Journal article
Protein Kinase C Modulates Calcium Channels in Isolated Presynaptic Nerve Terminals of Rat Hippocampus
Journal of neurochemistry, Vol.64(5), pp.2064-2072
05/1995
DOI: 10.1046/j.1471-4159.1995.64052064.x
PMID: 7536806
Abstract
: Nerve terminals (“synaptosomes”) isolated from rat brain hippocampus were loaded with the fluorescent Ca2+ indicator fura‐2 and were subjected to depolarization with an elevated K+ concentration in a stopped‐flow spectrophotometer to measure the activity of voltage‐gated Ca2+ channels in the presynaptic membrane. Three components of Ca2+ influx were seen, which were tentatively identified as two classes of voltage‐dependent Ca2+ channels with different inactivation kinetics (τ of ∼60 ms and 1 s, respectively) and Na+/Ca2+ exchange working in the “reverse” mode. The activity of both classes of voltage‐dependent Ca2+ channels was slightly augmented by the phorbol ester phorbol 12‐myristate 13‐acetate (PMA), an activator of protein kinase C (PKC), but the effect of PMA was markedly enhanced by the protein phosphatase inhibitor okadaic acid (OKA). The PKC inhibitors calphostin C and dihydrosphingosine (DHS) caused a prompt decrease in voltage‐dependent Ca2+ channel activity, but the effect of DHS could be showed by coaddition of OKA. These results suggest that the activity of presynaptic voltage‐dependent Ca2+ channels in the hippocampus is under a dynamic balance between PKC phosphorylation (leading to activation) and protein phosphatase dephosphorylation (leading to inactivation) and that both of these metabolic pathways are tonically active in the nerve terminals.
Details
- Title: Subtitle
- Protein Kinase C Modulates Calcium Channels in Isolated Presynaptic Nerve Terminals of Rat Hippocampus
- Creators
- D. K BartschatTroy E Rhodes
- Resource Type
- Journal article
- Publication Details
- Journal of neurochemistry, Vol.64(5), pp.2064-2072
- Publisher
- Blackwell Science Ltd
- DOI
- 10.1046/j.1471-4159.1995.64052064.x
- PMID
- 7536806
- ISSN
- 0022-3042
- eISSN
- 1471-4159
- Language
- English
- Date published
- 05/1995
- Academic Unit
- Cardiovascular Medicine; Internal Medicine
- Record Identifier
- 9984094716902771
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