Evidence for a physiological role of pulmonary arterial baroreceptors in sympathetic neural activation in healthy humans

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Author
Simpson, Lydia
Meah, Victoria L.
Steele, Andrew
Thapamagar, Suman
Gasho, Chris
Anholm, James
Drane, Aimee L.
Dawkins, Tony
Busch, Stephen
Oliver, Samuel
Lawley, Justin
Tymko, Mike
Ainslie, Philip
Steinback, Craig
Stembridge, Mike
Moore, Jonathan
Date
2020-01-24Acceptance date
2020-01-20
Date Deposited
2020-01-24
Type
Article
acceptedVersion
Publisher
Wiley
ISSN
0022-3751
1469-7793
Metadata
Show full item recordAbstract
In animal models, distension of baroreceptors located in the pulmonary artery induces a reflex increase in sympathetic outflow; however, this has not been examined in humans. Therefore, we investigated whether reductions in pulmonary arterial pressure influenced sympathetic outflow and baroreflex control of muscle sympathetic nerve activity (MSNA). Healthy lowlanders (n=13; 5 females) were studied 4-8 days following arrival at high-altitude (4383m; Cerro de Pasco, Peru), a setting that increases both pulmonary arterial pressure and sympathetic outflow. MSNA (microneurography) and blood pressure (BP; photoplethysmography) were measured continuously during 1) ambient air breathing (Amb) and 2) a six-minute inhalation of the vasodilator nitric oxide (iNO; 40ppm in 21% O2), to selectively lower pulmonary arterial pressure. A modified Oxford test was performed under both conditions. Pulmonary artery systolic pressure (PASP) was determined using Doppler echocardiography. iNO reduced PASP (24±3 vs 32±5 mmHg; P < 0.001) compared to Amb, without changing heart rate (P= 0.6) or vascular-sympathetic baroreflex gain (P = 0.85). In conclusion, unloading of pulmonary arterial baroreceptors reduced basal sympathetic outflow to the skeletal muscle vasculature and reset vascular-sympathetic baroreflex control of MSNA downward and leftward in healthy humans at high-altitude. These data suggest the existence of a lesser-known reflex input involved in sympathetic activation in humans.
Journal/conference proceeding
Journal of Physiology;
Citation
Simpson, L.L., Meah, V.L., Steele, A., Thapamagar, S., Gasho, C., Anholm, J.D., Drane, A.L., Dawkins, T.G., Busch, S.A., Oliver, S.J. and Lawley, J.S. (2020) 'Evidence for a physiological role of pulmonary arterial baroreceptors in sympathetic neural activation in healthy humans', Journal of Physiology.
Description
Article published in Journal of Physiology on 24 January 2020, available at: https://doi.org/10.1113/JP278731.
Sponsorship
Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada (NSERC Canadian Network for Research and Innovation in Machining Technology): Craig D Steinback, RGPIN 06637; Heart and Stroke Foundation of Canada - Joint Alberta and new investigator award: Craig D Steinback, HSCF NNIA; Canadian Research Chair in Cerebrovascular Physiology: Philip N Ainslie, 950-230970; Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada (NSERC Canadian Network for Research and Innovation in Machining Technology): Philip N Ainslie, 20150821-01
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