Furosemide- and bumetanide-sensitive ion transport and volume control in primary astrocyte cultures from rat brain.
K+ and Cl- transport using 42K+ and 36Cl- was studied in primary astrocyte cultures prepared from neonatal rat brains. A component of 42K+ uptake was sensitive to both furosemide and bumetanide with maximum inhibition being obtained at 1 and 0.01 mM concentrations of the inhibitors, respectively. Furosemide and bumetanide also markedly inhibited uptake of 36Cl-. 42K+ uptake in the presence of ouabain was also sensitive to the omission of medium Na+ and Cl-. These results suggest the existence of a K+ + Na+ + Cl- cotransport system in astrocyte cultures which in many cells has been shown to be involved in volume regulation. We studied volume changes using uptake of [14C]3-O- methyl-D-glucose ([14C]3-OMG), and also ion transport, in attached cells in response to exposure to hyper- or hypotonic medium. Exposure to medium made hypertonic with mannitol resulted in shrinkage of the [14C]3-OMG space of the cells, but did not affect 36Cl- content, expressed as nmol/mg protein. Exposure to hypotonic medium led to a marked increase in the [14C]3-OMG space, rapidly followed by a decrease towards control values. After the cells were then exposed to isotonic medium there was an immediate decrease followed by a slower increase in the [14C]3-OMG space. The increase in the [14C]3-OMG space was partially inhibited by 1 mM furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)
D019325:3-O-Methylglucose; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D004232:Diuretics / Q000494:pharmacology*; D005665:Furosemide / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D008757:Methylglucosides / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002712:Chlorides; D004232:Diuretics; D008757:Methylglucosides; D002034:Bumetanide; D019325:3-O-Methylglucose; D010042:Ouabain; D005665:Furosemide; D005947:Glucose; D011188:Potassium