Studies on the Activity of the Sympathetic Nervous System in Essential Hypertension

Abstract

Plasma catecholamine and norepinephrine concentrations have been measured in carefully characterized ambulatory patients with essential hypertension under basal conditions and following experimental procedures known to enhance sympathetic activity. The studies have demonstrated increased levels of plasma catecholamines in patients with mild hypertension as compared with matched controls following 70 degree upright tilt or cold pressor testing. Considerable heterogeneity was apparent in the population of patients with essential hypertension with respect to their plasma norepinephrine concentrations. Significantly greater levels of plasma norepinephrine were present in patients with high plasma renin activity and lesser levels in patients with low renin activity than in normal renin or labile hypertensives. Blood pressure correlated significantly with plasma norepinephrine in male patients with normal renin essential hypertension but not in females. Administration of the diuretic furosemide produced an increase in plasma norepinephrine in almost all hypertensive subjects studied. These studies suggest that peripheral sympathetic activity is abnormal in certain patients with essential hypertension. The results underscore the need to differentiate between subgroups of essential hypertension in studies relating to the role of the adrenergic system in the hypertension. The findings also suggest that the recently developed sensitive techniques for measuring plasma catecholamines of plasma norepinephrine are of value in assessing changes in peripheral sympathetic activity but that enzymatic assays of serum dopamine-beta-hydroxylase activity are probably not useful for this purpose.

Hemodynamic and catecholamine responses during tracheal intubation using a lightwand device (Trachlight) in elderly patients with hypertension

“…In the present study, the patients received fentanyl 2 µg ·kg Ϫ1 in addition to suitable propofol. It has been reported that patients with essential hypertension have increased activity of the sympathetic nervous system [1][2][3] and show an exaggerated hemodynamic response to the induction of anesthesia compared with normotensive patients [14]. Low et al [14] reported that there was a marked increase in NE concentration after laryngoscopy in hypertensive patients.…”

“…These hemodynamic changes are caused by increased activity of the sympathetic nervous system [1][2][3].…”

Plasma catecholamines and essential hypertension. An analytical review.

“…This rather surprising finding may be explained by the inclusion in positive studies of a greater proportion of high-renin hypertensives. 9 ' 27> M ' 73 Alternatively, positive studies may have included hypertensives still under the influence of diuretic therapy, since volume depletion should -at least temporarily -increase both renin activity and NE. The latter explanation is somewhat unlikely, since some studies in untreated hypertensives have reported significant renin-NE relationships.…”

Localization of Autonomic Nervous System Dysfunction in Dialysis Patients

“…However, since resting plasma norepinephrine concentration is determined by both the rate of spillover of norepineph rine from synaptic cleft and the rate of removal of nor epinephrine from plasma [22], the value of resting plasma catecholamine levels as an index of sympathetic activity has been seriously questioned [23]. In contrast, the acute response of circulating norepinephrine to spe cific stimuli was found to be more useful as an indicator of sympathetic responses; this applies in particular to rapid changes in plasma norepinephrine, blood pressure and heart rate in response to head-up tilt [24][25][26], There was a significant elevation of plasma norepinephrine during head-up tilt (from 21 to 176%) observed in our patients, suggesting both intact efferent sympathetic pathways and adequate sensing of the stimulus.…”