Effects of high-potassium-induced depolarization on amino acid chemistry of the dorsal cochlear nucleus in rat brain slices.
High K+ was used to depolarize glia and neurons in order to study the effects on amino acid release from and concentrations within the dorsal cochlear nucleus (DCN) of brain slices. The release of glutamate, gamma-aminobutyrate (GABA) and glycine increased significantly during exposure to 50 mM K+, while glutamine and serine release decreased significantly during and/or after exposure, respectively. After 10 min of exposure to 50 mM K+, glutamine concentrations increased in all three layers of DCN slices, to more than 5 times the values in unexposed slices. In the presence of a glutamate uptake blocker, L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC), glutamine concentrations in all layers did not increase as much during 50 mM K+. Similar but smaller changes occurred for serine. Mean ATP concentrations were lower in 50 mM K(+)-exposed slices compared to control. The results suggest that depolarization, such as during increased neural activity, can greatly affect amino acid metabolism in the cochlear nucleus.
Zheng
L
L
Department of Otolaryngology, Head and Neck Surgery, Medical College of Ohio, Toledo 43614, USA. dgodfrey@mco.edu
Godfrey
D A
DA
Waller
H J
HJ
Godfrey
T G
TG
Chen
K
K
Sun
Y
Y
D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000008:administration & dosage; D017626:Cochlear Nucleus / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D011188:Potassium / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000596:Amino Acids; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D011188:Potassium; D002118:Calcium