title: Analysis of electroretinogram during systemic hypercapnia with intraretinal K(+)-microelectrodes in cats.
abstract: OBJECTIVE
  Systemic hypercapnia alters the intraretinal pH and metabolism and profoundly affects the vitreal electroretinogram (ERG). Using intraretinal K(+)-selective microelectrodes (ISMs), the authors examined the effects of systemic hypercapnia on ERG in the intact cat eye in vivo.
  
  
  METHODS
  Double-barreled K(+)-ISMs were used to record intraretinal, light-evoked [K+]o decrease, intraretinal ERG, vitreal ERG, and standing potential (SP) in the dark-adapted retina. Hypercapnia was induced by adding CO2 to the inhaled mixture of gas (without significant hypoxia).
  
  
  RESULTS
  The standing potential was elevated, and the vitreal ERG c-wave increased in amplitude whereas the b-wave decreased during hypercapnia. Intraretinal recordings showed that the amplitudes of slow PIII and the transepithelial (TEP) c-wave decreased. The slow PIII decreased more than the TEP c-wave. The light-evoked [K+]o decrease also was reduced, but no change was noted in the subretinal [K+]o.
  
  
  CONCLUSIONS
  The neural retina was more sensitive than the retinal pigment epithelium to the intraretinal acidification caused by systemic hypercapnia. However, the change in the SP and b-wave suggested complicated effects other than acidosis.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Kyoto University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hiroi
authors.forename: F
authors.initials: F
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Honda
mesh_terms: D000818:Animals; D002415:Cats; D003623:Dark Adaptation; D004596:Electroretinography; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000503:physiopathology*; D008839:Microelectrodes; D011188:Potassium; D012160:Retina / Q000502:physiology*
chemical_list: D011188:Potassium