The overall aim of this proposal is to prepare the applicant for an independent career in the area of cardiovascular sciences. The research planned is concerned with the physiological mechanisms associated with hypertension and their behavioral correlates This will be accomplished by training the applicant in research skills in cardiovascular vascular physiology and biochemical endocrinology. The objective is to study the central peptidergic and catecholaminergic mechanisms and related behaviors involved in hypertension in a model of genetically hypertensive rats. Experiments will investigate the behavioral and central vasopressin and catecholamine responses to centrally and peripherally administered hypertonic saline and angiotensin II, with and without central pretreatment with a vasopressin (V1) antagonist in young and adult spontaneously hypertensive (SHR) and normotensive rats. Using the push-pull technique, the third cerebral ventricle will be perfused with artificial CSF while collecting samples for the measurement of vasopressin and catecholamines in the awake, unrestrained rat. The protocol includes the simultaneous monitoring of blood pressure and behavior and the collection of periodic blood samples for peripheral vasopressin detection. These studies should enable a more complete characterization of peptidergic, catecholaminergic, and behavioral response differences in the SHR to be made, offering evidence for the hypothesis of altered functioning of the central vasopressin system in the hypertensive rat, while simultaneously training the applicant for a research career in the area of hypertension.