Evidence against elevated sympathetic activity in borderline hypertension.
ASN 30th Annual Meeting, San Antonio
J Am Soc Nephrol (Sep) 8:322A 1997
Altered activity of the sympathetic nervous system in patients with essential hypertension may play a pathogenetic role in the development of the disease. Indeed, in patients with cerebral palsy and other conditions that are expected to result in variable sympathetic output, hypertension is a frequent finding.
The authors examined the relationship between resting level of muscle sympathetic nerve activity (MSNA), plasma norepinephrine (NE) concentration, mean arterial blood pressure (MAP), central venous pressure (CVP) and heart rate (HR). 20 young men (24 ±2 y) with lean body (body mass index; BMI 24.4 ± 3 kg/m2) and borderline hypertension were compared to 21 age and BMI matched normotensive male controls. The general sympathetic responsiveness was evaluated by cold stress test (CPT). The MAP and HR were significantly higher in the study group (113 ± 9 vs. 89± 9 mmHg and 74 ± 8 vs. 62 ±8/min, respectively; p<0.0001). The CVP was not different between the two groups, neither was the resting MSNA (12±6 vs. 14±9 burst/min or 16±8 vs. 22±13 burst/100 heartbeat). The MSNA did not correlate with the MAP or BMI whereas significant correlation was found between the MSNA and plasma NE levels in both groups (p< 0.05; "r" value not provided). CPT caused comparable hemodynamic and sympathetic nerve responses in both groups.
Comment: It is reassuring that an expected correlation between resting MSNA and plasma NE was indeed demonstrated by the study. The fact that neither of these two parameters correlated with MAP may simply reflect a relatively narrow variation of these parameters under resting condition. The lack of difference in resting and CPT stimulation of MSNA and plasma NE however does challenge existing views regarding the role of altered sympathetic activity in early stages of essential hypertension. (Laszlo Hopp, Alfred I. duPont Hospital for Children; Wilmington, DE)
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ASN 30th Annual Meeting, San Antonio
H: Pathophysiology : Sympathetic nervous system