Increased aquaporin-4 expression in ammonia-treated... : NeuroReport (original) (raw)
GLIAL CELLS
Increased aquaporin-4 expression in ammonia-treated cultured astrocytes
Rama Rao, K. V.1; Chen, M.2; Simard, J. M.2; Norenberg, M. D.1 3 4 CA
1Departments of Pathology
3Biochemistry and Molecular Biology, University of Miami School of Medicine, P.O. Box 016960, Miami, FL 33101
4Veterans Affairs Medical Center, Miami
2Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
CA,1Corresponding Author and Address: [email protected]
Received 7 August 2003; accepted 20 September 2003
Abstract
Brain edema is a serious complication of hepatic encephalopathy associated with fulminant hepatic failure (FHF). Factors responsible for such swelling are not clear, but ammonia, a toxin strongly implicated in FHF, is known to induce astrocyte swelling. The mechanism(s) responsible for ammonia-induced swelling, however, are not known. Aquaporins are plasma membrane proteins that mediate transmembrane water movement. To investigate the potential role of aquaporins in astrocyte swelling, we measured aquaporin-4 (AQP-4) protein expression in cultured astrocytes exposed to 5 mM NH4Cl. AQP-4 levels significantly increased 10 h after treatment with ammonia, and displayed a progressive rise up to 48 h, which appeared to precede the onset of astrocyte swelling. AQP-4 may be involved in the astrocyte swelling associated with hyperammonemic states.
© 2003 Lippincott Williams & Wilkins, Inc.