title: Different effects of propofol and isoflurane on cochlear blood flow and hearing function in Guinea pigs.
abstract: OBJECTIVE
  To investigate the effects of isoflurane and propofol on mean arterial pressure (MAP), cochlear blood flow (CoBF), distortion-product otoacoustic emission (DPOAE), and the ultrastructure of outer hair cells (OHCs) in guinea pig cochleae.
  
  
  METHODS
  Forty-eight male guinea pigs were randomly assigned to one of six treatment groups. Groups 1 to 3 were infused (i.v.) with a loading dose of propofol (5 mg/kg) for 5 min and three maintenance doses (10, 20, or 40 mg kg-1·h-1, respectively) for 115 min. Groups 4 to 6 were inhaled with isoflurane at concentrations of 1.15 vol%, 2.30 vol% or 3.45 vol% respectively for 120 min. CoBF and MAP were recorded prior to and at 5 min intervals during drug administration. DPOAE was measured before, immediately after, and 1 h after administration. Following the final DPOAE test, cochleae were examined using scanning electron microscopy.
  
  
  RESULTS
  Propofol treatment reduced MAP in a dose-dependent manner. CoBF and DPOAE showed increases at propofol maintenance doses of 10 and 20 mg kg-1·h-1. Inhalation of isoflurane at concentrations of 2.30 vol% and 3.45 vol% reduced MAP and CoBF. DPOAE amplitude increased following inhalation of 1.15 vol% isoflurane, but decreased following inhalations of 2.30 vol% and 3.45 vol%. Cochlear structure was changed following inhalation of either 2.30 vol% or 3.45 vol% isoflurane.
  
  
  CONCLUSIONS
  Propofol could decrease MAP and increase both CoBF and DPOAE without affecting OHC structure. Inhalation of isoflurane at concentrations >2.30 vol% decreased CoBF and DPOAE, and produced injury to OHCs.
authors.affiliation: Department of Anesthesiology, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, P.R.China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: Department of Anesthesiology, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, P.R.China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wen
authors.affiliation: Department of Otolaryngology, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, P.R.China.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Department of Anesthesiology, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, P.R.China.
authors.forename: Na
authors.initials: N
authors.lastname: Duan
authors.affiliation: Department of Anesthesiology, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, P.R.China.
authors.forename: G X
authors.initials: GX
authors.lastname: Jing
mesh_terms: D000818:Animals; D003051:Cochlea / Q000098:blood supply* / Q000187:drug effects*; D006168:Guinea Pigs; D006309:Hearing / Q000187:drug effects; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D008855:Microscopy, Electron, Scanning; D015742:Propofol / Q000494:pharmacology*
chemical_list: D007530:Isoflurane; D015742:Propofol