Premium
Acute and Chronic Increases in Sodium and Cardiac Vagal Baroreflex Sensitivity
Author(s) -
Babcock Matthew C,
Watso Joseph,
Brian Michael S,
Edwards David G,
Stocker Sean D,
Wenner Megan M,
Farquhar William B
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.848.12
Subject(s) - baroreflex , medicine , heart rate variability , heart rate , anesthesia , plasma osmolality , sodium , blood pressure , cardiology , chemistry , vasopressin , organic chemistry
Elevations in serum sodium (sNa + ) and plasma osmolality (pOsm) have been shown to increase baroreflex sensitivity. However, the time course of these changes is not clear. PURPOSE To determine whether acute and/or chronic elevations in sNa + and pOsm alter cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV). METHODS An acute increase in sNa + was achieved with a 23‐minute hypertonic saline infusion (HSI) in 14 subjects (age: 22±1 yrs, BMI: 23±1 kg/m 2 , 7 men). A chronic increase in sNa + was achieved with 7 days of a high sodium diet (300 mmol/day) compared to 7 days of a low sodium diet (20 mmol/day; diet order randomized) in 16 subjects (age: 39±4 yrs, BMI: 23±1 kg/m 2 , 7 men). In the acute and chronic protocols, subjects lay quietly for 5 minutes while undergoing simultaneous measurement of beat‐to‐beat blood pressure (via photoplethysmography) and R‐R interval (via 3‐lead ECG). cBRS was evaluated using the sequence method. Root‐mean‐square of successive differences in R‐R interval (RMSSD) was used as an index of HRV. RESULTS HSI increased sNa + (137.9±0.4 vs. 140.9±0.5 mEq/L, p<0.05) and pOsm (285±1 vs. 290±1 mOsm/kg H 2 O, p<0.05). Despite these acute increases, cBRS (26±5 vs. 27±4 ms/mmHg, p=0.73) and RMSSD (63±9 vs. 63±8 ms, p=0.99) were not different. High sodium diet similarly increased sNa + (137.3±0.6 vs. 140.0±0.4 mEq/L, p<0.05) and pOsm (285±1 vs. 290±1 mOsm/kg H 2 O, p<0.05). cBRS was significantly increased on the high sodium diet (18±2 vs. 25±3 ms/mmHg, p<0.05), as was RMSSD (61±6 vs. 84±10 ms, p<0.05). CONCLUSION These preliminary data suggest that chronic, but not acute, elevations in sNa + and pOsm are associated with increases in cBRS and HRV. Support or Funding Information Supported by NIH Grant 1R01HL128388‐01A1