Respiratory modulation of sympathetic transduction to blood pressure in health and type 2 diabetes.

Type 2 diabetes (T2D) is often accompanied by hypertension, exaggerated blood pressure (BP) responses to sympatho-excitatory stressors, and raised cardiovascular disease risk. Appropriate respiratory-sympathetic coupling and sympathetic transduction to BP are important for short- and longer-term BP control. We tested the hypotheses that respiratory modulation of muscle sympathetic nerve activity (MSNA) and its transduction to BP would be impaired in T2D and associated with higher BP and respiratory-coupled BP variability.

Sex differences in sympathetic transduction in black and white adults: implications for racial disparities in hypertension and cardiovascular disease risk.

The prevalence of hypertension in non-Hispanic black (BL) individuals is the greatest of any racial/ethnic group. Whereas women generally display lower rates of hypertension than men of the same background, BL women display a similar if not greater burden of hypertension compared with BL men. The risk for cardiovascular disease and related events is also highest in BL individuals.

Relation of forward and backward traveling pressure waves with subclinical carotid artery wall remodeling and central pulse pressure.

Central pulse pressure (PP) is the sum of forward and backward traveling pressure waves that have been associated with cardiovascular disease (CVD) risk. However, previous studies have reported differential findings regarding the importance of the forward versus the backward wave for CVD risk. Therefore, we sought to determine the degree to which the forward and backward pressure waves are associated with subclinical carotid artery wall remodeling and central PP in healthy adults.

Cardiopulmonary baroreceptors modify pain intensity in patients with chronic back pain.

Objective: Baroreceptors play a significant role in nociceptive pain. However, the extent to which baroreceptors modulate nociception in patients with chronic pain is unclear. We tested the hypothesis that cardiopulmonary baroreceptor unloading via LBNP would significantly increase pressure pain threshold and habituation to heat pain among patients with chronic back pain.

Low- and high-frequency spinal cord stimulation and arterial blood pressure in patients with chronic pain and hypertension: a retrospective study.

Purpose: Evidence suggests that traditional low-frequency spinal cord stimulation (LF-SCS) reduces arterial blood pressure (BP) in patients with chronic pain and hypertension independent of improved pain symptoms. However, it remains unclear whether high-frequency spinal cord stimulation (HF-SCS) also lowers BP in chronic pain patients with hypertension. Therefore, in a retrospective study design, we tested the hypothesis that clinic BP would be significantly reduced following implantation of HF-SCS in patients with chronic pain and hypertension.

Sex-specific associations of reservoir-excess pressure parameters with age and subclinical vascular remodeling.

Objective: Central artery reservoir pressure and excess pressure (XSP) are associated with cardiovascular disease (CVD) events and mortality. However, sex differences in the trajectory of central reservoir pressure and XSP with advancing age and their relations with vascular markers of subclinical CVD risk are incompletely understood. Therefore, we tested the hypothesis that central reservoir pressure and XSP would be positively associated with advancing age and vascular markers of subclinical CVD risk in men and women.

Concomitantly higher resting arterial blood pressure and transduction of sympathetic neural activity in human obesity without hypertension.

Objective: Central (abdominal) obesity is associated with elevated adrenergic activity and arterial blood pressure (BP). Therefore, we tested the hypothesis that transduction of spontaneous muscle sympathetic nerve activity (MSNA) to BP, that is, sympathetic transduction, is augmented in abdominal obesity (increased waist circumference) and positively related to prevailing BP.

Methods: Young/middle-aged obese (32 ± 7 years; BMI: 36 ± 5 kg/m2, n = 14) and nonobese (29 ± 10 years; BMI: 23 ± 4 kg/m2, n = 14) without hypertension (24-h ambulatory average BP < 130/80 mmHg) were included.

CORP: Standardizing methodology for assessing spontaneous baroreflex control of muscle sympathetic nerve activity in humans.

The use of spontaneous bursts of muscle sympathetic nerve activity (MSNA) to assess arterial baroreflex control of sympathetic nerve activity has seen increased utility in studies of both health and disease. However, methods used for analyzing spontaneous MSNA baroreflex sensitivity are highly variable across published studies. Therefore, we sought to comprehensively examine methods of producing linear regression slopes to quantify spontaneous MSNA baroreflex sensitivity in a large cohort of subjects ( = 150) to support a standardized procedure for analysis that would allow for consistent and comparable results across laboratories.

Beat-to-Beat Blood Pressure Variability in the First Trimester Is Associated With the Development of Preeclampsia in a Prospective Cohort: Relation With Aortic Stiffness.

Women with preeclampsia, a hypertensive disorder of pregnancy, exhibit greater beat-to-beat blood pressure variability (BPV) in the third trimester after clinical onset of the disorder. However, it remains unknown whether elevated BPV precedes the development of preeclampsia. A prospective study cohort of 139 women (age 30.

Aortic stiffness is associated with changes in retinal arteriole flow pulsatility mediated by local vasodilation in healthy young/middle-age adults.

Aortic stiffness is associated with augmented pressure pulsatility in large conduit arteries and remodeling of the microcirculation. However, studies in humans examining the relation between aortic stiffness and end-organ microvascular flow pulsatility are limited. Therefore, we used the retinal microvasculature as an end-organ in vivo model to examine the hypothesis that aortic stiffness would be positively associated with microvascular flow pulsatility index (PI) (flow pulse amplitude/mean flow) in humans.

Dissociation between reduced pain and arterial blood pressure following epidural spinal cord stimulation in patients with chronic pain: A retrospective study.

Purpose: Acute pain and resting arterial blood pressure (BP) are positively correlated in patients with chronic pain. However, it remains unclear whether treatment for chronic pain reduces BP. Therefore, in a retrospective study design, we tested the hypothesis that implantation of an epidural spinal cord stimulator (SCS) device to treat chronic pain would significantly reduce clinic pain ratings and BP and that these reductions would be significantly correlated.

Augmented pressor and sympathoexcitatory responses to the onset of isometric handgrip in patients with type 2 diabetes.

Patients with type 2 diabetes (T2D) exhibit greater daytime blood pressure (BP) variability, increasing their cardiovascular risk. Given the number of daily activities that incorporate short-duration isometric muscle contractions (e.g.

Sex and age differences in the association between sympathetic outflow and central elastic artery wall thickness in humans.

Aging is characterized by increased wall thickness of the central elastic arteries (i.e., aorta and carotid arteries), although the mechanisms involved are unclear.

Sympathetic Transduction in Type 2 Diabetes Mellitus.

Approximately 60% of patients with type 2 diabetes mellitus (T2D) develop hypertension. Recent work also indicates greater blood pressure (BP) excursions throughout the day in T2D. Collectively, these findings suggest altered BP control in T2D.

Elevated Muscle Sympathetic Nerve Activity Contributes to Central Artery Stiffness in Young and Middle-Age/Older Adults.

Muscle sympathetic nerve activity (MSNA) influences the mechanical properties (ie, vascular smooth muscle tone and stiffness) of peripheral arteries, but it remains controversial whether MSNA contributes to stiffness of central arteries, such as the aorta and carotids. We examined whether elevated MSNA (age-related) would be independently associated with greater stiffness of central (carotid-femoral pulse wave velocity [PWV]) and peripheral (carotid-brachial PWV) arteries, in addition to lower carotid compliance coefficient, in healthy men and women (n=88, age: 19-73 years, 52% men). We also examined whether acute elevations in MSNA without increases in mean arterial pressure using graded levels of lower body negative pressure would augment central and peripheral artery stiffness in young (n=15, 60% men) and middle-age/older (MA/O, n=14, 43% men) adults.

Femoral vascular conductance and peroneal muscle sympathetic nerve activity responses to acute epidural spinal cord stimulation in humans.

New Findings: What is the central question of this research? Does acute spinal cord stimulation increase vascular conductance and decrease muscle sympathetic nerve activity in the lower limbs of humans? What is the main finding and its importance? Acute spinal cord stimulation led to a rapid rise in femoral vascular conductance, and peroneal muscle sympathetic nerve activity demonstrated a delayed reduction that was not associated with the initial increase in femoral vascular conductance. These findings suggest that neural mechanisms in addition to attenuated muscle sympathetic nerve activity might be involved in the initial increase in femoral vascular conductance during acute spinal cord stimulation.

Abstract: Clinical cases have indicated an increase in peripheral blood flow after continuous epidural spinal cord stimulation (SCS) and that reduced muscle sympathetic nerve activity (MSNA) might be a potential mechanism.

Insulin increases ventilation during euglycemia in humans.

Evidence from animal studies indicates that hyperinsulinemia, without changes in glucose, increases ventilation via a carotid body-mediated mechanism. However, whether insulin elevates ventilation in humans independently of changes in glucose remains unclear. Therefore, we tested the hypothesis that insulin increases ventilation in humans during a hyperinsulinemic-euglycemic clamp in which insulin was elevated to postprandial concentrations while glucose was maintained at fasting concentrations.

Relative burst amplitude of muscle sympathetic nerve activity is an indicator of altered sympathetic outflow in chronic anxiety.

Relative burst amplitude of muscle sympathetic nerve activity (MSNA) is an indicator of augmented sympathetic outflow and contributes to greater vasoconstrictor responses. Evidence suggests anxiety-induced augmentation of relative MSNA burst amplitude in patients with panic disorder; thus we hypothesized that acute stress would result in augmented relative MSNA burst amplitude and vasoconstriction in individuals with chronic anxiety. Eighteen participants with chronic anxiety (ANX; 8 men, 10 women, 32 ± 2 yr) and 18 healthy control subjects with low or no anxiety (CON; 8 men, 10 women, 39 ± 3 yr) were studied.