Effect of Acute Elevations in Serum Phosphate on Cardiac Baroreflex Sensitivity in Young Healthy Adults
Authors: Stephens Brandi Y. , Kaur Jasdeep , Barbosa Thales C. , Vranish Jennifer R. , Smith Scott A. , Vongpatanasin Wanpen , Fadel Paul J. 
Published: June 2021

Over the last 20 years, with the growing abundance of processed foods in the United States, dietary intake of inorganic phosphate (Pi) has more than doubled the daily‐recommended allowance. Importantly, chronic consumption of Pi is associated with an increased risk of cardiovascular diseases in the general population, such as atherosclerosis, hypertension, and stroke. However, investigation of the potential underlying mechanisms by which high Pi intake affects the cardiovascular system has been limited. Given the strong link between impairments in cardiac baroreflex sensitivity (cBRS) and reductions in heart rate variability (HRV) to greater cardiovascular morbidity and mortality, we examined the impact of acute high Pi consumption on cBRS and HRV. We tested the hypotheses that acute high Pi consumption attenuates cBRS and decreases HRV in young adults. Fourteen young men were studied on two separate days in which they consumed either a phosphate drink containing 2,000 mg Phosphorus and 1,520 sodium (n=13; 23 ± 1 yrs; mean ± SEM) or a sodium chloride drink (NaCl) containing 1,520 mg sodium (n=5; 23 ± 2 yrs) to match the sodium in the phosphate drink and to serve as a control. Resting heart rate (ECG) and arterial blood pressure (finger photoplethysmography and automated sphygmomanometer) were measured for a 10 min period before and 60 min post‐Pi (a time period known to elicit peak elevations in serum phosphate following Pi consumption) or post‐NaCl consumption. Blood draws were performed at baseline, 60 min, and 120 min to measure serum phosphate. The Sequence Method was used to estimate spontaneous cBRS separately for up sequences (increase systolic blood pressure: increase R‐R interval), down sequences (decrease systolic blood pressure: decrease R‐R interval), and for all sequences combined (overall cBRS). HRV was determined in the time‐domain as Root Mean Square of the Successive Differences (RMSSD), Standard Deviation of Successive Differences (SDSD), and Standard Deviation of Normal to Normal R‐R intervals (SDNN). Serum phosphate was significantly elevated at 60 min (baseline: 3.2 ± 0.2 mg/dL; 60 min: 4.5 ± 0.2 mg/dL; p<0.01) and was maintained at 120 min post‐ Pi consumption. Resting blood pressure was not affected by Pi consumption (mean BP: pre 84 ± 2 vs. post 85 ± 2; p=0.23). Overall cBRS showed no differences between pre‐and post‐Pi (25.1 ± 2.4 vs. 26.1 ± 2.9 ms/mmHg; p=0.50). Up sequences and down sequences were also not different pre‐ and post‐Pi. The number of sequences were similar pre‐ and post‐Pi. For HRV, no differences were observed pre‐and post‐Pi (e.g. RMSSD: 93.9 ± 15.06 vs. 86.4 ± 13.67 ms; p=0.37). NaCl consumption had no effect on serum phosphate (p=0.51), or any measured cardiovascular variable. These preliminary data suggest that acute exposure to high Pi is not directly associated with an impairment in resting cBRS or decrease in HRV in young, healthy men.Support or Funding InformationSupported by UTA College of Nursing and Health InnovationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.