title: Effect of naloxone on spectral shifts of the diaphragm EMG during inspiratory loading.
abstract: Shifts in the power spectrum of the diaphragm EMG to lower frequencies may occur in the presence of fatiguing inspiratory flow-resistive loads (IRL). However, such a shift of the centroid frequency (fc) could follow a reduction in central output through a differential reduction in end-inspiratory high-frequency power (HFP). In unanesthetized goats, we tested the hypothesis that activation of the endogenous opioid system by IRL would differentially reduce central respiratory output, causing a reduction in fc. IRL was imposed for 180 min after which naloxone (0.1 mg/kg, NLX) was given. fc was computed from the power spectral density estimated by the Welch method. IRL reduced fc from 148.0 +/- 9.8 (SE) Hz at base line to 141.1 +/- 8.9 Hz or to 95.5 +/- 1.3% of base line by 180 min (both P less than 0.05). NLX increased fc to 148.9 +/- 9.9 Hz or to 100.6 +/- 1.1% of base line (both P less than 0.05). The decline in fc during IRL was found to be the result of a reduction in HFP, predominantly toward the end of inspiration. The reversibility of this fc shift with NLX suggests a central mechanism consequent to elaboration of endogenous opioids and not a peripheral (muscular) event consequent to muscle fatigue.
authors.affiliation: Department of Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick 08903-0019.
authors.forename: J J
authors.initials: JJ
authors.lastname: Petrozzino
authors.forename: A T
authors.initials: AT
authors.lastname: Scardella
authors.forename: J K
authors.initials: JK
authors.lastname: Li
authors.forename: N
authors.initials: N
authors.lastname: Krawciw
authors.forename: N H
authors.initials: NH
authors.lastname: Edelman
authors.forename: T V
authors.initials: TV
authors.lastname: Santiago
mesh_terms: D000818:Animals; D003964:Diaphragm / Q000502:physiology*; D004576:Electromyography; D006041:Goats; D001239:Inhalation / Q000502:physiology; D007700:Kinetics; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010100:Oxygen / Q000008:administration & dosage*; D012119:Respiration / Q000187:drug effects / Q000502:physiology*
chemical_list: D009270:Naloxone; D010100:Oxygen