title: Chemical activation of pre-Bötzinger complex in vivo reduces respiratory network complexity.
abstract: In the in vivo anesthetized adult cat model, multiple patterns of inspiratory motor discharge have been recorded in response to chemical stimulation and focal hypoxia of the pre-Bötzinger complex (pre-BötC), suggesting that this region may participate in the generation of complex respiratory dynamics. The complexity of a signal can be quantified using approximate entropy (ApEn) and multiscale entropy (MSEn) methods, both of which measure the regularity (orderliness) in a time series, with the latter method taking into consideration temporal fluctuations in the underlying dynamics. The current investigation was undertaken to examine the effects of pre-BötC-induced excitation of phasic phrenic nerve discharge, which is characterized by high-amplitude, rapid-rate-of-rise, short-duration bursts, on the complexity of the central inspiratory neural controller in the vagotomized, chloralose-anesthetized adult cat model. To assess inspiratory neural network complexity, we calculated the ApEn and MSEn of phrenic nerve bursts during eupneic (basal) discharge and during pre-BötC-induced excitation of phasic inspiratory bursts. Chemical stimulation of the pre-BötC using DL-homocysteic acid (DLH; 10 mM; 10-20 nl; n=10) significantly reduced the ApEn from 0.982+/-0.066 (mean+/-SE) to 0.664+/-0.067 (P<0.001) followed by recovery ( approximately 1-2 min after DLH) of the ApEn to 1.014+/-0.067; a slightly enhanced magnitude reduction in MSEn was observed. Focal pre-BötC hypoxia (induced by sodium cyanide; NaCN; 1 mM; 20 nl; n=2) also elicited a reduction in both ApEn and MSEn, similar to those observed for the DLH-induced response. These observations demonstrate that activation of the pre-BötC reduces inspiratory network complexity, suggesting a role for the pre-BötC in regulation of complex respiratory dynamics.
authors.affiliation: Dept. of Biomedical Engineering, Basic Science Tower T6 Rm. 140, State Univ. of New York at Stony Brook, Stony Brook, NY 11794-8661, USA.
authors.forename: Xinnian
authors.initials: X
authors.lastname: Chen
authors.forename: Ki H
authors.initials: KH
authors.lastname: Chon
authors.forename: Irene C
authors.initials: IC
authors.lastname: Solomon
mesh_terms: D000818:Animals; D002415:Cats; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000860:Hypoxia / Q000139:chemically induced / Q000503:physiopathology*; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology; D010100:Oxygen / Q000494:pharmacology; D010791:Phrenic Nerve / Q000187:drug effects* / Q000502:physiology*; D012119:Respiration / Q000187:drug effects; D012125:Respiratory Center / Q000187:drug effects* / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology*; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D012966:Sodium Cyanide / Q000494:pharmacology; D013223:Statistics as Topic
chemical_list: D006710:Homocysteine; C007956:homocysteic acid; D012966:Sodium Cyanide; D010100:Oxygen