Linked Life Data

10417816

Source:http://linkedlifedata.com/resource/pubmed/id/10417816

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1999-12-9
pubmed:abstractText
Müller (radial glial) cells span the retina from the outer to the inner limiting membranes. They are the only glial cells found in the amphibian retina. The thickness of the frog (Rana pipiens) retina decreases by a factor of about four from the center to the periphery. Thus, Müller cells were isolated, by enzymatic dissociation, with stalk lengths from 20 to 140 microm. Their ability to transfer K(+) via the stalk between soma and endfoot was studied. Membrane currents were recorded using the whole-cell voltage-clamp technique with the pipette sealed to either the endfoot or the soma. Inward (I(KIN)) or outward (I(KO)) currents were elicited by rapid increases (3 to 10 mM) or decreases (3 to 1 mM) of the extracellular K(+) concentration ([K(+)](o)) either by local application (close or distant to the recording pipette) or around the entire cell (whole cell perfusion). For the long central cells, the ratio I(KIN)/I(KO) was 4.6 +/- 0.6 SE (n = 9) at the endfoot and 1.7 +/- 0.1 SE (n = 8) at the soma. In cells from the retinal periphery, the ratio I(KIN)/I(KO) was higher, 7.0 +/- 0.27 (n = 8) at the endfoot and 3.2 +/- 0.1 (n = 10) at the soma. The results suggest that there is less inward rectification in the somatic than in the endfoot membrane. As expected from previous studies, the sensitivity of the cells to K(+) was higher at the endfoot than at the soma. The amplitude of I(KIN) at the endfoot compared to the soma was about 8-fold for the long central cells but only about 1.5-fold for the short peripheral cells. Currents spread readily from endfoot to soma in the peripheral cells. In the long central Müller cells the soma and endfoot appeared electrotonically isolated. The "functional length constant", lambda, of cell stalk processes was about 70 microm. The relative decrement of large inward currents was stronger than that of smaller outward currents; this difference ("artificial rectification") is explained by a simple model, where larger currents (inward) are attenuated more than smaller (outward) currents. The data support the hypothesis that in the retinal periphery, Müller cells provide extensive spatial K(+) buffering from both plexiform layers into the vitreous body. In the central retina, however, such currents are limited within a short (interlaminar) range.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0894-1491
pubmed:author
pubmed:copyrightInfo
Copyright 1999 Wiley-Liss, Inc.
pubmed:issnType
Print
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
171-80
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Potassium buffering by Müller cells isolated from the center and periphery of the frog retina.
pubmed:affiliation
CMBN, Department of Biochemistry, School of Medicine, Central Caribbean University, Bayamon, Puerto Rico, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't