S100B secretion in acute brain slices: modulation by extracellular levels of Ca(2+) and K (+).
Hippocampal slices have been widely used to investigate electrophysiological and metabolic neuronal parameters, as well as parameters of astroglial activity including protein phosphorylation and glutamate uptake. S100B is an astroglial-derived protein, which extracellularly plays a neurotrophic activity during development and excitotoxic insult. Herein, we characterized S100B secretion in acute hippocampal slices exposed to different concentrations of K(+) and Ca(2+) in the extracellular medium. Absence of Ca(2+) and/or low K(+) (0.2 mM KCl) caused an increase in S100B secretion, possibly by mobilization of internal stores of Ca(2+). In contrast, high K(+) (30 mM KCl) or calcium channel blockers caused a decrease in S100B secretion. This study suggests that exposure of acute hippocampal slices to low- and high-K(+) could be used as an assay to evaluate astrocyte activity by S100B secretion: positively regulated by low K(+) (possibly involving mobilization of internal stores of Ca(2+)) and negatively regulated by high-K(+) (likely secondary to influx of K(+)).
Nardin
Patrícia
P
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos, Porto Alegre, RS, Brazil.
Tortorelli
Lucas
L
Quincozes-Santos
André
A
de Almeida
Lúcia Maria V
LM
Leite
Marina C
MC
Thomazi
Ana Paula
AP
Gottfried
Carmem
C
Wofchuk
Susana T
ST
Donato
Rosario
R
Gonçalves
Carlos-Alberto
CA
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009414:Nerve Growth Factors / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579158:S100b protein, rat; D018698:Glutamic Acid; D014700:Verapamil; D010751:Phosphopyruvate Hydratase; D005978:Glutathione; D011188:Potassium; D002118:Calcium