If the doctor finds that you are a healthy candidate you will be invited to participate in the second part of the study. During Phase II, we will perform physiological tests after you are placed on a low salt diet and again after you are placed on a higher salt diet. If you are on blood pressure medication, it may be necessary to discontinue taking your present medication for up to three months before beginning the study. Patients discontinuing their current blood pressure medication may be placed on a different blood pressure medication during this 'washout' period if necessary to maintain blood pressure at pre-study levels.