activity (MSNA; Dinenno et al. 1999) and augmented α-adrenergic vasoconstrictor tone (Dinenno et al. 2001c). Female ageing is unique because of the menopause, the resulting loss of circulating oestrogen and the use of oestrogen-based hormone replacement therapy (HRT) by some postmenopausal women to relieve the symptoms of menopause. These factors may affect basal limb perfusion, given the potent acute vasodilatory (Gilligan et al. 1994; Volterrani et al. 1995; Dubey & Jackson, 2001) and possible sympathoinhibitory (Sudhir et al. 1997; Vongpatanasin et al. 2001; Weitz et al. 2001) actions of oestrogen. Despite these potential effects of changes in circulating oestrogen status on basal limb perfusion with female ageing, no information is available on these issues. Accordingly, in the present study our primary experimental aims were to determine whether: (1) basal whole-Leg Blood Flow is reduced in healthy oestrogen-deficient postmenopausal women compared with premenopausal women, (2) basal limb Blood Flow is augmented in oestrogen-supplemented postmenopausal women compared with their oestrogen-deficient peers and (3) these age- and oestrogen status-related differences in basal Leg Blood Flow are associated with corresponding differences in Leg vascular conductance, MSNA and/or systemic arterial Blood Flow.

Anthony J Donato - One of the best experts on this subject based on the ideXlab platform.

  • Endothelin-A-Mediated Vasoconstriction During Exercise With Advancing Age
    The journals of gerontology. Series A Biological sciences and medical sciences, 2014
    Co-Authors: Zachary Barrett-o'keefe, Joel D. Trinity, Anthony J Donato, Matthew J. Rossman, Stephen J. Ives, David E. Morgan, Sean Runnels, Garrett Morgan, Benjamin S. Gmelch, Amber D. Bledsoe
    Abstract:

    The endothelin-1 vasoconstrictor pathway contributes to age-related elevations in resting peripheral vascular tone primarily through activation of the endothelin subtype A (ET(A)) receptor. However, the regulatory influence of ET(A)-mediated vasoconstriction during exercise in the elderly is unknown. Thus, in 17 healthy volunteers (n = 8 young, 24±2 years; n = 9 old, 70±2 years), we examined Leg Blood Flow, mean arterial pressure, Leg arterial-venous oxygen (O2) difference, and Leg O2 consumption (VO2) at rest and during knee-extensor exercise before and after intra-arterial administration of the ET(A) antagonist BQ-123. During exercise, BQ-123 administration increased Leg Blood Flow to a greater degree in the old (+29±5 mL/min/W) compared with the young (+16±3 mL/min/W). The increase in Leg Blood Flow with BQ-123 was accompanied by an increase in Leg VO2 in both groups, suggesting a reduced efficiency following ET(A) receptor blockade. Together, these findings have identified an age-related increase in ET(A)-mediated vasoconstrictor activity that persists during exercise, suggesting an important role of this pathway in the regulation of exercising skeletal muscle Blood Flow and maintenance of arterial Blood pressure in the elderly.

  • high dose ascorbic acid infusion abolishes chronic vasoconstriction and restores resting Leg Blood Flow in healthy older men
    Journal of Applied Physiology, 2007
    Co-Authors: Kristen L Jablonski, Douglas R Seals, Iratxe Eskurza, Kevin D Monahan, Anthony J Donato
    Abstract:

    Resting whole Leg Blood Flow and vascular conductance decrease linearly with advancing age in healthy adult men. The potential role of age-related increases in oxidative stress in these changes is unknown. Resting Leg Blood Flow during saline and ascorbic acid infusion was studied in 10 young (25 +/- 1 yr) and 11 older (63 +/- 2 yr) healthy normotensive men. Plasma oxidized LDL, a marker of oxidative stress, was greater in the older men (P /= 0.70). As a result, the lower baseline femoral artery Blood Flow in the older men was mediated solely by a 32% lower femoral artery vascular conductance (P < 0.05). Baseline femoral vascular conductance also was inversely related to plasma oxidized LDL (r = -0.65, P < 0.01). Ascorbic acid increased femoral vascular conductance by 36% in the older men (P < 0.05) but not in the young men (P = 0.31). In conclusion, ascorbic acid infused at concentrations known to scavenge reactive oxygen species restores resting femoral artery Blood Flow in healthy older adult men by increasing vascular conductance. These results support the hypothesis that oxidative stress plays a major role in the reduced resting whole Leg Blood Flow and increased Leg vasoconstriction observed with aging in men.

  • High-dose ascorbic acid infusion abolishes chronic vasoconstriction and restores resting Leg Blood Flow in healthy older men
    Journal of applied physiology (Bethesda Md. : 1985), 2007
    Co-Authors: Kristen L Jablonski, Douglas R Seals, Iratxe Eskurza, Kevin D Monahan, Anthony J Donato
    Abstract:

    Resting whole Leg Blood Flow and vascular conductance decrease linearly with advancing age in healthy adult men. The potential role of age-related increases in oxidative stress in these changes is ...

  • Differential effects of aging on limb Blood Flow in humans
    American journal of physiology. Heart and circulatory physiology, 2005
    Co-Authors: Anthony J Donato, Steven K. Nishiyama, Abbhimanyu Uberoi, Walter D. Wray, Lesley Lawrenson, Russel S. Richardson
    Abstract:

    Aging appears to attenuate Leg Blood Flow during exercise; in contrast, such data are scant and do not support this contention in the arm. Therefore, to determine whether aging has differing effect...

  • Basal Leg Blood Flow in healthy women is related to age and hormone replacement therapy status.
    The Journal of physiology, 2002
    Co-Authors: Kerrie L Moreau, Anthony J Donato, Hirofumi Tanaka, Pamela Parker Jones, Phillip E Gates, Douglas R Seals
    Abstract:

    Basal Leg Blood Flow declines with age in healthy men, an effect that is mediated by augmented sympathetic vasoconstriction. However, in women the presence or absence of oestrogen and selective use of hormone replacement therapy (HRT) may alter these relationships with ageing. We studied 103 healthy women: 73 postmenopausal (41 HRT, mean +/- S.E.M. 61 +/- 1 years; 32 no-HRT, 63 +/- 2 years) and 30 premenopausal (29 +/- 1 years). Compared with the premenopausal controls, absolute femoral artery Blood Flow (duplex ultrasound) was 23 % lower (P < 0.001) in the postmenopausal no-HRT group, but only 13 % lower in the HRT group (P < 0.01). The age and HRT group differences in Leg Blood Flow were consistently associated with differences in Leg vascular conductance, but not with femoral artery lumen diameter, Leg muscle sympathetic nerve activity or cardiac output (systemic arterial Blood Flow). Leg fat-free mass was smaller in the postmenopausal groups (P < 0.05). Femoral Blood Flow normalized for Leg fat-free mass was 17 % lower (P < 0.01) in the postmenopausal no-HRT compared with the premenopausal women, but was not different in the postmenopausal HRT and premenopausal groups. Femoral artery shear stress was similar in the postmenopausal HRT and premenopausal women, but was lower in the postmenopausal no-HRT group (P < 0.01). Basal whole-Leg Blood Flow declines with age in healthy, oestrogen-deficient women, a phenomenon that is mediated primarily by reductions in Leg vascular conductance. Among postmenopausal women, chronic HRT use is associated with augmented basal Leg Blood Flow and vascular conductance. Leg Blood Flow normalized for Leg fat-free mass is preserved with age in women taking chronic HRT. In contrast to men, differences in Leg sympathetic vasoconstrictor nerve activity do not explain group differences in Leg Blood Flow and vascular conductance with ageing in women.