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There may be a link among stress, adrenal medullary activation, and the development of hypertension. Obesity is characterized by sympathetic activation and predisposes to hypertension, but may be associated with low or normal adrenal medullary activity. We hypothesized that plasma epinephrine (E) levels and adrenal medullary responsiveness to mental stress are lower in overweight than in lean borderline hypertensive subjects.We compared groups of lean (n = 62) and overweight (n = 29) borderline hypertensive young men as well as lean (n = 36) and overweight (n = 7) normotensive young men from the same population. Plasma catecholamines and heart rate (HR) were measured at rest during a hyperinsulinemic glucose clamp and during mental arithmetic-induced stress.Plasma norepinephrine (NE) and E, HR, and responses to stress were increased in borderline hypertensive subjects. Our results showed that NE was increased only in lean borderline hypertensive subjects at rest, but in overweight subjects as well during stress, with ΔNE being similar in lean and overweight subjects. We found that E was higher in lean than in overweight borderline hypertensive subjects at rest and during stress (both P < .001), as were ΔE and ΔHR (both P < .05). Independent of BP status, body mass index was negatively related to E during stress (P < .01) and waist circumference negatively related to resting E (P < .001) and ΔHR (P = .02).Sympathetic neural activity and responsiveness are increased in borderline hypertensive young men, but measures of overweight are independently related to lower plasma E and HR responses. We suggest that adrenal medullary activation in borderline hypertension mainly characterizes lean subjects. Am J Hypertens 2004;17:611-618 © 2004 American Journal of Hypertension, Ltd.