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Pressor response to intravenous tyramine is a marker of cardiac, but not vascular, adrenergic functionIntravenous injections of the indirect sympathetic amine, tyramine, are used as a test of peripheral adrenergic function. The authors measured the time course of increases in ejection fraction, heart rate, systolic and diastolic pressure, popliteal artery flow, and greater saphenous vein diameter before and after an injection of 4.0 mg/m(2) body surface area of tyramine in normal human subjects. The tyramine caused moderate, significant increases in systolic pressure and significant decreases in total peripheral resistance. The earliest changes were a 30% increase in ejection fraction and a 16% increase in systolic pressure, followed by a 60% increase in popliteal artery flow and a later 11% increase in greater saphenous vein diameter. There were no changes in diastolic pressure or heart rate. These results suggest that pressor responses during tyramine injections are primarily due to an inotropic response that increases cardiac output and pressure and causes a reflex decrease in vascular resistance. Thus, tyramine pressor tests are a measure of cardiac, but not vascular, sympathetic function.
Document ID
20040087918
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Meck, Janice V.
(NASA Johnson Space Center Houston TX United States)
Martin, David S.
D'Aunno, Dominick S.
Waters, Wendy W.
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Publication Information
Publication: Journal of cardiovascular pharmacology
Volume: 41
Issue: 1
ISSN: 0160-2446
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Cardiopulmonary
Clinical Trial
NASA Center JSC

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