FATTY ACIDS, ANGIOTENSIN AND OXIDATIVE STRESS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to determine how the amount of potassium, magnesium and sodium in diets affect blood pressure and the amount of oxidative stress. Measurements on different diets will be made after an overnight fast and again when fatty acids in the blood have been raised. To complete the study requires 24 visits over a 14 week time period. Pre-menopausal women will have up to one week of rest at the end of each dietary phase so that the beginning of each phase coincides with the same time point in the hormonal cycle. Fatty acids are one of the fats normally present in blood. Levels of these fats can be raised by infusing Intralipid, a fat solution made from soybeans, together with heparin, a drug that is sometimes used to treat or prevent blood clots, through a small catheter in the arm vein. The increase of fatty acids produced by the infusion of Intralipid and heparin raises the amount of oxidative stress in the body for a few hours. The effects of this infusion will disappear shortly after the cessation of the Intralipid heparin infusion. Oxidative stress will result from an interaction of oxygen with other molecules and cells. The interaction of oxygen with the cells is essential for life. However, an excessive interaction may contribute to high blood pressure. The body has several defenses against the harmful effects of oxygen, i.e., anti-oxidants. Some of these defenses are provided in the foods we eat. In this study, we will look at the effects of diets that are high and low in natural anti-oxidants to see how this affects blood pressure and markers of oxygen-related injury under baseline conditions i.e.; fasting condition before starting the infusion, and when blood fats are raised by the infusion. Potassium and magnesium are more plentiful in foods that have a high content of anti-oxidants. Potassium and magnesium may also have anti-oxidant effects. Sodium, which is contained in table salt and is present in high amounts in many processed foods, can increase blood pressure. The increase in blood pressure elicited by a high sodium diet, and the decrease in blood pressure with a low sodium diet varies from person to person depending on some inherited traits. To help separate the effects of sodium in subjects with varied genetic markers, this study includes a three-week low sodium dietary phase. The Tissue Kallikrein (TK) system influences blood pressure. In this study we expect that the type of TK gene inherited will affect blood pressure responses to the different diets. For this reason, blood samples will be drawn to study the chemical sequences that make up individual's genetic information. The scientific information from individual's genes and those of other subjects in this study may help researchers better understand the reaction to the diet and the responses of when blood fats are raised. The information may also help scientists better understand the connection between fatty acids (a blood fat), insulin resistance and blood pressure. Further still, the information may help scientists better understand the way specific genes regulate the variations in blood pressure in response to various dietary interventions.