| Nitric oxide and regulation of heart rate in patients with postural tachycardia syndrome and healthy subjects. | |
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MedLine Citation:
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PMID: 23283362 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The objective is to study the role of nitric oxide (NO) on cardiovascular regulation in healthy subjects and postural tachycardia syndrome (POTS) patients. Reduced neuronal NO function, which could contribute to a hyperadrenergic state, and increased NO-induced vasodilation, which could contribute to orthostatic intolerance, have been reported in POTS. In protocol 1, 13 healthy volunteers (33 ± 3 years) underwent autonomic blockade with trimethaphan and were administered equipressor doses of Nω-monomethyl-L-arginine (L-NMMA, a NO synthase inhibitor) and phenylephrine to determine the direct chronotropic effects of NO (independent of baroreflex modulation). In protocol 2, we compared the effects of L-NMMA in 9 POTS patients (31 ± 3 years) and 14 healthy (32 ± 2 years) volunteers, during autonomic blockade. During autonomic blockade, L-NMMA and phenylephrine produced similar increases in systolic blood pressure (27 ± 2 versus 27 ± 3 mm Hg). Phenylephrine produced only minimal heart rate changes, whereas L-NMMA produced a modest, but significant, bradycardia (-0.8 ± 0.4 versus -4.8 ± 1.2 bpm; P=0.011). There were no differences between POTS and healthy volunteers in the systolic blood pressure increase (22 ± 2 and 28 ± 5 mm Hg) or heart rate decrease (-6 ± 2 and -4 ± 1 bpm for POTS and controls, respectively) produced by L-NMMA. In the absence of baroreflex buffering, inhibition of endogenous NO synthesis results in a significant bradycardia, reflecting direct tonic modulation of heart rate by NO in healthy individuals. We found no evidence of a primary alteration in NO function in POTS. If NO dysfunction plays a role in POTS, it is through its interaction with the autonomic nervous system. |
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Authors:
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Alfredo Gamboa; Luis E Okamoto; Satish R Raj; André Diedrich; Cyndya A Shibao; David Robertson; Italo Biaggioni |
Publication Detail:
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Type: Clinical Trial; Journal Article; Research Support, N.I.H., Extramural Date: 2013-01-02 |
Journal Detail:
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Title: Hypertension Volume: 61 ISSN: 1524-4563 ISO Abbreviation: Hypertension Publication Date: 2013 Feb |
Date Detail:
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Created Date: 2013-01-17 Completed Date: 2013-03-20 Revised Date: 2013-04-16 |
Medline Journal Info:
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Nlm Unique ID: 7906255 Medline TA: Hypertension Country: United States |
Other Details:
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Languages: eng Pagination: 376-81 Citation Subset: IM |
Affiliation:
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Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN, USA. |
| Data Bank Information | |
Bank Name/Acc. No.:
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ClinicalTrials.gov/NCT00770484 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Autonomic Nervous System / drug effects, physiopathology* Baroreflex / drug effects, physiology Blood Pressure / drug effects, physiology* Enzyme Inhibitors / pharmacology Female Heart Rate / drug effects, physiology* Humans Male Nitric Oxide / physiology* Nitric Oxide Synthase / antagonists & inhibitors Phenylephrine / pharmacology Postural Orthostatic Tachycardia Syndrome / physiopathology* omega-N-Methylarginine / pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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K23 HL-95905/HL/NHLBI NIH HHS; K23 HL095905/HL/NHLBI NIH HHS; P01 HL056693/HL/NHLBI NIH HHS; U54 NS065736/NS/NINDS NIH HHS; UL1 TR000445/TR/NCATS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Enzyme Inhibitors; 10102-43-9/Nitric Oxide; 17035-90-4/omega-N-Methylarginine; 59-42-7/Phenylephrine; EC 1.14.13.39/Nitric Oxide Synthase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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