The broad objective of this proposal is to examine the influence of fish oil (omega-3 fatty acids) on neurovascular control in humans. Specifically, this project will examine the effect of fish oil on: 1) resting blood pressure and muscle sympathetic nerve activity (MSNA) in normotensive and hypertensive individuals, and 2) neurovascular responses to mental stress in normotensive and hypertensive individuals. The specific aims of this project are: 1. To determine the effect of fish oil on blood pressure and MSNA at rest in humans. Resting blood pressure and MSNA will be measured before and after an eight-week fish oil supplementation period. Both normotensive and hypertensive subjects will be studied. It is hypothesized that fish oil will reduce blood pressure in hypertensive subjects, and that reductions in blood pressure will be associated with reductions in resting MSNA. 2. To determine the effect of fish oil on blood pressure and MSNA responses to mental stress. MSNA responses to mental stress will be measured directly from the peroneal nerve before and after an eight-week fish oil supplementation period. Both normotensive and hypertensive subjects will be studied. It is hypothesized that fish oil will inhibit blood pressure and MSNA responses to mental stress in hypertensive subjects. 3. To determine the effect of fish oil on forearm and calf vascular responses to mental stress. Forearm and calf blood flow responses to mental stress will be simultaneously recorded using venous occlusion plethysmography before and after an eight-week fish oil supplementation period. Both normotensive and hypertensive subjects will be studied. It is hypothesized that fish oil will enhance the forearm vasodilation response to mental stress, and that this response will be more dramatic in hypertensive subjects. 4. To determine the effect of fish oil on sympathetic and vascular recovery responses to mental stress. Post mental-stress blood pressure, MSNA and blood flow will be measured before and after an eight-week fish oil supplementation period. Both normotensive and hypertensive subjects will be studied. It is hypothesized that fish oil will reduce the amount of time required to return blood pressure, MSNA, and blood flow to baseline conditions after mental stress. Fish oil reduces the incidence of cardiovascular disease, but the mechanisms underlying this relationship remain unclear. This project will provide new knowledge regarding the effect of fish oil on neurovascular control in both normotensive and hypertensive humans.