Publications by authors named "Massimo Nardone"

Article Synopsis
  • A study examined how bursts of muscle sympathetic nerve activity (MSNA) affect regional blood flow and overall blood pressure (BP) in 14 young adults after a meal and rest.
  • Researchers recorded various metrics, including MSNA, heart rate, BP, and blood flow in the femoral artery, to analyze the relationship between changes in BP and vascular conductance.
  • The findings showed that changes in BP are moderately related to regional vascular conductance, suggesting that measuring BP can provide insight into localized vascular responses to sympathetic nerve activity.
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Article Synopsis
  • The study investigates the reliability of blood pressure (BP) measurements during submaximal and maximal exercise, considering the potential influence of biological sex on results.
  • A total of 84 participants underwent two maximal treadmill tests, with systolic BP being measured frequently and assessed for test-retest reliability using statistical methods.
  • Results indicated that systolic BP reliability was substantial for both sexes during submaximal and maximal exercise, but females exhibited higher reliability compared to males, especially in submaximal conditions.
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Volume overload represents a hallmark clinical feature linked to the development and progression of heart failure (HF). Alleviating signs and symptoms of volume overload represents a foundational HF treatment target that is achieved using loop diuretics in the acute and chronic setting. Recent work has provided evidence to support guideline-directed medical therapies, such as sodium glucose cotransporter 2 (SGLT2) inhibitors and mineralocorticoid receptor (MR) antagonists, as important adjunct diuretics that may act synergistically when used with background loop diuretics in people with chronic HF.

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Microneurographic recordings of muscle sympathetic nerve activity (MSNA) and the succeeding changes in beat-to-beat blood pressure (i.e., sympathetic transduction) provide important insights into the neural control of the circulation in humans.

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Discharge of postganglionic muscle sympathetic nerve activity (MSNA) is related poorly to blood pressure (BP) in adults. Whether neural measurements beyond the prevailing level of MSNA can account for interindividual differences in BP remains unclear. The current study sought to evaluate the relative contributions of sympathetic-BP transduction and sympathetic baroreflex gain on resting BP in young adults.

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Purpose: Our aim was to test the hypothesis that patients with chronic kidney disease (CKD) would exhibit augmented resting beat-to-beat blood pressure variability (BPV) that is associated with poor clinical outcomes independent of mean blood pressure (BP). In addition, since the arterial baroreflex plays a critical role in beat-to-beat BP regulation, we further hypothesized that an impaired baroreflex control would be associated with an augmented resting beat-to-beat BPV.

Methods: In 25 sedentary patients with CKD stages III-IV (62 ± 9 years) and 20 controls (57 ± 10 years), resting beat-to-beat BP (finger photoplethysmography) and heart rate (electrocardiography) were continuously measured for 10 min.

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The sympathetic nervous system is important for cardiovascular regulation, particularly during acute stress. Efferent sympathetic outflow can be regulated in an organ-dependent manner, but whether renal and leg vasoconstriction are associated at rest or during sympathetic stressors is unknown. Therefore, we sought to determine the relationships between muscle sympathetic nerve activity (MSNA), leg vascular conductance (LVC), and renal vascular conductance (RVC) at rest and during common laboratory-based sympathoexcitatory stimuli in a cohort of young healthy adults.

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Post-hypoxia sympathoexcitation does not elicit corresponding changes in vascular tone, suggesting diminished sympathetic signalling. Blunted sympathetic transduction following acute hypoxia, however, has not been confirmed and the effects of hypoxia on the sympathetic transduction of mean arterial pressure (MAP) as a function of action potential (AP) activity is unknown. We hypothesized that MAP changes would be blunted during acute hypoxia but restored in recovery and asynchronous APs would elicit smaller MAP changes than synchronous APs.

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The effects of sympathetic activity on vasoconstriction are dampened in active skeletal muscle during exercise, a phenomenon termed functional sympatholysis. Limited work has examined the influence of sex on the magnitude of sympatholysis or the test-retest reliability of measurements. In 16 women and 15 men, forearm blood flow (FBF; Doppler ultrasound), muscle oxygenation (near-infrared spectroscopy, NIRS), and beat-to-beat mean arterial pressure (MAP; photoplethysmography) were measured during lower-body negative pressure (LBNP; -20 mmHg) at rest and simultaneously during rhythmic handgrip exercise (30% maximum contraction).

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Baroreflex resetting permits sympathetic long-term facilitation (sLTF) following hypoxia; however, baroreflex control of action potential (AP) clusters and AP recruitment patterns facilitating sLTF is unknown. We hypothesized that baroreflex resetting of arterial pressure operating points (OPs) of AP clusters and recruitment of large-amplitude APs would mediate sLTF following hypoxia. Eight men (age: 24 (3) years; body mass index: 24 (3) kg/m ) underwent 20 min isocapnic hypoxia ( : 47 (2) mmHg) and 30 min recovery.

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Sympathetic transduction of blood pressure (BP) is correlated negatively with resting muscle sympathetic nerve activity (MSNA) in cross-sectional data, but the acute effects of increasing MSNA are unclear. Sixteen (4 female) healthy adults (26 ± 3 years) underwent continuous measurement of heart rate, BP, and MSNA at rest and during graded lower body negative pressure (LBNP) at -10, -20, and -30 mmHg. Sympathetic transduction of BP was quantified in the time (signal averaging) and frequency (MSNA-BP gain) domains.

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Resting beat-to-beat blood pressure variability is a powerful predictor of cardiovascular events and end-organ damage. However, its underlying mechanisms remain unknown. Herein, we tested the hypothesis that a potentiation of GABAergic synaptic transmission by diazepam would acutely increase resting beat-to-beat blood pressure variability.

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Background: Coronary microvascular function can be distinctly quantified using the coronary flow reserve (CFR) and index of microvascular resistance (IMR). Patients with low CFR can present with low or high IMR, although the prevalence and clinical characteristics of these patient groups remain unclear.

Methods: One hundred ninety-nine patients underwent coronary microvascular assessments using coronary thermodilution techniques.

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Signal-averaged sympathetic transduction of blood pressure (BP) is inversely related to resting muscle sympathetic nerve activity (MSNA) burst frequency in healthy cohorts. Whether this represents a physiological compensatory adaptation or a methodological limitation, remains unclear. The current analysis aimed to determine the contribution of methodological limitations by evaluating the dependency of MSNA transduction at different levels of absolute BP.

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Purpose: Larger blood pressure (BP) responses to relative-intensity static exercise in men versus women are thought to involve altered muscle metaboreflex activation, but whether this is because of an intrinsic sex difference in metabolite production or differences in muscle strength and absolute load is unknown.

Methods: Continuous BP and heart rate were recorded in 200 healthy young men and women (women: n = 109) during 2 min of static handgrip exercise at 30% of maximal voluntary contraction (MVC), followed by 2 min of postexercise circulatory occlusion (PECO). Muscle sympathetic nerve activity (MSNA) was recorded in a subset of participants (n = 39; women, n = 21), permitting calculation of signal-averaged resting sympathetic transduction (MSNA-diastolic BP).

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Calculating the blood pressure (BP) response to a burst of muscle sympathetic nerve activity (MSNA), termed sympathetic transduction, may be influenced by an individual's resting burst frequency. We examined the relationships between sympathetic transduction and MSNA in 107 healthy males and females and developed a normalized sympathetic transduction metric to incorporate resting MSNA. Burst-triggered signal averaging was used to calculate the peak diastolic BP response following each MSNA burst (sympathetic transduction of BP) and following incorporation of MSNA burst cluster patterns and amplitudes (sympathetic transduction slope).

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