Experimental studies will be conducted in subhuman primates in which maintained hypertension will be induced through a conditioning regimen of stress. The feasibility of this approach has been previously demonstrated. The aim of the proposed studies will be to examine the possible role of adrenergic mechanisms both in peripheral organs and within the central nervous system in the pathogenesis of this form of experimental hypertension. Cardiovascular measurements, during the development of the condition will be made with chronically implanted sensors. The role of adrenergic mechanisms will be examined using blood, urine and tissue biochemical and histochemical evaluation of adrenergic amines and especially by determination of amine turnover rates in peripheral organs as well as in the hypothalamus. The responsiveness of the carotid sinus reflex will be also studied especially as it is affected by the adrenergic innervation of this organ.