Increased aquaporin-4 expression in ammonia-treated cultured astrocytes.
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.
Rama Rao
K V
KV
Department of Pathology, University of Miami School of Medicine, FL 33101, USA.
Chen
M
M
Simard
J M
JM
Norenberg
M D
MD
D000641:Ammonia / Q000494:pharmacology*; D000818:Animals; D051401:Aquaporin 4; D020346:Aquaporins / Q000096:biosynthesis* / Q000235:genetics; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D013997:Time Factors
C496032:Aqp4 protein, rat; D051401:Aquaporin 4; D020346:Aquaporins; D000641:Ammonia