Aldosterone Impairs Baroreflex Sensitivity in Healthy Adults.
From: Penn State Heart and Vascular Institute, The Milton S. Hershey Medical Center, Campus Box H047, 500 University Dr., Hershey, PA 17033-2390, USA. kmonahan@psu.edu
American journal of physiology. Heart and circulatory physiology
- Publish Date: Jan 2007
- ISSN: 0363-6135
- Volume: 292
- Issue: 1
- Pages: H190-7
- Medium: Print
- Language: English
- Citation (JAMA): Monahan Kevin D, Leuenberger Urs A, Ray Chester A, et al. Aldosterone Impairs Baroreflex Sensitivity in Healthy Adults.. Am. J. Physiol. Heart Circ. Physiol. Jan 2007;292:H190-7
Abstract
Animal studies suggest that acute and chronic aldosterone administration impairs baroreceptor/baroreflex responses. We tested the hypothesis that aldosterone impairs baroreflex control of cardiac period [cardiovagal baroreflex sensitivity (BRS)] and muscle sympathetic nerve activity (MSNA, sympathetic BRS) in humans. Twenty-six young (25 +/- 1 yr old, mean +/- SE) adults were examined in this study. BRS was determined by using the modified Oxford technique (bolus infusion of nitroprusside, followed 60 s later by bolus infusion of phenylephrine) in triplicate before (Pre) and 30-min after (Post) beginning aldosterone (experimental, 12 pmol.kg(-1).min(-1); n = 10 subjects) or saline infusion (control; n = 10). BRS was quantified from the R-R interval-systolic blood pressure (BP) (cardiovagal BRS) and MSNA-diastolic BP (sympathetic BRS) relations. Aldosterone infusion increased serum aldosterone levels approximately fourfold (P < 0.05) and decreased (P < 0.05) cardiovagal (19.0 +/- 2.3 vs. 15.6 +/- 1.7 ms/mmHg Pre and Post, respectively) and sympathetic BRS [-4.4 +/- 0.4 vs. -3.0 +/- 0.4 arbitrary units (AU).beat(-1).mmHg(-1)]. In contrast, neither cardiovagal (19.3 +/- 3.3 vs. 20.2 +/- 3.3 ms/mmHg) nor sympathetic BRS (-3.8 +/- 0.5 vs. -3.6 +/- 0.5 AU.beat(-1).mmHg(-1)) were altered (Pre vs. Post) in the control group. BP, heart rate, and MSNA at rest were similar in experimental and control subjects before and after the intervention. Additionally, neural and cardiovascular responses to a cold pressor test and isometric handgrip to fatigue were unaffected by aldosterone infusion (n = 6 subjects). These data provide direct experimental support for the concept that aldosterone impairs baroreflex function (cardiovagal and sympathetic BRS) in humans. Therefore, aldosterone may be an important determinant/modulator of baroreflex function in humans.
Mesh Headings (Keywords): Adaptation, Physiological, Adult, Aldosterone, Baroreflex, Blood Pressure, Dose-Response Relationship, Drug, Female, Heart Rate, Humans, Male, Sympathetic Nervous System, Vagus Nerve
Check for Full Text / PubMed Unique Identifier (PMID): 16920805
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