Neural Sympathetic Activity in Essential Hypertension

To the Editor: We read with great interest the article by Schlaich et al1 dealing with the issue of sympathetic augmentation in hypertension. In 1993, we demonstrated that neural sympathetic activity predominance is registered in essential hypertensive patients.2 These findings were supported by the overwhelming circulating noradrenaline (NA) versus adrenaline (Ad) levels registered throughout the oral glucose tolerance test. This NA versus Ad predominance has also been demonstrated through the supine-resting/1-minute orthostasis/5-minute moderate exercise test. This test is based on the findings of Robertson et al, who demonstrated that NA, but not Ad, peaks at 1-minute orthostasis. Thus, this test allowed the investigation of both neural and adrenal sympathetic release, separately. With respect to this, we have performed this test in some 25 000 normal and diseased subjects, and the results have been published in >50 research articles and in 3 books dealing with the autonomic nervous system.3,4 Our results …