DISSOCIATION BETWEEN MUSCLE AND SKIN SYMPATHETIC-NERVE ACTIVITY IN ESSENTIAL-HYPERTENSION, OBESITY, AND CONGESTIVE-HEART-FAILURE

Essential hypertension, obesity, and congestive heart failure are char acterized by an increase in muscle sympathetic nerve activity. Whether in these conditions skin sympathetic nerve activity is also increased has never been systematically examined, however. In 10 untreated mild essential hypertensive, 12 untreated normotensive obese, 10 mild (New York Heart Association class II) heart failure, and 10 normotensive l ean healthy control subjects, we measured beat-to-beat arterial blood pressure (Finapres technique), body mass index, and postganglionic Sym pathetic nerve activity in skeletal muscle and skin areas (microneurog raphic technique, peroneal nerve). The muscle and skin nerve measureme nts were made in a randomized sequence. AU data were obtained with the subject supine in a quiet, semidark environment at constant temperatu re over two periods of 30 minutes each, separated by a 20- to 30-minut e interval. Blood pressure was increased only in hypertensive and body mass index only in obese subjects. Muscle sympathetic nerve activity quantified as bursts/min was markedly and significantly (P<.01) greate r in essential hypertensive (33.3+/-1.7), obese (42.2+/-2.8), and cong estive heart failure subjects (55.8+/-4.3) in comparison with control subjects (23.9+/-1.6). This was the case also for muscle sympathetic n erve activity, quantified as bursts per 100 heart beats. In contrast, skin sympathetic nerve activity (bursts per minute) was superimposable in hypertensive, obese, heart failure, and control subjects, its abil ity to increase being documented in all four groups by the marked resp onse to an acoustic stimulus. Thus, in various diseases, muscle but no t skin sympathetic activity is increased, with the sympathetic activat ion not being uniformly distributed over the whole cardiovascular syst em.