Barium reverses the transretinal potassium gradient of the amphibian retina.
Barium chloride (Ba2+) was added to the bathing medium of the perfused retina-eyecup preparation of the tiger salamander. The electroretinogram (ERG) and intraretinal extracellular potassium activity ([K+]o) were analyzed using a double-barrel electrode, one of which was ion-selective for K+. The action of Ba2+ on the ERG was to attenuate the c-wave/slow PIII complex. In addition, Ba2+ dramatically decreased the [K+]o in the outer retina, enough to reverse the transretinal potassium gradient. These findings, together with the known properties of Müller cell K+ channels, form the basis of an explanation of why Ba2+ blocks slow PIII and not the b-wave of the ERG.
D000818:Animals; D001464:Barium / Q000494:pharmacology*; D017609:Barium Compounds; D002712:Chlorides; D004596:Electroretinography; D007473:Ion Channels / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012160:Retina / Q000187:drug effects / Q000502:physiology*; D014562:Caudata / Q000502:physiology*
D017609:Barium Compounds; D002712:Chlorides; D007473:Ion Channels; C024986:barium chloride; D001464:Barium; D011188:Potassium