engleski

Changes in the autonomic nervous system during high-salt loading in young healthy individuals

Introduction: High-salt (HS) intake, high levels of angiotensin II and increased sympathetic (SNS) activity are all injurious to the cardiovascular (CV) system, and play a role in a multitude of CV diseases. In recent years it became evident that HS dietary intake affects vascular and particularly endothelial functions even in the absence of changes in blood pressure (BP) in healthy individuals. HS intake suppress renin-angiotensin system (RAS) in healthy individuals, but it is still not elucidated how HS intake affects SNS activity in healthy population in the absence of BP changes (does it inhibit or potentiate SNS activity). The aim of our project is to assess SNS/parasympathetic (PSNS) activity by measurement of heart rate variability (HRV), and level of catecholamines and their metabolites in 24h urine sample before and after HS diet protocol in young healthy individuals. Methods: 10 young healthy men were assigned to 7-days low salt (LS) diet (<3.5 g salt/day) followed by 7-days HS diet (~14 g salt/day) (pilot measurements). 5-minute HRV was assessed by Hearth Rhythm Scanner (Biocom), and 24h- urine epinephrine, metanephrine, norepinephrine, normetanephrine, vanillylmandelic acid (VMA), dopamine, homovanillic acid (HVA) were measured before and after diet protocols. Results: 7-days HS diet significantly decreased level of epinephrine and metanephrine in 24h urine samples. Both time domain and frequency domain analysis did not show significant changes in HRV following HS diet in young healthy men. There was no significant correlation between salt intake and measured HRV parameters, as well as salt intake and catecholamines and their metabolites level. Discussion and Conclusion: Although reduced epinephrine and methanephrine levels may indicate a decrease in SNS activity due to HS intake, functional measurements of HRV did not show any significant change in both SNS and PSNS activity level following HS diet in young healthy men. Nevertheless, the final conclusions will be make after the inclusion of young healthy women as well as the increase of the total number of healthy individuals in the present study. Ethical Committee: The study protocol conformed with the standards set by the latest revision of the Declaration of Helsinki and were approved by the Ethical Committee of the Faculty of Medicine, University of Osijek (Cl: 602-04/15-08/08 ; No: 2158-61-07-15-68). Grants: The present study was supported by Croatian Science Foundation under the project #IP-2016-06-8744 Interaction of Renin- Angiotensin and Adrenergic System in Oxidative Stress Induced Endothelial Activation (RAS- AdrenOX).

high salt diet ; autonomic nervous system ; heart rate variability ; catecholamines

nije evidentirano