Heredity and Phenotype Intervention (HAPI) Heart Study

The aspirin intervention (81 mg per day) will last a total of 14 days. Pills will be provided in a pre-loaded pillbox. The field team will visit the subject at his/her home at least once to insure adherence to the aspirin intervention and to monitor for adverse side effects. On day 14 of the aspirin intervention, the subject will visit the clinic for a fasting blood draw for platelet aggregation and inflammatory marker studies. A pill count will be performed to assess adherence. The subject can miss up to four aspirin doses over the two-week period; however, an aspirin must be taken each day for the three days prior to clinic visit 2. The aspirin intervention can be extended for up to three days (17 days total) to meet the latter criteria. If more than four doses were missed, then the physician should be contacted and the patient should be withdrawn from the aspirin intervention. Platelet aggregation will be measured 1 hour after the last dose of aspirin.

This intervention consists of the participant placing his or her hand and wrist into ice water for 2½ minutes. The blood pressure is taken before and after the arm is removed from the water. An ultrasound machine is used to take pictures of the brachial artery in the left arm before and after the arm is removed from the water.

The participants are given a high fat milk shake consisting of 83% fat. Blood samples are drawn from a catheter placed in the participant's arm prior to the test. The samples are drawn before the milk shake and at 1, 2, 3, 4, and 6 hours after the milk shake is consumed. Before and at 2, 4 and 6 hours following the meal the ultrasound is used to obtain images of the brachial artery.

The salt intervention will consist of 6 days of an isocaloric high salt diet (270 mmol/d) followed by a washout period of at least 8 days and then a low salt diet (40 mmol/d). All food will be prepared by a registered dietician and dietary technicians in a specially equipped kitchen. The specific foods will consist of approximately 50% carbohydrates, 35% fat, and 15% protein. Dietary potassium will remain constant at 120 mmol/d. A food diary will be kept for each diet and subjects will be instructed to eat only the food provided. A field nurse will visit the home on days 3 and 5 of each diet to insure that neither diet is acutely affecting the health status of the subject. A first AM void spot urine will be obtained to measure sodium, potassium and creatinine on the 4th, 5th, and 6th days of each diet to insure compliance. Blood pressure will be measured using an ambulatory blood pressure monitor for 24 hours on the last day of each diet.