Salt Study: Inhibited Breathing Pattern and Sodium Inhibitors in Sodium Sensitivity of Blood Pressure
The purpose of this study is to test the hypothesis that blood pressure sensitivity to high sodium intake in healthy humans is characterized by increased urinary excretion of two endogenous sodium pump inhibitors, marinobufagenin (MBG), and ouabain-like compound (OLC). The study also tests the hypothesis that women who breathe slowly and have high resting end tidal CO2 at rest are more likely to have low plasma renin activity and sodium sensitivity of blood pressure than those who breathe more rapidly and maintain lower end tidal CO2.
|Study Design:||Observational Model: Cohort
Time Perspective: Prospective
|Official Title:||Inhibited Breathing Pattern and Sodium Inhibitors in Sodium Sensitivity of Blood Pressure|
- The sodium loading procedures will be identical in both experiments, except that 24-hr urine collection will be collected all 12 days in experiment one, but only on the last two days of each sodium diet in experiment two. [ Time Frame: Group 1- daily; Group 2 - days 6 & 12 ] [ Designated as safety issue: No ]
|Study Start Date:||March 2003|
|Study Completion Date:||December 2006|
|Primary Completion Date:||December 2006 (Final data collection date for primary outcome measure)|
Eight men and eight women to define the time course of changes in MBG \ and OLC accompanying sodium loading
32 additional women to determine whether breathing pattern is predictive of sodium sensitivity in that gender. Women are being studied in the second experiment because they, but not men, have been shown to have an association of breathing pattern with high perceived stress11 and an association of high resting end tidal CO2 with high resting blood pressure.
The experiments will involve a common procedure of sodium restriction followed by sodium loading of normotensive (having normal blood pressure) humans. However, the first experiment will involve continuous urine collection throughout the experimental period in a smaller group of men and women, while the second experiment will involve urine collection only at the end of each diet period in a larger group of normotensive women. If, as expected, experiment one shows that sodium loading produces MBG increases that are sustained throughout the sodium loading period, then experiment two will also be able to address a third issue: that is whether MBG or OLC response to sodium loading is specific to breathing pattern or sodium sensitivity. It is hypothesized that women with inhibited breathing who are sodium sensitive will show higher levels of MBG, even before sodium loading, but also following sodium loading.
Each participant will be seen at the Clinical Research Unit for a screening visit and on days 6 and 12, and consume a low sodium diet for 6 days followed by a high sodium diet for 6 days. Research staff will meet with the participant at regular intervals for meal provision and transfer of 24-hr urine collections (if applicable). Respiration and blood pressure will be measured on the last day of each sodium diet.
|United States, Maryland|
|NIA Clinical Research Unit|
|Baltimore, Maryland, United States, 21225|
|Principal Investigator:||David Anderson, PhD||National Institute on Aging (NIA)|