Direct immunogold labeling of aquaporin-4 in square arrays of astrocyte and ependymocyte plasma membranes in rat brain and spinal cord

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dc.contributor.author Nielsen, S
dc.contributor.author Agre, P
dc.contributor.author Hudson, C S
dc.contributor.author Yasumura, T
dc.contributor.author Rash, J E
dc.date.accessioned 2010-03-10T21:58:49Z
dc.date.available 2010-03-10T21:58:49Z
dc.date.issued 1998-09-29
dc.identifier.citation Proc Natl Acad Sci U S A. 1998 Sep 29;95(20):11981-6. http://www.pnas.org/content/95/20/11981.full en
dc.identifier.uri http://jhir.library.jhu.edu/handle/1774.2/33958
dc.description.abstract Aquaporin (AQP) water channels are abundant in the brain and spinal cord, where AQP1 and AQP4 are believed to play major roles in water metabolism and osmoregulation. Immunocytochemical analysis of the brain recently revealed that AQP4 has a highly polarized distribution, with marked expression in astrocyte end-feet that surround capillaries and form the glia limitans; however, the structural organization of AQP4 has remained unknown. In freeze-fracture replicas, astrocyte end-feet contain abundant square arrays of intramembrane particles that parallel the distribution of AQP4. To determine whether astrocyte and ependymocyte square arrays contain AQP4, we employed immunogold labeling of SDS-washed freeze-fracture replicas and stereoscopic confirmation of tissue binding. Antibodies to AQP4 directly labeled approximately 33% of square arrays in astrocyte and ependymocyte plasma membranes in rat brain and spinal cord. Overall, 84% of labels were present beneath square arrays; 11% were beneath particle clusters that resembled square arrays that had been altered during fixation or cleaving; and 5% were beneath the much larger areas of glial plasma membrane that were devoid of square arrays. Based on this evidence that AQP4 is concentrated in glial square arrays, freeze-fracture methods may now provide biophysical insights regarding neuropathological states in which abnormal fluid shifts are accompanied by alterations in the aggregation state or the molecular architecture of square arrays. en
dc.description.provenance Submitted by Janice Chen (janice.chen@jhu.edu) on 2010-03-10T19:31:47Z No. of bitstreams: 1 PNAS-1998-Rash-11981-6.pdf: 802758 bytes, checksum: 589ee1677ab66107f850fa1d367e101f (MD5) en
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dc.description.provenance Made available in DSpace on 2010-03-10T21:58:49Z (GMT). No. of bitstreams: 1 PNAS-1998-Rash-11981-6.pdf: 802758 bytes, checksum: 589ee1677ab66107f850fa1d367e101f (MD5) Previous issue date: 1998-09-29 en
dc.language.iso en_US en
dc.publisher National Academy of Sciences en
dc.subject Spinal Cord/metabolism en
dc.subject Ion Channels/metabolism en
dc.subject Brain/metabolism en
dc.subject Astrocytes/metabolism en
dc.subject Aquaporins en
dc.title Direct immunogold labeling of aquaporin-4 in square arrays of astrocyte and ependymocyte plasma membranes in rat brain and spinal cord en
dc.type Article en

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