As with blood pressure, age-related changes in muscle sympathetic nerve activity (MSNA) may differ nonlinearly between sexes. Data acquired from 398 male (age: 39±17; range: 18-78 years [mean±SD]) and 260 female 37±18; 18-81 years) normotensive healthy nonmedicated volunteers were analyzed using linear regression models resting MSNA burst frequency as the outcome predictors sex, age, MSNA, body mass index modelled natural cubic splines. Age contributed 41% 11%, respectively, of variance...

This study aimed to determine whether: (a) isometric handgrip (IHG) training lowers resting blood pressure (BP), (b) cardiovascular reactivity a serial subtraction (SST), IHG (IHGT), and cold pressor (CPT) task predicts this hypotensive response, (c) is attenuated posttraining. Resting BP SST, IHGT, CPT were measured in 24 hypertensives (51-74 years) before after 10 weeks of (n = 12) or control 12). lowered (Δ8/5 mmHg), whereby the decrease systolic was correlated pretraining SST (r -.85)...

This study quantified the effect of age on cerebrovascular reactivity and conductance while accounting for differences in grey matter volume younger (YA: n = 12; 24 ± 4 years, six females) older adults (OA: 10; 66 7 years; five females). Cerebral blood flow velocity (CBFV; transcranial Doppler) middle cerebral artery (MCA), MCA cross-sectional area (CSA), intracranial volumes (magnetic resonance imaging), mean arterial pressure (MAP; Finometer), were measured under normocapnic hypercapnic...

This study tested the hypothesis that neural coding patterns exist within autonomic nervous system. We investigated sympathetic axonal recruitment strategies in humans during chemoreflex- and baroreflex-mediated sympathoexcitation using a novel action potential (AP) analysis technique. Muscle nerve activity (microneurography) was collected 11 young individuals (6 females) baseline two subsequent protocols: 1) severe chemoreflex stimulation (maximal end-inspiratory apnea following rebreathe),...

In response to acute physiological stress, the sympathetic nervous system modifies neural outflow through increased firing frequency of lower-threshold axons, recruitment latent subpopulations higher-threshold and/or modifications synaptic delays. Aging and coronary artery disease (CAD) often modify efferent muscle nerve activity (MSNA). Therefore, we investigated whether CAD (n = 14; 61 ± 10 yr) healthy aging without (OH; n 59 9 modified these strategies that normally are observed in young...

Sympathetic outflow is modified during acute homeostatic stress through increased firing of low-threshold axons, recruitment latent and synaptic delay modifications. However, the role central mechanisms versus peripheral reflex control over sympathetic remains unknown. Here, we examined discharge patterns fatiguing static handgrip (SHG) exercise postexercise circulatory occlusion (PECO) to study vs. elements neural coding. Muscle nerve activity (MSNA; microneurography) was measured in six...

Corin (an atrial natriuretic peptide–converting enzyme) represents a potential biomarker for gestational hypertensive disorders; yet, its role in blood pressure (BP) regulation throughout pregnancy remains unclear. We investigated the time course of change corin content relation to BP and sympathetic nerve activity pregnancy. Forty-four women (29±0.9 years) participated. Following-term, 23 had low-risk (no personal history disorders) normal pregnancies, 13 high-risk (personal 8 developed...

Background Autonomic dysregulation represents a hallmark of coronary artery disease (CAD). Therefore, we investigated the effects exercise-based cardiac rehabilitation (CR) on autonomic function and neuro-cardiovascular stress reactivity in CAD patients. Methods Results Twenty-two patients (4 women; 62±8 years) were studied before following 6 months aerobic- resistance-training-based CR. similarly aged, healthy individuals (CTRL; 7 62±11 served as controls. We measured blood pressure, muscle...

Posttraumatic stress disorder (PTSD) is more prevalent in women and associated with greater risk of major forms cardiovascular disease, but physiological mechanisms underlying this association remain unknown. We hypothesized that abnormal sympathetic responses to sympathoexcitatory stimuli might predispose PTSD patients a disease. examined changes integrated muscle nerve activity (MSNA) burst multiunit action potential (AP) recruitment patterns as well hemodynamic during cold pressor test...

Heart failure with reduced ejection fraction (HFrEF) is associated cardiac β-adrenergic signal transduction in response to chronic elevations neurally released and circulating norepinephrine. Whether muscle sympathetic nerve activity (MSNA) are accompanied by attenuated α-adrenoceptor-mediated vasoconstriction remains unclear. Therefore, the objective of current work was compare firing into blood pressure (BP) treated patients HFrEF healthy controls.Twenty-three (4 females, left ventricular...

This study investigated the influence of ventilation on sympathetic action potential (AP) discharge patterns during varying levels high chemoreflex stress. In seven trained breath-hold divers (age 33 ± 12 yr), we measured muscle nerve activity (MSNA) at baseline, preparatory rebreathing (RBR), and 1) functional residual capacity apnea (FRCApnea) 2) continued RBR. Data from RBR were analyzed matched (i.e., to FRCApnea) hemoglobin saturation (HbSat) (RBRMatched) or more severe (RBREnd). A...

We provide the first description in a patient with heart failure preserved ejection fraction of "paradoxical," exaggerated reflex increase muscle sympathetic nerve activity opposite, stationary limb during dynamic 1-leg cycling exercise that was documented previously patients reduced fraction. (Level Difficulty: Advanced.).

We tested the hypotheses that spontaneous baroreflex control of integrated muscle sympathetic nerve activity (MSNA) burst occurrence and action potential (AP) subpopulations would be blunted in older compared with young adults transduction will relative to adults. Integrated underlying APs were obtained using microneurography a continuous wavelet analysis approach, respectively, during 5 min supine rest 13 (45-75 yr, 6 females) 14 (21-30 7 Baroreflex threshold relationships quantified as...

This study provides new insight to baroreflex resetting of MSNA during exercise in humans. Both fatiguing IHG and PECO reset control sympathetic APs higher blood pressures greater MSNA. However, only increased threshold gain medium-sized APs, an effect that was concealed when focusing on the integrated neurogram quantify gain. These data suggest descending central versus ascending muscle metaboreflex mechanisms differentially affect APs.

Key points Haemorrhage is the leading cause of battlefield and civilian trauma deaths. Given that a haemorrhagic injury on almost always associated with pain, it paramount administered pain medication does not disrupt physiological mechanisms are beneficial in defending against insult. Current guidelines from US Army's Committee Tactical Combat Casualty Care (CoTCCC) for selection medications to haemorrhaging soldier based upon limited scientific evidence, clear majority supporting studies...

This study tested the hypothesis that older hypertensive women display augmented pressor responses and aberrant sympathetic neural discharge patterning in response to orthostatic stress versus men. We evaluated, normotensive men (n=12 each group), blood pressure, heart rate, cardiac index (acetylene rebreathing), total peripheral resistance, muscle nerve activity (microneurography) at baseline (supine; 3 minutes) during graded head-up tilt (30° for 5 minutes 60° 20 minutes). Sympathetic...