Low chloride-dependent release of taurine by a furosemide-sensitive process in the in vivo rat hippocampus.
Extracellular amino acid levels and field potentials evoked by perforant pathway stimuli were studied in vivo by means of a dialysis device, perfusing the rat dentate gyrus with low chloride solutions. When balanced with acetate, these perfusions enhanced the granule cell population spike amplitude. A specific extracellular taurine enhancement occurred whenever Cl- was replaced by acetate solution, reaching an increase of 20-fold over the basal taurine levels when 125 mM Cl- was replaced, whereas other amino acids remained unchanged. A considerable degree of Cl- replacement with iodide was needed, however, to obtain significant increases of extracellular taurine. Perfusions with bromide instead of Cl- did not cause any change in levels of extracellular amino acids including taurine. Furosemide, an inhibitor of Cl- transport, greatly reduced the taurine increase evoked by the low extracellular concentration of permeant anions. This drug also inhibited the taurine release induced by perfusion with 9 mM K+. These findings indicate that the extracellular increase of taurine, evoked by low permeant anion concentrations, may result from the taurine release through a furosemide-sensitive process.
Solis
J M
JM
Departmento Investigación, Hospital Ramón y Cajal, Madrid, Spain.
Herranz
A S
AS
Herreras
O
O
Lerma
J
J
Martin Del Rio
R
R
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002712:Chlorides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005665:Furosemide / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D010477:Perfusion; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013654:Taurine / Q000378:metabolism*
D000596:Amino Acids; D002712:Chlorides; D013654:Taurine; D005665:Furosemide; D011188:Potassium