Betaine is an osmolyte in RAW 264.7 mouse macrophages.
Hyperosmotic (405 mosmol/l) exposure of RAW 264.7 mouse macrophages led to a stimulation of betaine uptake and an increase in betaine transporter (BGT-1) mRNA levels. Conversely, hypoosmotic (205 mosmol/l) exposure decreased betaine uptake and diminished BGT-1 mRNA levels. Betaine uptake was Na(+)-dependent and was inhibited by about 90% by GABA, whereas inhibition by methylaminoisobutyrate and myoinositol was less than 15%. Addition of betaine strongly diminished BGT-1 mRNA levels in cells exposed to normoosmotic or hyperosmotic media. When mouse macrophages were preloaded with betaine, lowering of the extracellular osmolarity was followed by a rapid betaine efflux from the cells. This study identifies a constitutively expressed and osmosensitive betaine transporter in RAW 264.7 macrophages and the use of betaine as an osmolyte in these cells.
Warskulat
U
U
Medizinische Universitätsklinik, Heinrich-Heine-Universität, Düsseldorf, Germany.
Wettstein
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M
Häussinger
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D
D000621:Aminoisobutyric Acids / Q000494:pharmacology; D000818:Animals; D001622:Betaine / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics; D002460:Cell Line; D002712:Chlorides / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology; D050485:GABA Plasma Membrane Transport Proteins; D007294:Inositol / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000378:metabolism; D012964:Sodium / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000621:Aminoisobutyric Acids; D002352:Carrier Proteins; D002712:Chlorides; D050485:GABA Plasma Membrane Transport Proteins; D012333:RNA, Messenger; C072207:betaine plasma membrane transport proteins; C017911:2-(methylamino)isobutyric acid; D001622:Betaine; D007294:Inositol; D005680:gamma-Aminobutyric Acid; D008094:Lithium; D012964:Sodium; D002794:Choline