Inhibition of high K+-evoked gamma-aminobutyric acid release by sodium nitroprusside in rat hippocampus.
To clarify whether nitric oxide (NO) modifies high K(+)-evoked gamma-aminobutyric acid (GABA) release, we examined the effects of sodium nitroprusside, an NO donor; diethyldithiocarbamate, an NO trapper; dithiothreitol, a superoxide radical scavenger; and 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one, a specific guanylyl cyclase inhibitor, on high (100 mM) K(+)-evoked GABA release from rat hippocampus in vivo using microdialysis. Perfusion with 0.5 or 5 mM sodium nitroprusside significantly reduced high K(+)-evoked GABA release. Co-perfusion with 0.5 mM sodium nitroprusside and 5 mM diethyldithiocarbamate or 0.5 mM 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one significantly enhanced high K(+)-evoked GABA release. Co-perfusion with 0.5 mM sodium nitroprusside and 1 mM dithiothreitol tended to increase it. These results demonstrate that sodium nitroprusside reduces high K(+)-evoked GABA release both via an NO/cyclic GMP-dependent pathway and via an NO-dependent, but cyclic GMP-independent, pathway in rat hippocampus in vivo.
Hada
Junichi
J
Department of Medical Physics and Chemistry, Hyogo College of Medicine, 1-1, Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan. jhada@hyo-med.ac.jp
Kaku
Tomohiro
T
Jiang
Min Hai
MH
Morimoto
Kazuyoshi
K
Hayashi
Yasamasa
Y
D000818:Animals; D004229:Dithiothreitol / Q000494:pharmacology; D004050:Ditiocarb / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D010069:Oxadiazoles / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D016166:Free Radical Scavengers; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D011810:Quinoxalines; D009599:Nitroprusside; D009569:Nitric Oxide; D005680:gamma-Aminobutyric Acid; D004050:Ditiocarb; D006162:Guanylate Cyclase; D011188:Potassium; D004229:Dithiothreitol