title: Effects of carbogen on cochlear blood flow and hearing function following acute acoustic trauma in guinea pigs.
abstract: OBJECTIVE
  Disturbances of microcirculation and hemorheological changes in the inner ear are the results of noise-induced hearing loss (NIHL). Both the disturbances of microcirculation and hemorheological changes are the etiologies of NIHL development, but they are also the results. Although previous reports that inhalation of high concentration of CO(2) may increase cochlear blood flow (CoBF), the effects of carbogen on the cochlear microcirculation and NIHL remain unclear.
  
  
  METHODS
  Changes induced by noise, carbogen and pure oxygen within the cochlear lateral wall microvasculature and in hearing thresholds were observed in guinea pigs using intravital microscopy and the auditory brainstem response. At the same time, arterial oxygen saturation and morphologic changes of cochlear hair cells were observed.
  
  
  RESULTS
  Carbogen inhalation increased vessel diameters and blood flow velocities. Hearing thresholds elevation in the carbogen group was smaller than those in the control and oxygen group (p <0.05). Carbogen inhalation produced a trend toward less threshold shift after noise exposure, which reached statistical significance after day 3 (p <0.01). Respiratory acidosis was not found in our study. The segmented basal membranes of Corti in three groups indicated that no losses or discorders of hair cells were found.
  
  
  CONCLUSIONS
  Carbogen inhalation can preserve hearing in animal models after acute acoustic trauma.
authors.affiliation: Department of Beijing Naval General Hospital, Center of Otorhinolaryngology, PLA, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Jianjun
authors.initials: J
authors.lastname: Sun
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000138:Acidosis; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000494:pharmacology*; D003051:Cochlea / Q000098:blood supply* / Q000187:drug effects / Q000503:physiopathology*; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects; D006309:Hearing / Q000187:drug effects* / Q000502:physiology; D006317:Hearing Loss, Noise-Induced / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D008833:Microcirculation / Q000187:drug effects; D010100:Oxygen / Q000008:administration & dosage / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects
chemical_list: D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen