K+ Channel density increases selectively in the endfoot of retinal glial cells during development of Rana catesbiana.
Glia
; 25(2): 199-203, 1999 Jan 15.
Article
em En
| MEDLINE
| ID: mdl-9890634
The radial glial cells that span the retina, described by Müller in 1851, have a remarkable distribution of ion channels in adult amphibia that mediate extracellular K+ spatial buffering. 94% of the total membrane conductance of these cells resides in inward rectifier K+ channels in the endfoot processes apposed to the vitreous humour. We now report that this regional specialization is found in Müller cells isolated from adult (>120 day old) bullfrogs but to a far less extent in those from 10-20 day old tadpoles (stages 34-36). Using the cell attached configuration of the patch-clamp technique, we found, in agreement with previous studies in salamanders, that the endfoot of adult cells had 19.2+/-2.4 (mean +/- S.E., n = 81) channels/patch, whereas the soma had 1.81+/-0.28 (n = 21) channels/patch. In the tadpole, the respective values were 4.29+/-0.26 (n = 79) for the endfoot and 2.26+/-0.24 (n = 27) for the soma. The slope conductance of the inward rectifier K+ channel in 115 mM K+, 19.2+/-0.25 pS (n = 205), channel kinetics and the resting membrane potential (-69+/-2.7 mV, n = 224) were similar at both the endfoot and soma of both adults and embryos. We conclude that during development, the K+ conductance of the Müller cell endfoot, but not of the soma, increases due to a selective clustering of inwardly rectifying K+ channels in that specific region of the cell membrane. The properties of the channels change little during the transformation from tadpole to adult bullfrog.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Retina
/
Canais de Potássio
/
Neuroglia
Limite:
Animals
Idioma:
En
Revista:
Glia
Assunto da revista:
NEUROLOGIA
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Porto Rico
País de publicação:
Estados Unidos