Neurogenic abnormalities in masked hypertension

Patients with hypertension exhibit an increased sympathetic activity. No information exists as to whether this is the case in normotensive individuals in whom there is an increased ambulatory blood pressure, a condition termed "masked" hypertension. We studied 18 middle-aged subjects with masked hypertension in whom we measured muscle sympathetic nerve traffic (peroneal nerve and microneurography) and beat-to-beat arterial blood pressure at rest and during baroreceptor deactivation and activation. Measurements also included anthropometric values and insulin sensitivity (homeostasis model assessment index). Data were compared with those of 20 normotensive subjects, 18 subjects with white-coat hypertension, and 20 patients with "in-office" and "out-of-office" hypertension. All of the individuals were pharmacologically untreated and age-matched with subjects with masked hypertension. Patients with in- and out-of-office and white-coat hypertension displayed resting sympathetic nerve activity values significantly greater than normotensive subjects (75.8±2.5 and 70.8±2.2 versus 45.5±2.0 bursts per 100 heartbeats respectively; P