Long‐term Recording of Sympathetic Nerve Activity: The New Frontier in Understanding the Development of Hypertension?

Abstract

1. With increasing evidence that the sympathetic nervous system plays a critical role in the development of hypertension, focus is turning to how these signals translate to a chronic increase in arterial pressure. 2. The kidney's role in the control of salt and water homeostasis makes it an obvious target for such investigations. However, to date, many studies have been restricted to experiments lasting only a few hours or, at most, a few days, whereas others may use indirect methods of assessing sympathetic activity rather than direct recordings. 3. We review current approaches used to determine the effects of renal sympathetic nerve activity (SNA) on arterial pressure and suggest possible avenues of future investigation. We propose that although afferent inputs, such as from chemoreceptors and baroreceptors, are important for the short-term control of blood pressure via regulation of SNA to multiple organs, it is highly likely that alternative signals are important for setting the long-term level of renal SNA. 4. Emerging evidence indicates circulating angiotensin II is hormone that may act on the central nervous system to regulate renal SNA, renal function and, thus, blood pressure. 5. We propose that an integral part of future studies seeking an understanding of the genesis of hypertension should include chronic direct recordings of renal SNA.

The Nervous Mechanism of Sympathetic over Activity Induced by Chronic Intermittent Hypoxia

“…Guild et al have pronounced another index of total sympathetic activity by administration of ganglionic blockade [8]. The fall in MAP in response to hexamethonium (a ganglionic blockade) after injection of losartan (AT1 receptor antagonist) was higher in CIH than in normoxic rats and the MAP was decreased to similar levels in both groups, despite the fact that losartan or hexamethonium alone produced no significant changes [9].…”

Brain angiotensin peptides regulate sympathetic tone and blood pressure

“…The sympathetic nervous system plays an essential part in the short-term control of arterial blood pressure (BP) [1], but the contribution of the sympathetic system to the long-term control of BP and its implications in the pathogenesis of hypertension has been a matter of debate for a long time [2][3][4]. However, recent clinical evidence that physiologically verified afferent and efferent renal denervation produces a substantial and sustained reduction in BP in patients with drug-resistant essential hypertension now clearly confirms a role of the (renal) sympathetic nervous system in the long-term control of BP also [5][6][7][8][9].…”

Procoagulant stress reactivity and recovery in apparently healthy men with systolic and diastolic hypertension

“…Mechanisms potentially mediating cardiovascular and thrombotic threat in hypertensive individuals are increased shear to the vessel wall [3], heightened sympathetic nervous system activity [4], and a hypercoagulable state [5]. These promote endothelial injury, vasoconstriction, and blood stasis altogether describing Virchow's triad of arterial thrombogenesis [6].…”