Simultaneous Measurement of Nitrite and Nitrate Levels as Indices of Nitric Oxide Release in the Cerebellum of Conscious Rats |
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Authors: | Kiyofumi Yamada Toshitaka Nabeshima |
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Affiliation: | Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University School of Medicine, Nagoya, Japan |
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Abstract: | Abstract: We examined the modulation of nitric oxide production in vivo by measuring levels of nitrite (NO2−) and nitrate (NO3−) in the dialysate of the cerebellum in conscious rats, by using an in vivo brain microdialysis technique. The levels of both NO2− and NO3− were decreased by the intraperitoneal injection of N G-nitro- l -arginine methyl ester, an inhibitor of nitric oxide synthase, whereas N G-nitro- d -arginine methyl ester had no effect. l -Arginine by itself increased NO2− and NO3− levels and diminished the reduction of their levels caused by N G-nitro- l -arginine methyl ester. Direct infusion of l -glutamate, N -methyl- d -aspartate, or KCl into the cerebellum through a dialysis probe resulted in an increase in NO2− and/or NO3− levels. The effects of N -methyl- d -aspartate and KCl were dependent on extracellular calcium. Furthermore, the stimulatory effects of l -glutamate and N -methyl- d -aspartate were inhibited by N G-nitro- l -arginine methyl ester and (±)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP), an N -methyl- d -aspartate receptor antagonist. These results suggest that NO2− and NO3− levels may be related to nitric oxide production in vivo. |
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Keywords: | Nitric oxide N G-Nitro-l-arginine methyl ester l-Arginine NMDA receptors In vivo brain microdialysis Cerebellum |
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