The Effects of Acute Salt Loading on Hemodynamic Parameters in Young Caucasian Males

Abstract

Impedance cardiography (ICG) is a useful tool for non-invasive hemodynamic monitoring in clinical populations. However, the acute effects of salt (NaCl) loading have not been extensively studied in healthy young men. PURPOSE: The purpose of the current investigation was to determine the effects of non-dietary NaCl loading on hemodynamic parameters in Caucasian males using ICG. METHODS: Twenty four apparently healthy, young (23.6 ±2 yr) Caucasian males volunteered to participate in the current investigation. Subjects underwent two experimental trials consisting of a 30 minute baseline period, a 60 minute ingestion period (SALT vs. WATER), followed by a 120 minute recovery period. During the SALT trial, subjects ingested 11.3g of NaCl as well as 1136.5 ml of water; during the WATER trial, subjects only ingested water. Mean arterial pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI) were recorded every 10 minutes throughout the trials. All measurements were made in the seated position and urine output was quantified at the end of each trial. RESULTS: Data were analyzed using a 2 trial by 22 time point Analysis of Variance (ANOVA). Significant main effects and trial by time interactions were further explored with post hoc t-tests. The ANOVA revealed a main effect for time for changes in CI and increases in MAP and SVRI (p<0.001). A main effect for trial was observed for CI with values higher in the salt trial (p<0.001). Trial by time interactions were observed for CI and MAP (p<0.001). CI values increased during ingestion in the SALT trial while decreasing in the water trial. MAP values increased more so in the SALT vs. WATER trial during ingestion and into recovery. SVRI increased similarly in both trials. CONCLUSIONS: NaCl loading caused CI to increase during ingestion, relative to WATER, which increased MAP. This NaCl challenge appears to alter hemodynamics in this subclinical population of healthy young men. Further research could examine the effects of NaCl on other body systems.