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Nitrous Oxide Inhalation Attenuates an Increase in Muscle Sympathetic Nerve Activity during Cold Stress
Author(s) -
Isono Kazushige,
Okada Yoshiyuki,
Mitsui Tatsuhisa,
Masuda Yuji,
Ogasawara Tadashi
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.650.2
Subject(s) - nitrous oxide , inhalation , microneurography , anesthesia , cold pressor test , blood pressure , heart rate , medicine , baroreflex
Nitrous oxide inhalation was reported to suppress pressor response to pain stimulation, while an increase in heart rate (HR) remained unchanged. We evaluated whether nitrous oxide inhalation attenuates an increase in muscle sympathetic nerve activity (MSNA) during cold stress. MSNA (microneurography), arm cuff and beat‐to‐beat blood pressure (BP), and HR were measured during 5‐min baseline, 2‐min cold pressor test (CPT) in 12 young men [30±1 (SE) yrs] after they receive room air, 100% oxygen, 30%, and 40% nitrous oxide for 20 min through a mask, respectively. BP increased during CPT in all conditions, while the increase of systolic BP tended to be smaller during inhalation of 40% nitrous oxide than room air (26±5 vs 15±4 mmHg, P=0.081). HR also increased during CPT without any difference the increase between the conditions. MSNA burst frequency increased during CPT, while the increase was smaller during the inhalation of 40% nitrous oxide than room air (21±4 vs 12±3 burst/min, P=0.045). Change (Δ) in systolic BP during CPT was correlated with ΔMSNA burst frequency (r=0.40), but not ΔHR (r=0.06) in all conditions. These results suggest that suppressed pressor response to pain stimuli by inhalation of nitrous oxide is attributable to the attenuation of increase in muscle sympathetic nerve activity. Supported by JSPSKAKENHI 70566661 .