Hyper-responsiveness of adrenal sympathetic nerve activity in spontaneously hypertensive rats to ganglionic blockade, mental stress and neuronglucopenia |
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Authors: | Weiguo Zhang Peter Thorén |
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Institution: | (1) Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden, SE;(2) Department of Internal Medicine/Hypertension Division, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., J4.132, Dallas, TX 75235–8586, USA e-mail: wzhang@mednet.swmed.edu Tel.: +1-214-6487944, Fax: +1-214-6487902, US |
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Abstract: | Previous investigations indicate that the spontaneously hypertensive rat (SHR) has elevated sympathetic tone at rest. The
present study aimed to determine whether SHR has exaggerated sympatho-adrenal activation in response to various sympathetic
stimuli. The mean blood pressure (MBP), heart rate (HR) and preganglionic adrenal sympathetic nerve activity (SNA) were recorded
from conscious, unrestrained SHR and from its normotensive control, the Wistar-Kyoto rat (WKY) (n=7, respectively).Ganglionic blockade (trimethaphan, 5 mg/kg) reduced MBP identically in both groups of rats. It did not change
HR in SHR, but increased HR significantly in WKY (P<0.05). The adrenal SNA increased in both groups, but the magnitude of the increase was more than threefold greater in SHR
(P<0.05). Mental stress caused by air-jet induced significantly greater tachycardia (threefold) and sympatho-adrenal activation
(tenfold) in SHR than in WKY rats. In SHR the inhibition of glycolysis (2-deoxy-d-glucose, 500 mg/kg) also produced a profound activation of adrenal SNA (sevenfold) and the increased adrenal SNA was not
paralleled by an increased HR. We conclude that a variety of sympathetic stimuli, including ganglionic blockade, mental stress
and neuronglucopenia, cause exaggerated activation of preganglionic adrenal SNA in SHR compared with WKY, indicating that
adrenal SNA in SHR is hyper-responsive.
Received: 26 May 1998 / Received after revision: 30 July 1998 / Accepted: 11 August 1998 |
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Keywords: | Adrenal sympathetic nerve activity (SNA) Ganglionic blockade Mental stress Neuronglucopenia Spontaneously hypertensive rats (SHR) |
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