Ryosuke Takeda

• Doctor of Philosophy
• Postdoctoral fellow at University of Texas Southwestern Medical Center

In our previous study (Manabe et al., J Appl Physiol 128:1196–1206, 1985), we demonstrated that the cerebral and cardiovascular responses induced by a pre-exercise countdown elicited peripheral vasodilation via baroreflex-mediated sympathetic withdrawal, which is likely advantageous for rapid oxygen delivery to contracting skeletal muscles in young...

Recent studies have reported blunted increases in blood pressure (BP) during static handgrip (SHG) in patients with heart failure with preserved ejection fraction (HFpEF), which may be attributed to abnormal sympathetic reactivity during exercise and/or impaired muscle metaboreflex function. However, it is unknown whether the sympathetic neural res...

Background: The prevalence of heart failure with preserved ejection fraction (HFpEF) is higher in older women than in older men, with worse clinical outcomes for older women. The underlying mechanisms are unclear, but aberrant sympathetic neural control may in part contribute. Notably, >80% of patients with HFpEF, particularly women, are overweight...

Background: Hypertension remains a significant health problem for older women (≥60 y). Though effective blood pressure (BP) interventions exist (e.g., exercise, medication), adherence to these options is low. Lower leg heat therapy represents a promising and easily implementable adjuvant treatment that may offer cardioprotective benefits. However,...

Hypertension is a leading risk factor for cardiovascular morbidity and mortality and is often accompanied by microvascular dysfunction. Despite a clear effcacy in men, standard antihypertensive medications are less effective in post-menopausal women. Consequently, adjuvant therapies are needed to improve blood pressure control and microvascular fun...

Background We tested the hypothesis that patients with heart failure with preserved ejection fraction (HFpEF) would have greater muscle sympathetic nerve activity (MSNA) at rest and sympathetic reactivity during a cold pressor test compared with non–heart failure controls. Further, given the importance of the baroreflex modulation of MSNA in the co...

Maternal obesity increases the risk of adverse pregnancy outcomes. The mechanisms that contribute to this elevated risk are unclear but may be related to greater activity of the sympathetic nervous system, which is associated with hypertensive disorders of pregnancy. We hypothesized that resting muscle sympathetic nerve activity (MSNA) would be gre...

Bursts of muscle sympathetic nerve activity (MSNA) and the ensuing vasoconstriction are pivotal determinants of beat-by-beat blood pressure regulation. Although age and sex impact blood pressure regulation, how these factors affect the central and peripheral arcs of the baroreflex remains unclear. In 27 young (25[3] years) males (YM; n=14) and fema...

The impact of age on exercise pressor responses is equivocal, likely because of sex‐specific neuro‐cardiovascular changes with age. However, assessments of the interactive effects of age and sex on muscle sympathetic nerve activity (MSNA) responses to exercise are lacking. We tested the hypothesis that older females would exhibit exaggerated increa...

Sex-disparities exist in the risk of developing hypertension throughout the lifespan, with a greater prevalence of hypertension amongst postmenopausal females compared to similarly aged males. Though the underlying mechanisms are multifactorial, exaggerated sympathetic neuro-cardiovascular reactivity may be an important contributor. Indeed, postmen...

Background: Hypertension remains a significant public health issue for older women (>60 y) in the United States. Diuretics are an important first-line treatment for blood pressure (BP) management. Our group and others have demonstrated that certain diuretics (e.g., chlorthalidone [CTD], hydrochlorothiazide) can increase muscle sympathetic nerve act...

Background: Exercise intolerance is a hallmark of heart failure, which significantly impacts activities of daily living and quality of life. In heart failure with reduced ejection fraction, exercise intolerance is associated with sympathetic nervous system hyperactivity during exercise. Whether this is also true in heart failure with preserved ejec...

Introduction: The transduction of sympathetic vasoconstrictor drive to blood pressure (BP) at rest is blunted in patients with hypertension and heart failure with reduced ejection fraction. Whether this is the case in patients with heart failure with preserved ejection fraction (HFpEF), who have a high prevalence of hypertension, remains unknown. F...

The incidence of syncope during orthostasis increases in early human pregnancy, which may be associated with cerebral blood flow (CBF) dysregulation in the upright posture. In addition, obesity and/or sleep apnea per se may influence CBF regulation due to their detrimental impacts on cerebrovascular function. However, it is unknown whether early pr...

Excessive sympathetic activity during exercise causes heightened peripheral vasoconstriction, which can reduce oxygen delivery to active muscles, resulting in exercise intolerance. Although both patients suffering from heart failure with preserved and reduced ejection fraction (HFpEF and HFrEF, respectively) exhibit reduced exercise capacity, accum...

Normal pregnancy is associated with vast adjustments in cardiovascular autonomic control. Sympathetic baroreflex sensitivity has been reported to be attenuated during pregnancy in animal models, but most studies in humans are cross-sectional and findings from longitudinal case studies are inconclusive. It remains unclear how sympathetic baroreflex...

Women who reached early menopause (EM, 40‐44 yrs) have a greater risk for cardiovascular disease than women with normal menopause (NM, 50‐54 yrs), which may be attributed to a longer duration of estrogen loss and a greater reduction in nitric oxide bioavailability in both the peripherals and center. Previous studies have shown that dietary nitrate...

Maternal obesity increases the risk of adverse pregnancy outcomes. The mechanisms that contribute to this elevated risk are unclear but may be related to overactivation of the sympathetic nervous system. Indeed, sympathetic activation during pregnancy is now regarded as a normal adaptation to maintain homeostasis. However, sympathetic overactivatio...

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder that is more prevalent in women than men and has been linked to an elevated risk of developing cardiovascular disease. Although the physiological mechanisms are unclear, it is thought that exaggerated neuro-cardiovascular reactivity is partially responsible. Indeed, women w...

Background: Posttraumatic stress disorder (PTSD) is more prevalent in women than men and is associated with an increased risk for dementia. Indeed, we previously showed that cognitive function is impaired in women with PTSD, but the underlying mechanisms remain unknown. In patients with mild cognitive impairment, the cardiovascular response during...

Post‐menopausal women are at greater risk for cardiovascular disease compared with age‐matched men. An exaggerated morning blood pressure surge (MBPS) in post‐menopausal women is well established as an independent risk factor for cardiovascular events. Dietary nitrate supplements such as nitrate‐rich beetroot juice (BRJ) may reduce blood pressure (...

Muscle sympathetic nerve activity (MSNA) increases during isometric exercise via increased firing of low-threshold action potentials (AP), recruitment of larger, higher-threshold APs, and synaptic delay modifications. Recent work found that women with post-traumatic stress disorder (PTSD) demonstrate exaggerated early-onset MSNA responses to exerci...

Previous studies have demonstrated that sympathetic baroreflex sensitivity (BRS) increases during orthostatic stress in humans. We recently showed that dietary salt intake affects sympathetic neural control in healthy premenopausal women. This study aimed to determine whether salt loading versus salt reduction would impact sympathetic BRS during or...

Excessive salt intake is considered a risk factor for the development of hypertension. Additionally, aberrant neuro-circulatory responses to a cold stimulus are associated with an increased risk of hypertension. This study aimed to determine whether salt loading versus salt reduction would impact hemodynamic and sympathetic neural responses during...

Salt intake may alter blood pressure (BP) regulation, but no study has investigated the impact of salt reduction versus salt loading on morning blood pressure surge (MBPS) and sympathetic neural control in premenopausal women with a history of normal pregnancy. Nine healthy women [42±3 (SD) yr] were given a low-salt (LS; 50 mEq sodium/day) and high...

Background Excessive salt intake is considered a risk factor for the development of hypertension. Previous studies have demonstrated that augmented neural and pressor responses to a cold stimulus are associated with an increased risk of hypertension. This study aimed to determine whether salt loading impacts sympathetic neural responses during the...

Maternal obesity is a major risk factor for adverse pregnancy outcomes and this increased risk is attributed, at least in part, to obstructive sleep apnea (OSA; defined as an Apnea and Hypopnea Index ≥5). However, whether obesity and OSA increase the risk of adverse outcomes through sympathetic neural mechanisms is unknown. We hypothesized that obe...

Pregnancy is a dynamic process with systemic neuro‐vascular adaptations. Normal pregnancy is associated with sympathetic activation and attenuated vasoconstrictor responsiveness to alpha‐adrenergic stimulation, which starts as early as 4 weeks of gestation. However, little is known about changes in the exercise pressor reflex in pregnancy, a robust...