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Effect of morphine on sympathetic nerve activity in humansThere are conflicting reports for the role of endogenous opioids on sympathetic and cardiovascular responses to exercise in humans. A number of studies have utilized naloxone (an opioid-receptor antagonist) to investigate the effect of opioids during exercise. In the present study, we examined the effect of morphine (an opioid-receptor agonist) on sympathetic and cardiovascular responses at rest and during isometric handgrip (IHG). Eleven subjects performed 2 min of IHG (30% maximum) followed by 2 min of postexercise muscle ischemia (PEMI) before and after systemic infusion of morphine (0.075 mg/kg loading dose + 1 mg/h maintenance) or placebo (saline) in double-blinded experiments on separate days. Morphine increased resting muscle sympathetic nerve activity (MSNA; 17 +/- 2 to 22 +/- 2 bursts/min; P < 0.01) and increased mean arterial pressure (MAP; 87 +/- 2 to 91 +/- 2 mmHg; P < 0.02), but it decreased heart rate (HR; 61 +/- 4 to 59 +/- 3; P < 0.01). However, IHG elicited similar increases for MSNA, MAP, and HR between the control and morphine trial (drug x exercise interaction = not significant). Moreover, responses to PEMI were not different. Placebo had no effect on resting, IHG, and PEMI responses. We conclude that morphine modulates cardiovascular and sympathetic responses at rest but not during isometric exercise.
Document ID
20040088045
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Carter, Jason R.
(Pennsylvania State University College of Medicine Hershey, Pennsylvania 17033, United States)
Sauder, Charity L.
Ray, Chester A.
Date Acquired
August 21, 2013
Publication Date
November 1, 2002
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 93
Issue: 5
ISSN: 8750-7587
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: HL-58503
CONTRACT_GRANT: HL-24962
CONTRACT_GRANT: HL-36224
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Neuroscience

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