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Immunogold evidence suggests that coupling of K + siphoning and water transport in rat retinal Müller cells is mediated by a coenrichment of Kir4.1 and AQP4 in specific membrane domains
Author(s) -
Nagelhus Erlend A.,
Horio Yoshiyuki,
Inanobe Atsushi,
Fujita Akikazu,
Haug Finnm.,
Nielsen Søren,
Kurachi Yoshihisa,
Ottersen Ole Petter
Publication year - 1999
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199903)26:1<47::aid-glia5>3.0.co;2-5
Subject(s) - immunogold labelling , biology , aquaporin , microbiology and biotechnology , retina , aquaporin 4 , biophysics , retinal , extracellular , water transport , biochemistry , anatomy , ultrastructure , neuroscience , water flow , environmental engineering , engineering
Postembedding immunogold labeling was used to examine the subcellular distribution of the inwardly rectifying K + channel Kir4.1 in rat retinal Müller cells and to compare this with the distribution of the water channel aquaporin‐4 (AQP4). The quantitative analysis suggested that both molecules are enriched in those plasma membrane domains that face the vitreous body and blood vessels. In addition, Kir4.1, but not AQP4, was concentrated in the basal ∼300–400 nm of the Müller cell microvilli. These data indicate that AQP4 may mediate the water flux known to be associated with K + siphoning in the retina. By its highly differentiated distribution of AQP4, the Müller cell may be able to direct the water flux to select extracellular compartments while protecting others (the subretinal space) from inappropriate volume changes. The identification of specialized membrane domains with high Kir4.1 expression provides a morphological correlate for the heterogeneous K + conductance along the Müller cell surface. GLIA 26:47–54, 1999. © 1999 Wiley‐Liss, Inc.