A5084954833- Cardiovascular and exercise physiology
- Heart Rate Variability and Autonomic Control
- Nitric Oxide and Endothelin Effects
- Thermoregulation and physiological responses
- Cardiovascular Health and Disease Prevention
- Sports Performance and Training
- High Altitude and Hypoxia
- Blood Pressure and Hypertension Studies
- Cardiovascular Syncope and Autonomic Disorders
- Hemodynamic Monitoring and Therapy
- Cardiovascular Effects of Exercise
- Cardiovascular Disease and Adiposity
- Exercise and Physiological Responses
- Muscle metabolism and nutrition
- Muscle activation and electromyography studies
- Cardiovascular Function and Risk Factors
- Antioxidant Activity and Oxidative Stress
- Adipose Tissue and Metabolism
- Autism Spectrum Disorder Research
- Eicosanoids and Hypertension Pharmacology
- Neuroscience of respiration and sleep
- Erythrocyte Function and Pathophysiology
- Climate Change and Health Impacts
- Neonatal Health and Biochemistry
- Ion channel regulation and function
Colorado State University
2015-2025
Vidant Health
2025
Masonic Medical Research Laboratory
2024
Medical Research Institute
2024
Collins College
2015
University of Colorado Health
1999-2013
Colorado Health Foundation
2013
University of New Mexico
2012
Valley Health System
2012
University of Colorado Boulder
1998-2006
Background —A reduction in compliance of the large-sized cardiothoracic (central) arteries is an independent risk factor for development cardiovascular disease with advancing age. Methods and Results —We determined role habitual exercise on age-related decrease central arterial by using both cross-sectional interventional approaches. First, we studied 151 healthy men aged 18 to 77 years: 54 were sedentary, 45 recreationally active, 53 endurance exercise–trained. Central (simultaneous B-mode...
Background —In sedentary humans endothelium-dependent vasodilation is impaired with advancing age contributing to their increased cardiovascular risk, whereas endurance-trained adults demonstrate lower age-related risk. We determined the influence of regular aerobic exercise on decline in vasodilation. Methods and Results a cross-sectional study, 68 healthy men 22 35 or 50 76 years who were either endurance exercise–trained studied. Forearm blood flow (FBF) responses intra-arterial infusions...
Background —We tested the hypothesis that basal (resting) limb blood flow and vascular conductance are reduced with age in adult humans these changes related to elevations sympathetic vasoconstrictor nerve activity reductions oxygen demand. Methods Results —Sixteen young (28±1 years; mean±SEM) 15 older (63±1 years) healthy normotensive men were studied. Diastolic pressure body fat higher ( P <0.005) men, but there no other age-related differences subject characteristics. Femoral artery...
1 In experimental animals chronic elevations in arterial blood flow increase the lumen diameter and reduce intima-media thickness (IMT) of segment involved. We determined whether intermittent active muscle associated with regular aerobic leg exercise induced such expansive remodelling common femoral artery humans. 2 cross-sectional study 53 sedentary (47 ± years) 55 endurance exercise-trained men were studied. Common (B-mode ultrasound) was 7 % greater (9.62 0.12 vs. 9.03 0.13 mm), IMT (0.46...
Cardiovagal baroreflex sensitivity (BRS) declines with advancing age in humans, but the underlying mechanism has not been established. Using two different approaches, we determined relation between age-associated decline cardiovagal BRS and compliance of an artery which arterial baroreceptors are located. First, measured carotid (via simultaneous application ultrasonography applanation tonometry) (phase IV Valsalva maneuver) 47 healthy sedentary men that varied widely (19–76 yr). declined...
Background Cardiovagal baroreflex sensitivity (BRS) declines with age but is favorably modulated by habitual aerobic exercise. We tested the hypothesis that compliance (transducing capacity) of an elastic artery in which baroreceptors are located associated these age-exercise interactions. Methods and Results Nine young (28±1 years old) 9 older (65±1) sedentary 10 (27±1) (63±2) endurance-trained healthy men were studied. BRS was assessed conventionally (R-R interval–systolic blood pressure...
We tested the hypothesis that inhibition of synthesis either nitric oxide (NO) or vasodilating prostaglandins (PGs) would not alter exercise hyperaemia significantly, but combined synergistically reduce hyperaemia. Fourteen subjects performed 20 min moderate rhythmic forearm (10% maximal voluntary contraction). Forearm blood flow (FBF) was measured by Doppler ultrasound. Saline study drugs were infused (2 ml −1 ) into via a brachial artery catheter to locally inhibit NO and PGs during steady...
1 Cardiovagal baroreflex sensitivity (BRS), the arterial baroreflex-mediated change in R-R interval per unit systolic blood pressure, decreases with advancing age sedentary adult humans. We determined effects of regular aerobic exercise on age-related decline cardiovagal BRS. 2 In cross-sectional study, 133 healthy men 18-79 years who were either sedentary, performing moderate exercise, or endurance trained studied. Among men, BRS (phase IV Valsalva's manoeuvre) was progressively lower (P <...
Background— Muscle sympathetic vasoconstrictor nerve activity increases with age in healthy humans but does not result an augmented forearm tone. We tested the hypothesis that this is due to a reduction postjunctional α-adrenergic responsiveness endogenous norepinephrine (NE) release and determined whether was specific α 1 - or 2 -adrenergic receptors. Methods Results— Forearm blood flow (FBF, by strain-gauge plethysmography) responses local intra-arterial infusions of tyramine (which evokes...
Arterial wall hypertrophy occurs with age in humans and is a strong predictor of cardiovascular disease risk. The responsible mechanism unknown, but data from studies experimental animals suggest that elevated sympathetic-adrenergic tone may be involved. To test this hypothesis we studied 11 young (29 ± 1 yr; means SE) 13 older (63 1) healthy normotensive men under supine resting conditions. Muscle sympathetic nerve activity (MSNA) burst frequency (peroneal microneurography) was 70% higher...
We tested the hypothesis that nitric oxide (NO) is responsible for blunting sympathetic alpha-adrenergic vasoconstriction in active muscles of humans (functional sympatholysis). measured forearm blood flow (Doppler ultrasound) and calculated reductions vascular conductance (FVC) response to receptor stimulation during rhythmic handgrip exercise a control non-exercise vasodilator condition (intra-arterial adenosine), before after local NO synthase (NOS) inhibition healthy men. The...
1 Basal whole-limb blood flow and vascular conductance decrease with age in men. We determined whether these age-associated changes limb haemodynamics are mediated by tonically augmented sympathetic α-adrenergic vasoconstriction. 2 Seven young (28 ± years; mean ±s.e.m.) eight older (64 years) healthy, normotensive adult men were studied. Baseline femoral artery (Doppler ultrasound) calculated 29 31 % lower, respectively, resistance was 53 higher the (all P < 0.001). 3 Local (intra-femoral...
Carotid artery intima-media thickness (IMT), an independent risk factor for stroke, increases with age. Habitual exercise is associated a lower prevalence of but it unclear whether this protective effect could be mediated through favorable influence on carotid IMT. We examined possibility using both cross-sectional and intervention approaches. First, 137 healthy men (age 18–77 yr) who were either sedentary or endurance trained studied. In groups, IMT IMT-to-lumen ratio progressively higher...
We tested the hypothesis that mechanical deformation of forearm blood vessels via acute increases in extravascular pressure elicits rapid vasodilatation humans. In healthy adults, we measured flow (Doppler ultrasound) and calculated vascular conductance (FVC) responses to whole compressions isometric muscle contractions with arm above heart level. used several experimental protocols gain insight into how factors contribute contraction-induced vasodilatation. The findings from present study...
Recent evidence indicates that older healthy humans demonstrate greater vasoconstrictor tone in their active muscles during exercise compared with young adults. Therefore, we tested the hypothesis normal ability of muscle contractions to blunt sympathetic α‐adrenergic vasoconstriction (functional sympatholysis) is impaired age humans. We measured forearm blood flow (FBF; Doppler ultrasound) and calculated vascular conductance (FVC) responses receptor stimulation rhythmic handgrip (15%...
Age-related increases in oxidative stress impair endothelium-dependent vasodilatation humans, leading to the speculation that endothelial dysfunction contributes impaired muscle blood flow and vascular control during exercise older adults. We directly tested this hypothesis 14 young (22 +/- 1 years) healthy men women (65 2 years). measured forearm (FBF; Doppler ultrasound) calculated conductance (FVC) responses single contractions at 10, 20 40% maximum voluntary contraction (MVC) before...
Skeletal muscle blood flow is coupled with the oxygenation state of hemoglobin in young adults, whereby erythrocyte functions as an oxygen sensor and releases ATP during deoxygenation to evoke vasodilation. Whether this function impaired humans advanced age unknown.To test hypothesis that older adults demonstrate lower intravascular conditions deoxygenation.We showed forearm responses 2 (systemic hypoxia graded handgrip exercise) age, which was caused by reduced local In both exercise...
Recent evidence suggests that adenosine triphosphate (ATP) can inhibit vasoconstrictor responses to endogenous noradrenaline release via tyramine in the skeletal muscle circulation, similar what is observed contracting muscle. Whether this involves direct modulation of postjunctional alpha-adrenoceptor responsiveness, or selective for alpha(1)- alpha(2)-receptors remains unclear. Therefore, Protocol 1, we tested hypothesis exogenous ATP blunt alpha-adrenergic vasoconstriction humans. We...
Reactive hyperemia (RH) in the forearm circulation is an important marker of cardiovascular health, yet underlying vasodilator signaling pathways are controversial and thus remain unclear.We hypothesized that RH occurs via activation inwardly rectifying potassium (KIR) channels Na(+)/K(+)-ATPase largely independent combined production endothelial autocoids nitric oxide (NO) prostaglandins young healthy humans.In 24 (23±1 years) subjects, we performed trials by measuring blood flow (FBF;...
Acute ascorbic acid (AA) administration increases muscle blood flow during dynamic exercise in older adults, and this is associated with improved endothelium-dependent vasodilation. We directly tested the hypothesis that increase AA mediated via endothelium-derived vasodilators nitric oxide (NO) prostaglandins (PGs). In 14 healthy adults (64 ± 3 yr), we measured forearm (FBF; Doppler ultrasound) rhythmic handgrip at 10% maximum voluntary contraction. After 5-min steady-state saline, was...
Key points ATP is a substance in the blood vessels that can cause vasodilatation and increase flow oxygen delivery humans. The exact signalling pathways stimulates to are not well known. We show large portion of ATP‐mediated occurs through activation inwardly rectifying potassium channels (K ir ). Our results lend insight into vasodilator mechanisms ATP, important for vascular control. Further, our may stimulate additional investigations humans regarding K subsequent hyperpolarization during...
This randomized, double-blind, placebo-controlled trial showed that blueberries improve endothelial function through reduced oxidative stress in postmenopausal women with above-normal blood pressure.
1 Basal whole-limb blood flow is lower in older than young healthy sedentary men due to a limb vascular conductance. 2 In Study 1, we determined whether age-associated reductions basal whole-leg (femoral artery) and conductance are modulated by habitual physical activity studying 89 aged 20-35 or 55-75 years (26 sedentary, 31 physically active 32 endurance exercise trained). Femoral (duplex Doppler) were ≈20-30 % (P < 0.01) the all three groups. 3 2, determine temporal pattern relation local...