Cardiac baroreflex sensitivity is not correlated to sympathetic baroreflex sensitivity within healthy, young humans.

• The purpose of this study was to evaluate the relationship between the cardiac and sympathetic baroreflex sensitivities within healthy, young humans. The sensitivities of the cardiac and sympathetic baroreflexes were compared in 53 normotensive individuals (28 men and 25 women; age: 24.0 ± 0.9 years; body mass index: 24.0 ± 0.3 cm/kg², mean ± SEM). Heart rate, arterial blood pressure, and peroneal muscle sympathetic nerve activity were recorded under resting conditions (heart rate: 58 ± 1 bpm; systolic blood pressure: 126 ± 2 mm Hg; diastolic blood pressure: 72 ± 1 mm Hg; mean arterial blood pressure: 89 ± 1 mm Hg; muscle sympathetic nerve activity: 18 ± 1 bursts per min) and during rapid changes in blood pressure induced by sequential boluses of nitroprusside and phenylephrine. Cardiac and sympathetic baroreflex sensitivities were analyzed using the slopes of the linear portions of the muscle sympathetic nerve activity-diastolic blood pressure and R-R interval-systolic blood pressure relationships, respectively. When individual cardiac baroreflex sensitivity was compared with sympathetic baroreflex sensitivity, no correlation (R-R interval: r = -0.13; heart rate: r = 0.21) was observed when studied as a group. Analysis by sex unveiled a correlation in women between the cardiac and sympathetic baroreflex sensitivities (R-R interval: r = -0.54; P = 0.01; no correlation with hazard ratio: r = 0.29). No relationship was found in men (R-R interval: r = 0.17; heart rate: r = 0.12). These results indicate that, although both cardiac and sympathetic efferents function in baroreflex control of arterial pressure, there is no correlation in their sensitivities within healthy normotensive humans. However, sex-stratified data indicate that sex-based differential correlations might exist.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Nyckelord

Adult

Baroreflex

drug effects

physiology

Blood Pressure

physiology

Body Mass Index

Female

Heart

drug effects

physiology

Heart Rate

drug effects

physiology

Humans

Male

Nitroprusside

administration & dosage

Phenylephrine

administration & dosage

Sex Factors

Sympathetic Nervous System

drug effects

physiology

Young Adult

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