Baroreflex control of muscle sympathetic nerve activity in mild hypertension

Baroreflex control of muscle sympathetic nerve activity in mild hypertension

The importance of the arterial baroreflex control of muscle sympathetic nerve activity (MSNA) has been investigated in physiological conditions and in cardiovascular dysfunctions. However, there is no consensus about the role played by the MSNA in hypertensive states, probably due to the diversity o...

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Bibliographic Details
Published in:American journal of hypertension Vol. 10; no. 2; pp. 162 - 167
Main Authors: Meyrelles, Silvana S., Tinucci, Tais, Hollanda, Heloisa E.M., Mion, Décio
Format: Journal Article
Language:English
Published: New York, NY Elsevier Inc 01-02-1997
Oxford University Press
Elsevier Science
Subjects:
Adult
Animals
Antihypertensive Agents - pharmacology
Arterial baroreflex
arterial hypertension
Arterial hypertension. Arterial hypotension
Arteries
Baroreflex - drug effects
Baroreflex - physiology
Biological and medical sciences
Blood and lymphatic vessels
Cardiology. Vascular system
Clinical manifestations. Epidemiology. Investigative techniques. Etiology
Dogs
Humans
Hypertension - physiopathology
Medical sciences
muscle sympathetic nerve activity
Nitroprusside - pharmacology
Phenylephrine - pharmacology
Sympathetic Nervous System - physiology
Time Factors
Vasoconstrictor Agents - pharmacology
arterial hypertension
muscle sympathetic nerve activity
Arterial baroreflex
Human
Hypertension
Pharmacologic test
Vasodilator agent
Baroreflex
Organic nitrate
Phenylephrine
Cardiovascular disease
Exploration
Arterial pressure
Striated muscle
Sympathetic nervous system
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Summary:The importance of the arterial baroreflex control of muscle sympathetic nerve activity (MSNA) has been investigated in physiological conditions and in cardiovascular dysfunctions. However, there is no consensus about the role played by the MSNA in hypertensive states, probably due to the diversity of the methods used to study the arterial baroreflex control of MSNA. In the present study we evaluated the reflex changes in MSNA by increasing and decreasing the mean arterial pressure (MAP) through 1 min intravenous infusion of phenylephrine (1 μg/kg) and sodium nitroprusside (1 μg/kg), respectively, in eight normotesive and eight mild hypertesive subjects. Both MAP and MSNA were significantly higher in hypertensive (117 ± 2 mm Hg and 30 ± 3 bursts/min) than in normotensive (96 ± 4 mm Hg and 20 ± 3 bursts/min) subjects. The reflex gain was calculated by the ratio percent of changes in MSNA/percent changes in MAP. The maximal reflex gain was statistically similar in normotensive and hypertensive groups during phenylephrine (5.1 ± 1.4 ν 4.3 ± 0.4 bursts/mm Hg, respectively) and nitroprusside (10.7 ± 2.3 ν 8.1 ± 1.3 bursts/mm Hg, respectively) infusion. The present data showing that arterial baroreflex control of MSNA is not depressed in hypertensive subjects indicate that the elevated basal MSNA and the mild hypertension in human beings is not a consequence of baroreflex control of MSNA dysfunction.
Bibliography:This study was supported in part by The National Council for the Development of Science and Technology, Brazil (CNPq).
Address correspondence and reprint requests to Silvana S. Meyrelles, Medical Research Center #602, The University of Iowa, Iowa City, IA 52242-1178.
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ISSN:0895-7061
1879-1905
1941-7225
DOI:10.1016/S0895-7061(96)00353-6