The overall objective of this project is to identify the key salt-sensing regions of the brain and determine the underlying mechanism of sodium sensing. The investigators will assess how the brain responds to an acute increase of salt in the blood using MRI. This will be done during a 30-minute infusion of a saline solution containing 3% salt. One trial will be conducted with a salt sensing channel blocker and one trial without the salt sensing channel blocker. This will help to assess the role of a specific salt sensing channel in the brain. Salt sensitivity of BP will be assessed using 7-day dietary feeding where participants will be given food to consume for 7-days. Comparisons will be made between salt resistant (no change in blood pressure going from low to high salt diets) and salt sensitive adults (a change in blood pressure going from low to high salt diets). The investigators think the changes in MRI will be greater in salt sensitive compared to salt resistant subjects.
Age: > 40 years or < 60 years
Blood pressure: > 100/60 mmHg or < 140/90 mmHg
BMI: > 18.5 kg/m2 or < 35 kg/m2
Serum potassium: > 3.5 mmol/L or < 5.5 mmol/L
Age: < 40 years or > 60 years
Blood pressure: < 100/60 mmHg or > 140/90 mmHg
BMI: < 18.5 kg/m2 or > 30 kg/m2
Serum potassium: < 3.5 mmol/L or > 5.5 mmol/L
Crossover
Furosemide (Diuretic)
DrugThe diuretic furosemide will be given during a 3% hypertonic saline infusion to examine blockade of the NKCC2.
Hypertonic Saline Infusion
Other intervention3% Hypertonic saline infusion to acutely increase sodium and osmolality
Bold fMRI
Intensity of sodium sensing regions of the brain
Blood Pressure
Systolic and Diastolic Blood pressure responses to hypertonic saline
Sympathetic Nerve Activity
sympathetic bursts per minute
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University of Delaware
Lead sponsor
National Heart, Lung, and Blood Institute (NHLBI)
Collaborator
