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Reduced vagal activity in salt-sensitive subjects during mental challenge

Item Type:Article
Title:Reduced vagal activity in salt-sensitive subjects during mental challenge
Creators Name:Buchholz, K. and Schaechinger, H. and Wagner, M. and Sharma, A.M. and Deter, H.C.
Abstract:Background: Salt-sensitive normotensive men exhibit an enhanced pressor and heart rate (HR) response to mental stress. Stress-induced HR acceleration may result from sympathetic activation or vagal withdrawal. We studied the importance of vagal withdrawal for the increased stress responsiveness of salt-sensitive subjects. Methods: We studied cardiovascular reactivity to mental challenge in 17 salt-sensitive healthy white male students and 56 salt-resistant control subjects who were comparable with respect to age, body mass index, and physical fitness. Salt sensitivity was determined by a 2-week dietary protocol (20 mmol v 240 mmol sodium/day). Mental stress was induced by a computerized information-processing task (manometer test). Electrocardiogram and finger blood pressure (BP; Finapres, Ohmeda, Louisville, CO) were registered continuously to determine HR and interbeat-interval length. Time and frequency domain (spectral power) based measures of respiratory-related heart rate variability (HRV) were calculated to estimate vagal cardiac control; diastolic BP reactivity was assessed to estimate peripheral sympathetic effects. Results: Stress-induced increase in HR was higher in salt-sensitive than in salt-resistant subjects. Salt-sensitive subjects, in comparison to salt-resistant subjects, showed significantly reduced respiratory-related HRV during baseline and mental stress conditions (P < .01). The increase in diastolic BP during mental challenge was significantly greater in salt-sensitive subjects (P < .05). Conclusions: Our findings suggest reduced vagal and increased sympathetic tone during mental challenge in salt-sensitive subjects. Altered autonomic nervous system function may contribute to later development of hypertension in salt-sensitive individuals.
Keywords:Heart Rate Variability, Vagal Activity, Mental Stress, Sodium-Dependent Hypertension, Blood Pressure
Source:American Journal of Hypertension
Page Range:531-536
Date:July 2003
Official Publication:https://doi.org/10.1016/S0895-7061(03)00905-1
PubMed:View item in PubMed

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