Presynaptic Calcium Currents and their Relation to Synaptic Transmission: Voltage Clamp Study in Squid Giant Synapse and Theoretical Model for the Calcium Gate
Abstract
A voltage clamp study of the presynaptic terminal in squid stellate ganglion has given quantitative results relating inward Ca2+ current to presynaptic membrane potential and postsynaptic response to inward Ca2+ current. The results indicate an S-shaped curve for the relationship between presynaptic potential and Ca2+ current and a linear relationship between Ca2+ current and postsynaptic potential. A similar S-shaped curve was found for the time-dependent properties of the Ca2+ conductance. Based on these results a mathematical model was developed which accounts for the experimental results in this and previously published papers by other authors. The model suggests that five subunits are involved in the Ca2+ gate and that the subunits change noncooperatively from an inactive to an active form upon membrane depolarization.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- August 1976
- DOI:
- 10.1073/pnas.73.8.2918
- Bibcode:
- 1976PNAS...73.2918L