52. Sympathetic and cardiovascular reactivity during mental stress in patients with essential hypertension

Essential hypertension (EH) has been associated with abnormal sympathetic outflow particularly during mental stress. However data were unclear because of associated pharmacological drugs often taken by patients. The aim of this study is to ascertain abnormalities of sympathetic during mental stress in patients with untreated EH. We studied 7 untreated patients with established criteria for EH, and 10 sex and age matched healthy subjects. Patients with EH underwent an extensive laboratory screening excluding secondary causes of hypertension. Subjects underwent sitting microneurographic recording of muscle sympathetic activity (MSNA) from peroneal nerve, heart rate (HR) and blood pressure (BP) during resting state and mental stress (3-min of paced auditory serial arithmetic test -PASAT) and a cold test (two minutes immersion of a hand in ice water). The pharmacological treatment for EH was usually started after the microneurographby evaluation. As expected EH patients showed increased resting BP compared to controls but MSNA was not significantly increased although showed a tendency toward the increase. During mental stress BP was increased compared to controls but HR and MSNA did not show a significant difference. Sympathetic and cardiovascular parameters did not differ during cold test. Our data confirmed the higher BP reactivity in EH patients but this was not due to increased MSNA. However these data are preliminary and a larger cohort of patients must be recruited before drawing a definite conclusion.