title: Differential expression and distribution of Kir5.1 and Kir4.1 inwardly rectifying K+ channels in retina.
abstract: Kir5.1 is an inwardly rectifying K+ channel subunit whose functional role has not been fully elucidated. Expression and distribution of Kir5.1 in retina were examined with a specific polyclonal antibody. Kir5.1 immunoreactivity was detected in glial Müller cells and in some retinal neurons. In the Kir5.1-positive neurons the expression of glutamic acid decarboxylase (GAD65) was detected, suggesting that they may be GABAergic-amacrine cells. In Müller cells, spots of Kir5.1 immunoreactivity distributed diffusely at the cell body and in the distal portions, where Kir4.1 immunoreactivity largely overlapped. In addition, Kir4.1 immunoreactivity without Kir5.1 was strongly concentrated at the endfoot of Müller cells facing the vitreous surface or in the processes surrounding vessels. The immunoprecipitant obtained from retina with anti-Kir4.1 antibody contained Kir5.1. These results suggest that heterotetrameric Kir4.1/Kir5.1 channels may exist in the cell body and distal portion of Müller cells, whereas homomeric Kir4.1 channels are clustered in the endfeet and surrounding vessels. It is possible that homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels play different functional roles in the K+-buffering action of Müller cells.
authors.affiliation: Department of Pharmacology II, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Ishii
authors.forename: Akikazu
authors.initials: A
authors.lastname: Fujita
authors.forename: Kaori
authors.initials: K
authors.lastname: Iwai
authors.forename: Shunji
authors.initials: S
authors.lastname: Kusaka
authors.forename: Kayoko
authors.initials: K
authors.lastname: Higashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Inanobe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hibino
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Kurachi
mesh_terms: D025042:Amacrine Cells / Q000166:cytology / Q000378:metabolism; D000818:Animals; D002196:Capillaries / Q000166:cytology / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D024661:Potassium Channels, Inwardly Rectifying; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2; D011188:Potassium