Rabbit retinal neurons and glia express a variety of ENaC/DEG subunits.
Some members of the epithelial Na+ channel/degenerin (ENaC/DEG) family of ion channels have been detected in mammalian brain. Therefore, we examined the RNA and protein expression of these channels in another part of the central nervous system, the rabbit retina. We next sought to demonstrate physiological evidence for an amiloride-sensitive current in Müller glia, which, on the basis of a previous study, are thought to express alpha-ENaC (Golestaneh N, de Kozak Y, Klein C, and Mirshahi M. Glia 33: 160-168, 2001). RT-PCR of retinal RNA revealed the presence of alpha-, beta-, gamma-, and delta-ENaC as well as acid-sensing ion channel (ASIC)1, ASIC2, ASIC3, and ASIC4. Immunohistochemical localization with antibodies against alpha-ENaC and beta-ENaC showed labeling in Müller cells and neurons, respectively. The presence of alpha-ENaC, beta-ENaC, and ASIC1 was detected by Western blotting. Cultured Müller cells were whole cell patch clamped. These cells exhibited an inward Na+ current that was blocked by amiloride. These data demonstrate for the first time both the expression of a variety of ENaC and ASIC subunits in the rabbit retina as well as distinct cellular expression patterns of specific subunits in neurons and glia.
Brockway
L M
LM
Vision Science Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. brockwaylm@cs.com
Zhou
Z-H
ZH
Bubien
J K
JK
Jovov
B
B
Benos
D J
DJ
Keyser
K T
KT
D062565:Acid Sensing Ion Channels; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D062626:Degenerin Sodium Channels; D004285:Dogs; D004553:Electric Conductivity; D053503:Epithelial Sodium Channels; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009457:Neuroglia / Q000378:metabolism* / Q000502:physiology; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*
C568266:ASIC1 protein, human; C568424:ASIC2 protein, human; C112231:ASIC3 protein, human; C568270:ASIC4 protein, human; D062565:Acid Sensing Ion Channels; D062626:Degenerin Sodium Channels; D053503:Epithelial Sodium Channels; D007473:Ion Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D015222:Sodium Channels