Synaptosomal calcium influx is activated by sodium fluoride.
Neuronal calcium channels can be modulated by changes in membrane potential or by activation of channel-associated receptors. The latter may be modulated by guanine nucleotide binding proteins. NaF, which activates guanine nucleotide binding proteins, caused a large stimulation of 45Ca2+ uptake by synaptosomes prepared from rat brain. Stimulation of 45Ca2+ influx by NaF (i) was apparent in media containing either 5 mM-K+ or 50 mM-K+, (ii) was slower than the fast-phase of voltage-dependent 45Ca2+ influx but continued for a longer period of time than did depolarization-induced 45Ca2+ influx, and (iii) was not mimicked or modified by a number of drugs, including ouabain, dinitrophenol, sodium azide or sodium vanadate. These results are consistent with the hypothesis that NaF activates a guanine nucleotide binding protein associated with receptor-coupled calcium channels, resulting in stimulation of calcium influx.
D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012969:Sodium Fluoride / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D002132:Calcium Radioisotopes; D007473:Ion Channels; D012969:Sodium Fluoride; D011188:Potassium; D002118:Calcium