|Group III and IV muscle afferents contribute to ventilatory and cardiovascular response to rhythmic exercise in humans.|
|PMID: 20634355 Owner: NLM Status: MEDLINE|
|We investigated the role of somatosensory feedback on cardioventilatory responses to rhythmic exercise in five men. In a double-blind, placebo-controlled design, subjects performed the same leg cycling exercise (50/100/150/325 ± 19 W, 3 min each) under placebo conditions (interspinous saline, L(3)-L(4)) and with lumbar intrathecal fentanyl impairing central projection of spinal opioid receptor-sensitive muscle afferents. Quadriceps strength was similar before and after fentanyl administration. To evaluate whether a cephalad migration of fentanyl affected cardioventilatory control centers in the brain stem, we compared resting ventilatory responses to hypercapnia (HCVR) and cardioventilatory responses to arm vs. leg cycling exercise after each injection. Similar HCVR and minor effects of fentanyl on cardioventilatory responses to arm exercise excluded direct medullary effects of fentanyl. Central command during leg exercise was estimated via quadriceps electromyogram. No differences between conditions were found in resting heart rate (HR), ventilation [minute ventilation (VE)], or mean arterial pressure (MAP). Quadriceps electromyogram, O(2) consumption (VO(2)), and plasma lactate were similar in both conditions at the four steady-state workloads. Compared with placebo, a substantial hypoventilation during fentanyl exercise was indicated by the 8-17% reduction in VE/CO(2) production (VCO(2)) secondary to a reduced breathing frequency, leading to average increases of 4-7 Torr in end-tidal PCO(2) (P < 0.001) and a reduced hemoglobin saturation (-3 ± 1%; P < 0.05) at the heaviest workload (∼90% maximal VO(2)) with fentanyl. HR was reduced 2-8%, MAP 8-13%, and ratings of perceived exertion by 13% during fentanyl vs. placebo exercise (P < 0.05). These findings demonstrate the essential contribution of muscle afferent feedback to the ventilatory, cardiovascular, and perceptual responses to rhythmic exercise in humans, even in the presence of unaltered contributions from other major inputs to cardioventilatory control.|
|Markus Amann; Gregory M Blain; Lester T Proctor; Joshua J Sebranek; David F Pegelow; Jerome A Dempsey|
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|Type: Journal Article; Randomized Controlled Trial; Research Support, N.I.H., Extramural Date: 2010-07-15|
|Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 109 ISSN: 1522-1601 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2010 Oct|
|Created Date: 2010-10-13 Completed Date: 2011-05-23 Revised Date: 2014-09-08|
Medline Journal Info:
|Nlm Unique ID: 8502536 Medline TA: J Appl Physiol (1985) Country: United States|
|Languages: eng Pagination: 966-76 Citation Subset: IM|
|APA/MLA Format Download EndNote Download BibTex|
Analgesics, Opioid / administration & dosage
Analysis of Variance
Exercise / physiology*
Fentanyl / administration & dosage
Hemodynamics* / drug effects
Hemoglobins / metabolism
Hypercapnia / physiopathology
Lactic Acid / blood
Neurons, Afferent / drug effects, physiology*
Pulmonary Ventilation* / drug effects
Quadriceps Muscle / innervation*
|K99 HL103786/HL/NHLBI NIH HHS; K99 HL103786-01/HL/NHLBI NIH HHS; K99 HL103786-02/HL/NHLBI NIH HHS; R01 HL-15469/HL/NHLBI NIH HHS|
|0/Analgesics, Opioid; 0/Hemoglobins; 33X04XA5AT/Lactic Acid; UF599785JZ/Fentanyl|
J Appl Physiol (1985). 2011 May;110(5):1499; author reply 1500
J Appl Physiol (1985). 2010 Oct;109(4):947-8 [PMID: 20689092 ]
J Appl Physiol (1985). 2011 Mar;110(3):862; author reply 863 [PMID: 21386014 ]
J Appl Physiol (1985). 2011 Mar;110(3):860; author reply 861 [PMID: 21386012 ]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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