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Nitroprusside and Cyclic GMP Stimulate Na + ‐Ca 2+ Exchange Activity in Neuronal Preparations and Cultured Rat Astrocytes
Author(s) -
Asano Shoichi,
Matsuda Toshio,
Takuma Kazuhiro,
Kim Hye Sun,
Sato Tomoaki,
Nishikawa Takashige,
Baba Akemichi
Publication year - 1995
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1995.64062437.x
Subject(s) - monensin , sodium nitroprusside , ouabain , chemistry , nitric oxide , biophysics , medicine , synaptic vesicle , endocrinology , biochemistry , vesicle , sodium , biology , membrane , organic chemistry
The effects of nitric oxide (NO)‐generating agents on 45 Ca 2+ uptake in rat brain slices and cultured rat astrocytes were studied in the presence of monensin, which is considered to drive the Na + ‐Ca 2+ exchanger in the reverse mode. Sodium nitroprusside (SNP) at >10 µ M increased monensin‐stimulated Ca 2+ uptake in the slices, although it did not affect high K + ‐stimulated Ca 2+ uptake. Another NO donor, 3‐morpholinosydnonimine, was effective. The effect of SNP was antagonized by hemoglobin (50 µ M ), a NO scavenger, and mimicked by 8‐bromo‐cyclic GMP (100 µ M ). In rat brain synaptosomes, SNP increased monensin‐stimulated Ca 2+ uptake, but it did not affect high K + ‐stimulated Ca 2+ uptake. 8‐Bromocyclic GMP, but not SNP, increased Na + ‐dependent Ca 2+ uptake significantly in synaptic membrane vesicles in the absence of monensin. In cultured rat astrocytes, SNP and 8‐bromo‐cyclic GMP increased Ca 2+ uptake in the presence of ouabain and monensin, which were required for the Ca 2+ uptake in the cells. These findings suggest that NO stimulates the Na + ‐Ca 2+ exchanger in neuronal preparations and astrocytes in a cyclic GMP‐dependent mechanism.