Calcium channels in rat brain synaptosomes: identification and pharmacological characterization. High affinity blockade by organic Ca2+ channel blockers

TJ Turner, SM Goldin
1985 Journal of Neuroscience  
Rat brain synaptosomes are shown to contain functional voltage-sensitive Ca*+ channels that are inhibited by organic Ca*+ channel blockers. Depolarization of synaptosomes with high K+ stimulates uptake of 45Ca2+ which is biphasic in its time course. Replacement of external Na+ with choline eliminates the slower phase of depolarization-stimulated Ca*+ uptake, leaving only a rapid uptake process which terminates within 1 sec. This rapid, tetrodotoxin-insensitive Ca*+ uptake can be inactivated by
more » ... be inactivated by prior depolarization of the synaptosomes. Depolarization has no effect on the rate of synaptosomal **Na+ efflux. These results are interpreted as ruling out Na+/Ca*+ exchange as a mediator of the rapid phase of depolarization-stimulated Ca*+ uptake. A portion (30 to 50%) of the rapid phase of depolarizationstimulated Ca*+ uptake is inhibited by nitrendipine, as is depolarization-stimulated
doi:10.1523/jneurosci.05-03-00841.1985 pmid:2579220 fatcat:7fqayjjpd5ge7dyr37op7andp4